Desirable Traits of a Good Biocontrol Agent against Verticillium Wilt.

PubMed

Deketelaere, Silke; Tyvaert, Lien; França, Soraya C; Höfte, Monica

2017-01-01

The soil-borne fungus Verticillium causes serious vascular disease in a wide variety of annual crops and woody perennials. Verticillium wilt is notoriously difficult to control by conventional methods, so there is great potential for biocontrol to manage this disease. In this study we aimed to review the research about Verticillium biocontrol to get a better understanding of characteristics that are desirable in a biocontrol agent (BCA) against Verticillium wilt. We only considered studies in which the BCAs were tested on plants. Most biocontrol studies were focused on plants of the Solanaceae, Malvaceae , and Brassicaceae and within these families eggplant, cotton, and oilseed rape were the most studied crops. The list of bacterial BCAs with potential against Verticillium was dominated by endophytic Bacillus and Pseudomonas isolates, while non-pathogenic xylem-colonizing Verticillium and Fusarium isolates topped the fungal list. Predominant modes of action involved in biocontrol were inhibition of primary inoculum germination, plant growth promotion, competition and induced resistance. Many BCAs showed in vitro antibiosis and mycoparasitism but these traits were not correlated with activity in vivo and there is no evidence that they play a role in planta . Good BCAs were obtained from soils suppressive to Verticillium wilt, disease suppressive composts, and healthy plants in infested fields. Desirable characteristics in a BCA against Verticillium are the ability to (1) affect the survival or germination of microsclerotia, (2) colonize the xylem and/or cortex and compete with the pathogen for nutrients and/or space, (3) induce resistance responses in the plant and/or (4) promote plant growth. Potential BCAs should be screened in conditions that resemble the field situation to increase the chance of successful use in practice. Furthermore, issues such as large scale production, formulation, preservation conditions, shelf life, and application methods should be

Desirable Traits of a Good Biocontrol Agent against Verticillium Wilt

PubMed Central

Deketelaere, Silke; Tyvaert, Lien; França, Soraya C.; Höfte, Monica

2017-01-01

The soil-borne fungus Verticillium causes serious vascular disease in a wide variety of annual crops and woody perennials. Verticillium wilt is notoriously difficult to control by conventional methods, so there is great potential for biocontrol to manage this disease. In this study we aimed to review the research about Verticillium biocontrol to get a better understanding of characteristics that are desirable in a biocontrol agent (BCA) against Verticillium wilt. We only considered studies in which the BCAs were tested on plants. Most biocontrol studies were focused on plants of the Solanaceae, Malvaceae, and Brassicaceae and within these families eggplant, cotton, and oilseed rape were the most studied crops. The list of bacterial BCAs with potential against Verticillium was dominated by endophytic Bacillus and Pseudomonas isolates, while non-pathogenic xylem-colonizing Verticillium and Fusarium isolates topped the fungal list. Predominant modes of action involved in biocontrol were inhibition of primary inoculum germination, plant growth promotion, competition and induced resistance. Many BCAs showed in vitro antibiosis and mycoparasitism but these traits were not correlated with activity in vivo and there is no evidence that they play a role in planta. Good BCAs were obtained from soils suppressive to Verticillium wilt, disease suppressive composts, and healthy plants in infested fields. Desirable characteristics in a BCA against Verticillium are the ability to (1) affect the survival or germination of microsclerotia, (2) colonize the xylem and/or cortex and compete with the pathogen for nutrients and/or space, (3) induce resistance responses in the plant and/or (4) promote plant growth. Potential BCAs should be screened in conditions that resemble the field situation to increase the chance of successful use in practice. Furthermore, issues such as large scale production, formulation, preservation conditions, shelf life, and application methods should be

Methods for the Evaluation of the Bioactivity and Biocontrol Potential of Species of Trichoderma.

PubMed

Steyaert, Johanna; Hicks, Emily; Kandula, Janaki; Kandula, Diwakar; Alizadeh, Hossein; Braithwaite, Mark; Yardley, Jessica; Mendoza-Mendoza, Artemio; Stewart, Alison

2016-01-01

Members of the genus Trichoderma comprise the majority of commercial fungal biocontrol agents of plant diseases. As such, there is a wealth of information available on the analysis of their biocontrol potential and the mechanisms behind their superior abilities. This chapter aims to summarize the most common methods utilized within a Trichoderma biocontrol program for assessing the biological properties of individual strains.

A numerical study of combined use of two biocontrol agents with different biocontrol mechanisms in controlling foliar pathogens.

PubMed

Xu, X-M; Jeffries, P; Pautasso, M; Jeger, M J

2011-09-01

Effective use of biocontrol agents is an important component of sustainable agriculture. A previous numerical study of a generic model showed that biocontrol efficacy was greatest for a single biocontrol agent (BCA) combining competition with mycoparasitism or antibiosis. This study uses the same mathematical model to investigate whether the biocontrol efficacy of combined use of two BCAs with different biocontrol mechanisms is greater than that of a single BCA with either or both of the two mechanisms, assuming that two BCAs occupy the same host tissue as the pathogen. Within the parameter values considered, a BCA with two biocontrol mechanisms always outperformed the combined use of two BCAs with a single but different biocontrol mechanism. Similarly, combined use of two BCAs with a single but different biocontrol mechanism is shown to be far less effective than that of a single BCA with both mechanisms. Disease suppression from combined use of two BCAs was very similar to that achieved by the more efficacious one. As expected, a higher BCA introduction rate led to increased disease suppression. Incorporation of interactions between two BCAs did not greatly affect the disease dynamics except when a mycoparasitic and, to a lesser extent, an antibiotic-producing BCA was involved. Increasing the competitiveness of a mycoparasitic BCA over a BCA whose biocontrol mechanism is either competition or antibiosis may lead to improved biocontrol initially and reduced fluctuations in disease dynamics. The present study suggests that, under the model assumptions, combined use of two BCAs with different biocontrol mechanisms in most cases only results in control efficacies similar to using the more efficacious one alone. These predictions are consistent with published experimental results, suggesting that combined use of BCAs should not be recommended without clear understanding of their main biocontrol mechanisms and relative competitiveness, and experimental evaluation.

Impact of climate change environmental conditions on the resilience of different formulations of the biocontrol agent Candida sake CPA-1 on grapes.

PubMed

Carbó, A; Torres, R; Teixidó, N; Usall, J; Medina, A; Magan, N

2018-07-01

Biocontrol agents have become components of integrated crop protection systems for controlling economically important fungal pathogens. Candida sake CPA-1 is a biocontrol agent of fungal pathogens of fruits, both pre- and post-harvest. While the efficacy of different formulations have been examined previously, few studies have considered the resilience of different formulations under changing climatic conditions of elevated temperature, drought stress and increased atmospheric CO 2 . This study examined the effect of (a) temperature × RH × elevated CO 2 (400 vs 1000 ppm) on the temporal establishment and viability of two dry and one liquid C. sake CPA-1 formulations on grape berry surfaces; (b) temperature stress (25 vs 35°C); and (c) elevated CO 2 levels. Results indicated that temperature, RH and CO 2 concentration influenced the establishment and viability of the formulations but there was no significant difference between formulations. For the combined three-component factors, increased temperature (35°C) and lower RH (40%) reduced the viable populations on grapes. The interaction with elevated CO 2 improved the establishment of viable populations of the formulations tested. Viable populations greater than Log 4 CFUs per g were recovered from the grape surfaces suggesting that these had conserved resilience for control of Botrytis rot in grapes. The interaction between environmental factors that are expected to occur in response to climate change (CC) will have a significant impact on food security and availability. Little information exists on how elevated temperature, drought stress and increased CO 2 will have on the efficacy of biocontrol agents. The impact of these factors on the viability of different formulations of the biocontrol yeast Candida sake on the surface of grapes berries was evaluated for the first time. Such knowledge is critical for projecting the efficacy of biocontrol under climate change conditions and to identify formulations

Proliferation of the biocontrol agent Fusarium oxysporum f. sp. strigae and its impact on indigenous rhizosphere fungal communities in maize under different agro-ecologies.

PubMed

Zimmermann, Judith; Musyoki, Mary K; Cadisch, Georg; Rasche, Frank

2016-06-01

Our objectives were to (1) monitor the proliferation of the biocontrol agent (BCA) Fusarium oxysporum f. sp. strigae strain "Foxy-2", an effective soil-borne BCA against the parasitic weed Striga hermonthica , in the rhizosphere of maize under different agro-ecologies, and (2) investigate its impact on indigenous rhizosphere fungal community abundance and composition. Field experiments were conducted in Busia and Homa Bay districts in western Kenya during two cropping seasons to account for effects of soil type, climate, growth stage and seasonality. Maize seeds were coated with or without "Foxy-2" and soils were artificially infested with S. hermonthica seeds. One treatment with nitrogen rich organic residues ( Tithonia diversifolia ) was established to compensate hypothesized resource competition between "Foxy-2" and the indigenous fungal community. Rhizosphere soil samples collected at three growth stages (i.e., EC30, EC60, EC90) of maize were subjected to abundance measurement of "Foxy-2" and total indigenous fungi using quantitative polymerase chain reaction (qPCR) analysis. Terminal restriction fragment length polymorphism (TRFLP) analysis was used to assess potential alterations in the fungal community composition in response to "Foxy-2" presence. "Foxy-2" proliferated stronger in the soils with a sandy clay texture (Busia) than in those with a loamy sand texture (Homa Bay) and revealed slightly higher abundance in the second season. "Foxy-2" had, however, only a transient suppressive effect on total indigenous fungal abundance which ceased in the second season and was further markedly compensated after addition of T. diversifolia residues. Likewise, community structure of the indigenous fungal community was mainly altered by maize growth stages, but not by "Foxy-2". In conclusion, no adverse effects of "Foxy-2" inoculation on indigenous fungal rhizosphere communities were observed corroborating the safety of this BCA under the given agro-ecologies.

Medium components and culture conditions affect the thermotolerance of aerial conidia of fungal biocontrol agent Beauveria bassiana.

PubMed

Ying, S-H; Feng, M-G

2006-09-01

To produce more thermotolerable conidia of Beauveria bassiana, a well-known fungal biocontrol agent, by optimizing the medium components and culture conditions. The conidia produced on media including 0.5-6% glucose, sucrose or starch as carbon source and 50-300-microg ml(-1) Cu2+, Zn2+, Mn2+ or Fe3+ as additive to Sabouraud dextrose medium at 15-30 degrees C, pH 4-8 or KCl-adjusted water availabilities were exposed to 30-min wet heat stress at 48 degrees C. The medium components for conidial production with greatly enhanced thermotolerance included 4% glucose as optimum or 1% starch as alternative for the carbon source and < or =50-microg ml(-1) Mn2+ for the metal additive. The culture conditions were optimized as 25 degrees C and pH 5-6. Conidial thermotolerance decreased remarkably when sucrose and Fe3+ or Cu2+ were used in the cultures, but altered slightly when 50-200-microg ml(-1) Zn2+ were included. The tolerance of B. bassiana conidia to the thermal stress was significantly affected by the medium composition and culture conditions under which the conidia were produced. Proper treatment of small grains as mass production substrates for more glucose release and supplement of glucose or 50-microg ml(-1) Mn2+ are possible means to enhancing conidial thermotolerance and field persistence for improved insect control.

Biocontrol agents promote growth of potato pathogens, depending on environmental conditions.

PubMed

Cray, Jonathan A; Connor, Mairéad C; Stevenson, Andrew; Houghton, Jonathan D R; Rangel, Drauzio E N; Cooke, Louise R; Hallsworth, John E

2016-05-01

There is a pressing need to understand and optimize biological control so as to avoid over-reliance on the synthetic chemical pesticides that can damage environmental and human health. This study focused on interactions between a novel biocontrol-strain, Bacillus sp. JC12GB43, and potato-pathogenic Phytophthora and Fusarium species. In assays carried out in vitro and on the potato tuber, the bacterium was capable of near-complete inhibition of pathogens. This Bacillus was sufficiently xerotolerant (water activity limit for growth = 0.928) to out-perform Phytophthora infestans (~0.960) and challenge Fusarium coeruleum (~0.847) and Fusarium sambucinum (~0.860) towards the lower limits of their growth windows. Under some conditions, however, strain JC12GB43 stimulated proliferation of the pathogens: for instance, Fusarium coeruleum growth-rate was increased under chaotropic conditions in vitro (132 mM urea) by >100% and on tubers (2-M glycerol) by up to 570%. Culture-based assays involving macromolecule-stabilizing (kosmotropic) compatible solutes provided proof-of-principle that the Bacillus may provide kosmotropic metabolites to the plant pathogen under conditions that destabilize macromolecular systems of the fungal cell. Whilst unprecedented, this finding is consistent with earlier reports that fungi can utilize metabolites derived from bacterial cells. Unless the antimicrobial activities of candidate biocontrol strains are assayed over a full range of field-relevant parameters, biocontrol agents may promote plant pathogen infections and thereby reduce crop yields. These findings indicate that biocontrol activity, therefore, ought to be regarded as a mode-of-behaviour (dependent on prevailing conditions) rather than an inherent property of a bacterial strain. © 2016 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Yeast Biocontrol of a Fungal Plant Disease: A Model for Studying Organism Interrelationships

ERIC Educational Resources Information Center

Chanchaichaovivat, Arun; Panijpan, Bhinyo; Ruenwongsa, Pintip

2008-01-01

An experiment on the action of the yeast, "Saccharomyces cerevisiae", against a fungal plant disease is proposed for secondary students (Grade 11) to support their study of organism interrelationship. This biocontrol experiment serves as the basis for discussing relationships among three organisms (red chilli fruit, "Saccharomyces cerevisiae," and…

Effect of seed pelleting with biocontrol agents on growth and colonisation of roots of mungbean by root-infecting fungi.

PubMed

Ramzan, Nadia; Noreen, Nayara; Perveen, Zahida; Shahzad, Saleem

2016-08-01

Mungbean (Vigna radiata (L.) Wilczek) is a leguminous pulse crop that is a major source of proteins, vitamins and minerals. Root-infecting fungi produce severe plant diseases like root rot, charcoal rot, damping-off and stem rot. The soil-borne pathogens can be controlled by chemicals, but these chemicals have several negative effects. Use of microbial antagonist such as fungi and bacteria is a safe, effective and eco-friendly method for the control of many soil-borne pathogens. Biological control agents promote plant growth and develop disease resistance. Application of bacteria and fungi as seed dressing suppressed the root-infecting fungi on leguminous crops. Seeds of mungbean were pelleted with different biocontrol agents to determine their effect on plant growth and colonisation of roots by root-infecting fungi, viz. Fusarium solani, Macrophomina phaseolina, Pythium aphanidermatum, Rhizoctonia solani and Sclerotium rolfsii. Treatment of mungbean seeds with fungal antagonists showed more shoot and root length as compared to bacterial antagonists, whereas seed treated with bacterial antagonists showed maximum shoot and root weight. Trichoderma harzianum and Bacillus subtilis were the best among all the biocontrol agents since they provided the highest plant growth and greater reduction in root colonisation by all root-infecting fungi. Bacillus cereus, Trichoderma virens, Pseudomonas fluorescens and Micrococcus varians were also effective against root-infecting fungi but to a lesser extent. T. harzianum, T. virens, B. subtilis and P. fluorescens were found to be best among all biocontrol agents. The root-infecting fungi can be controlled by pelleting seeds with biocontrol agents as it is safe and effective method. Additionally, plant growth was promoted more by this method. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Biocontrol of fouling pests: Effect of diversity, identity and density of control agents.

PubMed

Atalah, Javier; Newcombe, Emma M; Zaiko, Anastasija

2016-04-01

Augmentative biocontrol, using native natural enemies, has been suggested as a promising tool to control marine biofouling pests on artificial structures. However, there are still important knowledge gaps to be addressed before biocontrol can be considered as a management tool. In a field experiment on floating marine structures we examined intra- and interspecific consumer interactions among biocontrol agents on different surface orientations. We tested the effect of identity, density and diversity of three invertebrates (the 11-arm seastar Coscinasterias muricata, the sea urchin Evechinus chloroticus and the gastropod Cook's turban Cookia sulcata) to reduce established biofouling and to prevent fouling growth on defouled surfaces. High densities of biocontrol agents were not more effective at fouling control (cover and biomass) than low densities. Nor did multi-species treatments function more effectively than mono-specific ones. However, biocontrol agent identity was important, with the 11-arm seastar and Cook's turban being the most effective at fouling reduction and prevention, respectively. Surface orientation had a strong effect on the effectiveness of control agents, with the best results obtained on vertical compared to diagonal and underside surfaces. This study confirmed the potential of biocontrol as a management tool for marine pest, indicating that identity is more important than richness and density of control agents. It also highlighted the limitations of this approach on diagonal and underside surfaces, where control agents have limited retention ability. Copyright © 2016 Elsevier Ltd. All rights reserved.

Human exposure to airborne fungi from genera used as biocontrol agents in plant production.

PubMed

Madsen, Anne Mette; Hansen, Vinni Mona; Meyling, Nicolai Vitt; Eilenberg, Jørgen

2007-01-01

The fungi Trichoderma harzianum, T. polysporum, T. viride, Paeciliomyces fumosoroseus, P. lilacinus, Verticillium/lecanicillium lecanii, Ulocladium oudemansii, U. atrum and Beauveria bassiana are used or considered to be used for biocontrol of pests and plant diseases. Human exposure to these fungi in environments where they may naturally occur or are used as biocontrol agents has not been directly investigated to date. This review aims to provide an overview of the current knowledge of human exposure to fungi from the relevant genera. The subject of fungal taxonomy due to the rapid development of this issue is also discussed. B. bassiana, V. lecanii, T. harzianum, T. polysporum, P. lilacinus and U. oudemansii were infrequently present in the air and thus people in general seem to be seldom exposed to these fungi. However, when V. lecanii was present, high concentrations were measured. Fungi from the genera Trichoderma, Paecilomyces and Ulocladium were rarely identified to the species level and sometimes high concentrations were reported. T. viride and U. atrum were detected frequently in different environments and sometimes with a high frequency of presence in samples. Thus, people seem to be frequently exposed to these fungi. Sequence data have led to recent revisions of fungal taxonomy, and in future studies it is important to specify the taxonomy used for identification, thus making comparisons possible.

Responses of Yeast Biocontrol Agents to Environmental Stress

PubMed Central

Sui, Yuan; Wisniewski, Michael; Droby, Samir

2015-01-01

Biological control of postharvest diseases, utilizing wild species and strains of antagonistic yeast species, is a research topic that has received considerable attention in the literature over the past 30 years. In principle, it represents a promising alternative to chemical fungicides for the management of postharvest decay of fruits, vegetables, and grains. A yeast-based biocontrol system is composed of a tritrophic interaction between a host (commodity), a pathogen, and a yeast species, all of which are affected by environmental factors such as temperature, pH, and UV light as well as osmotic and oxidative stresses. Additionally, during the production process, biocontrol agents encounter various severe abiotic stresses that also impact their viability. Therefore, understanding the ecological fitness of the potential yeast biocontrol agents and developing strategies to enhance their stress tolerance are essential to their efficacy and commercial application. The current review provides an overview of the responses of antagonistic yeast species to various environmental stresses, the methods that can be used to improve stress tolerance and efficacy, and the related mechanisms associated with improved stress tolerance. PMID:25710368

Biocontrol of Sugarcane Smut Disease by Interference of Fungal Sexual Mating and Hyphal Growth Using a Bacterial Isolate.

PubMed

Liu, Shiyin; Lin, Nuoqiao; Chen, Yumei; Liang, Zhibin; Liao, Lisheng; Lv, Mingfa; Chen, Yufan; Tang, Yingxin; He, Fei; Chen, Shaohua; Zhou, Jianuan; Zhang, Lianhui

2017-01-01

Sugarcane smut is a fungal disease caused by Sporisorium scitamineum , which can cause severe economic losses in sugarcane industry. The infection depends on the mating of bipolar sporida to form a dikaryon and develops into hyphae to penetrate the meristematic tissue of sugarcane. In this study, we set to isolate bacterial strains capable of blocking the fungal mating and evaluate their potential in control of sugarcane smut disease. A bacterial isolate ST4 from rhizosphere displayed potent inhibitory activity against the mating of S. scitamineum bipolar sporida and was selected for further study. Phylogenetic analyses and biochemical characterization showed that the isolate was most similar to Pseudomonas guariconensis . Methanol extracts from minimum and potato dextrose agar (PDA) agar medium, on which strain ST4 has grown, showed strong inhibitory activity on the sexual mating of S. scitamineum sporida, without killing the haploid cells MAT-1 or MAT-2. Further analysis showed that only glucose, but not sucrose, maltose, and fructose, could support strain ST4 to produce antagonistic chemicals. Consistent with the above findings, greenhouse trials showed that addition of 2% glucose to the bacterial inoculum significantly increased the strain ST4 biocontrol efficiency against sugarcane smut disease by 77% than the inoculum without glucose. The results from this study depict a new strategy to screen for biocontrol agents for control and prevention of the sugarcane smut disease.

A Three-Way Transcriptomic Interaction Study of a Biocontrol Agent (Clonostachys rosea), a Fungal Pathogen (Helminthosporium solani), and a Potato Host (Solanum tuberosum).

PubMed

Lysøe, Erik; Dees, Merete W; Brurberg, May Bente

2017-08-01

Helminthosporium solani causes silver scurf, which affects the quality of potato. The biocontrol agent Clonostachys rosea greatly limited the severity of silver scurf symptoms and amount of H. solani genomic DNA in laboratory experiments. Transcriptomic analysis during interaction showed that H. solani gene expression was highly reduced when coinoculated with the biocontrol agent C. rosea, whereas gene expression of C. rosea was clearly boosted as a response to the pathogen. The most notable upregulated C. rosea genes were those encoding proteins involved in cellular response to oxidative stress, proteases, G-protein signaling, and the methyltransferase LaeA. The most notable potato response to both fungi was downregulation of defense-related genes and mitogen-activated protein kinase kinase kinases. At a later stage, this shifted, and most potato defense genes were turned on, especially those involved in terpenoid biosynthesis when H. solani was present. Some biocontrol-activated defense-related genes in potato were upregulated during early interaction with C. rosea alone that were not triggered by H. solani alone. Our results indicate that the reductions of silver scurf using C. rosea are probably due to a combination of mechanisms, including mycoparasitism, biocontrol-activated stimulation of plant defense mechanisms, microbial competition for nutrients, space, and antibiosis.

Bacillus amyloliquefaciens subsp. plantarum GR53, a potent biocontrol agent resists Rhizoctonia disease on Chinese cabbage through hormonal and antioxidants regulation.

PubMed

Kang, Sang-Mo; Radhakrishnan, Ramalingam; Lee, In-Jung

2015-10-01

The fungus Rhizoctonia solani is one of the causal agents of numerous diseases that affect crop growth and yield. The aim of this present investigation was to identify a biocontrol agent that acts against R. solani and to determine the agent's protective effect through phytohormones and antioxidant regulation in experimentally infected Chinese cabbage plants. Four rhizospheric soil bacterial isolates GR53, GR169, GR786, and GR320 were tested for their antagonistic activity against R. solani. Among these isolates, GR53 significantly suppressed fungal growth. GR53 was identified as Bacillus amyloliquefaciens subsp. plantarum by phylogenetic analysis of the 16S rDNA sequence. The biocontrol activity of B. amyloliquefaciens subsp. plantarum GR53 was tested in Chinese cabbage plants under controlled conditions. Results showed that R. solani inhibited plant growth (length, width, fresh and dry weight of leaves) by reducing chlorophyll and total phenolic content, as well as by increasing the levels of salicylic acid, jasmonic acid, abscisic acid, and DPPH scavenging activity. By regulating the levels of these compounds, the co-inoculation of B. amyloliquefaciens subsp. plantarum GR53 heightened induced systemic resistance in infected Chinese cabbage, effectively mitigating R. solani-induced damaging effects and improving plant growth. The results obtained from this study suggest that B. amyloliquefaciens subsp. plantarum GR53 is an effective biocontrol agent to prevent the damage caused by R. solani in Chinese cabbage plants.

Cystofilobasidium infirmominiatum as a biocontrol agent of postharvest diseases of apple and citrus

USDA-ARS?s Scientific Manuscript database

Two psycrotrophic yeasts isolated from the surface of lemons have been selected as biocontrol agents of the most common postharvest diseases of apples and citrus that develops during cold storage. The biocontrol yeasts were identified as Cystofilobasidium infirmominiatum and Leucosporidium scottii....

Dragonflies are biocontrol agents in Wisconsin cranberry marshes

USDA-ARS?s Scientific Manuscript database

Dragonflies (Order Odonata) are abundant predators that emerge in large hatch events each summer in Wisconsin cranberry marshes. They seem to be a potential group of biocontrol agents for pest management that may be influenced by the diversity found on the marsh. In fact, our evidence shows that dra...

The Potential of Streptomyces as Biocontrol Agents against the Rice Blast Fungus, Magnaporthe oryzae (Pyricularia oryzae).

PubMed

Law, Jodi Woan-Fei; Ser, Hooi-Leng; Khan, Tahir M; Chuah, Lay-Hong; Pusparajah, Priyia; Chan, Kok-Gan; Goh, Bey-Hing; Lee, Learn-Han

2017-01-01

Rice is a staple food source for more than three billion people worldwide. However, rice is vulnerable to diseases, the most destructive among them being rice blast, which is caused by the fungus Magnaporthe oryzae (anamorph Pyricularia oryzae ). This fungus attacks rice plants at all stages of development, causing annual losses of approximately 10-30% in various rice producing regions. Synthetic fungicides are often able to effectively control plant diseases, but some fungicides result in serious environmental and health problems. Therefore, there is growing interest in discovering and developing new, improved fungicides based on natural products as well as introducing alternative measures such as biocontrol agents to manage plant diseases. Streptomyce s bacteria appear to be promising biocontrol agents against a wide range of phytopathogenic fungi, which is not surprising given their ability to produce various bioactive compounds. This review provides insight into the biocontrol potential of Streptomyces against the rice blast fungus, M. oryzae . The ability of various S treptomyces spp. to act as biocontrol agents of rice blast disease has been studied by researchers under both laboratory and greenhouse/growth chamber conditions. Laboratory studies have shown that Streptomyces exhibit inhibitory activity against M. oryzae . In greenhouse studies, infected rice seedlings treated with Streptomyces resulted in up to 88.3% disease reduction of rice blast. Studies clearly show that Streptomyces spp. have the potential to be used as highly effective biocontrol agents against rice blast disease; however, the efficacy of any biocontrol agent may be affected by several factors including environmental conditions and methods of application. In order to fully exploit their potential, further studies on the isolation, formulation and application methods of Streptomyces along with field experiments are required to establish them as effective biocontrol agents.

The Potential of Streptomyces as Biocontrol Agents against the Rice Blast Fungus, Magnaporthe oryzae (Pyricularia oryzae)

PubMed Central

Law, Jodi Woan-Fei; Ser, Hooi-Leng; Khan, Tahir M.; Chuah, Lay-Hong; Pusparajah, Priyia; Chan, Kok-Gan; Goh, Bey-Hing; Lee, Learn-Han

2017-01-01

Rice is a staple food source for more than three billion people worldwide. However, rice is vulnerable to diseases, the most destructive among them being rice blast, which is caused by the fungus Magnaporthe oryzae (anamorph Pyricularia oryzae). This fungus attacks rice plants at all stages of development, causing annual losses of approximately 10–30% in various rice producing regions. Synthetic fungicides are often able to effectively control plant diseases, but some fungicides result in serious environmental and health problems. Therefore, there is growing interest in discovering and developing new, improved fungicides based on natural products as well as introducing alternative measures such as biocontrol agents to manage plant diseases. Streptomyces bacteria appear to be promising biocontrol agents against a wide range of phytopathogenic fungi, which is not surprising given their ability to produce various bioactive compounds. This review provides insight into the biocontrol potential of Streptomyces against the rice blast fungus, M. oryzae. The ability of various Streptomyces spp. to act as biocontrol agents of rice blast disease has been studied by researchers under both laboratory and greenhouse/growth chamber conditions. Laboratory studies have shown that Streptomyces exhibit inhibitory activity against M. oryzae. In greenhouse studies, infected rice seedlings treated with Streptomyces resulted in up to 88.3% disease reduction of rice blast. Studies clearly show that Streptomyces spp. have the potential to be used as highly effective biocontrol agents against rice blast disease; however, the efficacy of any biocontrol agent may be affected by several factors including environmental conditions and methods of application. In order to fully exploit their potential, further studies on the isolation, formulation and application methods of Streptomyces along with field experiments are required to establish them as effective biocontrol agents. PMID:28144236

A new method to evaluate the biocontrol potential of single spore isolates of fungal entomopathogens

PubMed Central

Posada, Francisco J.; Vega, Fernando E.

2005-01-01

Fifty Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) strains isolated from the coffee berry borer were used to develop a novel screening method aimed at selecting strains with the highest biocontrol potential. The screening method is based on percent insect mortality, average survival time, mortality distribution, percent spore germination, fungal life cycle duration, and spore production on the insect. Based on these parameters, only 11 strains merited further study. The use of a sound scientific protocol for the selection of promising fungal entomopathogens should lead to more efficient use of time, labor, and financial resources in biological control programs. PMID:17119619

Environmental factors affect the activity of biocontrol agents against ochratoxigenic Aspergillus carbonarius on wine grape.

PubMed

De Curtis, F; de Felice, D V; Ianiri, G; De Cicco, V; Castoria, R

2012-09-17

The influence of temperature and relative humidity (RH) on the activity of three biocontrol agents-the yeast Metschnikowia pulcherrima LS16 and two strains of the yeast-like fungus Aureobasidium pullulans LS30 and AU34-2-against infection by A. carbonarius and ochratoxin A (OTA) accumulation in wine grape berries was investigated in lab-scale experiments. The presence of wounds on grape skin dramatically favored infection of berries by A. carbonarius strain A1102, since unwounded berries showed very low levels of infection at all conditions of RH and temperature tested. Artificially wounded berries pre-treated with the biocontrol agents were inoculated with the ochratoxigenic A. carbonarius strain A1102 and were incubated for 5 days at two levels of RH (60% and 100%) and three different temperatures (20, 25 and 30 °C). The three biocontrol agents were able to prevent infections at 60% RH and 20 °C. At 60% RH and 25 °C only strain AU34-2 achieved some protection on day 5, whereas at 30 °C a limited biocontrol efficacy was evident only up to day 2. At 100% RH, LS16, LS30 and AU34-2 showed effective protection of grape berries at 20 °C until the 5th day of incubation. The three biocontrol agents achieved significant protection at higher temperatures only until the 2nd day after the beginning of the experiment: all three strains at 25 °C, and only strain LS16 at 30 °C. After 5 days, the three biocontrol agents were able to significantly reduce the level of OTA in berries at all the conditions tested. This occurred even when protection from infection was not significant, except at 30 °C and 100% of RH for all the three strains, and at 25 °C and 100% of RH for strain LS16. The biocontrol agents displayed a higher rate of colonization on grape berries at 20 and 25 °C than at 30 °C. The higher value of RH (100%) appeared to increase the rate of colonization, in particular at 20 and 25 °C. Taken together, our results emphasize the significant influence of

Study on Interactions between the Major Apple Valsa Canker Pathogen Valsa mali and Its Biocontrol Agent Saccharothrix yanglingensis Hhs.015 Using RT-qPCR

PubMed Central

Fan, Dongying; Li, Yanfang; Zhao, Lingyun; Li, Zhengpeng; Huang, Lili; Yan, Xia

2016-01-01

The mechanism of biocontrol agent Saccharothrix yanglingensis Hhs.015 action against Valsa mali, a major apple Valsa canker pathogen, was examined using a novel, sensitive (minimum detection limit 100 pg/μL) and reliably RT-qPCR technique. Prior to lesion formation, total concentration of V. mali in the bark showed a significant decrease (p<0.05) after 24 h of Hhs.015 treatment. This was more pronounced at 48 and 96 h post treatment. After lesion formation, levels of V. mali remained constant at the boundary between infected and uninfected bark tissues, although the relative expansion rate of the lesion was significantly reduced (p<0.05). Gene expression levels of endo-polygalacturonase, a marker for fungal pathogenicity, were sharply reduced while host induced resistance callose synthase levels increased significantly (p<0.05) at the boundary bark at 9 d after Hhs.015 treatment. The results showed that biocontrol agent Hhs.015 prevented infection of V. mali by inhibiting pathogen growth, down-regulating pathogenicity factor expression and inducing a high level of host resistance. PMID:27611855

Pseudomonas fluorescens F113 mutant with enhanced competitive colonization ability and improved biocontrol activity against fungal root pathogens.

PubMed

Barahona, Emma; Navazo, Ana; Martínez-Granero, Francisco; Zea-Bonilla, Teresa; Pérez-Jiménez, Rosa María; Martín, Marta; Rivilla, Rafael

2011-08-01

Motility is one of the most important traits for efficient rhizosphere colonization by Pseudomonas fluorescens F113rif (F113). In this bacterium, motility is a polygenic trait that is repressed by at least three independent pathways, including the Gac posttranscriptional system, the Wsp chemotaxis-like pathway, and the SadB pathway. Here we show that the kinB gene, which encodes a signal transduction protein that together with AlgB has been implicated in alginate production, participates in swimming motility repression through the Gac pathway, acting downstream of the GacAS two-component system. Gac mutants are impaired in secondary metabolite production and are unsuitable as biocontrol agents. However, the kinB mutant and a triple mutant affected in kinB, sadB, and wspR (KSW) possess a wild-type phenotype for secondary metabolism. The KSW strain is hypermotile and more competitive for rhizosphere colonization than the wild-type strain. We have compared the biocontrol activity of KSW with those of the wild-type strain and a phenotypic variant (F113v35 [V35]) which is hypermotile and hypercompetitive but is affected in secondary metabolism since it harbors a gacS mutation. Biocontrol experiments in the Fusarium oxysporum f. sp. radicis-lycopersici/Lycopersicum esculentum (tomato) and Phytophthora cactorum/Fragaria vesca (strawberry) pathosystems have shown that the three strains possess biocontrol activity. Biocontrol activity was consistently lower for V35, indicating that the production of secondary metabolites was the most important trait for biocontrol. Strain KSW showed improved biocontrol compared with the wild-type strain, indicating that an increase in competitive colonization ability resulted in improved biocontrol and that the rational design of biocontrol agents by mutation is feasible.

Antibiosis and bmyB Gene Presence As Prevalent Traits for the Selection of Efficient Bacillus Biocontrol Agents against Crown Gall Disease.

PubMed

Frikha-Gargouri, Olfa; Ben Abdallah, Dorra; Bhar, Ilhem; Tounsi, Slim

2017-01-01

This study aimed to improve the screening method for the selection of Bacillus biocontrol agents against crown gall disease. The relationship between the strain biocontrol ability and their in vitro studied traits was investigated to identify the most important factors to be considered for the selection of effective biocontrol agents. In fact, previous selection procedure relying only on in vitro antibacterial activity was shown to be not suitable in some cases. A direct plant-protection strategy was performed to screen the 32 Bacillus biocontrol agent candidates. Moreover, potential in vitro biocontrol traits were investigated including biofilm formation, motility, hemolytic activity, detection of lipopeptide biosynthetic genes ( sfp, ituC and bmyB ) and production of antibacterial compounds. The obtained results indicated high correlations of the efficiency of the biocontrol with the reduction of gall weight ( p = 0.000) and the antibacterial activity in vitro ( p = 0.000). Moreover, there was strong correlations of the efficiency of the biocontrol ( p = 0.004) and the reduction in gall weight ( p = 0.000) with the presence of the bmyB gene. This gene directs the synthesis of the lipopeptide bacillomycin belonging to the iturinic family of lipopeptides. These results were also confirmed by the two-way hierarchical cluster analysis and the correspondence analysis showing the relatedness of these four variables. According to the obtained results a new screening procedure of Bacillus biocontrol agents against crown gall disease could be advanced consisting on two step selection procedure. The first consists on selecting strains with high antibacterial activity in vitro or those harbouring the bmyB gene. Further selection has to be performed on tomato plants in vivo . Moreover, based on the results of the biocontrol assay, five potent strains exhibiting high biocontrol abilities were selected. They were identified as Bacillus subtilis or Bacillus amyloliquefaciens

Antibiosis and bmyB Gene Presence As Prevalent Traits for the Selection of Efficient Bacillus Biocontrol Agents against Crown Gall Disease

PubMed Central

Frikha-Gargouri, Olfa; Ben Abdallah, Dorra; Bhar, Ilhem; Tounsi, Slim

2017-01-01

This study aimed to improve the screening method for the selection of Bacillus biocontrol agents against crown gall disease. The relationship between the strain biocontrol ability and their in vitro studied traits was investigated to identify the most important factors to be considered for the selection of effective biocontrol agents. In fact, previous selection procedure relying only on in vitro antibacterial activity was shown to be not suitable in some cases. A direct plant-protection strategy was performed to screen the 32 Bacillus biocontrol agent candidates. Moreover, potential in vitro biocontrol traits were investigated including biofilm formation, motility, hemolytic activity, detection of lipopeptide biosynthetic genes (sfp, ituC and bmyB) and production of antibacterial compounds. The obtained results indicated high correlations of the efficiency of the biocontrol with the reduction of gall weight (p = 0.000) and the antibacterial activity in vitro (p = 0.000). Moreover, there was strong correlations of the efficiency of the biocontrol (p = 0.004) and the reduction in gall weight (p = 0.000) with the presence of the bmyB gene. This gene directs the synthesis of the lipopeptide bacillomycin belonging to the iturinic family of lipopeptides. These results were also confirmed by the two-way hierarchical cluster analysis and the correspondence analysis showing the relatedness of these four variables. According to the obtained results a new screening procedure of Bacillus biocontrol agents against crown gall disease could be advanced consisting on two step selection procedure. The first consists on selecting strains with high antibacterial activity in vitro or those harbouring the bmyB gene. Further selection has to be performed on tomato plants in vivo. Moreover, based on the results of the biocontrol assay, five potent strains exhibiting high biocontrol abilities were selected. They were identified as Bacillus subtilis or Bacillus amyloliquefaciens. These

Bioprospecting endophytic diazotrophic Lysinibacillus sphaericus as biocontrol agents of rice sheath blight disease.

PubMed

Shabanamol, S; Sreekumar, J; Jisha, M S

2017-10-01

The present study tried to explore the possible in vitro biocontrol mechanisms of Lysinibacillus sphaericus , a diazotrophic endophyte from rice against the rice sheath blight pathogen Rhizoctonia solani. The in vivo biocontrol potential of the isolate and the induction of systemic resistance under greenhouse conditions have also been experimented employing different treatments with positive control carbendazim, the chemical fungicide. The endophytic isolate showed 100% growth inhibition of the fungal pathogen via volatile organic compound production and was positive for the production of siderophores, biosurfactants, HCN, and ammonia. Under greenhouse conditions, foliar and soil application of L. sphaericus significantly decreased the percentage of disease incidence. All bacterized treatments are superior to chemical fungicide treatment. Application of L. sphaericus in single and combination treatments induces systemic resistance as evident from the significant accumulation of defense enzymes such as peroxides, polyphenol oxides and phenylalanine ammonia in addition to the increase of phenolic compounds. The results biologically prospect endophytic diazotroph L. sphaericus as a potent plant growth promoter with excellent biocontrol efficiency.

The Transition from a Phytopathogenic Smut Ancestor to an Anamorphic Biocontrol Agent Deciphered by Comparative Whole-Genome Analysis[W][OPEN

PubMed Central

Lefebvre, François; Joly, David L.; Labbé, Caroline; Teichmann, Beate; Linning, Rob; Belzile, François; Bakkeren, Guus; Bélanger, Richard R.

2013-01-01

Pseudozyma flocculosa is related to the model plant pathogen Ustilago maydis yet is not a phytopathogen but rather a biocontrol agent of powdery mildews; this relationship makes it unique for the study of the evolution of plant pathogenicity factors. The P. flocculosa genome of ∼23 Mb includes 6877 predicted protein coding genes. Genome features, including hallmarks of pathogenicity, are very similar in P. flocculosa and U. maydis, Sporisorium reilianum, and Ustilago hordei. Furthermore, P. flocculosa, a strict anamorph, revealed conserved and seemingly intact mating-type and meiosis loci typical of Ustilaginales. By contrast, we observed the loss of a specific subset of candidate secreted effector proteins reported to influence virulence in U. maydis as the singular divergence that could explain its nonpathogenic nature. These results suggest that P. flocculosa could have once been a virulent smut fungus that lost the specific effectors necessary for host compatibility. Interestingly, the biocontrol agent appears to have acquired genes encoding secreted proteins not found in the compared Ustilaginales, including necrosis-inducing-Phytophthora-protein- and Lysin-motif- containing proteins believed to have direct relevance to its lifestyle. The genome sequence should contribute to new insights into the subtle genetic differences that can lead to drastic changes in fungal pathogen lifestyles. PMID:23800965

Endophytic fungal diversity in Theobroma cacao (cacao) and T. grandiflorum (cupuaçu) trees and their potential for growth promotion and biocontrol of black-pod disease.

PubMed

Hanada, Rogério Eiji; Pomella, Alan William V; Costa, Heron Salazar; Bezerra, José Luiz; Loguercio, Leandro L; Pereira, José O

2010-01-01

The endophytic niches of plants are a rich source of microbes that can directly and indirectly promote plant protection, growth and development. The diversity of culturable endophytic fungi from stems and branches of Theobroma cacao (cacao) and Theobroma grandiflorum (cupuaçu) trees growing in the Amazon region of Brazil was assessed. The collection of fungal endophytic isolates obtained was applied in field experiments to evaluate their potential as biocontrol agents against Phytophthora palmivora, the causal agent of the black-pod rot disease of cacao, one of the most important pathogens in cocoa-producing regions worldwide. The isolated endophytic fungi from 60 traditional, farmer-planted, healthy cacao and 10 cupuaçu plants were cultured in PDA under conditions inducing sporulation. Isolates were classified based upon the morphological characteristics of their cultures and reproductive structures. Spore suspensions from a total of 103 isolates that could be classified at least up to genus level were tested against P. palmivora in pods attached to cacao trees in the field. Results indicated that ∼70% of isolates showed biocontrol effects to a certain extent, suggesting that culturable endophytic fungal biodiversity in this system is of a mostly mutualistic type of interaction with the host. Eight isolates from genera Trichoderma (reference isolate), Pestalotiopsis, Curvularia, Tolypocladium and Fusarium showed the highest level of activity against the pathogen, and were further characterized. All demonstrated their endophytic nature by colonizing axenic cacao plantlets, and confirmed their biocontrol activity on attached pods trials by showing significant decrease in disease severity in relation to the positive control. None, however, showed detectable growth-promotion effects. Aspects related to endophytic biodiversity and host-pathogen-endophyte interactions in the environment of this study were discussed on the context of developing sustainable strategies

Fungal Genomics Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grigoriev, Igor

The JGI Fungal Genomics Program aims to scale up sequencing and analysis of fungal genomes to explore the diversity of fungi important for energy and the environment, and to promote functional studies on a system level. Combining new sequencing technologies and comparative genomics tools, JGI is now leading the world in fungal genome sequencing and analysis. Over 120 sequenced fungal genomes with analytical tools are available via MycoCosm (www.jgi.doe.gov/fungi), a web-portal for fungal biologists. Our model of interacting with user communities, unique among other sequencing centers, helps organize these communities, improves genome annotation and analysis work, and facilitates new larger-scalemore » genomic projects. This resulted in 20 high-profile papers published in 2011 alone and contributing to the Genomics Encyclopedia of Fungi, which targets fungi related to plant health (symbionts, pathogens, and biocontrol agents) and biorefinery processes (cellulose degradation, sugar fermentation, industrial hosts). Our next grand challenges include larger scale exploration of fungal diversity (1000 fungal genomes), developing molecular tools for DOE-relevant model organisms, and analysis of complex systems and metagenomes.« less

Use of mixed cultures of biocontrol agents to control sheep nematodes.

PubMed

Baloyi, M A; Laing, M D; Yobo, K S

2012-03-23

Biological control is a promising non-chemical approach for the control of gastrointestinal nematodes of sheep. Use of combinations of biocontrol agents have been reported to be an effective method to increase the efficacy of biological control effects. In this study, combinations of either two Bacillus thuringiensis (Bt) or Clonostachys rosea (C. rosea) isolates and Bt+C. rosea isolates were evaluated in vitro in microtitre plates for their biocontrol activity on sheep nematodes. The Baermann technique was used to extract the surviving L3 larval stages of intestinal nematodes and counted under a dissecting microscope to determine the larval counts. Results indicate that there was a significant reduction of nematode counts due to combination of biocontrol agents (P<0.001). Combinations of Bt isolates reduced nematodes counts by 72.8%, 64% and 29.8%. The results revealed a control level of 57% when C. rosea isolates P3+P8 were combined. Combination of Bt and C. rosea isolates B10+P8 caused the greatest mortality of 76.7%. Most combinations were antagonistic, with only a few combinations showing an additive effect. None were synergistic. The isolate combinations were more effective than when isolates were used alone. Copyright © 2011 Elsevier B.V. All rights reserved.

Pseudomonas fluorescens F113 Mutant with Enhanced Competitive Colonization Ability and Improved Biocontrol Activity against Fungal Root Pathogens ▿

PubMed Central

Barahona, Emma; Navazo, Ana; Martínez-Granero, Francisco; Zea-Bonilla, Teresa; Pérez-Jiménez, Rosa María; Martín, Marta; Rivilla, Rafael

2011-01-01

Motility is one of the most important traits for efficient rhizosphere colonization by Pseudomonas fluorescens F113rif (F113). In this bacterium, motility is a polygenic trait that is repressed by at least three independent pathways, including the Gac posttranscriptional system, the Wsp chemotaxis-like pathway, and the SadB pathway. Here we show that the kinB gene, which encodes a signal transduction protein that together with AlgB has been implicated in alginate production, participates in swimming motility repression through the Gac pathway, acting downstream of the GacAS two-component system. Gac mutants are impaired in secondary metabolite production and are unsuitable as biocontrol agents. However, the kinB mutant and a triple mutant affected in kinB, sadB, and wspR (KSW) possess a wild-type phenotype for secondary metabolism. The KSW strain is hypermotile and more competitive for rhizosphere colonization than the wild-type strain. We have compared the biocontrol activity of KSW with those of the wild-type strain and a phenotypic variant (F113v35 [V35]) which is hypermotile and hypercompetitive but is affected in secondary metabolism since it harbors a gacS mutation. Biocontrol experiments in the Fusarium oxysporum f. sp. radicis-lycopersici/Lycopersicum esculentum (tomato) and Phytophthora cactorum/Fragaria vesca (strawberry) pathosystems have shown that the three strains possess biocontrol activity. Biocontrol activity was consistently lower for V35, indicating that the production of secondary metabolites was the most important trait for biocontrol. Strain KSW showed improved biocontrol compared with the wild-type strain, indicating that an increase in competitive colonization ability resulted in improved biocontrol and that the rational design of biocontrol agents by mutation is feasible. PMID:21685161

Effect of nutrition and environmental factors on the endoparasitic fungus Esteya vermicola, a biocontrol agent against pine wilt disease.

PubMed

Xue, Jianjie; Zhang, Yongan; Wang, Chunyan; Wang, Yuzhu; Hou, Jingang; Wang, Zhen; Wang, Yunbo; Gu, Lijuan; Sung, Changkeun

2013-09-01

The nematophagous fungus Esteya vermicola has tremendous potential for biological control. This species exhibits strong infectious activity against pinewood nematodes, whereas the study on the effect of nutrition and environmental factors is still of paucity. Carbon (C), nitrogen (N), pH value, temperature, and water activity have great impact on the fungal growth, sporulation, and germination. In nutrition study, the greatest number of conidia (2.36 × 10(9) per colony) was obtained at the C:N ratio of 100:1 with a carbon concentration 32 g l(-1). In addition, the germination rate and radial growth of E. vermicola were used to evaluate the effects of environmental conditions and they were optimized as following: pH 5.5, 26 °C and water activity of 0.98. Our results also confirmed that variation of environmental factors has a detrimental influence on the efficacy of active conidia and growth of fungus. Moreover, under above optimal condition, the biocontrol efficacy was significantly improved in regard to the increase of adhesive and mortality rate, which highlight the study on the application of E. vermicola as pine wilt disease biocontrol agent.

Plant Growth Promoting and Biocontrol Activity of Streptomyces spp. as Endophytes.

PubMed

Vurukonda, Sai Shiva Krishna Prasad; Giovanardi, Davide; Stefani, Emilio

2018-03-22

There has been many recent studies on the use of microbial antagonists to control diseases incited by soilborne and airborne plant pathogenic bacteria and fungi, in an attempt to replace existing methods of chemical control and avoid extensive use of fungicides, which often lead to resistance in plant pathogens. In agriculture, plant growth-promoting and biocontrol microorganisms have emerged as safe alternatives to chemical pesticides. Streptomyces spp. and their metabolites may have great potential as excellent agents for controlling various fungal and bacterial phytopathogens. Streptomycetes belong to the rhizosoil microbial communities and are efficient colonizers of plant tissues, from roots to the aerial parts. They are active producers of antibiotics and volatile organic compounds, both in soil and in planta , and this feature is helpful for identifying active antagonists of plant pathogens and can be used in several cropping systems as biocontrol agents. Additionally, their ability to promote plant growth has been demonstrated in a number of crops, thus inspiring the wide application of streptomycetes as biofertilizers to increase plant productivity. The present review highlights Streptomyces spp.-mediated functional traits, such as enhancement of plant growth and biocontrol of phytopathogens.

JGI Fungal Genomics Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grigoriev, Igor V.

2011-03-14

Genomes of energy and environment fungi are in focus of the Fungal Genomic Program at the US Department of Energy Joint Genome Institute (JGI). Its key project, the Genomics Encyclopedia of Fungi, targets fungi related to plant health (symbionts, pathogens, and biocontrol agents) and biorefinery processes (cellulose degradation, sugar fermentation, industrial hosts), and explores fungal diversity by means of genome sequencing and analysis. Over 50 fungal genomes have been sequenced by JGI to date and released through MycoCosm (www.jgi.doe.gov/fungi), a fungal web-portal, which integrates sequence and functional data with genome analysis tools for user community. Sequence analysis supported by functionalmore » genomics leads to developing parts list for complex systems ranging from ecosystems of biofuel crops to biorefineries. Recent examples of such 'parts' suggested by comparative genomics and functional analysis in these areas are presented here« less

Surfactin triggers biofilm formation of Bacillus subtilis in melon phylloplane and contributes to the biocontrol activity.

PubMed

Zeriouh, Houda; de Vicente, Antonio; Pérez-García, Alejandro; Romero, Diego

2014-07-01

The biocontrol activity of many Bacillus species has been traditionally related to the direct antagonism of pathogens. In previous works, we reported that B. subtilis strain UMAF6614 was an efficient biocontrol agent that produced bacillomycin, fengycin and surfactin lipopeptides. Bacillomycins and fengycins were shown to have antagonistic activity towards fungal and bacterial pathogens of cucurbits; however, the functionality of surfactin remained unclear. In this study, the role of surfactin in the biocontrol activity of this strain was investigated. We observed that a deficiency in surfactin production led to a partial reduction of disease suppression by this biocontrol agent, which coincided with a defect in biofilm formation and the colonization of the melon phylloplane. These effects were due to a dramatic reduction in the production of exopolysaccharide and the TasA protein, which are the two major components of the extracellular matrix. We propose that the biocontrol activity of this strain is the result of the coordinated action of the three families of lipopeptides. B. subtilis UMAF6614 produces surfactin to trigger biofilm formation on melon phylloplane, which ensures the long-term persistence and the adequate secretion of suppressive lipopeptides, bacillomycins and fengycins, which efficiently target pathogens. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

Bio-prospecting of distillery yeasts as bio-control and bio-remediation agents.

PubMed

Ubeda, Juan F; Maldonado, María; Briones, Ana I; Francisco, J Fernández; González, Francisco J

2014-05-01

This work constitutes a preliminary study in which the capacity of non-Saccharomyces yeasts isolated from ancient distilleries as bio-control agents against moulds and in the treatment of waste waters contaminated by heavy metals-i.e. bio-remediation-is shown. In the first control assays, antagonist effect between non-Saccharomyces yeasts, their extracts and supernatants against some moulds, analysing the plausible (not exhaustive) involved factors were qualitatively verified. In addition, two enzymatic degrading properties of cell wall plant polymers, quitinolitic and pectinolitic, were screened. Finally, their use as agents of bio-remediation of three heavy metals (cadmium, chromium and lead) was analysed semi-quantitatively. The results showed that all isolates belonging to Pichia species effectively inhibited all moulds assayed. Moreover, P. kudriavzevii is a good candidate for both bio-control and bio-remediation because it inhibited moulds and accumulated the major proportion of the three tested metals.

Differential Selection by Nematodes on an Introduced Biocontrol Fungus vs. Indigenous Fungi in Nonsterile Soil.

PubMed

Kim, Tae Gwan; Knudsen, Guy R

2018-03-15

Trophic interactions of introduced biocontrol fungi with soil animals can bea key determinant in the fungal proliferation and activity.This study investigated trophic interaction of an introduced biocontrol fungus with soil nematodes. The biocontrol fungus Trichoderma harzianum ThzID1-M3 and the fungivorous nematode Aphelenchoides sp. (10 per gram of soil) were added to nonsterile soil, and microbial populations were monitored for 40 days. Similar results were obtained when the experiment was duplicated. ThzID1-M3 stimulated the population growth of indigenous nematodes ( p <0.05), regardless of whether Aphelenchoides sp.was added.Without ThzID1-M3, indigenous nematodes did not increase in number and the added Aphelenchoides sp. nematodes almost disappeared by day 10. With ThzID1-M3, population growth of nematodes was rapid between 5 and 10 days after treatment. ThzID1-M3 biomass peaked on day 5, dropped at day 10, and then almost disappeared at day 20, which was not influenced by the addition of nematodes.In contrast, a large quantity of ThzID1-M3 hyphae were present in a heat-treated soil in which nematodes were eliminated.Total fungal biomass in all treatments peaked on day 5 and subsequently decreased.Addition of nematodes increased the total fungal biomass ( p <0.05), but ThzID1-M3 addition did not affect the fungal biomass.Hyphae oftotal fungi when homogenously distributed did not support the nematode population growth; however, hyphae of the introduced fungus when densely localized did.The results suggest that soil fungivorous nematodes are an important constraint onhyphal proliferation of fungal agents introduced into natural soils.

Induction of defense responses against Magnaporthe oryzae in rice seedling by a new potential biocontrol agent Streptomyces JD211.

PubMed

Shao, Zhengying; Li, Zhang; Fu, Yanhui; Wen, Yangping; Wei, Saijin

2018-06-14

The induced resistance against plant pathogens via biocontrol agents is considered as an eco-friendly and promising strategy. In this study, the induced resistance against Magnaporthe oryzae (M. oryzae) in rice seedling by a new potential biocontrol agent Streptomyces JD211 (JD211) was evaluated. The effects of JD211 on defense-related enzymes activities and defense genes expression were investigated. The biocontrol efficacy of different JD211 concentrations was different, and the treatment of 10 g kg -1 JD211 achieved the highest biocontrol efficacy. Activities of catalase, phenylalanine ammonia-lyase (PAL) and β-1,3-glucanase significantly increased in the presence of JD211. The gene expression level of both PAL and pathogenesis related protein 1 increased when rice seedlings were inoculated with JD211 alone or co-inoculated with M. oryzae, and the expression level of chitinase gene was enhanced by JD211 in the later stage. All results suggested that JD211 could increase the rice resistance by stimulating a series of defense responses, which was the result of induced systemic resistance by JD211. This work will provide a new biocontrol agent against Magnaporthe oryzae in rice seedling. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Combinations of biocontrol agents for management of plant-parasitic nematodes and soilborne plant-pathogenic fungi.

PubMed

Meyer, Susan L F; Roberts, Daniel P

2002-03-01

Numerous microbes are antagonistic to plant-parasitic nematodes and soilborne plant-pathogenic fungi, but few of these organisms are commercially available for management of these pathogens. Inconsistent performance of applied biocontrol agents has proven to be a primary obstacle to the development of successful commercial products. One of the strategies for overcoming inconsistent performance is to combine the disease-suppressive activity of two (or more) beneficial microbes in a biocontrol preparation. Such combinations have potential for more extensive colonization of the rhizosphere, more consistent expression of beneficial traits under a broad range of soil conditions, and antagonism to a larger number of plant pests or pathogens than strains applied individually. Conversely, microbes applied in combination also may have antagonistic interactions with each other. Increased, decreased, and unaltered suppression of the target pathogen or pest has been observed when biocontrol microbes have been applied in combination. Unfortunately, the ecological basis for increased or decreased suppression has not been determined in many cases and needs further consideration. The complexity of interactions involved in the application of multiple organisms for biological control has slowed progress toward development of successful formulations. However, this approach has potential for overcoming some of the efficacy problems that occur with application of individual biocontrol agents.

Cucumber rhizosphere microbial community response to biocontrol agent Bacillus subtilis B068150

USDA-ARS?s Scientific Manuscript database

Gram-positive bacteria Bacillus subtilis B068150 has been used as a biocontrol agent against the pathogen Fusarium oxysporum f. sp. Cucumerinum. However, their survival ability in cucumber rhizosphere and non-rhizosphere as well as their influence on native microbial communities has not been fully i...

Are Bacterial Volatile Compounds Poisonous Odors to a Fungal Pathogen Botrytis cinerea, Alarm Signals to Arabidopsis Seedlings for Eliciting Induced Resistance, or Both?

PubMed Central

Sharifi, Rouhallah; Ryu, Choong-Min

2016-01-01

Biological control (biocontrol) agents act on plants via numerous mechanisms, and can be used to protect plants from pathogens. Biocontrol agents can act directly as pathogen antagonists or competitors or indirectly to promote plant induced systemic resistance (ISR). Whether a biocontrol agent acts directly or indirectly depends on the specific strain and the pathosystem type. We reported previously that bacterial volatile organic compounds (VOCs) are determinants for eliciting plant ISR. Emerging data suggest that bacterial VOCs also can directly inhibit fungal and plant growth. The aim of the current study was to differentiate direct and indirect mechanisms of bacterial VOC effects against Botrytis cinerea infection of Arabidopsis. Volatile emissions from Bacillus subtilis GB03 successfully protected Arabidopsis seedlings against B. cinerea. First, we investigated the direct effects of bacterial VOCs on symptom development and different phenological stages of B. cinerea including spore germination, mycelial attachment to the leaf surface, mycelial growth, and sporulation in vitro and in planta. Volatile emissions inhibited hyphal growth in a dose-dependent manner in vitro, and interfered with fungal attachment on the hydrophobic leaf surface. Second, the optimized bacterial concentration that did not directly inhibit fungal growth successfully protected Arabidopsis from fungal infection, which indicates that bacterial VOC-elicited plant ISR has a more important role in biocontrol than direct inhibition of fungal growth on Arabidopsis. We performed qRT-PCR to investigate the priming of the defense-related genes PR1, PDF1.2, and ChiB at 0, 12, 24, and 36 h post-infection and 14 days after the start of plant exposure to bacterial VOCs. The results indicate that bacterial VOCs potentiate expression of PR1 and PDF1.2 but not ChiB, which stimulates SA- and JA-dependent signaling pathways in plant ISR and protects plants against pathogen colonization. This study

Benefits of pre-release population genetics: a case study using Psyttalia lounsburyi, a biocontrol agent of the olive fruit fly in California

USDA-ARS?s Scientific Manuscript database

From a pest management perspective, limited knowledge on the genetics of released biocontrol agents has been repeatedly considered as one possible cause of failures in classical biological control. Introduced biocontrol agents are expected to experience a loss in genetic diversity as the result of s...

Tolerance of triazole-based fungicides by biocontrol agents used to control Fusarium head blight in wheat in Argentina.

PubMed

Palazzini, J M; Torres, A M; Chulze, S N

2018-05-01

Fusarium head blight (FHB) caused by Fusarium graminearum species complex is a devastating disease that causes extensive yield and quality losses to wheat around the world. Fungicide application and breeding for resistance are among the most important tools to counteract FHB. Biological control is an additional tool that can be used as part of an integrated management of FHB. Bacillus velezensisRC 218, Brevibacillus sp. RC 263 and Streptomyces sp. RC 87B were selected by their potential to control FHB and deoxynivalenol production. The aim of this work was to test the tolerance of these biocontrol agents to triazole-based fungicides such as prothioconazole, tebuconazole and metconazole. Bacterial growth was evaluated in Petri dishes using the spread plating technique containing the different fungicides. Bacillus velezensisRC 218 and Streptomyces sp. RC 87B showed better tolerance to fungicides than Brevibacillus sp. RC 263. Complete growth inhibition was observed at concentrations of 20 μg ml -1 for metconazole, 40 μg ml -1 for tebuconazole and 80 μg ml -1 for prothioconazole. The results obtained indicate the possibility of using these biocontrol agents in combination with fungicides as part of an integrated management to control FHB of wheat. This study evaluates the possibility to use biocontrol agents (Bacillus velezensisRC 218, Brevibacillus sp. RC 263 and Streptomyces sp. RC 87B) in combination with triazole-based fungicides to control Fusarium head blight in wheat. The evaluation of biocontrol agents' growth under in vitro conditions was carried out in Petri dishes containing either prothioconazole, tebuconazole or metconazole. Viability studies demonstrated that B. velezensisRC 218 and Streptomyces sp. RC 87B were more tolerant to the fungicides evaluated. Results obtained reflect the possibility to use fungicides at low doses combined with biocontrol agents. © 2018 The Society for Applied Microbiology.

Biocontrol of foliar pathogens: mechanisms and application.

PubMed

Elad, Y

2003-01-01

Biocontrol offers attractive alternatives or supplements to the use of conventional methods for plant disease management. Vast experience has been gained in the biocontrol of plant diseases. Prevention of infection by biocontrol agents or suppression of disease is based on various modes of action. Pathogens are typically affected by certain modes of actions and not by others according to their nature (i.e. biotrophs vs. necrotrophs). Resistance in the host plant may be induced locally or systemically by either live or dead cells of the biocontrol agent and may affect pathogens of various groups. As some pathogens are negatively affected by lake of nutrients in the infection court, competition for nutrients and space was long recognized as antagonism trait. Antibiosis and hyperparasitism affect pathogens of various groups. Other valid mechanisms are reduction of the saprophytic ability and reducing spore dissemination. Recently it was revealed that restraining of pathogenicity factors of the pathogens, i.e. host hydrolyzing proteins or reactive oxygen species takes place when biocontrol is used. It is likely that several modes of action concomitantly participate in pathogens suppression but the relative importance of each one of them is not clear. Examples of effective prevention of infection in the phyllosphere that rely on multiple modes of action will be demonstrated with Trichodermo harzianum T39 (TRICHODEX), Bacillus mycoides and Pichia guilermondii, a filamentous fungus, bacterium and yeast biocontrol agents, respectively. Several commercial products based on microorganisms have been developed and are starting to penetrate the market. However, large-scale use is still limited because of variability and inconsistency of biocontrol activity. In some cases this may be caused by sensitivity of the biocontrol agents to environmental influences. Ways to overcome biocontrol limitations and to improve its efficacy are i. integration of biocontrol with chemical

Potential Bio-Control Agent from Rhodomyrtus tomentosa against Listeria monocytogenes

PubMed Central

Odedina, Grace Fiyinfoluwa; Vongkamjan, Kitiya; Voravuthikunchai, Supayang Piyawan

2015-01-01

Listeria monocytogenes is an important foodborne pathogen implicated in many outbreaks of listeriosis. This study aimed at screening for the potential use of Rhodomyrtus tomentosa ethanolic leaf extract as a bio-control agent against L. monocytogenes. Twenty-two L. monocytogenes isolates were checked with 16 commercial antibiotics and isolates displayed resistance to 10 antibiotics. All the tested isolates were sensitive to the extract with inhibition zones ranging from 14 to 16 mm. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranged from 16 to 32 µg/mL and 128 to 512 µg/mL, respectively. Time-kill assay showed that the extract had remarkable bactericidal effects on L. monocytogenes. The extract at a concentration of 16 µg/mL reduced tolerance to 10% NaCl in L. monocytogenes in 4 h. Stationary phase L. monocytogenes cells were rapidly inactivated by greater than 3-log units within 30 min of contact time with R. tomentosa extract at 128 µg/mL. Electron microscopy revealed fragmentary bacteria with changes in the physical and morphological properties. Our study demonstrates the potential of the extract for further development into a bio-control agent in food to prevent the incidence of L. monocytogenes contamination. PMID:26371033

Effects of carbon concentration and carbon to nitrogen ratio on the growth and sporulation of several biocontrol fungi.

PubMed

Gao, Li; Sun, Man H; Liu, Xing Z; Che, Yong S

2007-01-01

Effects of carbon concentration and carbon to nitrogen (C:N) ratio on six biocontrol fungal strains are reported in this paper. All fungal strains had extensive growth on the media supplemented with 6-12 gl(-1) carbon and C:N ratios from 10:1 to 80:1, and differed in nutrient requirements for sporulation. Except for the two strains of Paecilomyces lilacinus, all selected fungi attained the highest spore yields at a C:N ratio of 160:1 when the carbon concentration was 12 gl(-1) for Metarhizium anisopliae SQZ-1-21, 6 gl(-1) for M. anisopliae RS-4-1 and Trichoderma viride TV-1, and 8 gl(-1) for Lecanicillium lecanii CA-1-G. The optimal conditions for P. lilacinus sporulation were 8 gl(-1) carbon with a C:N ratio of 10:1 for M-14 and 12 gl(-1) carbon with a C:N ratio of 20:1 for IPC-P, respectively. The results indicated that the influence of carbon concentration and C:N ratio on fungal growth and sporulation is strain dependent; therefore, consideration for the complexity of nutrient requirements is essential for improving yields of fungal biocontrol agents.

Genomic characterization of key bacteriophages to formulate the potential biocontrol agent to combat enteric pathogenic bacteria.

PubMed

Parmar, Krupa M; Dafale, Nishant A; Tikariha, Hitesh; Purohit, Hemant J

2018-05-01

Combating bacterial pathogens has become a global concern especially when the antibiotics and chemical agents are failing to control the spread due to its resistance. Bacteriophages act as a safe biocontrol agent by selectively lysing the bacterial pathogens without affecting the natural beneficial microflora. The present study describes the screening of prominent enteric pathogens NDK1, NDK2, NDK3, and NDK4 (Escherichia, Klebsiella, Enterobacter, and Serratia) mostly observed in domestic wastewater; against which KNP1, KNP2, KNP3, and KNP4 phages were isolated. To analyze their potential role in eradicating enteric pathogens and toxicity issue, these bacteriophages were sequenced using next-generation sequencing and characterized based on its genomic content. The isolated bacteriophages were homologous to Escherichia phage (KNP1), Klebsiella phage (KNP2), Enterobacter phage (KNP3), Serratia phage (KNP4), and belonged to Myoviridae family of Caudovirales except for the unclassified KNP4 phage. Draft genome analysis revealed the presence of lytic enzymes such as holing and lysozyme in KNP1 phage, endolysin in KNP2 phage, and endopeptidase with holin in KNP3 phage. The absence of any lysogenic and virulent genes makes this bacteriophage suitable candidate for preparation of phage cocktail to combat the pathogens present in wastewater. However, KNP4 contained a virulent gene rendering it unsuitable to be used as a biocontrol agent. These findings make the phages (KNP1-KNP3) as a promising alternative for the biocontrol of pathogens in wastewater which is the main culprit to spread these dominated pathogens in different natural water bodies. This study also necessitates for genomic screening of bacteriophages for lysogenic and virulence genes prior to its use as a biocontrol agent.

Transcriptomic responses of a simplified soil microcosm to a plant pathogen and its biocontrol agent reveal a complex reaction to harsh habitat.

PubMed

Perazzolli, Michele; Herrero, Noemí; Sterck, Lieven; Lenzi, Luisa; Pellegrini, Alberto; Puopolo, Gerardo; Van de Peer, Yves; Pertot, Ilaria

2016-10-27

Soil microorganisms are key determinants of soil fertility and plant health. Soil phytopathogenic fungi are one of the most important causes of crop losses worldwide. Microbial biocontrol agents have been extensively studied as alternatives for controlling phytopathogenic soil microorganisms, but molecular interactions between them have mainly been characterised in dual cultures, without taking into account the soil microbial community. We used an RNA sequencing approach to elucidate the molecular interplay of a soil microbial community in response to a plant pathogen and its biocontrol agent, in order to examine the molecular patterns activated by the microorganisms. A simplified soil microcosm containing 11 soil microorganisms was incubated with a plant root pathogen (Armillaria mellea) and its biocontrol agent (Trichoderma atroviride) for 24 h under controlled conditions. More than 46 million paired-end reads were obtained for each replicate and 28,309 differentially expressed genes were identified in total. Pathway analysis revealed complex adaptations of soil microorganisms to the harsh conditions of the soil matrix and to reciprocal microbial competition/cooperation relationships. Both the phytopathogen and its biocontrol agent were specifically recognised by the simplified soil microcosm: defence reaction mechanisms and neutral adaptation processes were activated in response to competitive (T. atroviride) or non-competitive (A. mellea) microorganisms, respectively. Moreover, activation of resistance mechanisms dominated in the simplified soil microcosm in the presence of both A. mellea and T. atroviride. Biocontrol processes of T. atroviride were already activated during incubation in the simplified soil microcosm, possibly to occupy niches in a competitive ecosystem, and they were not further enhanced by the introduction of A. mellea. This work represents an additional step towards understanding molecular interactions between plant pathogens and biocontrol

Isolation and identification of biocontrol agent Streptomyces rimosus M527 against Fusarium oxysporum f. sp. cucumerinum.

PubMed

Lu, Dandan; Ma, Zheng; Xu, Xianhao; Yu, Xiaoping

2016-08-01

Actinomycetes have received considerable attention as biocontrol agents against fungal plant pathogens and as plant growth promoters. In this study, a total of 320 actinomycetes were isolated from various habitats in China. Among which, 77 strains have been identified as antagonistic activities against Fusarium oxysporum f. sp. cucumerinum which usually caused fusarium wilt of cucumber. Of these, isolate actinomycete M527 not only displayed broad-spectrum antifungal activity but also showed the strongest antagonistic activity against the spore germination of F. oxysporum f. sp. cucumerinum. In pot experiments, the results indicated that isolate M527 could promote the shoot growth and prevent the development of the disease on cucumber caused by F. oxysporum f. sp. cucumerinum. The control efficacy against seedling fusarium wilt of cucumber after M527 fermentation broth root-irrigation was up to 72.1% as compared to control. Based on 16S rDNA sequence analysis, the isolate M527 was identified as Streptomyces rimosus. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biocontrol Agents Increase the Specific Rate of Patulin Production by Penicillium expansum but Decrease the Disease and Total Patulin Contamination of Apples

PubMed Central

Zheng, Xiangfeng; Yang, Qiya; Zhang, Xiaoyun; Apaliya, Maurice T.; Ianiri, Giuseppe; Zhang, Hongyin; Castoria, Raffaello

2017-01-01

Synthetic fungicides are commonly employed for the control of postharvest diseases of fruits. However, due to health concerns about the use of these chemicals, alternative control methods including biocontrol based on antagonistic yeasts are gaining in popularity. In this study, we investigated the effects of two biocontrol yeasts, Rhodotorula mucilaginosa strain 3617 and Rhodotorula kratochvilovae strain LS11, on blue mold and patulin (PAT) contamination caused by Penicillium expansum strains PY and FS7 in artificially inoculated Fuji apples stored at 20°C for 9 days. To correlate the development of the P. expansum strains in yeast-treated and untreated apples with PAT production, we quantified their biomass in the infected fruits using a recently published quantitative real-time polymerase chain reaction method based on specific primers for patF, a gene from P. expansum that is involved in PAT biosynthesis. Both yeasts significantly reduced the disease incidence caused by the two strains of P. expansum up to 5–7 days of incubation, and lowered their biomass and the progression of symptoms up to 9 days. Interestingly, both yeasts strains increased the rate of PAT production (expressed as ng patulin/μg fungal DNA) by the two pathogenic strains. Nevertheless, both biocontrol agents reduced the total PAT contamination, especially in the case of P. expansum strain FS7, the higher PAT producer of the two tested P. expansum strains. Comparing between the yeast strains, R. kratochvilovae LS11 was more effective than R. mucilaginosa 3617 for the control of P. expansum. PMID:28713362

Exploiting the behaviour of wild malaria vectors to achieve high infection with fungal biocontrol agents

PubMed Central

2012-01-01

Background Control of mosquitoes that transmit malaria has been the mainstay in the fight against the disease, but alternative methods are required in view of emerging insecticide resistance. Entomopathogenic fungi are candidate alternatives, but to date, few trials have translated the use of these agents to field-based evaluations of their actual impact on mosquito survival and malaria risk. Mineral oil-formulations of the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana were applied using five different techniques that each exploited the behaviour of malaria mosquitoes when entering, host-seeking or resting in experimental huts in a malaria endemic area of rural Tanzania. Results Survival of mosquitoes was reduced by 39-57% relative to controls after forcing upward house-entry of mosquitoes through fungus treated baffles attached to the eaves or after application of fungus-treated surfaces around an occupied bed net (bed net strip design). Moreover, 68 to 76% of the treatment mosquitoes showed fungal growth and thus had sufficient contact with fungus treated surfaces. A population dynamic model of malaria-mosquito interactions shows that these infection rates reduce malaria transmission by 75-80% due to the effect of fungal infection on adult mortality alone. The model also demonstrated that even if a high proportion of the mosquitoes exhibits outdoor biting behaviour, malaria transmission was still significantly reduced. Conclusions Entomopathogenic fungi strongly affect mosquito survival and have a high predicted impact on malaria transmission. These entomopathogens represent a viable alternative for malaria control, especially if they are used as part of an integrated vector management strategy. PMID:22449130

Non-aflatoxigenic Aspergillus flavus as potential biocontrol agents to reduce aflatoxin contamination in peanuts harvested in Northern Argentina.

PubMed

Alaniz Zanon, María Silvina; Barros, Germán Gustavo; Chulze, Sofía Noemí

2016-08-16

Biological control is one of the most promising strategies for preventing aflatoxin contamination in peanuts at field stage. A population of 46 native Aspergillus flavus nonaflatoxin producers were analysed based on phenotypic, physiological and genetic characteristics. Thirty-three isolates were characterized as L strain morphotype, 3 isolates as S strain morphotype, and 10 isolates did not produce sclerotia. Only 11 of 46 non-aflatoxigenic isolates did not produce cyclopiazonic acid. The vegetative compatibility group (VCG) diversity index for the population was 0.37. For field trials we selected the non-aflatoxigenic A. flavus AR27, AR100G and AFCHG2 strains. The efficacy of single and mixed inocula as potential biocontrol agents in Northern Argentina was evaluated through a 2-year study (2014-2015). During the 2014 peanut growing season, most of the treatments reduced the incidence of aflatoxigenic strains in both soil and peanut kernel samples, and no aflatoxin was detected in kernels. During the 2015 growing season, there was a reduction of aflatoxigenic strains in kernel samples from the plots treated with the potential biocontrol agents. Reductions of aflatoxin contamination between 78.36% and 89.55% were observed in treated plots in comparison with the un-inoculated control plots. This study provides the first data on aflatoxin biocontrol based on competitive exclusion in the peanut growing region of Northern Argentina, and proposes bioproducts with potential use as biocontrol agents. Copyright © 2016. Published by Elsevier B.V.

Microscopic Examination of Chitosan Polyphosphate Beads with Entrapped Spores of the Biocontrol Agent, Streptomyces melanosporofaciens EF-76

NASA Astrophysics Data System (ADS)

Jobin, Guy; Grondin, Gilles; Couture, Geneviève; Beaulieu, Carole

2005-04-01

Spores of the biocontrol agent, Streptomyces melanosporofaciens EF-76, were entrapped by complex coacervation in beads composed of a macromolecular complex (MC) of chitosan and polyphosphate. A proportion of spores entrapped in beads survived the entrapment procedure as shown by treating spores from chitosan beads with a dye allowing the differentiation of live and dead cells. The spore-loaded chitosan beads could be digested by a chitosanase, suggesting that, once introduced in soil, the beads would be degraded to release the biocontrol agent. Spore-loaded beads were examined by optical and scanning electron microscopy because the release of the biological agent depends on the spore distribution in the chitosan beads. The microscopic examination revealed that the beads had a porous surface and contained a network of inner microfibrils. Spores were entrapped in both the chitosan microfibrils and the bead lacuna.

Fungal Endophytes: Beyond Herbivore Management

PubMed Central

Bamisile, Bamisope S.; Dash, Chandra K.; Akutse, Komivi S.; Keppanan, Ravindran; Wang, Liande

2018-01-01

The incorporation of entomopathogenic fungi as biocontrol agents into Integrated Pest Management (IPM) programs without doubt, has been highly effective. The ability of these fungal pathogens such as Beauveria bassiana and Metarhizium anisopliae to exist as endophytes in plants and protect their colonized host plants against the primary herbivore pests has widely been reported. Aside this sole role of pest management that has been traditionally ascribed to fungal endophytes, recent findings provided evidence of other possible functions as plant yield promoter, soil nutrient distributor, abiotic stress and drought tolerance enhancer in plants. However, reports on these additional important effects of fungal endophytes on the colonized plants remain scanty. In this review, we discussed the various beneficial effects of endophytic fungi on the host plants and their primary herbivore pests; as well as some negative effects that are relatively unknown. We also highlighted the prospects of our findings in further increasing the acceptance of fungal endophytes as an integral part of pest management programs for optimized crop production. PMID:29628919

Unsuccessful introduced biocontrol agents can act as pollinators of invasive weeds: Bitou Bush (Chrysanthemoides monilifera ssp. rotundata) as an example.

PubMed

Gross, Caroline L; Whitehead, Joshua D; Silveira de Souza, Camila; Mackay, David

2017-10-01

The extent of self-compatibility and reliance on pollinators for seed set are critical determinants of reproductive success in invasive plant species. Seed herbivores are commonly used as biocontrol agents but may also act as flower visitors, potentially resulting in pollination. However, such contrasting or potentially counterproductive interaction effects are rarely considered or evaluated for biological control programs. We investigated the breeding system and pollinators of Bitou Bush ( Chrysanthemoides monilifera ssp. rotundata ), an invasive species in Australia that has been the subject of biocontrol programs since 1987. We found the species to be obligate outcrossing in all six populations tested. From 150 video hours, we found 21 species of potential pollinators, including Mesoclanis polana , the Bitou Seedfly, native to South Africa and released in Australia as a biocontrol agent in 1996. Mesoclanis polana transferred pollen to stigmas and was the most common pollinator (52% of pollinator visits), followed by the syrphid fly Simosyrphus grandicornis (9%) and introduced honeybee, Apis mellifera (6.5%). Fruit-to-flower ratios ranged from 0.12 to 0.45 and were highest in the population with the greatest proportion of Mesoclanis polana visits. In an experimental trial, outside the naturalized range, the native bee Homalictus sphecodoides and the native syrphid Melangyna viridiceps were the primary pollinators, and fruit-to-flower ratios were 0.35, indicating that Bitou Bush would have ready pollinators if its range expanded inland. Synthesis . Invasive Bitou Bush requires pollinators, and this is effected by a range of generalist pollinators in eastern Australia including the Bitou Seedfly, introduced as a biocontrol agent, and the major pollinator detected in this study. Fruit-to-flower ratios were highest when the Bitou Seedfly was in high abundance. This study underscores the importance of evaluating the pollination biology of invasive species in their

Evaluation of behaviour of Lachancea thermotolerans biocontrol agents on grape fermentations.

PubMed

Nally, M C; Ponsone, M L; Pesce, V M; Toro, M E; Vazquez, F; Chulze, S

2018-07-01

Previous researches have showed that Lachancea thermotolerans strains RCKT4 and RCKT5 inhibited the growth of Aspergillus. However, currently, there are no data on their nutritional preferences, as a possible substrate competitor against Saccharomyces cerevisiae, and their effects on fermentation. In this work, we observed that the biocontrol yeasts and S. cerevisiae BSc203, based on the utilization of 16 carbonate sources, revealed significant differences in the nutritional profile (biocontrol yeasts NS:0·25, BSc203 NS:0·56). Lachancea thermotolerans strains did not occupy the same niche as that of BSc203 (NOI:0·44). The biocontrol agents and BSc203 presented similar competitive attitude in terms of the sugar, ethanol and sulphite tolerances. During fermentation, the biocontrol yeasts were found to tolerate up to 12% v/v ethanol, 250 mg ml -1 of total SO 2 and 30° Brix sugar. In mixed cultures, L. thermotolerans strains did not negatively affect the growth of BSc203 and the wine quality, except when RCKT4 was initially inoculated at a high proportion in the mixed culture 1MSK4 (1%BSc203/99%RCKT4), resulting in a lower production of CO 2 and ethanol, in comparison with pure BSc203. RCKT5, at a high proportion, in 1MSK5 (1%BSc203/99%RCKT5) presented promising oenological properties. This fermentation showed lower acetic acid contents and higher total acidity than pure BSc203. Generally it is not evaluated if the biofungicide yeasts sprayed on vegetables alter the quality of the fermented products. This work focused on the importance of assessing the possible effects of yeast-based fungicides used in vineyards on grape fermentation, especially on Saccharomyces cerevisiae growth. In this context, the competition between biofungicide yeasts and S. cerevisiae under winemaking conditions is investigated. © 2018 The Society for Applied Microbiology.

Novel Trichoderma polysporum Strain for the Biocontrol of Pseudogymnoascus destructans, the Fungal Etiologic Agent of Bat White Nose Syndrome.

PubMed

Zhang, Tao; Chaturvedi, Vishnu; Chaturvedi, Sudha

2015-01-01

White-nose syndrome (WNS), an emerging disease of hibernating bats, has rapidly spread across eastern North America killing millions of bats. Pseudogymnoascus destructans (Pd), the sole etiologic agent of WNS, is widespread and persistent in bat hibernacula. Control of Pd in the affected sites is urgently needed to break the transmission cycle while minimizing any adverse impact on the native organisms. We isolated a novel strain of Trichoderma polysporum (Tp) from one of the caves at the epicenter of WNS zoonotic. Detailed experimental studies revealed: (1) Tp WPM 39143 was highly adapted to grow at temperatures simulating the cave environment (6°C-15°C), (2) Tp WPM 39143 restricted Pd colony growth in dual culture challenges, (3) Tp WPM 39143 caused four logs reduction of Pd colony forming units and genome copies in autoclaved soil samples from one of the WNS affected caves, (4) Tp WPM 39143 extract showed specific fungicidal activity against Pd in disk diffusion assay, but not against closely related fungus P. pannorum (Pp), (5) Tp WPM 39143 extract retained inhibitory activity after exposure to high temperatures, light and proteinase K, and (6) Inhibitory metabolites in Tp WPM 39143 extract comprised of water-soluble, high polarity compounds. These results suggest that Tp WPM 39143 is a promising candidate for further evaluation as a biocontrol agent of Pd in WNS affected sites.

Novel Trichoderma polysporum Strain for the Biocontrol of Pseudogymnoascus destructans, the Fungal Etiologic Agent of Bat White Nose Syndrome

PubMed Central

Zhang, Tao; Chaturvedi, Vishnu; Chaturvedi, Sudha

2015-01-01

White-nose syndrome (WNS), an emerging disease of hibernating bats, has rapidly spread across eastern North America killing millions of bats. Pseudogymnoascus destructans (Pd), the sole etiologic agent of WNS, is widespread and persistent in bat hibernacula. Control of Pd in the affected sites is urgently needed to break the transmission cycle while minimizing any adverse impact on the native organisms. We isolated a novel strain of Trichoderma polysporum (Tp) from one of the caves at the epicenter of WNS zoonotic. Detailed experimental studies revealed: (1) Tp WPM 39143 was highly adapted to grow at temperatures simulating the cave environment (6°C-15°C), (2) Tp WPM 39143 restricted Pd colony growth in dual culture challenges, (3) Tp WPM 39143 caused four logs reduction of Pd colony forming units and genome copies in autoclaved soil samples from one of the WNS affected caves, (4) Tp WPM 39143 extract showed specific fungicidal activity against Pd in disk diffusion assay, but not against closely related fungus P. pannorum (Pp), (5) Tp WPM 39143 extract retained inhibitory activity after exposure to high temperatures, light and proteinase K, and (6) Inhibitory metabolites in Tp WPM 39143 extract comprised of water-soluble, high polarity compounds. These results suggest that Tp WPM 39143 is a promising candidate for further evaluation as a biocontrol agent of Pd in WNS affected sites. PMID:26509269

Development of biocontrol agents from food microbial isolates for controlling post-harvest peach brown rot caused by Monilinia fructicola.

PubMed

Zhou, Ting; Schneider, Karin E; Li, Xiu-Zhen

2008-08-15

An unconventional strategy of screening food microbes for biocontrol activity was used to develop biocontrol agents for controlling post-harvest peach brown rot caused by Monilinia fructicola. Forty-four microbial isolates were first screened for their biocontrol activity on apple fruit. Compared with the pathogen-only check, seven of the 44 isolates reduced brown rot incidence by >50%, including four bacteria: Bacillus sp. C06, Lactobacillus sp. C03-b and Bacillus sp. T03-c, Lactobacillus sp. P02 and three yeasts: Saccharomyces delbrueckii A50, S. cerevisiae YE-5 and S. cerevisiae A41. Eight microbial isolates were selected for testing on peaches by wound co-inoculation with mixtures of individual microbial cultures and conidial suspension of M. fructicola. Only two of them showed significant biocontrol activity after five days of incubation at 22 degrees C. Bacillus sp. C06 suppressed brown rot incidence by 92% and reduced lesion diameter by 88% compared to the pathogen-only check. Bacillus sp.T03-c reduced incidence and lesion diameter by 40% and 62%, respectively. The two isolates were compared with Pseudomonas syringae MA-4, a biocontrol agent for post-harvest peach diseases, by immersing peaches in an aliquot containing individual microbial isolates and the pathogen conidia. Treatments with isolates MA-4, C06 and T03-c significantly controlled brown rot by 91, 100, and 100% respectively. However, only isolates MA-4 and C06 significantly reduced brown rot by 80% and 15%, respectively when bacterial cells alone were applied. On naturally infected peaches, both the bacterial culture and its cell-free filtrate of the isolate C06 significantly controlled peach decay resulting in 77 and 90% reduction, respectively, whereas the treatment using only the bacterial cells generally had no effect. Isolate C06 is a single colony isolate obtained from a mesophilic cheese starter, and has been identified belonging to Bacillus amyloliquefaciens. The results have clearly

Selective flowers to attract and enhance Telenomus laeviceps (Hymenoptera: Scelionidae): a released biocontrol agent of Mamestra brassicae (Lepidoptera: Noctuidae).

PubMed

Barloggio, G; Tamm, L; Nagel, P; Luka, H

2018-05-10

The importance of the right food source for the survival and reproduction of certain insect species is well documented. In the case of biocontrol agents, this is even more important in order to reach a high predation or parasitation performance. The egg parasitoid Telenomus laeviceps (Förster, 1861) (Hymenoptera: Scelionidae) is a promising candidate for mass release as a biological control agent of the cabbage moth Mamestra brassicae (Linnaeus, 1758) (Lepidoptera: Noctuidae). However, adult T. laeviceps need a sugar-rich food source to increase their parasitation performance and produce a good amount of female offspring. Released biocontrol agents were shown to benefit from conservation biocontrol, which includes the provision of selected flowers as nectar resources for beneficial insects. In Switzerland, Centaurea cyanus L. (Asteraceae), Fagopyrum esculentum Moench (Polygonaceae) and Vicia sativa L. (Fabaceae) are successfully implemented in the field to attract and promote natural enemies of different cabbage pests. In this study, we investigated the potential of these selected flowers to attract and promote T. laeviceps under laboratory conditions. In Y-tube olfactometer experiments, we first tested whether the three nectar providing plant species are attractive to T. laeviceps. Furthermore, we assessed their effects on survival and parasitation performance of adult T. laeviceps. We found that flowers of F. esculentum and C. cyanus were attractive in contrast to V. sativa. Also fecundity and the number of female offspring produced were higher for females kept on F. esculentum and C. cyanus than on V. sativa. In contrast, survival was similar on all treatments. Our findings present a further key step towards the implementation of T. laeviceps as a biocontrol agent.

Biocontrol agent Bacillus amyloliquefaciens LJ02 induces systemic resistance against cucurbits powdery mildew.

PubMed

Li, Yunlong; Gu, Yilin; Li, Juan; Xu, Mingzhu; Wei, Qing; Wang, Yuanhong

2015-01-01

Powdery mildew is a fungal disease found in a wide range of plants and can significantly reduce crop yields. Bacterial strain LJ02 is a biocontrol agent (BCA) isolated from a greenhouse in Tianjin, China. In combination of morphological, physiological, biochemical and phylogenetic analyses, strain LJ02 was classified as a new member of Bacillus amyloliquefaciens. Greenhouse trials showed that LJ02 fermentation broth (LJ02FB) can effectively diminish the occurrence of cucurbits powdery mildew. When treated with LJ02FB, cucumber seedlings produced significantly elevated production of superoxide dismutase, peroxidase, polyphenol oxidase and phenylalanine ammonia lyase as compared to that of the control. We further confirmed that the production of free salicylic acid (SA) and expression of one pathogenesis-related (PR) gene PR-1 in cucumber leaves were markedly elevated after treating with LJ02FB, suggesting that SA-mediated defense response was stimulated. Moreover, LJ02FB-treated cucumber leaves could secrete resistance-related substances into rhizosphere that inhibit the germination of fungi spores and the growth of pathogens. Finally, we separated bacterium and its fermented substances to test their respective effects and found that both components have SA-inducing activity and bacterium plays major roles. Altogether, we identified a BCA against powdery mildew and its mode of action by inducing systemic resistance such as SA signaling pathway.

Fungal Genomics for Energy and Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grigoriev, Igor V.

2013-03-11

Genomes of fungi relevant to energy and environment are in focus of the Fungal Genomic Program at the US Department of Energy Joint Genome Institute (JGI). One of its projects, the Genomics Encyclopedia of Fungi, targets fungi related to plant health (symbionts, pathogens, and biocontrol agents) and biorefinery processes (cellulose degradation, sugar fermentation, industrial hosts) by means of genome sequencing and analysis. New chapters of the Encyclopedia can be opened with user proposals to the JGI Community Sequencing Program (CSP). Another JGI project, the 1000 fungal genomes, explores fungal diversity on genome level at scale and is open for usersmore » to nominate new species for sequencing. Over 200 fungal genomes have been sequenced by JGI to date and released through MycoCosm (www.jgi.doe.gov/fungi), a fungal web-portal, which integrates sequence and functional data with genome analysis tools for user community. Sequence analysis supported by functional genomics leads to developing parts list for complex systems ranging from ecosystems of biofuel crops to biorefineries. Recent examples of such parts suggested by comparative genomics and functional analysis in these areas are presented here.« less

Encountering epidemic effects of leaf spot disease (Alternaria brassicae) on Aloe vera by fungal biocontrol agents in agrifields-An ecofriendly approach.

PubMed

Ghosh, Swapan Kumar; Banerjee, Subhankar; Pal, Sujoy; Chakraborty, Niloy

2018-01-01

Aloe vera (L.) Burm.f. is a highly important and extensively cultivated medicinal plant and that is also extensively used in the cosmetic industry. It has been frequently reported to suffer from Alternaria leaf spot disease in various parts of the world. Various fungicides used to combat this disease, have deleterious effects on the environment and on pharmacologically important constituents of Aloe vera. To avoid the harmful effects of fungicides an ecofriendly approach has been adopted here. A weekly survey was conducted during 2013-2015 in and around North 24 Parganas (West Bengal) to obtain the percentage of disease index (PDI). For biological control of the disease, screening of the antagonistic efficacy of biocontrol agents was carried out through the in vitro dual-culture-plate method and scanning electron microscopy (SEM) was used to study the mechanism. The in vitro effects of fungicides on the radial growth of the pathogen were evaluated through the poison food method and were compared with potent antagonistic fungi. Field application of potent antagonistic fungi was conducted through the dip-and-spray method. The results showed that, the PDI peaked during the hot and humid conditions of May to September (76.57%-98.57%) but decreased during the winter, December-January (35.71-46.66%). Trichoderma asperellum exerted the greatest inhibition of the radial growth of A. brassicae acting through non volatile (70.39%) and volatile metabolites (72.17%). A SEM study confirmed the hyperparasitic nature of T. asperellum through hyphal coiling-T. asperellum was similar to 2% blitox-50 (73.92%) and better than 2% bavistin (59.77%) (in vitro). In agricultural field trials (2013-15), Trichoderma application restricted the disease to the smallest area (PDI 24.00-29.33%) in comparison to untreated plots (73.33%). In conclusion, saplings treated with the dip method (108 spores / mL) and sprayed 4 times with a spore suspension of biocontrol agents such as T. asperellum, T

Encountering epidemic effects of leaf spot disease (Alternaria brassicae) on Aloe vera by fungal biocontrol agents in agrifields—An ecofriendly approach

PubMed Central

Banerjee, Subhankar; Pal, Sujoy; Chakraborty, Niloy

2018-01-01

Aloe vera (L.) Burm.f. is a highly important and extensively cultivated medicinal plant and that is also extensively used in the cosmetic industry. It has been frequently reported to suffer from Alternaria leaf spot disease in various parts of the world. Various fungicides used to combat this disease, have deleterious effects on the environment and on pharmacologically important constituents of Aloe vera. To avoid the harmful effects of fungicides an ecofriendly approach has been adopted here. A weekly survey was conducted during 2013–2015 in and around North 24 Parganas (West Bengal) to obtain the percentage of disease index (PDI). For biological control of the disease, screening of the antagonistic efficacy of biocontrol agents was carried out through the in vitro dual-culture-plate method and scanning electron microscopy (SEM) was used to study the mechanism. The in vitro effects of fungicides on the radial growth of the pathogen were evaluated through the poison food method and were compared with potent antagonistic fungi. Field application of potent antagonistic fungi was conducted through the dip-and-spray method. The results showed that, the PDI peaked during the hot and humid conditions of May to September (76.57%–98.57%) but decreased during the winter, December-January (35.71–46.66%). Trichoderma asperellum exerted the greatest inhibition of the radial growth of A. brassicae acting through non volatile (70.39%) and volatile metabolites (72.17%). A SEM study confirmed the hyperparasitic nature of T. asperellum through hyphal coiling-T. asperellum was similar to 2% blitox-50 (73.92%) and better than 2% bavistin (59.77%) (in vitro). In agricultural field trials (2013–15), Trichoderma application restricted the disease to the smallest area (PDI 24.00–29.33%) in comparison to untreated plots (73.33%). In conclusion, saplings treated with the dip method (108 spores / mL) and sprayed 4 times with a spore suspension of biocontrol agents such as T

Biocontrol ability and putative mode of action of yeasts against Geotrichum citri-aurantii in citrus fruit.

PubMed

Ferraz, Luriany Pompeo; Cunha, Tatiane da; da Silva, Aline Caroline; Kupper, Katia Cristina

2016-01-01

Sour rot is a major postharvest disease of citrus fruit and is caused by the fungal pathogen Geotrichum citri-aurantii. A lack of chemicals certified for the control of this disease has led to the consideration of alternative methods and strategies, such as the use of yeasts as biocontrol agents. The purpose of the present study was to test the ability of yeasts isolated from leaves, flowers, fruit, and soil, and six Saccharomyces cerevisiae isolates to control citrus sour rot, to assess the mechanisms of action of the yeast isolates that were demonstrated to be effective for biocontrol, and to identify the most effective yeast isolates for the biocontrol of G. citri-aurantii. In in vivo assays, three yeast isolates (ACBL-23, ACBL-44, and ACBL-77) showed a potential for controlling sour rot in citrus fruits, both preventatively and curatively. Most of the eight yeast isolates that were assessed for a mechanism of action did not produce antifungal compounds in an amount sufficient to inhibit the growth of the pathogen. Additionally, nutrient competition among the yeast strains was not found to be a biocontrol strategy. Instead, killer activity and hydrolytic enzyme production were identified as the major mechanisms involved in the biocontrol activity of the yeasts. Isolates ACBL-23, ACBL-44, and ACBL-77, which controlled sour rot most effectively, were identified as Rhodotorula minuta, Candida azyma, and Aureobasidium pullulans, respectively. To our knowledge, this is the first report of the potential of C. azyma as a biological control agent against a postharvest pathogen and its ability to produce a killer toxin. Copyright © 2016 Elsevier GmbH. All rights reserved.

Impact of a Recombinant Biocontrol Bacterium, Pseudomonas fluorescens pc78, on Microbial Community in Tomato Rhizosphere.

PubMed

Kong, Hyun Gi; Kim, Nam Hee; Lee, Seung Yeup; Lee, Seon-Woo

2016-04-01

Pseudomonas fluorescens pc78 is an effective biocontrol agent for soil-borne fungal diseases. We previously constructed a P43-gfp tagged biocontrol bacteria P. fluorescens pc78-48 to investigate bacterial traits in natural ecosystem and the environmental risk of genetically modified biocontrol bacteria in tomato rhizosphere. Fluctuation of culturable bacteria profile, microbial community structure, and potential horizontal gene transfer was investigated over time after the bacteria treatment to the tomato rhizosphere. Tagged gene transfer to other organisms such as tomato plants and bacteria cultured on various media was examined by polymerase chain reaction, using gene specific primers. Transfer of chromosomally integrated P43-gfp from pc78 to other organisms was not apparent. Population and colony types of culturable bacteria were not significantly affected by the introduction of P. fluorescens pc78 or pc78-48 into tomato rhizosphere. Additionally, terminal restriction fragment length polymorphism profiles were investigated to estimate the influence on the microbial community structure in tomato rhizosphere between non-treated and pc78-48-treated samples. Interestingly, rhizosphere soil treated with strain pc78-48 exhibited a significantly different bacterial community structure compared to that of non-treated rhizosphere soil. Our results suggest that biocontrol bacteria treatment influences microbial community in tomato rhizosphere, while the chromosomally modified biocontrol bacteria may not pose any specific environmental risk in terms of gene transfer.

Selection and evaluation of micro-organisms for biocontrol of Verticillium dahliae in olive.

PubMed

Varo, A; Raya-Ortega, M C; Trapero, A

2016-09-01

To identify potential biological control agents against Verticillium wilt in olive through a mass screening approach. A total of 47 strains and nine mixtures of micro-organisms were evaluated against Verticillium dahliae in a three stage screening: (i) in vitro, by the effect on the mycelial growth and spore germination of the pathogen; (ii) in natural infested soil, by the effect on the reduction of microsclerotia of the pathogen; (iii) in planta, by the effect on the infection of olive plants under controlled conditions. Various fungal and bacterial strains and mixtures inhibited the pathogen and showed consistent biocontrol activity against Verticillium wilt of olive. The screening has resulted in promising fungi and bacteria strains with antagonistic activity against Verticillium, such as two non-pathogenic Fusarium oxysporum, one Phoma sp., one Pseudomonas fluorescens and two mixtures of micro-organisms that may possess multiple modes of action. This study provides a practical basis for the potential use of selected strains as biocontrol agents for the protection of olive plants against V. dahliae infection. In addition, our study presented an effective method to evaluate antagonistic micro-organisms of V. dahliae in olive. © 2016 The Society for Applied Microbiology.

Mycotoxigenic Fusarium and Deoxynivalenol Production Repress Chitinase Gene Expression in the Biocontrol Agent Trichoderma atroviride P1

PubMed Central

Lutz, Matthias P.; Feichtinger, Georg; Défago, Geneviève; Duffy, Brion

2003-01-01

repression was specific for nag1-gox and had no effect, either positive or negative, on expression of another key chitinase gene, ech42. This is the first demonstration that a target pathogen down-regulates genes in a fungal biocontrol agent, and our results provide evidence that mycotoxins have a novel ecological function as factors in Fusarium competitiveness. PMID:12788701

RNA Interference of Endochitinases in the Sugarcane Endophyte Trichoderma virens 223 Reduces Its Fitness as a Biocontrol Agent of Pineapple Disease

PubMed Central

Romão-Dumaresq, Aline S.; de Araújo, Welington Luiz; Talbot, Nicholas J.; Thornton, Christopher R.

2012-01-01

The sugarcane root endophyte Trichoderma virens 223 holds enormous potential as a sustainable alternative to chemical pesticides in the control of sugarcane diseases. Its efficacy as a biocontrol agent is thought to be associated with its production of chitinase enzymes, including N-acetyl-ß-D-glucosaminidases, chitobiosidases and endochitinases. We used targeted gene deletion and RNA-dependent gene silencing strategies to disrupt N-acetyl-ß-D-glucosaminidase and endochitinase activities of the fungus, and to determine their roles in the biocontrol of soil-borne plant pathogens. The loss of N-acetyl-ß-D-glucosaminidase activities was dispensable for biocontrol of the plurivorous damping-off pathogens Rhizoctonia solani and Sclerotinia sclerotiorum, and of the sugarcane pathogen Ceratocystis paradoxa, the causal agent of pineapple disease. Similarly, suppression of endochitinase activities had no effect on R. solani and S. sclerotiorum disease control, but had a pronounced effect on the ability of T. virens 223 to control pineapple disease. Our work demonstrates a critical requirement for T. virens 223 endochitinase activity in the biocontrol of C. paradoxa sugarcane disease, but not for general antagonism of other soil pathogens. This may reflect its lifestyle as a sugarcane root endophyte. PMID:23110120

Tailoring biocontrol to maximize top-down effects: on the importance of underlying site fertility.

PubMed

Hovick, Stephen M; Carson, Walter P

2015-01-01

The degree to which biocontrol agents impact invasive plants varies widely across landscapes, often for unknown reasons. Understanding this variability can help optimize invasive species management while also informing our understanding of trophic linkages. To address these issues, we tested three hypotheses with contrasting predictions regarding the likelihood of biocontrol success. (1) The biocontrol effort hypothesis: invasive populations are regulated primarily by top-down effects, predicting that increased biocontrol efforts alone (e.g., more individuals of a given biocontrol agent or more time since agent release) will enhance biocontrol success. (2) The relative fertility hypothesis: invasive populations are regulated primarily by bottom-up effects, predicting that nutrient enrichment will increase dominance by invasives and thus reduce biocontrol success, regardless of biocontrol efforts. (3) The fertility-dependent biocontrol effort hypothesis: top-down effects will only regulate invasive populations if bottom-up effects are weak. It predicts that greater biocontrol efforts will increase biocontrol success, but only in low-nutrient sites. To test these hypotheses, we surveyed 46 sites across three states with prior releases of Galerucella beetles, the most common biocontrol agents used against invasive purple loosestrife (Lythrum salicaria). We found strong support for the fertility-dependent biocontrol effort hypothesis, as biocontrol success occurred most often with greater biocontrol efforts, but only in low-fertility sites. This result held for early stage metrics of biocontrol success (higher Galerucella abundance) and ultimate biocontrol outcomes (decreased loosestrife plant size and abundance). Presence of the invasive grass Phalaris arundinacea was also inversely related to loosestrife abundance, suggesting that biocontrol-based reductions in loosestrife made secondary invasion by P. arundinacea more likely. Our data suggest that low-nutrient sites

The biocontrol agent Pseudomonas chlororaphis PA23 primes Brassica napus defenses through distinct gene networks.

PubMed

Duke, Kelly A; Becker, Michael G; Girard, Ian J; Millar, Jenna L; Dilantha Fernando, W G; Belmonte, Mark F; de Kievit, Teresa R

2017-06-19

The biological control agent Pseudomonas chlororaphis PA23 is capable of protecting Brassica napus (canola) from the necrotrophic fungus Sclerotinia sclerotiorum via direct antagonism. While we have elucidated bacterial genes and gene products responsible biocontrol, little is known about how the host plant responds to bacterial priming on the leaf surface, including global changes in gene activity in the presence and absence of S. sclerotiorum. Application of PA23 to the aerial surfaces of canola plants reduced the number of S. sclerotiorum lesion-forming petals by 91.1%. RNA sequencing of the host pathogen interface showed that pretreatment with PA23 reduced the number of genes upregulated in response to S. sclerotiorum by 16-fold. By itself, PA23 activated unique defense networks indicative of defense priming. Genes encoding MAMP-triggered immunity receptors detecting flagellin and peptidoglycan were downregulated in PA23 only-treated plants, consistent with post-stimulus desensitization. Downstream, we observed reactive oxygen species (ROS) production involving low levels of H 2 O 2 and overexpression of genes associated with glycerol-3-phosphate (G3P)-mediated systemic acquired resistance (SAR). Leaf chloroplasts exhibited increased thylakoid membrane structures and chlorophyll content, while lipid metabolic processes were upregulated. In addition to directly antagonizing S. sclerotiorum, PA23 primes the plant defense response through induction of unique local and systemic defense networks. This study provides novel insight into the effects of biocontrol agents applied to the plant phyllosphere. Understanding these interactions will aid in the development of biocontrol systems as an alternative to chemical pesticides for protection of important crop systems.

Integrated effect of gamma radiation and biocontrol agent on quality parameters of apple fruit: An innovative commercial preservation method

NASA Astrophysics Data System (ADS)

Ahari Mostafavi, Hossein; Mahyar Mirmajlessi, Seyed; Fathollahi, Hadi; Shahbazi, Samira; Mohammad Mirjalili, Seyed

2013-10-01

Effects of gamma irradiation and biocontrol agent (Pseudomonas fluorescens) on the physico-chemical parameters (including moisture, total soluble solids, antioxidant activity, phenolic content and firmness) of cv. Golden Delicious apples were investigated for their ability to avoid the post-harvest blue mold caused by Penicillium expansum during cold storage. Freshly harvested apples were inoculated with P. expansum. Treated fruits were irradiated at doses of 0, 200, 400, 600 and 800 Gy and then inoculated with P. fluorescens suspension. Samples were evaluated at 3 month intervals. The results demonstrated a clear link between antioxidant activity and phenolic content, so that dose range of 200-400 Gy significantly increased phenolic content and antioxidant activity. Effect of P. fluorescens was similar to irradiation at 200 and 400 Gy that could prevent lesion diameter in pathogen-treated apples. As dose and storage time increased firmness decreased but, combination of P. fluorescens as well as irradiation (at 200-400 Gy) could decrease softening apple fruits during storage. In all parameters, P. fluorescens (as biocontrol agent) inhibited P. expansum similar to irradiation at 200-400 Gy. So, integrated treatment of irradiation and biocontrol agent explored the potential dual benefit of low doses (200 and 400 Gy) as a suitable method to sustain physico-chemical quality and conclusively reduce apple fruits losses during post-harvest preservation.

Complete Genome Sequence of Ralstonia solanacearum FJAT-1458, a Potential Biocontrol Agent for Tomato Wilt.

PubMed

Chen, Deju; Liu, Bo; Zhu, Yujing; Wang, Jieping; Chen, Zheng; Che, Jiamei; Zheng, Xuefang; Chen, Xiaoqiang

2017-04-06

An avirulent strain of Ralstonia solanacearum FJAT-1458 was isolated from a living tomato. Here, we report the complete R. solanacearum FJAT-1458 genome sequence of 6,059,899 bp and 5,241 genes. This bacterial strain is a potential candidate as a biocontrol agent in the form of a plant vaccine for bacterial wilt. Copyright © 2017 Chen et al.

Striga Biocontrol on a Toothpick: A Readily Deployable and Inexpensive Method for Smallholder Farmers.

PubMed

Nzioki, Henry S; Oyosi, Florence; Morris, Cindy E; Kaya, Eylul; Pilgeram, Alice L; Baker, Claire S; Sands, David C

2016-01-01

Striga hermonthica (witchweed) is a parasitic weed that attacks and significantly reduces the yields of maize, sorghum, millet, and sugarcane throughout sub-Saharan Africa. Low cost management methods such as hand weeding, short crop rotations, trap cropping, or conventional biocontrol have not been effective. Likewise, Striga-tolerant or herbicide-resistant maize cultivars are higher yielding, but are often beyond the economic means of sustenance farmers. The fungal pathogen, Fusarium oxysporum f.sp. strigae, has been the object of numerous studies to develop Striga biocontrol. Under experimental conditions this pathogen can reduce the incidence of Striga infestation but field use is not extensive, perhaps because it has not been sufficiently effective in restoring crop yield and reducing the soil Striga seed bank. Here we brought together Kenyan and US crop scientists with smallholder farmers to develop and validate an effective biocontrol strategy for management of Striga on smallholder farms. Key components of this research project were the following: (1) Development of a two-step method of fungal delivery, including laboratory coating of primary inoculum on toothpicks, followed by on-farm production of secondary field inoculum in boiled rice enabling delivery of vigorous, fresh inoculum directly to the seedbed; (2) Training of smallholder farmers (85% women), to produce the biocontrol agent and incorporate it into their maize plantings in Striga-infested soils and collect agronomic data. The field tests expanded from 30 smallholder farmers to a two-season, 500-farmer plot trial including paired plus and minus biocontrol plots with fertilizer and hybrid seed in both plots and; (3) Concerted selection of variants of the pathogen identified for enhanced virulence, as has been demonstrated in other host parasite systems were employed here on Striga via pathogen excretion of the amino acids L-leucine and L-tyrosine that are toxic to Striga but innocuous to maize

Striga Biocontrol on a Toothpick: A Readily Deployable and Inexpensive Method for Smallholder Farmers

PubMed Central

Nzioki, Henry S.; Oyosi, Florence; Morris, Cindy E.; Kaya, Eylul; Pilgeram, Alice L.; Baker, Claire S.; Sands, David C.

2016-01-01

Striga hermonthica (witchweed) is a parasitic weed that attacks and significantly reduces the yields of maize, sorghum, millet, and sugarcane throughout sub-Saharan Africa. Low cost management methods such as hand weeding, short crop rotations, trap cropping, or conventional biocontrol have not been effective. Likewise, Striga-tolerant or herbicide-resistant maize cultivars are higher yielding, but are often beyond the economic means of sustenance farmers. The fungal pathogen, Fusarium oxysporum f.sp. strigae, has been the object of numerous studies to develop Striga biocontrol. Under experimental conditions this pathogen can reduce the incidence of Striga infestation but field use is not extensive, perhaps because it has not been sufficiently effective in restoring crop yield and reducing the soil Striga seed bank. Here we brought together Kenyan and US crop scientists with smallholder farmers to develop and validate an effective biocontrol strategy for management of Striga on smallholder farms. Key components of this research project were the following: (1) Development of a two-step method of fungal delivery, including laboratory coating of primary inoculum on toothpicks, followed by on-farm production of secondary field inoculum in boiled rice enabling delivery of vigorous, fresh inoculum directly to the seedbed; (2) Training of smallholder farmers (85% women), to produce the biocontrol agent and incorporate it into their maize plantings in Striga-infested soils and collect agronomic data. The field tests expanded from 30 smallholder farmers to a two-season, 500-farmer plot trial including paired plus and minus biocontrol plots with fertilizer and hybrid seed in both plots and; (3) Concerted selection of variants of the pathogen identified for enhanced virulence, as has been demonstrated in other host parasite systems were employed here on Striga via pathogen excretion of the amino acids L-leucine and L-tyrosine that are toxic to Striga but innocuous to maize

Evaluation of Rhodosporidium fluviale as biocontrol agent against Botrytis cinerea on apple fruit.

PubMed

Sansone, G; Lambrese, Y; Calvente, V; Fernández, G; Benuzzi, D; Sanz Ferramola, M

2018-05-01

The aim of the present work was to evaluate the ability of the native yeast Rhodosporidium fluviale to control Botrytis cinerea on apple fruit and to study the possible mechanisms of action with the goal of improving the control of gray mold. For this, the influence of application time of the yeast was studied simulating preventive and curative effects. Also, the effect of nonviable cells of the yeast in the biocontrol was assessed. According to the results obtained, the following mechanisms of action of R. fluviale could be proposed: 1- competition for space, 2- direct interaction between antagonist and pathogen, 3- induction of β-1,3-glucanase in apple tissue, 4- Probable production of glucanase in the apple wounds and 5- antifungal action of cellular components, probably chitin, present in the wall of yeast cells that could be the explanation for the activity of nonviable cells. Significance and Impact of the Study: Botrytis cinerea Pers: Fr, which causes gray mold of fruits and vegetables around the world, is difficult to control successfully because it is genetically variable and rapidly develops resistance to the chemicals commonly used for its control. This study is a contribution to the biocontrol of this phytopathogen fungus. The evaluation of the native yeast Rhodosporidium fluviale as biocontrol agent and the elucidation of possible mechanisms of action, including the participation of nonviable cells of this yeast, have not been reported up to date. © 2018 The Society for Applied Microbiology.

Evaluation of yeasts obtained from Antarctic soil samples as biocontrol agents for the management of postharvest diseases of apple (Malus × domestica).

PubMed

Vero, Silvana; Garmendia, Gabriela; González, M Belén; Bentancur, Oscar; Wisniewski, Michael

2013-03-01

Psychrotrophic yeasts were isolated from Antarctic soils, selected based on their ability to grow in apple juice at low temperatures, and were evaluated as potential biocontrol agents for the management of postharvest diseases of apple during cold storage. Among the species recovered, an isolate of Leucosporidium scottii, designated At17, was identified as a good biocontrol agent for blue and gray mold of two apple cultivars. The selected isolate produced soluble and volatile antifungal substances that were inhibitory to apple pathogens. Siderophore production was also demonstrated, but it did not appear to play a role in pathogen inhibition. The selected yeast had the capacity to form a biofilm when grown in apple juice, which is considered an important attribute of postharvest antagonists to successfully colonize wounds and intact fruit surfaces. At17 was resistant to commonly used postharvest fungicides, so application of a combination of low-dose fungicide along with the biocontrol agent could be used as an integrated management practice. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Biocontrol of Aspergillus Species on Peanut Kernels by Antifungal Diketopiperazine Producing Bacillus cereus Associated with Entomopathogenic Nematode

PubMed Central

Kumar, Sasidharan Nishanth; Sreekala, Sreerag Ravikumar; Chandrasekaran, Dileep; Nambisan, Bala; Anto, Ruby John

2014-01-01

The rhabditid entomopathogenic nematode associated Bacillus cereus and the antifungal compounds produced by this bacterium were evaluated for their activity in reducing postharvest decay of peanut kernels caused by Aspergillus species in in vitro and in vivo tests. The results showed that B. cereus had a significant effect on biocontrol effectiveness in in vitro and in vivo conditions. The antifungal compounds produced by the B. cereus were purified using silica gel column chromatography and their structure was elucidated using extensive spectral analyses. The compounds were identified as diketopiperazines (DKPs) [cyclo-(L-Pro-Gly), cyclo(L-Tyr-L-Tyr), cyclo-(L-Phe-Gly) and cyclo(4-hydroxy-L-Pro-L-Trp)]. The antifungal activities of diketopiperazines were studied against five Aspergillus species and best MIC of 2 µg/ml was recorded against A. flavus by cyclo(4-hydroxy-L-Pro-L-Trp). To investigate the potential application of cyclo(4-hydroxy-L-Pro-L-Trp) to eliminate fungal spoilage in food and feed, peanut kernels was used as a food model system. White mycelia and dark/pale green spores of Aspergillus species were observed in the control peanut kernels after 2 days incubation. However the fungal growth was not observed in peanut kernels treated with cyclo(4-hydroxy-L-Pro-L-Trp). The cyclo(4-hydroxy-L-Pro-L-Trp) was nontoxic to two normal cell lines [fore skin (FS) normal fibroblast and African green monkey kidney (VERO)] up to 200 µg/ml in MTT assay. Thus the cyclo(4-hydroxy-L-Pro-L-Trp) identified in this study may be a promising alternative to chemical preservatives as a potential biopreservative agent which prevent fungal growth in food and feed. To the best of our knowledge, this is the first report demonstrating that the entomopathogenic nematode associated B. cereus and cyclo(4-hydroxy-L-Pro-L-Trp) could be used as a biocontrol agents against postharvest fungal disease caused by Aspergillus species. PMID:25157831

Impact of Biocontrol Pseudomonas fluorescens CHA0 and a Genetically Modified Derivative on the Diversity of Culturable Fungi in the Cucumber Rhizosphere

PubMed Central

Girlanda, M.; Perotto, S.; Moenne-Loccoz, Y.; Bergero, R.; Lazzari, A.; Defago, G.; Bonfante, P.; Luppi, A. M.

2001-01-01

Little is known about the effects of Pseudomonas biocontrol inoculants on nontarget rhizosphere fungi. This issue was addressed using the biocontrol agent Pseudomonas fluorescens CHA0-Rif, which produces the antimicrobial polyketides 2,4-diacetylphloroglucinol (Phl) and pyoluteorin (Plt) and protects cucumber from several fungal pathogens, including Pythium spp., as well as the genetically modified derivative CHA0-Rif(pME3424). Strain CHA0-Rif(pME3424) overproduces Phl and Plt and displays improved biocontrol efficacy compared with CHA0-Rif. Cucumber was grown repeatedly in the same soil, which was left uninoculated, was inoculated with CHA0-Rif or CHA0-Rif(pME3424), or was treated with the fungicide metalaxyl (Ridomil). Treatments were applied to soil at the start of each 32-day-long cucumber growth cycle, and their effects on the diversity of the rhizosphere populations of culturable fungi were assessed at the end of the first and fifth cycles. Over 11,000 colonies were studied and assigned to 105 fungal species (plus several sterile morphotypes). The most frequently isolated fungal species (mainly belonging to the genera Paecilomyces, Phialocephala, Fusarium, Gliocladium, Penicillium, Mortierella, Verticillium, Trichoderma, Staphylotrichum, Coniothyrium, Cylindrocarpon, Myrothecium, and Monocillium) were common in the four treatments, and no fungal species was totally suppressed or found exclusively following one particular treatment. However, in each of the two growth cycles studied, significant differences were found between treatments (e.g., between the control and the other treatments and/or between the two inoculation treatments) using discriminant analysis. Despite these differences in the composition and/or relative abundance of species in the fungal community, treatments had no effect on species diversity indices, and species abundance distributions fit the truncated lognormal function in most cases. In addition, the impact of treatments at the 32-day

Impact of biocontrol Pseudomonas fluorescens CHA0 and a genetically modified derivative on the diversity of culturable fungi in the cucumber rhizosphere.

PubMed

Girlanda, M; Perotto, S; Moenne-Loccoz, Y; Bergero, R; Lazzari, A; Defago, G; Bonfante, P; Luppi, A M

2001-04-01

Little is known about the effects of Pseudomonas biocontrol inoculants on nontarget rhizosphere fungi. This issue was addressed using the biocontrol agent Pseudomonas fluorescens CHA0-Rif, which produces the antimicrobial polyketides 2,4-diacetylphloroglucinol (Phl) and pyoluteorin (Plt) and protects cucumber from several fungal pathogens, including Pythium spp., as well as the genetically modified derivative CHA0-Rif(pME3424). Strain CHA0-Rif(pME3424) overproduces Phl and Plt and displays improved biocontrol efficacy compared with CHA0-Rif. Cucumber was grown repeatedly in the same soil, which was left uninoculated, was inoculated with CHA0-Rif or CHA0-Rif(pME3424), or was treated with the fungicide metalaxyl (Ridomil). Treatments were applied to soil at the start of each 32-day-long cucumber growth cycle, and their effects on the diversity of the rhizosphere populations of culturable fungi were assessed at the end of the first and fifth cycles. Over 11,000 colonies were studied and assigned to 105 fungal species (plus several sterile morphotypes). The most frequently isolated fungal species (mainly belonging to the genera Paecilomyces, Phialocephala, Fusarium, Gliocladium, Penicillium, Mortierella, Verticillium, Trichoderma, Staphylotrichum, Coniothyrium, Cylindrocarpon, Myrothecium, and Monocillium) were common in the four treatments, and no fungal species was totally suppressed or found exclusively following one particular treatment. However, in each of the two growth cycles studied, significant differences were found between treatments (e.g., between the control and the other treatments and/or between the two inoculation treatments) using discriminant analysis. Despite these differences in the composition and/or relative abundance of species in the fungal community, treatments had no effect on species diversity indices, and species abundance distributions fit the truncated lognormal function in most cases. In addition, the impact of treatments at the 32-day

Biocontrol of Botrytis cinerea and Calonectria gracilis by eucalypts growth promoters Bacillus spp.

PubMed

Paz, Isabel Cristina Padula; Santin, Rita de Cássia Madail; Guimarães, Alexandre Martins; Rosa, Osmar Paulo Pereira da; Quecine, Maria Carolina; Silva, Michele de Cássia Pereira E; Azevedo, João Lúcio; Matsumura, Aida Terezinha Santos

2018-05-17

The clonal Eucalyptus plants are commonly obtained by vegetative propagation under a protected environment. This system improves the Botrytis cinerea and Calonectria spp infection on the young eucalypts plantings, resulting gray mold and cutting rot respectively. Currently, the unique available control method is based on chemicals. As alternative, novel methods to manage plant diseases, endophytic microorganisms could be an interesting alternative. Thus, we aimed to evaluate endophytic Bacillus isolated from eucalypts as a biocontrol agent against Botrytis cinerea and Calonectria gracilis, important fungal pathogens in the greenhouse, using clonal plantlets of E. urograndis. Eight endophytic strains of Bacillus, previously described as eucalyptus growth promoters, were evaluated in vitro and in vivo against Botrytis cinerea and Calonectria gracilis. The diffusible metabolites assay showed the potential of endophytic Bacillus to decrease the growth of both pathogens. Differences in the susceptibility of the pathogens to bacterial volatile metabolites were observed, B. cinerea showed more susceptible than Calonectria gracilis. In vivo assays, Bacillus amyloliquefaciens EUCB 10 demonstrated better overall reductions in these diseases. Based on the results obtained from the in vitro and in vivo analyses, we suggest that the endophytic B. amyloliquefaciens strain EUCB 10 constitutes a promising biocontrol agent against B. cinerea and Calonectria gracilis. Furthermore, this is the first reporting of B. amyloliquefaciens previously describe as plant growth promoter and also as potential control agent of B. cinerea and Calonectria gracilis to eucalyptus. Copyright © 2018 Elsevier Ltd. All rights reserved.

Approaches for monitoring the release of Pochonia chlamydosporia var. catenulata, a biocontrol agent of root-knot nematodes.

PubMed

Atkins, Simon D; Hidalgo-Diaz, Leopoldo; Clark, Ian M; Morton, C Oliver; de Oca, Nivian Montes; Gray, Paul A; Kerry, Brian R

2003-02-01

Pochonia chlamydosporia var. catenulata is a potential biocontrol agent against root-knot nematodes. Diagnosis of isolates has relied on morphological identification, and is both time-consuming and difficult. beta-tubulin primers have been developed for the identification of this fungus that were specific enough to distinguish between varieties of the fungus within the same species. Separate primers have been developed for the specific detection of P. chlamydosporia var. catenulata based on ITS sequences, which were able to detect the fungus in soil from various sites in Cuba where the biocontrol agent had been added. When the PCR diagnosis was combined with serial dilution of soil samples on selective medium, colonies were rapidly identified. The fungus was still present, albeit at low densities, in soils inoculated five years previously. The development of a baiting method allowed quick in situ screening of the isolates' ability to infect nematode eggs, and when combined with PCR diagnosis both varieties of the fungus could be detected in infected eggs. RFLP analysis of ITS sequences from P. chlamydosporia provided an extra level of discrimination between isolates.

The vegetative compatibility group to which the US biocontrol agent Aspergillus flavus AF36 belongs is also endemic to Mexico.

PubMed

Ortega-Beltran, A; Grubisha, L C; Callicott, K A; Cotty, P J

2016-04-01

To assess frequencies of the Aspergillus flavus atoxigenic vegetative compatibility group (VCG) YV36, to which the biocontrol agent AF36 belongs, in maize-growing regions of Mexico. Over 3500 A. flavus isolates recovered from maize agroecosystems in four states of Mexico during 2005 through 2008 were subjected to vegetative compatibility analyses based on nitrate nonutilizing mutants. Results revealed that 59 (1·6%) isolates belong to VCG YV36. All 59 isolates had the MAT1-2 idiomorph at the mating-type locus and the single nucleotide polymorphism in the polyketide synthase gene that confers atoxigenicity. Additional degradation of the aflatoxin gene cluster was detected in three isolates. Microsatellite loci analyses revealed low levels of genetic diversity and no linkage disequilibrium within VCG YV36. The VCG to which the biocontrol agent AF36 belongs, YV36, is also native to Mexico. The North American Free Trade Agreement should facilitate adoption of AF36 for use by Mexico in aflatoxin prevention programs. An USEPA registered biocontrol agent effective at preventing aflatoxin contamination of crops in the US, is also native to Mexico. This should facilitate the path to registration of AF36 as the first biopesticide for aflatoxin mitigation of maize in Mexico. Economic and health benefits to the population of Mexico should result once aflatoxin mitigation programs based on AF36 applications are implemented. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Characterization of Novel Trichoderma asperellum Isolates to Select Effective Biocontrol Agents Against Tomato Fusarium Wilt

PubMed Central

El_Komy, Mahmoud H.; Saleh, Amgad A.; Eranthodi, Anas; Molan, Younes Y.

2015-01-01

The use of novel isolates of Trichoderma with efficient antagonistic capacity against Fusarium oxysporum f. sp. lycopersici (FOL) is a promising alternative strategy to pesticides for tomato wilt management. We evaluated the antagonistic activity of 30 isolates of T. asperellum against 4 different isolates of FOL. The production of extracellular cell wall degrading enzymes of the antagonistic isolates was also measured. The random amplified polymorphic DNA (RAPD) method was applied to assess the genetic variability among the T. asperellum isolates. All of the T. asperellum isolates significantly reduced the mycelial growth of FOL isolates but the amount of growth reduction varied significantly as well. There was a correlation between the antagonistic capacity of T. asperellum isolates towards FOL and their lytic enzyme production. Isolates showing high levels of chitinase and β-1,3-glucanase activities strongly inhibited the growth of FOL isolates. RAPD analysis showed a high level of genetic variation among T. asperellum isolates. The UPGMA dendrogram revealed that T. asperellum isolates could not be grouped by their anta- gonistic behavior or lytic enzymes production. Six isolates of T. asperellum were highly antagonistic towards FOL and potentially could be used in commercial agriculture to control tomato wilt. Our results are consistent with the conclusion that understanding the genetic variation within Trichoderma isolates and their biochemical capabilities are required for the selection of effective indigenous fungal strains for the use as biocontrol agents. PMID:25774110

Endophytic fungi harbored in the root of Sophora tonkinensis Gapnep: Diversity and biocontrol potential against phytopathogens.

PubMed

Yao, Yu Qun; Lan, Fang; Qiao, Yun Ming; Wei, Ji Guang; Huang, Rong Shao; Li, Liang Bo

2017-06-01

This work, for the first time, investigated the diversity of endophytic fungi harbored in the xylem and phloem of the root of Sophora tonkinensis Gapnep from three geographic localities with emphasis on the influence of the tissue type and geographic locality on endophytic fungal communities and their potential as biocontrol agents against phytopathogens of Panax notoginseng. A total of 655 fungal strains representing 47 taxa were isolated. Forty-two taxa (89.4%) were identified but not five taxa (10.6%) according to morphology and molecular phylogenetics. Out of identifiable taxa, the majority of endophyte taxa were Ascomycota (76.6%), followed by Basidiomycota (8.5%) and Zygomycota (4.3%). The alpha-diversity indices indicated that the species diversity of endophytic fungal community harbored in the root of S. tonkinensis was very high. The colonization and species diversity of endophytic fungal communities were significantly influenced by the geographic locality but not tissue type. The geographic locality and tissue type had great effects on the species composition of endophytic fungal communities. Forty-seven respective strains were challenged by three fungal phytopathogens of P. notoginseng and six strains exhibited significant inhibitory activity. It was noteworthy that endophytic Rhexocercosporidium sp. and F. solani strongly inhibited pathogenic F. solani and other fungal phytopathogens of P. notoginseng. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

A Novel Bacteriophage Targeting Cronobacter sakazakii Is a Potential Biocontrol Agent in Foods

PubMed Central

Lee, Ju-Hoon; Bai, Jaewoo; Shin, Hakdong; Kim, Yeran; Park, Bookyung; Heu, Sunggi

2015-01-01

Cronobacter sakazakii is an important pathogen that causes high mortality in infants. Due to its occasional antibiotic resistance, a bacteriophage approach might be an alternative effective method for the control of this pathogen. To develop a novel biocontrol agent using bacteriophages, the C. sakazakii-infecting phage CR5 was newly isolated and characterized. Interestingly, this phage exhibited efficient and relatively durable host lysis activity. In addition, a specific gene knockout study and subsequent complementation experiment revealed that this phage infected the host strain using the bacterial flagella. The complete genome sequence analysis of phage CR5 showed that its genome contains 223,989 bp of DNA, including 231 predicted open reading frames (ORFs), and it has a G+C content of 50.06%. The annotated ORFs were classified into six functional groups (structure, packaging, host lysis, DNA manipulation, transcription, and additional functions); no gene was found to be related to virulence or toxin or lysogen formation, but >80% of the predicted ORFs are unknown. In addition, a phage proteomic analysis using SDS-PAGE and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) revealed that seven phage structural proteins are indeed present, supporting the ORF predictions. To verify the potential of this phage as a biocontrol agent against C. sakazakii, it was added to infant formula milk contaminated with a C. sakazakii clinical isolate or food isolate, revealing complete growth inhibition of the isolates by the addition of phage CR5 when the multiplicity of infection (MOI) was 105. PMID:26497465

Biocontrol activity of surfactin A purified from Bacillus NH-100 and NH-217 against rice bakanae disease.

PubMed

Sarwar, Ambrin; Hassan, Muhammad Nadeem; Imran, Muhammad; Iqbal, Mazhar; Majeed, Saima; Brader, Günter; Sessitsch, Angela; Hafeez, Fauzia Yusuf

2018-04-01

The potential of the Bacillus genus to antagonize phytopathogens is associated with the production of cyclic lipopeptides. Depending upon the type of lipopeptide, they may serve as biocontrol agents that are eco-friendly alternatives to chemical fertilizers. This study evaluates the biocontrol activity of surfactin-producing Bacillus (SPB) strains NH-100 and NH-217 and purified surfactin A from these strains against rice bakanae disease. Biologically active surfactin fractions were purified by HPLC, and surfactin A variants with chain lengths from C12 to C16 were confirmed by LCMS-ESI. In hemolytic assays, a positive correlation between surfactin A production and halo zone formation was observed. The purified surfactin A had strong antifungal activity against Fusarium oxysporum, F. moniliforme, F. solani, Trichoderma atroviride and T. reesei. Maximum fungal growth suppression (84%) was recorded at 2000 ppm against F. moniliforme. Surfactin A retained antifungal activity at different pH levels (5-9) and temperatures (20, 50 and 121 °C). Hydroponic and pot experiments were conducted to determine the biocontrol activity of SPB strains and the purified surfactin A from these strains on Super Basmati rice. Surfactin production in the rice rhizosphere was detected by LCMS-ESI at early growth stages in hydroponics experiments inoculated with SPB strains. However, the maximum yield was observed with a consortium of SPB strains (T4) and purified surfactin A (T5) treatments in the pot experiment. The outcomes of the present study revealed that surfactin A significantly reduced rice bakanae disease by up to 80%. These findings suggest that purified surfactin A could be an effective biocontrol agent against bakanae disease in rice and should be incorporated into strategies for disease management. Copyright © 2018 Elsevier GmbH. All rights reserved.

Response to Thomas et al.: Biocontrol and indirect effects

Treesearch

Dean E. Pearson; Ragan M. Callaway

2004-01-01

In a recent TREE article [1], we identified three categories of unintended indirect effects that can arise from host-specific biological control agents: (i) ecological replacement; (ii) compensatory responses; and (iii) food-web interactions. Although our review focused on the biocontrol of plant pests, we suggested these concepts also apply to the biocontrol...

Population structure of Aspergillus flavus before and after biocontrol treatment

USDA-ARS?s Scientific Manuscript database

Aspergillus flavus is a fungal pathogen of many important crops worldwide. We sampled A. flavus strains from a cornfield in Rocky Mount, North Carolina, over a period of two years. Plots were inoculated at tasselling with either AF36 or NRRL 21882 (=Afla-Guard) biocontrol strains, both of which are ...

An Evaluation of Antifungal Agents for the Treatment of Fungal Contamination in Indoor Air Environments

PubMed Central

Rogawansamy, Senthaamarai; Gaskin, Sharyn; Taylor, Michael; Pisaniello, Dino

2015-01-01

Fungal contamination in indoor environments has been associated with adverse health effects for the inhabitants. Remediation of fungal contamination requires removal of the fungi present and modifying the indoor environment to become less favourable to growth.  This may include treatment of indoor environments with an antifungal agent to prevent future growth. However there are limited published data or advice on chemical agents suitable for indoor fungal remediation. The aim of this study was to assess the relative efficacies of five commercially available cleaning agents with published or anecdotal use for indoor fungal remediation. The five agents included two common multi-purpose industrial disinfectants (Cavicide® and Virkon®), 70% ethanol, vinegar (4.0%−4.2% acetic acid), and a plant-derived compound (tea tree (Melaleuca alternifolia) oil) tested in both a liquid and vapour form. Tea tree oil has recently generated interest for its antimicrobial efficacy in clinical settings, but has not been widely employed for fungal remediation. Each antifungal agent was assessed for fungal growth inhibition using a disc diffusion method against a representative species from two common fungal genera, (Aspergillus fumigatus and Penicillium chrysogenum), which were isolated from air samples and are commonly found in indoor air. Tea tree oil demonstrated the greatest inhibitory effect on the growth of both fungi, applied in either a liquid or vapour form. Cavicide® and Virkon® demonstrated similar, although less, growth inhibition of both genera. Vinegar (4.0%–4.2% acetic acid) was found to only inhibit the growth of P. chrysogenum, while 70% ethanol was found to have no inhibitory effect on the growth of either fungi. There was a notable inhibition in sporulation, distinct from growth inhibition after exposure to tea tree oil, Virkon®, Cavicide® and vinegar. Results demonstrate that common cleaning and antifungal agents differ in their capacity to inhibit the

An evaluation of antifungal agents for the treatment of fungal contamination in indoor air environments.

PubMed

Rogawansamy, Senthaamarai; Gaskin, Sharyn; Taylor, Michael; Pisaniello, Dino

2015-06-02

Fungal contamination in indoor environments has been associated with adverse health effects for the inhabitants. Remediation of fungal contamination requires removal of the fungi present and modifying the indoor environment to become less favourable to growth.  This may include treatment of indoor environments with an antifungal agent to prevent future growth. However there are limited published data or advice on chemical agents suitable for indoor fungal remediation. The aim of this study was to assess the relative efficacies of five commercially available cleaning agents with published or anecdotal use for indoor fungal remediation. The five agents included two common multi-purpose industrial disinfectants (Cavicide® and Virkon®), 70% ethanol, vinegar (4.0%-4.2% acetic acid), and a plant-derived compound (tea tree (Melaleuca alternifolia) oil) tested in both a liquid and vapour form. Tea tree oil has recently generated interest for its antimicrobial efficacy in clinical settings, but has not been widely employed for fungal remediation. Each antifungal agent was assessed for fungal growth inhibition using a disc diffusion method against a representative species from two common fungal genera, (Aspergillus fumigatus and Penicillium chrysogenum), which were isolated from air samples and are commonly found in indoor air. Tea tree oil demonstrated the greatest inhibitory effect on the growth of both fungi, applied in either a liquid or vapour form. Cavicide® and Virkon® demonstrated similar, although less, growth inhibition of both genera. Vinegar (4.0%-4.2% acetic acid) was found to only inhibit the growth of P. chrysogenum, while 70% ethanol was found to have no inhibitory effect on the growth of either fungi. There was a notable inhibition in sporulation, distinct from growth inhibition after exposure to tea tree oil, Virkon®, Cavicide® and vinegar. Results demonstrate that common cleaning and antifungal agents differ in their capacity to inhibit the growth

Optimization of a protective medium for freeze-dried Pichia membranifaciens and application of this biocontrol agent on citrus fruit.

PubMed

Niu, X; Deng, L; Zhou, Y; Wang, W; Yao, S; Zeng, K

2016-07-01

To optimize a protective medium for freeze-dried Pichia membranifaciens and to evaluate biocontrol efficacies of agents against blue and green mould and anthracnose in citrus fruit. Based on the screening assays of saccharides and antioxidants, response surface methodology was used to optimize sucrose, sodium glutamate and skim milk to improve viability of freeze-dried Pi. membranifaciens. Biocontrol assays were conducted between fresh and freeze-dried Pi. membranifaciens against Penicillium italicum, Penicillium digitatum and Colletotrichum gloeosporioides in citrus fruit. Solving the regression equation indicated that the optimal protective medium was 6·06% (w/v) sucrose combined with 3·40% (w/v) sodium glutamate and 5·43% (w/v) skim milk. Pi. membranifaciens freeze-dried in the optimal protective medium showed 76·80% viability, and retained biocontrol efficacy against Pe. italicum, Pe. digitatum and Co. gloeosporioides in citrus fruit. The optimal protective medium showed more effective protective properties than each of the three protectants used alone. The viability of freeze-dried Pi. membranifaciens finally reached 76·80%. Meanwhile, the biocontrol efficacies showed no significant difference between fresh and freeze-dried yeast against Pe. italicum, Pe. digitatum and Co. gloeosporioides in citrus fruit. The results showed the potential value of Pi. membranifaciens CICC 32259 for commercialization. © 2016 The Society for Applied Microbiology.

Influence of diluent and sample processing methods on the recovery of the biocontrol agent Pantoea agglomerans CPA-2 from different fruit surfaces.

PubMed

Torres, R; Viñas, I; Usall, J; Remón, D; Teixidó, N

2012-08-01

Determining the populations of biocontrol agents applied as a postharvest treatment on fruit surfaces is fundamental to the assessment of the microorganisms' ability to colonise and persist on fruit. To obtain maximum recovery, we must develop a methodology that involves both diluent and processing methods and that does not affect the viability of the microorganisms. The effect of diluent composition was evaluated using three diluents: phosphate buffer, peptone saline and buffered peptone saline. An additional study was performed to compare three processing methods (shaking plus sonication, stomaching and shaking plus centrifugation) on the recovery efficiency of Pantoea agglomerans strain CPA-2 from apples, oranges, nectarines and peaches treated with this biocontrol agent. Overall, slight differences occurred among diluents, although the phosphate buffer maintained the most ideal pH for CPA-2 growth (between 5.2 and 6.2). Stomaching, using the phosphate buffer as diluent, was the best procedure for recovering and enumerating the biocontrol agent; this fact suggested that no lethal effects from naturally occurring antimicrobial compounds present on the fruit skins and/or produced when the tissues were disrupted affected the recovery of the CPA-2 cells, regardless of fruit type. The growth pattern of CPA-2 on fruits maintained at 20°C and under cold conditions was similar to that obtained in previous studies, which confirms the excellent adaptation of this strain to conditions commonly used for fruit storage. Copyright © 2012 Elsevier B.V. All rights reserved.

Protozoa Drive the Dynamics of Culturable Biocontrol Bacterial Communities.

PubMed

Müller, Maren Stella; Scheu, Stefan; Jousset, Alexandre

2013-01-01

Some soil bacteria protect plants against soil-borne diseases by producing toxic secondary metabolites. Such beneficial biocontrol bacteria can be used in agricultural systems as alternative to agrochemicals. The broad spectrum toxins responsible for plant protection also inhibit predation by protozoa and nematodes, the main consumers of bacteria in soil. Therefore, predation pressure may favour biocontrol bacteria and contribute to plant health. We analyzed the effect of Acanthamoeba castellanii on semi-natural soil bacterial communities in a microcosm experiment. We determined the frequency of culturable bacteria carrying genes responsible for the production of the antifungal compounds 2,4-diacetylphloroglucinol (DAPG), pyrrolnitrin (PRN) and hydrogen cyanide (HCN) in presence and absence of A. castellanii. We then measured if amoebae affected soil suppressiveness in a bioassay with sugar beet seedlings confronted to the fungal pathogen Rhizoctonia solani. Amoebae increased the frequency of both DAPG and HCN positive bacteria in later plant growth phases (2 and 3 weeks), as well as the average number of biocontrol genes per bacterium. The abundance of DAPG positive bacteria correlated with disease suppression, suggesting that their promotion by amoebae may enhance soil health. However, the net effect of amoebae on soil suppressiveness was neutral to slightly negative, possibly because amoebae slow down the establishment of biocontrol bacteria on the recently emerged seedlings used in the assay. The results indicate that microfaunal predators foster biocontrol bacterial communities. Understanding interactions between biocontrol bacteria and their predators may thus help developing environmentally friendly management practices of agricultural systems.

Protozoa Drive the Dynamics of Culturable Biocontrol Bacterial Communities

PubMed Central

Müller, Maren Stella; Scheu, Stefan; Jousset, Alexandre

2013-01-01

Some soil bacteria protect plants against soil-borne diseases by producing toxic secondary metabolites. Such beneficial biocontrol bacteria can be used in agricultural systems as alternative to agrochemicals. The broad spectrum toxins responsible for plant protection also inhibit predation by protozoa and nematodes, the main consumers of bacteria in soil. Therefore, predation pressure may favour biocontrol bacteria and contribute to plant health. We analyzed the effect of Acanthamoeba castellanii on semi-natural soil bacterial communities in a microcosm experiment. We determined the frequency of culturable bacteria carrying genes responsible for the production of the antifungal compounds 2,4-diacetylphloroglucinol (DAPG), pyrrolnitrin (PRN) and hydrogen cyanide (HCN) in presence and absence of A. castellanii. We then measured if amoebae affected soil suppressiveness in a bioassay with sugar beet seedlings confronted to the fungal pathogen Rhizoctonia solani. Amoebae increased the frequency of both DAPG and HCN positive bacteria in later plant growth phases (2 and 3 weeks), as well as the average number of biocontrol genes per bacterium. The abundance of DAPG positive bacteria correlated with disease suppression, suggesting that their promotion by amoebae may enhance soil health. However, the net effect of amoebae on soil suppressiveness was neutral to slightly negative, possibly because amoebae slow down the establishment of biocontrol bacteria on the recently emerged seedlings used in the assay. The results indicate that microfaunal predators foster biocontrol bacterial communities. Understanding interactions between biocontrol bacteria and their predators may thus help developing environmentally friendly management practices of agricultural systems. PMID:23840423

Can Some Marine-Derived Fungal Metabolites Become Actual Anticancer Agents?

PubMed

Gomes, Nelson G M; Lefranc, Florence; Kijjoa, Anake; Kiss, Robert

2015-06-19

Marine fungi are known to produce structurally unique secondary metabolites, and more than 1000 marine fungal-derived metabolites have already been reported. Despite the absence of marine fungal-derived metabolites in the current clinical pipeline, dozens of them have been classified as potential chemotherapy candidates because of their anticancer activity. Over the last decade, several comprehensive reviews have covered the potential anticancer activity of marine fungal-derived metabolites. However, these reviews consider the term "cytotoxicity" to be synonymous with "anticancer agent", which is not actually true. Indeed, a cytotoxic compound is by definition a poisonous compound. To become a potential anticancer agent, a cytotoxic compound must at least display (i) selectivity between normal and cancer cells (ii) activity against multidrug-resistant (MDR) cancer cells; and (iii) a preferentially non-apoptotic cell death mechanism, as it is now well known that a high proportion of cancer cells that resist chemotherapy are in fact apoptosis-resistant cancer cells against which pro-apoptotic drugs have more than limited efficacy. The present review thus focuses on the cytotoxic marine fungal-derived metabolites whose ability to kill cancer cells has been reported in the literature. Particular attention is paid to the compounds that kill cancer cells through non-apoptotic cell death mechanisms.

Biocontrol of the Potato Blackleg and Soft Rot Diseases Caused by Dickeya dianthicola.

PubMed

Raoul des Essarts, Yannick; Cigna, Jérémy; Quêtu-Laurent, Angélique; Caron, Aline; Munier, Euphrasie; Beury-Cirou, Amélie; Hélias, Valérie; Faure, Denis

2016-01-01

Development of protection tools targeting Dickeya species is an important issue in the potato production. Here, we present the identification and the characterization of novel biocontrol agents. Successive screenings of 10,000 bacterial isolates led us to retain 58 strains that exhibited growth inhibition properties against several Dickeya sp. and/or Pectobacterium sp. pathogens. Most of them belonged to the Pseudomonas and Bacillus genera. In vitro assays revealed a fitness decrease of the tested Dickeya sp. and Pectobacterium sp. pathogens in the presence of the biocontrol agents. In addition, four independent greenhouse assays performed to evaluate the biocontrol bacteria effect on potato plants artificially contaminated with Dickeya dianthicola revealed that a mix of three biocontrol agents, namely, Pseudomonas putida PA14H7 and Pseudomonas fluorescens PA3G8 and PA4C2, repeatedly decreased the severity of blackleg symptoms as well as the transmission of D. dianthicola to the tuber progeny. This work highlights the use of a combination of biocontrol strains as a potential strategy to limit the soft rot and blackleg diseases caused by D. dianthicola on potato plants and tubers. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Biocontrol of the Potato Blackleg and Soft Rot Diseases Caused by Dickeya dianthicola

PubMed Central

Raoul des Essarts, Yannick; Cigna, Jérémy; Quêtu-Laurent, Angélique; Caron, Aline; Munier, Euphrasie; Beury-Cirou, Amélie

2015-01-01

Development of protection tools targeting Dickeya species is an important issue in the potato production. Here, we present the identification and the characterization of novel biocontrol agents. Successive screenings of 10,000 bacterial isolates led us to retain 58 strains that exhibited growth inhibition properties against several Dickeya sp. and/or Pectobacterium sp. pathogens. Most of them belonged to the Pseudomonas and Bacillus genera. In vitro assays revealed a fitness decrease of the tested Dickeya sp. and Pectobacterium sp. pathogens in the presence of the biocontrol agents. In addition, four independent greenhouse assays performed to evaluate the biocontrol bacteria effect on potato plants artificially contaminated with Dickeya dianthicola revealed that a mix of three biocontrol agents, namely, Pseudomonas putida PA14H7 and Pseudomonas fluorescens PA3G8 and PA4C2, repeatedly decreased the severity of blackleg symptoms as well as the transmission of D. dianthicola to the tuber progeny. This work highlights the use of a combination of biocontrol strains as a potential strategy to limit the soft rot and blackleg diseases caused by D. dianthicola on potato plants and tubers. PMID:26497457

Streptomyces globosus UAE1, a Potential Effective Biocontrol Agent for Black Scorch Disease in Date Palm Plantations.

PubMed

Saeed, Esam E; Sham, Arjun; Salmin, Zeinab; Abdelmowla, Yasmeen; Iratni, Rabah; El-Tarabily, Khaled; AbuQamar, Synan

2017-01-01

Many fungal diseases affect date palm causing considerable losses in date production worldwide. We found that the fungicide Cidely ® Top inhibited the mycelial growth of the soil-borne pathogenic fungus Thielaviopsis punctulata , the causal agent of black scorch disease of date palm, both in vitro and in vivo . Because the use of biocontrol agents (BCAs) can minimize the impact of pathogen control on economic and environmental concerns related to chemical control, we aimed at testing local actinomycete strains isolated from the rhizosphere soil of healthy date palm cultivated in the United Arab Emirates (UAE) against T. punctulata . The selected isolate can thus be used as a potential agent for integrated disease management programs. In general, the BCA showed antagonism in vitro and in greenhouse experiments against this pathogen. The most promising actinomycete isolate screened showed the highest efficacy against the black scorch disease when applied before or at the same time of inoculation with T. punctulata , compared with BCA or fungicide application after inoculation. The nucleotide sequence and phylogenetic analyses using the 16 S ribosomal RNA gene with other Streptomyces spp. in addition to morphological and cultural characteristics revealed that the isolated UAE strain belongs to Streptomyces globosus UAE1. The antagonistic activity of S. globosus against T. punctulata , was associated with the production by this strain of diffusible antifungal metabolites i.e., metabolites that can inhibit mycelial growth of the pathogen. This was evident in the responses of the vegetative growth of pure cultures of the pathogen when exposed to the culture filtrates of the BCA. Altogether, the pathogenicity tests, disease severity indices and mode of action tests confirmed that the BCA was not only capable of suppressing black scorch disease symptoms, but also could prevent the spread of the pathogen, as a potential practical method to improve disease management in the

From effective biocontrol agent to successful invader: the harlequin ladybird (Harmonia axyridis) as an example of good ideas that could go wrong

PubMed Central

Ortega-Iturriaga, Adrián; del-Val, Ek

2017-01-01

The use of biological control agents to control pests is an alternative to pesticides and a tool to manage invasive alien species. However, biocontrol agents can themselves become invasive species under certain conditions. The harlequin ladybird (Harmonia axyridis) is a native Asian biocontrol agent that has become a successful invader. We reviewed articles containing “Harmonia axyridis” to gather information on its presence and surveyed entomologists researching Coccinellidae around the world to investigate further insights about the current distribution, vectors of introduction, habitat use and threats this species pose. The harlequin ladybird has established populations in at least 59 countries outside its native range. Twenty six percent of the surveyed scientists considered it a potential threat to native Coccinellidae. Published studies and scientists suggest Adalia bipunctata, native to Europe, is under the highest risk of population declines. Strict policies should be incorporated to prevent its arrival to non-invaded areas and to prevent further expansion range. Managing invasive species is a key priority to prevent biodiversity loss and promote ecosystem services. PMID:28533958

From effective biocontrol agent to successful invader: the harlequin ladybird (Harmonia axyridis) as an example of good ideas that could go wrong.

PubMed

Camacho-Cervantes, Morelia; Ortega-Iturriaga, Adrián; Del-Val, Ek

2017-01-01

The use of biological control agents to control pests is an alternative to pesticides and a tool to manage invasive alien species. However, biocontrol agents can themselves become invasive species under certain conditions. The harlequin ladybird ( Harmonia axyridis ) is a native Asian biocontrol agent that has become a successful invader. We reviewed articles containing " Harmonia axyridis " to gather information on its presence and surveyed entomologists researching Coccinellidae around the world to investigate further insights about the current distribution, vectors of introduction, habitat use and threats this species pose. The harlequin ladybird has established populations in at least 59 countries outside its native range. Twenty six percent of the surveyed scientists considered it a potential threat to native Coccinellidae. Published studies and scientists suggest Adalia bipunctata , native to Europe, is under the highest risk of population declines. Strict policies should be incorporated to prevent its arrival to non-invaded areas and to prevent further expansion range. Managing invasive species is a key priority to prevent biodiversity loss and promote ecosystem services.

Proactive Management of Fermentation and Formulation Interactions to Improve Biocontrol Product Performance

USDA-ARS?s Scientific Manuscript database

The key components of biocontrol product development—discovery, fermentation, and formulation—are interactively linked to each other and ultimately to product performance. To identify biocontrol agents suited for commercial development, our discovery programs utilize a cumulative ranking system tha...

Optimization of storage condition for maintaining long-term viability of nematophagous fungus Esteya vermicola as biocontrol agent against pinewood nematode.

PubMed

Xue, Jian Jie; Hou, Jin Gang; Zhang, Yong An; Wang, Chun Yan; Wang, Zhen; Yu, Jiao Jiao; Wang, Yun Bo; Wang, Yu Zhu; Wang, Qing Hua; Sung, Chang Keun

2014-11-01

The fungus, Esteya vermicola has been proposed as biocontrol agent against pine wilting disease caused by Bursaphelenchus xylophilus. In this study, we reported the effects of temperature and different additives on the viability and biocontrol efficacy of E. vermicola formulated by alginate-clay. The viability of the E. vermicola formulation was determined for six consecutive months at temperature ranged from -70 to 25 °C. The fresh conidia without any treatment were used as control. Under the optimal storage conditions with E. vermicola alginate-clay formulation, the results suggested that E. vermicola alginate-clay formulation with a long shelf life could be a non-vacuum-packed formulation that contains 2 % sodium alginate and 5 % clay at 4 °C. Three conidial formulations prepared with additives of 15 % glycerol, 0.5 % yeast extract and 0.5 % herbal extraction, respectively significantly improved the shelf life. In addition, these tested formulations retained the same biocontrol efficacy as the fresh conidial against pinewood nematode. This study provided a tractable and low-cost method to preserve the shelf life of E. vermicola.

Evaluation of yeasts obtained from Antarctic soil samples as biocontrol agents for the management of postharvest diseases of apple (Malus x domestica)

USDA-ARS?s Scientific Manuscript database

Psychrotrophic yeasts isolated from soils collected in Antarctica and selected by its capacity of growing in apple juice at low temperatures were evaluated for their potential as biocontrol agents for the management of postharvest diseases of apple during cold storage. Among the species recovered, ...

Complete Genome Sequence of Biocontrol Strain Pseudomonas fluorescens LBUM223

PubMed Central

Roquigny, Roxane; Arseneault, Tanya; Gadkar, Vijay J.; Novinscak, Amy

2015-01-01

Pseudomonas fluorescens LBUM223 is a plant growth-promoting rhizobacterium (PGPR) with biocontrol activity against various plant pathogens. It produces the antimicrobial metabolite phenazine-1-carboxylic acid, which is involved in the biocontrol of Streptomyces scabies, the causal agent of common scab of potato. Here, we report the complete genome sequence of P. fluorescens LBUM223. PMID:25953163

An endophytic Streptomyces sp. strain DHV3-2 from diseased root as a potential biocontrol agent against Verticillium dahliae and growth elicitor in tomato (Solanum lycopersicum).

PubMed

Cao, Peng; Liu, Chongxi; Sun, Pengyu; Fu, Xuepeng; Wang, Shaoxian; Wu, Fengzhi; Wang, Xiangjing

2016-12-01

Plant endophytes play important roles in biocontrol of plant diseases. Actinomycetes are used for biocontrol of fungal diseases caused by Verticillium dahliae. Many studies have focused on the endophytic actinomycetes isolated from the roots of healthy plants, but few on those from the roots of diseased plants. In the present research, actinomycetes were isolated from the roots of diseased and healthy tomato plants, respectively. The results showed that, in total, 86 endophytic actinomycetes were isolated for screening of their antimicrobial activities, 8 of which showed antagonism to V. dahliae in vitro. Among the 8 antagonistic strains, 5 (out of 36) were from the roots of diseased plants, with inhibition diameter zones ranging from 11.2 to 18.2 mm, whereas 3 (out of 50) were from the roots of healthy plants, with inhibition diameter zones ranging from 11.5 to 15.5 mm. Endophytic strain DHV3-2 was isolated from the root of a diseased plant and demonstrated a potent effect against V. dahliae and other pathogenic fungi by showing the largest inhibition diameter zones among all the eight antagonistic strains. Thus, strain DHV3-2 was chosen to investigate its biological control efficacies in vivo. Further study showed that the disease incidence and disease severity indices of tomato Verticillium wilt decreased significantly (P < 0.05). We also found that the plant shoot fresh weight and height increased greatly (P < 0.05) upon treatment with strain DHV3-2 compared to the plants uninoculated in greenhouse conditions. Root colonization showed that strain DHV3-2 had the higher root-colonizing capacity in the roots of infected plants compared with the roots of healthy plants. This isolate was identified as Streptomyces sp. based on morphological characteristics and 16S rRNA gene analysis. In conclusion, the roots of diseased tomato plants are a potential reservoir of biological control actinomycetes, and Streptomyces sp. strain DHV3-2 is a potential biocontrol

Short-chain fatty acids and poly-beta-hydroxyalkanoates: (New) Biocontrol agents for a sustainable animal production.

PubMed

Defoirdt, Tom; Boon, Nico; Sorgeloos, Patrick; Verstraete, Willy; Bossier, Peter

2009-01-01

Because of the risk of antibiotic resistance development, there is a growing awareness that antibiotics should be used more carefully in animal production. However, a decreased use of antibiotics could result in a higher frequency of pathogenic bacteria, which in its turn could lead to a higher incidence of infections. Short-chain fatty acids (SCFAs) have long been known to exhibit bacteriostatic activity. These compounds also specifically downregulate virulence factor expression and positively influence the gastrointestinal health of the host. As a consequence, there is currently considerable interest in SCFAs as biocontrol agents in animal production. Polyhydroxyalkanoates (PHAs) are polymers of beta-hydroxy short-chain fatty acids. Currently, PHAs are applied as replacements for synthetic polymers. These biopolymers can be depolymerised by many different microorganisms that produce extracellular PHA depolymerases. Interestingly, different studies provided some evidence that PHAs can also be degraded upon passage through the gastrointestinal tract of animals and consequently, adding these compounds to the feed might result in biocontrol effects similar to those described for SCFAs.

Can Plant Microbiome Studies Lead to Effective Biocontrol of Plant Diseases?

PubMed

Ellis, Jeffrey G

2017-03-01

In this review, the wisdom and efficacy of studies seeking disease attenuating microbes and microbiomes only in healthy plant communities is questioned and an alternative view is posited, namely that success in biocontrol of crop diseases may also come from studies of microbiota, or at least individual species isolates, associated with diseased plants. In support of this view, I summarize the current extensive knowledge of the biology behind what is probably the most successful biocontrol of a plant disease, namely the biocontrol of crown gall of stone fruit using non-pathogenic Rhizobium rhizogenes K84, in which the biocontrol agent itself came from a diseased plant.

Method To immobilize the aphid-pathogenic fungus erynia neoaphidis in an alginate matrix for biocontrol

PubMed

Shah; Aebi; Tuor

1998-11-01

Erynia neoaphidis is an important fungal pathogen of aphid pests worldwide. There have been few reported attempts to formulate this natural agent for use in biocontrol. In the current study, factors involved in the immobilization of E. neoaphidis hyphae in an alginate matrix were investigated. Hyphae of two isolates cultured in liquid medium were 220 to 620 &mgr;m in length and 7 to 19 &mgr;m in diameter with a 74 to 83% cytoplasmic content. The optimal concentration of low-viscosity sodium alginate for production of conidia from entrapped hyphae was 1.5% (wt/vol), and 0.1 and 0.25 M calcium chloride were equally suitable for use as the gelling solution. Alginate beads were rinsed with 10% sucrose after gelling. However, beads should not be left for longer than 40 min in 0.1 M calcium chloride or 10% sucrose to prevent a 10% loss in conidial production. A 40% (vol/vol) concentration of fungal biomass produced significantly more conidia than either 20% or the standard concentration of 10%. This effect persisted even after beads were dried overnight in a laminar flow hood and stored at 4 degreesC for 4 days. Conidia from freshly produced alginate beads caused 27 to 32% infection in Pea aphids as determined by standardized laboratory bioassays. This finding was not significantly different from infections in aphids inoculated with fresh mycelial mats or plugs from Petri dish cultures. In conclusion, algination appears to be a promising technique for utilizing E. neoaphidis in the biocontrol of aphid pests.

Evaluation of antifungal activity of carbonate and bicarbonate salts alone or in combination with biocontrol agents in control of citrus green mold.

PubMed

Zamani, M; Sharifi Tehrani, A; Ali Abadi, A Alizadeh

2007-01-01

The aim of this research was to determine if the attacks of green mold on orange could be reduced by edible salts alone or in combination with biocontrol agent. For this purpose toxicity to Pantoea digitatum and practical use of sodium carbonate (SC), sodium bicarbonate (SBC) and potassium carbonate, and potassium bicarbonate alone or in combination with antagonistic bacteria (Pseudomonas fluorescens isolate PN, Bacillus subtilis isolate VHN, Pantoea agglomerans isolate CA) to control green mold were determined. All were fungistatic. SC and SBC were equal and superior to the other salts for control of green mold on oranges inoculated 6h before treatment and were chosen for subsequent trails under cold storage conditions. The biocontrol agents were found completely tolerant to 3% sodium bicarbonate and sodium carbonate at room temperature; although their culturability was reduced by > 1000-fold after 60 min in 1% other salt solutions. Satisfactory results were also obtained with the combined treatment for control of green mold. A significant increase in biocontrol activity of all isolate was observed when combined with sodium carbonate and sodium bicarbonate. The treatments comprising CA combined with SB was as effective as fungicide treatment. Thus, use of sodium bicarbonate treatment at 3% followed by the antagonist P. agglomerans CA could be an alternative to chemical fungicides for control of green mold on oranges.

Real-time PCR for detection and quantification of the biocontrol agent Trichoderma atroviride strain SC1 in soil.

PubMed

Savazzini, Federica; Longa, Claudia Maria Oliveira; Pertot, Ilaria; Gessler, Cesare

2008-05-01

Trichoderma (Hypocreales, Ascomycota) is a widespread genus in nature and several Trichoderma species are used in industrial processes and as biocontrol agents against crop diseases. It is very important that the persistence and spread of microorganisms released on purpose into the environment are accurately monitored. Real-time PCR methods for genus/species/strain identification of microorganisms are currently being developed to overcome the difficulties of classical microbiological and enzymatic methods for monitoring these populations. The aim of the present study was to develop and validate a specific real-time PCR-based method for detecting Trichoderma atroviride SC1 in soil. We developed a primer and TaqMan probe set constructed on base mutations in an endochitinase gene. This tool is highly specific for the detection and quantification of the SC1 strain. The limits of detection and quantification calculated from the relative standard deviation were 6000 and 20,000 haploid genome copies per gram of soil. Together with the low throughput time associated with this procedure, which allows the evaluation of many soil samples within a short time period, these results suggest that this method could be successfully used to trace the fate of T. atroviride SC1 applied as an open-field biocontrol agent.

Indirect effects of host-specific biological control agents

Treesearch

Dean E. Pearson; Ragan M. Callaway

2003-01-01

Biological control is a crucial tool in the battle against biological invasions, but biocontrol agents can have a deleterious impact on native species. Recognition of risks associated with host shifting has increased the emphasis on host specificity of biocontrol agents for invasive weeds. However, recent studies indicate host-specific biocontrol agents can...

The relationship of biofilm production to biocontrol activity of Burkholderia pyrrocinia FP62

USDA-ARS?s Scientific Manuscript database

Foliar biocontrol agent (BCA) efficacy is often inconsistent due to poor colonization and survival on plant surfaces. Burkholderia pyrrocinia FP62, a superior leaf colonist and BCA of Botrytis cinerea, forms unsaturated biofilms on plant surfaces. To determine the relationship between biocontrol act...

Formulation development of the biocontrol agent Bacillus subtilis strain CPA-8 by spray-drying.

PubMed

Yánez-Mendizábal, V; Viñas, I; Usall, J; Torres, R; Solsona, C; Abadias, M; Teixidó, N

2012-05-01

To prepare commercially acceptable formulations of Bacillus subtilis CPA-8 by spray-drying with long storage life and retained efficacy to control peach and nectarine brown rot caused by Monilinia spp. CPA-8 24-h- and 72-h-old cultures were spray dried using 10% skimmed milk, 10% skimmed milk plus 10% MgSO(4) , 10% MgSO(4) and 20% MgSO(4) as carriers/protectants. All carriers/protectants gave good percentages of powder recovery (28-38%) and moisture content (7-13%). CPA-8 survival varied considerably among spray-dried 24-h- and 72-h-old cultures. Seventy-two hours culture spray dried formulations showed the highest survival (28-32%) with final concentration products of 1·6-3·3 × 10(9) CFU g(-1) , while viability of 24-h-old formulations was lower than 1%. Spray-dried 72-h-old formulations were selected to subsequent evaluation. Rehydration of cells with water provided a good recovery of CPA-8 dried cells, similar to other complex rehydration media tested. Spray-dried formulations stored at 4 ± 1 and 20 ± 1°C showed good shelf life during 6 months, and viability was maintained or slightly decreased by 0·2-0·3-log. CPA-8 formulations after 4- and 6 months storage were effective in controlling brown rot caused by Monilinia spp. on nectarines and peaches resulting in a 90-100% reduction in disease incidence. Stable and effective formulations of biocontrol agent B. subtilis CPA-8 could be obtained by spray-drying. New shelf-stable and effective formulations of a biocontrol agent have been obtained by spray-drying to control brown rot on peach. © 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

De novo Genome Assembly of the Fungal Plant Pathogen Pyrenophora semeniperda

PubMed Central

Soliai, Marcus M.; Meyer, Susan E.; Udall, Joshua A.; Elzinga, David E.; Hermansen, Russell A.; Bodily, Paul M.; Hart, Aaron A.; Coleman, Craig E.

2014-01-01

Pyrenophora semeniperda (anamorph Drechslera campulata) is a necrotrophic fungal seed pathogen that has a wide host range within the Poaceae. One of its hosts is cheatgrass (Bromus tectorum), a species exotic to the United States that has invaded natural ecosystems of the Intermountain West. As a natural pathogen of cheatgrass, P. semeniperda has potential as a biocontrol agent due to its effectiveness at killing seeds within the seed bank; however, few genetic resources exist for the fungus. Here, the genome of P. semeniperda isolate assembled from sequence reads of 454 pyrosequencing is presented. The total assembly is 32.5 Mb and includes 11,453 gene models encoding putative proteins larger than 24 amino acids. The models represent a variety of putative genes that are involved in pathogenic pathways typically found in necrotrophic fungi. In addition, extensive rearrangements, including inter- and intrachromosomal rearrangements, were found when the P. semeniperda genome was compared to P. tritici-repentis, a related fungal species. PMID:24475219

Plot- and landscape-level changes in climate and vegetation following defoliation of exotic saltcedar (Tamarix sp.) from the biocontrol agent Diorhabda carinulata along a stream in the Mojave Desert (USA)

USGS Publications Warehouse

Bateman, H.L.; Nagler, P.L.; Glenn, E.P.

2013-01-01

The biocontrol agent, northern tamarisk beetle (Diorhabda carinulata), has been used to defoliate non-native saltcedar (Tamarix spp.) in USA western riparian systems since 2001. Biocontrol has the potential to impact biotic communities and climatic conditions in affected riparian areas. To determine the relationships between biocontrol establishment and effects on vegetation and climate at the plot and landscape scales, we measured temperature, relative humidity, foliage canopy, solar radiation, and used satellite imagery to assess saltcedar defoliation and evapotranspiration (ET) along the Virgin River in the Mojave Desert. Following defoliation solar radiation increased, daily humidity decreased, and maximum daily temperatures tended to increase. MODIS and Landsat satellite imagery showed defoliation was widespread, resulting in reductions in ET and vegetation indices. Because biocontrol beetles are spreading into new saltcedar habitats on arid western rivers, and the eventual equilibrium between beetles and saltcedar is unknown, it is necessary to monitor trends for ecosystem functions and higher trophic-level responses in habitats impacted by biocontrol.

Polysaccharide Production Benefits Dry Storage Survival of the Biocontrol Agent Pseudomonas fluorescens S11:P:12 Effective Against Several Maladies of Stored Potatoes

USDA-ARS?s Scientific Manuscript database

Pseudomonas fluorescens S11:P:12 (NRRL B-21133) is a biological control agent able to suppress several potato diseases and sprouting. Notably, it produces a polysaccharide during liquid cultivation; and the objective of this work was to determine the role of this material in the bio-control process...

Characterization and competitive ability of non-aflatoxigenic Aspergillus flavus isolated from the maize agro-ecosystem in Argentina as potential aflatoxin biocontrol agents.

PubMed

Alaniz Zanon, María Silvina; Clemente, María Paz; Chulze, Sofía Noemí

2018-07-20

Aspergillus flavus is an opportunistic pathogen and may produce aflatoxins in maize, one of the most important crops in Argentina. A promising strategy to reduce aflatoxin accumulation is the biological control based on competitive exclusion. In order to select potential biocontrol agents among isolates from the maize growing region in Argentina, a total of 512 A. flavus strains were isolated from maize kernels and soil samples. Thirty-six per cent of the isolates from maize kernels did not produce detectable levels of aflatoxins, while 73% of the isolates from soil were characterized as non-aflatoxin producers. Forty percent and 49% of the isolates from maize kernels and soil samples, respectively, were not producers of cyclopiazonic acid (CPA). Sclerotia morphology was evaluated using Czapek Dox media. Eighty-six per cent of the isolates from maize kernels and 85% of the isolates from soil samples were L sclerotia morphotype (average diameter > 400 μm). The remaining isolates did not produce sclerotia. All isolates had MAT 1-1 idiomorph. The competitive ability of 9 non aflatoxigenic strains, 4 CPA(+) and 5 CPA(-), was evaluated in co-inoculations of maize kernels with an aflatoxigenic strain. All evaluated strains significantly (p < 0.05) reduced aflatoxin contamination in maize kernels. The aflatoxin B 1 (AFB 1 ) reduction ranged from 6 to 60%. The strain A. flavus ARG5/30 isolated from maize kernels would be a good candidate as a potential biocontrol agent to be used in maize, since it was characterized as neither aflatoxin nor CPA producer, morphotype L, MAT 1-1 idiomorph, and reduced AFB 1 content in maize kernels by 59%. This study showed the competitive ability of potential aflatoxin biocontrol agents to be evaluated under field trials in a maize agro-ecosystem in Argentina. Copyright © 2018 Elsevier B.V. All rights reserved.

The roles of inoculants' carbon source use in the biocontrol of potato scab disease.

PubMed

Sun, Pingping; Zhao, Xinbei; Shangguan, Nini; Chang, Dongwei; Ma, Qing

2015-04-01

Despite the application of multiple strains in the biocontrol of plant diseases, multistrain inoculation is still constrained by its inconsistency in the field. Nutrients, especially carbons, play an important role in the biocontrol processes. However, little work has been done on the systematic estimation of inoculants' carbon source use on biocontrol efficacies in vivo. In the present study, 7 nonpathogenic Streptomyces strains alone and in different combinations were inoculated as biocontrol agents against the potato scab disease, under field conditions and greenhouse treatments. The influence of the inoculants' carbon source use properties on biocontrol efficacies was investigated. The results showed that increasing the number of inoculated strains did not necessarily result in greater biocontrol efficacy in vivo. However, single strains with higher growth rates or multiple strains with less carbon source competition had positive effects on the biocontrol efficacies. These findings may shed light on optimizing the consistent biocontrol of plant disease with the consideration of inoculants' carbon source use properties.

Biocontrol of Alternaria alternata on cherry tomato fruit by use of marine yeast Rhodosporidium paludigenum Fell & Tallman.

PubMed

Wang, Yifei; Bao, Yihong; Shen, Danhong; Feng, Wu; Yu, Ting; Zhang, Jia; Zheng, Xiao Dong

2008-04-30

The basidiomycetous yeast Rhodosporidium paludigenum Fell & Tallman isolated from the south of East China Sea was evaluated for its activity in reducing postharvest decay of cherry tomatoes caused by Alternaria alternata in vitro and in vivo tests. The results showed that washed cell suspension of R. paludigenum provided better control of A. alternata than any other treatment, while the autoclaved cell culture failed to provide protection against the pathogen. The concentration of antagonist had significant effect on biocontrol effectiveness in vivo: when the concentration of the washed yeast cell suspension was used at 1 x 10(9)cells/ml, the percentage rate of black rot of cherry tomato fruit was only 37%, which was remarkably lower than that treated with water (the control) after 5days of incubation at 25 degrees C. Furthermore, a great biocontrol efficacy of R. paludigenum was observed when it was applied prior to inoculation with A. alternata: the longer the incubation time of R. paludigenum, the lower disease incidence would be. However, there was little efficacy when R. paludigenum was applied after A. alternata inoculation. In addition, on the wounds of cherry tomato, it was observed that R. paludigenum grew rapidly increasing 50-fold during the first 12h at 25 degrees C. To the best of our knowledge, this is a first report concerning that the marine yeast R. paludigenum could be used as a biocontrol agent of postharvest fungal disease.

Isolation of Ralstonia solanacearum-infecting bacteriophages from tomato fields in Chiang Mai, Thailand, and their experimental use as biocontrol agents.

PubMed

Bhunchoth, A; Phironrit, N; Leksomboon, C; Chatchawankanphanich, O; Kotera, S; Narulita, E; Kawasaki, T; Fujie, M; Yamada, T

2015-04-01

To isolate and characterize novel bacteriophages infecting the phytopathogen, Ralstonia solanacearum, and to evaluate them as resources with potential uses in the biocontrol of bacterial wilt. Fourteen phages infecting R. solanacearum were isolated from soil samples collected in Chiang Mai, Thailand. The phages showed different host ranges when tested against 59 R. solanacearum strains isolated from Thailand and Japan. These phages were characterized as nine podoviruses and five myoviruses based on their morphology. Podovirus J2 in combination with another podovirus (φRSB2) lysed host cells very efficiently in contaminated soil. J2 treatment prevented wilting of tomato plants infected with a highly virulent R. solanacearum strain. Treatment with J2 effectively reduced the amount of the bacterial wilt pathogen in contaminated soil and prevented bacterial wilt of tomato in pot experiments. Myovirus J6 possessed jumbo phage features, giving a unique opportunity to study its utilization as a biocontrol agent. As exemplified by J2, the phages isolated in this study represent valuable resources with potential uses in biocontrol of bacterial wilt. A rare jumbo phage J6 served as a valuable subject to understand and utilize this new group of phages. © 2015 The Society for Applied Microbiology.

Endospore production allows using spray-drying as a possible formulation system of the biocontrol agent Bacillus subtilis CPA-8.

PubMed

Yánez-Mendizabal, V; Viñas, I; Usall, J; Cañamás, T; Teixidó, N

2012-04-01

The role of endospore production by Bacillus subtilis CPA-8 on survival during spray-drying was investigated by comparison with a non-spore-forming biocontrol agent Pantoea agglomerans CPA-2. Endospore formation promoted heat resistance in CPA-8 depending on growth time (72 h cultures were more resistant than 24 h ones). The survival of CPA-8 and CPA-2 after spray-drying was determined after being grown in optimised media for 24 and 72 h. Spray-dried 72 h CPA-8 had the best survival (32%), while CPA-2 viability was less than 2%. CPA-8 survival directly related with its ability to produce endospores. Spray-dried CPA-8 reduced Monilinia fructicola conidia germination similarly to fresh cells, demonstrating that spray-drying did not adversely affect biocontrol efficacy. Endospore production thus improves CPA-8 resistance to spray-drying. These results can provide a reliable basis for optimising of the spray-drying formulation process for CPA-8 and other microorganisms.

Quantifying the associations between fungal endophytes and biocontrol-induced herbivory of invasive purple loosestrife (Lythrum salicaria L.).

PubMed

David, Aaron S; Quiram, Gina L; Sirota, Jennie I; Seabloom, Eric W

2016-01-01

Fungal endophytes are one of several groups of heterotrophic organisms that associate with living plants. The net effects of these groups of organisms on each other and ultimately on their host plants depend in part on how they facilitate or antagonize one another. In this study we quantified the associations between endophyte communities and herbivory induced by a biological control in the invasive Lythrum salicaria at various spatial scales using a culture-based approach. We found positive associations between herbivory damage and endophyte isolation frequency and richness at the site level and weak, positive associations at the leaf level. Herbivory damage was more strongly influenced by processes at the site level than were endophyte isolation frequency and community structure, which were influenced by processes at the plant and leaf levels. Furthermore, endophytic taxa found in low herbivory sites were nested subsets of those taxa found at high herbivory sites. Our findings suggest that endophyte communities of L. salicaria are associated with, and potentially facilitated by, biocontrol-induced herbivory. Quantifying the associations between heterotrophic groups ultimately may lead to a clearer understanding of their complex interactions with plants. © 2016 by The Mycological Society of America.

Sustained release of a novel anti-quorum-sensing agent against oral fungal biofilms.

PubMed

Feldman, Mark; Shenderovich, Julia; Al-Quntar, Abed Al Aziz; Friedman, Michael; Steinberg, Doron

2015-04-01

Thiazolidinedione-8 (S-8) has recently been identified as a potential anti-quorum-sensing/antibiofilm agent against bacteria and fungi. Based on these results, we investigated the possibility of incorporating S-8 in a sustained-release membrane (SRM) to increase its pharmaceutical potential against Candida albicans biofilm. We demonstrated that SRM containing S-8 inhibits fungal biofilm formation in a time-dependent manner for 72 h, due to prolonged release of S-8. Moreover, the SRM effectively delivered the agent in its active form to locations outside the membrane reservoir. In addition, eradication of mature biofilm by the SRM containing S-8 was also significant. Of note, S-8-containing SRM affected the characteristics of mature C. albicans biofilm, such as thickness, exopolysaccharide (EPS) production, and morphogenesis of fungal cells. The concept of using an antibiofilm agent with no antifungal activity incorporated into a sustained-release delivery system is new in medicine and dentistry. This concept of an SRM containing a quorum-sensing quencher with an antibiofilm effect could pave the way for combating oral fungal infectious diseases. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Peptaibol, secondary-metabolite, and hydrophobin pattern of commercial biocontrol agents formulated with species of the Trichoderma harzianum complex.

PubMed

Degenkolb, Thomas; Fog Nielsen, Kristian; Dieckmann, Ralf; Branco-Rocha, Fabiano; Chaverri, Priscila; Samuels, Gary J; Thrane, Ulf; von Döhren, Hans; Vilcinskas, Andreas; Brückner, Hans

2015-04-01

The production of bioactive polypeptides (peptaibiotics) in vivo is a sophisticated adaptation strategy of both mycoparasitic and saprotrophic Trichoderma species for colonizing and defending their natural habitats. This feature is of major practical importance, as the detection of peptaibiotics in plant-protective Trichoderma species, which are successfully used against economically relevant bacterial and fungal plant pathogens, certainly contributes to a better understanding of these complex antagonistic interactions. We analyzed five commercial biocontrol agents (BCAs), namely Canna(®) , Trichosan(®) , Vitalin(®) , Promot(®) WP, and TrichoMax(®) , formulated with recently described species of the Trichoderma harzianum complex, viz. T. afroharzianum, T. simmonsii, and T. guizhouense. By using the well-established, HPLC/MS-based peptaibiomics approach, it could unequivocally be demonstrated that all of these formulations contained new and recurrent peptaibols, i.e., peptaibiotics carrying an acetylated N-terminus, the C-terminus of which is reduced to a 1,2-amino alcohol. Their chain lengths, including the amino alcohol, were 11, 14, and 18 residues, respectively. Peptaibols were also to be the dominating secondary metabolites in plate cultures of the four strains obtained from four of the Trichoderma- based BCAs, contributing 95% of the UHPLC-UV/VIS peak areas and 99% of the total ion count MS peak area from solid media. Furthermore, species-specific hydrophobins, as well as non-peptaibiotic secondary metabolites, were detected, the latter being known for their antifungal, siderophore, or plant-growth-promoting activities. Notably, none of the isolates produced low-molecular weight mycotoxins. Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.

What magnitude are observed non-target impacts from weed biocontrol?

USDA-ARS?s Scientific Manuscript database

A systematic review focused by plant on non-target impacts from agents deliberately introduced for the biological control of weeds found significant non-target impacts to be rare. The magnitude of direct impact of 43 biocontrol agents on 140 non-target plants was retrospectively categorized using a ...

Genome Sequence of the Biocontrol Strain Pseudomonas fluorescens F113

PubMed Central

Redondo-Nieto, Miguel; Barret, Matthieu; Morrisey, John P.; Germaine, Kieran; Martínez-Granero, Francisco; Barahona, Emma; Navazo, Ana; Sánchez-Contreras, María; Moynihan, Jennifer A.; Giddens, Stephen R.; Coppoolse, Eric R.; Muriel, Candela; Stiekema, Willem J.; Rainey, Paul B.; Dowling, David; O'Gara, Fergal; Martín, Marta

2012-01-01

Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR) that has biocontrol activity against fungal plant pathogens and is a model for rhizosphere colonization. Here, we present its complete genome sequence, which shows that besides a core genome very similar to those of other strains sequenced within this species, F113 possesses a wide array of genes encoding specialized functions for thriving in the rhizosphere and interacting with eukaryotic organisms. PMID:22328765

Antifungal modes of action of Saccharomyces and other biocontrol yeasts against fungi isolated from sour and grey rots.

PubMed

Nally, M C; Pesce, V M; Maturano, Y P; Rodriguez Assaf, L A; Toro, M E; Castellanos de Figueroa, L I; Vazquez, F

2015-07-02

The aim of this study was to determine the putative modes of action of 59 viticultural yeasts (31 Saccharomyces and 28 non-Saccharomyces) that inhibited fungi isolated from sour and grey rot in grapes. Inhibition of fungal mycelial growth by metabolites, enzyme activities (laminarinases, chitinases), antifungal volatiles, competition for nutrients (siderophores, Niche Overlap Index (NOI)), inhibition of fungal spore germination and decreased germinal tube length and induction of resistance were assayed. Biofungicide yeasts were classified into "antifungal patterns", according to their mechanisms of action. Thirty isolates presented at least two of the mechanisms assayed. We propose that inhibition of fungal mycelial growth by metabolites, laminarinases, competition for nutrients, inhibition of fungal spore germination and decreased germinal tube length, and antifungal volatiles by Saccharomyces and non-Saccharomyces viticultural yeasts is used as putative biocontrol mechanisms against phytopathogenic fungi. Twenty-four different antifungal patterns were identified. Siderophore production (N)and a combination of siderophore production and NOI>0.92 (M)were the most frequent antifungal patterns observed in the biofungicide yeasts assayed. Elucidation of these mechanisms could be useful for optimization of an inoculum formulation, resulting in a more consistent control of grey and sour rot with Saccharomyces and non-Saccharomyces biocontrol yeasts. Copyright © 2015 Elsevier B.V. All rights reserved.

An In vitro Study of Bio-Control and Plant Growth Promotion Potential of Salicaceae Endophytes.

PubMed

Kandel, Shyam L; Firrincieli, Andrea; Joubert, Pierre M; Okubara, Patricia A; Leston, Natalie D; McGeorge, Kendra M; Mugnozza, Giuseppe S; Harfouche, Antoine; Kim, Soo-Hyung; Doty, Sharon L

2017-01-01

Microbial communities in the endosphere of Salicaceae plants, poplar ( Populus trichocarpa ) and willow ( Salix sitchensis ), have been demonstrated to be important for plant growth promotion, protection from biotic and abiotic stresses, and degradation of toxic compounds. Our study aimed to investigate bio-control activities of Salicaceae endophytes against various soil borne plant pathogens including Rhizoctonia solani AG-8, Fusarium culmorum, Gaeumannomyces graminis var. tritici , and Pythium ultimum . Additionally, different plant growth promoting traits such as biological nitrogen fixation (BNF), indole-3-acetic acid (IAA) biosynthesis, phosphate solubilization, and siderophore production were assessed in all bio-control positive strains. Burkholderia, Rahnella, Pseudomonas , and Curtobacterium were major endophyte genera that showed bio-control activities in the in-vitro assays. The bio-control activities of Burkholderia strains were stronger across all tested plant pathogens as compared to other stains. Genomes of sequenced Burkholderia strains WP40 and WP42 were surveyed to identify the putative genes involved in the bio-control activities. The ocf and hcnABC gene clusters responsible for biosynthesis of the anti-fungal metabolites, occidiofungin and hydrogen cyanide, are present in the genomes of WP40 and WP42. Nearly all endophyte strains showing the bio-control activities produced IAA, solubilized tricalcium phosphate, and synthesized siderophores in the culture medium. Moreover, some strains reduced acetylene into ethylene in the acetylene reduction assay, a common assay used for BNF. Salicaceae endophytes could be useful for bio-control of various plant pathogens, and plant growth promotion possibly through the mechanisms of BNF, IAA production, and nutrient acquisition.

Biocontrol Ability and Action Mechanism of Starmerella bacillaris (Synonym Candida zemplinina) Isolated from Wine Musts against Gray Mold Disease Agent Botrytis cinerea on Grape and Their Effects on Alcoholic Fermentation

PubMed Central

Lemos Junior, Wilson José Fernandes; Bovo, Barbara; Nadai, Chiara; Crosato, Giulia; Carlot, Milena; Favaron, Francesco; Giacomini, Alessio; Corich, Viviana

2016-01-01

Gray mold is one of the most important diseases of grapevine in temperate climates. This plant pathogen affects plant growth and reduces wine quality. The use of yeasts as biocontrol agents to apply in the vineyard have been investigated in recent years as an alternative to agrochemicals. In this work, fermenting musts obtained from overripe grape berries, therefore more susceptible to infection by fungal pathogens such as Botrytis cinerea, were considered for the selection of yeasts carrying antifungal activity. Thirty-six isolates were identified as Starmerella bacillaris, a species recently proven to be of enological interest. Among them 14 different strains were studied and antifungal activity against B. cinerea was demonstrated, for the first time, to be present in S. bacillaris species. The production of volatile organic compounds (VOCs), tested in vitro, was found to be the main responsible of S. bacillaris antifungal effects. All the strains were able to reduce B. cinerea decay on wounded grape berries artificially inoculated with gray mold. The colonization level of wound was very high reaching, after 5 days, a concentration of 106 cells per ml of grape juice obtained after berry crushing. At this cell concentration S. bacillaris strains were used to ferment synthetic and natural musts. The sequential yeast inoculation, performed by adding S. cerevisiae 48 h after S. bacillaris, was needed to complete sugar consumption and determined a significant increase in glicerol content and a reduction of ethanol and acetic acid concentrations. The high wound colonization ability, found in this work, together with the propensity to colonize grape berry and the interesting enological traits possessed by the selected S. bacillaris strains allow the use of this yeast as biocontrol agent on vine and grape berries with possible positive effects on must fermentation, although the presence of S. cerevisiae is needed to complete the fermentation process. This work introduces

Molecular evolution and phylogenetic analysis of biocontrol genes acquired from SCoT polymorphism of mycoparasitic Trichoderma koningii inhibiting phytopathogen Rhizoctonia solani Kuhn.

PubMed

Gajera, H P; Hirpara, Darshna G; Katakpara, Zinkal A; Patel, S V; Golakiya, B A

2016-11-01

The biocontrol agent Trichoderma (T. harzianum, T. viride, T. virens, T. hamantum, T. koningii, T. pseudokoningii and Trichoderma species) inhibited variably (15.32 - 88.12%) the in vitro growth of Rhizoctonia solani causing root rot in cotton. The T. koningii MTCC 796 evidenced highest (88.12%) growth inhibition of test pathogen followed by T. viride NBAII Tv23 (85.34%). Scanning electron microscopic study confirmed mycoparasitism for MTCC 796 and Tv23 which were capable of completely overgrowing on R. solani by degrading mycelia, coiling around the hyphae with hook-like structures. The antagonists T. harzianum NBAII Th1 and, T. virens NBAII Tvs12 exhibited strong antibiosis and formed 2-4 mm zone of inhibition for 70.28% and 46.62%, respectively growth inhibition of test pathogen. Mycoparasitism is a strong mode of action for biocontrol activity compared with antibiosis. The antagonists Trichoderma strains were performed for start codon targeted (SCoT) polymorphism to acquire biocontrol genes from potent antagonist. The six unique SCoT fragments amplified by genomic DNA of best mycoparasitic antagonist MTCC 796 strain are subjected to DNA sequencing resulted to confirm two functional sequences for activity related to biocontrol genes. The phylogenetic and molecular evolution of functional 824 bp of SCoT-3 (920) and 776 bp of SCoT-6 (806) fragments signify sequence homology with biocontrol genes endochitinase (partial cds of 203 amino acids) and novel hmgR genes (partial cds of 239 amino acids), respectively and the same were annotated and deposited in NCBI GenBank database. The hmgR gene is liable to be express hmg - CoA reductase which is a key enzyme for regulation of terpene biosynthesis and mycoparasitic strains produced triterpenes during antagonism to inhibit growth of fungal pathogen as evidenced with GC-MS profile. The biocontrol genes are found in best antagonist T. koningii MTCC 796 for mycoparasitic activity to restrain the growth of test pathogen R

Seasonal variation in the biocontrol efficiency of bacterial wilt is driven by temperature-mediated changes in bacterial competitive interactions.

PubMed

Wei, Zhong; Huang, Jianfeng; Yang, Tianjie; Jousset, Alexandre; Xu, Yangchun; Shen, Qirong; Friman, Ville-Petri

2017-10-01

Microbe-based biocontrol applications hold the potential to become an efficient way to control plant pathogen disease outbreaks in the future. However, their efficiency is still very variable, which could be due to their sensitivity to the abiotic environmental conditions.Here, we assessed how environmental temperature variation correlates with ability of Ralstonia pickettii , an endophytic bacterial biocontrol agent, to suppress the Ralstonia solanacearum pathogen during different tomato crop seasons in China.We found that suppression of the pathogen was highest when the seasonal mean temperatures were around 20 °C and rapidly decreased with increasing mean crop season temperatures. Interestingly, low levels of disease incidence did not correlate with low pathogen or high biocontrol agent absolute densities. Instead, the biocontrol to pathogen density ratio was a more important predictor of disease incidence levels between different crop seasons. To understand this mechanistically, we measured the growth and strength of competition between the biocontrol agent and the pathogen over a naturally occurring temperature gradient in vitro . We found that the biocontrol strain grew relatively faster at low temperature ranges, and the pathogen at high temperature ranges, and that similar to field experiments, pathogen suppression peaked at 20 °C.Together, our results suggest that temperature-mediated changes in the strength of bacterial competition could potentially explain the variable R. solanacearum biocontrol outcomes between different crop seasons in China. Synthesis and applications . Our results suggest that abiotic environmental conditions, such as temperature, can affect the efficacy of biocontrol applications. Thus, in order to develop more consistent biocontrol applications in the future, we might need to find and isolate bacterial strains that can retain their functionality regardless of the changing environmental conditions.

AMF-induced biocontrol against plant parasitic nematodes in Musa sp.: a systemic effect.

PubMed

Elsen, A; Gervacio, D; Swennen, R; De Waele, D

2008-07-01

Although mycorrhizal colonization provides a bioprotectional effect against a broad range of soil-borne pathogens, including plant parasitic nematodes, the commercial use of arbuscular mycorrhizal fungi (AMF) as biocontrol agents is still in its infancy. One of the main reasons is the poor understanding of the modes of action. Most AMF mode of action studies focused on AMF-bacterial/fungal pathogens. Only few studies so far examined AMF-plant parasitic nematode interactions. Therefore, the aim of the study was to determine whether the AMF Glomus intraradices was able to incite systemic resistance in banana plants towards Radopholus similis and Pratylenchus coffeae, two plant parasitic nematodes using a split-root compartmental set-up. The AMF reduced both nematode species by more than 50%, even when the AMF and the plant parasitic nematodes were spatially separated. The results obtained demonstrate for the first time that AMF have the ability to induce systemic resistance against plant parasitic nematodes in a root system.

Can Some Marine-Derived Fungal Metabolites Become Actual Anticancer Agents?

PubMed Central

Gomes, Nelson G. M.; Lefranc, Florence; Kijjoa, Anake; Kiss, Robert

2015-01-01

Marine fungi are known to produce structurally unique secondary metabolites, and more than 1000 marine fungal-derived metabolites have already been reported. Despite the absence of marine fungal-derived metabolites in the current clinical pipeline, dozens of them have been classified as potential chemotherapy candidates because of their anticancer activity. Over the last decade, several comprehensive reviews have covered the potential anticancer activity of marine fungal-derived metabolites. However, these reviews consider the term “cytotoxicity” to be synonymous with “anticancer agent”, which is not actually true. Indeed, a cytotoxic compound is by definition a poisonous compound. To become a potential anticancer agent, a cytotoxic compound must at least display (i) selectivity between normal and cancer cells (ii) activity against multidrug-resistant (MDR) cancer cells; and (iii) a preferentially non-apoptotic cell death mechanism, as it is now well known that a high proportion of cancer cells that resist chemotherapy are in fact apoptosis-resistant cancer cells against which pro-apoptotic drugs have more than limited efficacy. The present review thus focuses on the cytotoxic marine fungal-derived metabolites whose ability to kill cancer cells has been reported in the literature. Particular attention is paid to the compounds that kill cancer cells through non-apoptotic cell death mechanisms. PMID:26090846

Biological Control Potential of Bacillus amyloliquefaciens KB3 Isolated from the Feces of Allomyrina dichotoma Larvae

PubMed Central

Nam, Hyo-Song; Yang, Hyun-Ju; Oh, Byung Jun; Anderson, Anne J.; Kim, Young Cheol

2016-01-01

Most biocontrol agents for plant diseases have been isolated from sources such as soils and plants. As an alternative source, we examined the feces of tertiary larvae of the herbivorous rhino beetle, Allomyrina dichotoma for presence of biocontrol-active microbes. The initial screen was performed to detect antifungal activity against two common fungal plant pathogens. The strain with strongest antifungal activity was identified as Bacillus amyloliquefaciens KB3. The inhibitory activity of this strain correlated with lipopeptide productions, including iturin A and surfactin. Production of these surfactants in the KB3 isolate varied with the culture phase and growth medium used. In planta biocontrol activities of cell-free culture filtrates of KB3 were similar to those of the commercial biocontrol agent, B. subtilis QST-713. These results support the presence of microbes with the potential to inhibit fungal growth, such as plant pathogens, in diverse ecological niches. PMID:27298603

Wonder world of phages: potential biocontrol agents safeguarding biosphere and health of animals and humans- current scenario and perspectives.

PubMed

Tiwari, Ruchi; Chakraborty, Sandip; Dhama, Kuldeep; Wani, Mohd Yaqoob; Kumar, Amit; Kapoor, Sanjay

2014-02-01

Darwin's theory of natural selection and concept of survival of fittest of Wallace is a universal truth which derives the force of life among all live entities on this biosphere. Issues regarding food safety along with increased drug resistance and emerging zoonotic infections have proved that multidisciplinary efforts are in demand for human and animal welfare. This has led to development of various novel therapies the list of which remains incomplete without mentioning about phages. Homologous and non-homologous recombination along with point mutation and addition of new genes play role in their evolution. The rapid emergence of the antibiotic resistant strains of bacteria have created keen interest in finding necessary alternatives to check microbial infections and there comes the importance of phages. Phages kill the bacteria either by lysis or by releasing holins. Bacteriophages; the viruses that live on bacteria are nowadays considered as the best biocontrol agents. They are used as replacers of antibiotics; food industry promoter; guard of aquatic life as well as of plants; pre-slaughter treatment agents; Generally Recognized As Safe (GRAS) food additives; Typing agent of bacteria; active tool of super bug therapy; in post harvest crops and food and during post infection and also to combat intracellular pathogens viz. Mycobacteria and Mycoplasma. Cyanophages/phycophages are particularly useful in controlling blooms produced by various genera of algae and cyanobacteria. By performing centrifugation studies and based on electron microscopy certain virus like particles containing ds RNA have been confirmed as mycophages. They are well proven as threat to pathogenic fungi (both fungal hyphae and yeast). Those that infect yeasts are called zymophages. Virophages have exquisite specificity for their viral host, hence can extensively be used for genetic studies and can also act as evolutionary link. After the discovery of very first virophage till now, a total of 3

Protection of groundnut plants from rust disease by application of glucan isolated from a biocontrol agent Acremonium obclavatum.

PubMed

Sathiyabama, M; Balasubramanian, R

2018-05-01

Prior treatment of groundnut leaves with glucan isolated from a biocontrol agent, Acremonium obclavatum, protected against the rust disease. Glucan treated leaves showed increased levels of chitinase and β-1,3-glucanase in the apoplastic fluid. An increase in endogenous levels of salicylic acid also was observed in treated leaves. Treated leaves also showed a significant reduction in rust disease development in groundnut leaves. Enhanced activities of glucanohydrolases of treated groundnut leaves might have affected the biotrophic rust pathogen, which is known to colonize in the apoplastic spaces. Copyright © 2018 Elsevier B.V. All rights reserved.

Cheatgrass (Bromus tectorum) biocontrol using indigenous fungal pathogens

Treesearch

Susan E. Meyer; David L. Nelson; Suzette Clement; Julie Beckstead

2008-01-01

Cheatgrass (Bromus tectorum) is an exotic winter annual grass weed that has invaded millions of hectares in the Intermountain West. Restoration of cheatgrass-invaded wildlands is generally impractical without some form of cheatgrass control. We are investigating the possibility of manipulating indigenous fungal pathogens that already occur on...

Endophytic Trichoderma gamsii YIM PH30019: a promising biocontrol agent with hyperosmolar, mycoparasitism, and antagonistic activities of induced volatile organic compounds on root-rot pathogenic fungi of Panax notoginseng.

PubMed

Chen, Jin-Lian; Sun, Shi-Zhong; Miao, Cui-Ping; Wu, Kai; Chen, You-Wei; Xu, Li-Hua; Guan, Hui-Lin; Zhao, Li-Xing

2016-10-01

Biocontrol agents are regarded as promising and environmental friendly approaches as agrochemicals for phytodiseases that cause serious environmental and health problems. Trichoderma species have been widely used in suppression of soil-borne pathogens. In this study, an endophytic fungus, Trichoderma gamsii YIM PH30019, from healthy Panax notoginseng root was investigated for its biocontrol potential. In vitro detached healthy roots, and pot and field experiments were used to investigate the pathogenicity and biocontrol efficacy of T. gamsii YIM PH30019 to the host plant. The antagonistic mechanisms against test phytopathogens were analyzed using dual culture, scanning electron microscopy, and volatile organic compounds (VOCs). Tolerance to chemical fertilizers was also tested in a series of concentrations. The results indicated that T. gamsii YIM PH30019 was nonpathogenic to the host, presented appreciable biocontrol efficacy, and could tolerate chemical fertilizer concentrations of up to 20%. T. gamsii YIM PH30019 displayed antagonistic activities against the pathogenic fungi of P . notoginseng via production of VOCs. On the basis of gas chromatography-mass spectrometry, VOCs were identified as dimethyl disulfide, dibenzofuran, methanethiol, ketones, etc., which are effective ingredients for antagonistic activity. T. gamsii YIM PH30019 was able to improve the seedlings' emergence and protect P. notoginseng plants from soil-borne disease in the continuous cropping field tests. The results suggest that the endophytic fungus T. gamsii YIM PH30019 may have a good potential as a biological control agent against notoginseng phytodiseases and can provide a clue to further illuminate the interactions between Trichoderma and phytopathogens.

Biocontrol Activity of the Local Strain of Metschnikowia pulcherrima on Different Postharvest Pathogens.

PubMed

Türkel, Sezai; Korukluoğlu, Mihriban; Yavuz, Mümine

2014-01-01

The strains of the yeast Metschnikowia pulcherrima have strong biocontrol activity against various microorganisms. Biocontrol activity of M. pulcherrima largely depends on its iron immobilizing pigment pulcherrimin. Biocontrol activity of pulcherrimin producing strain, M. pulcherrima UMY15, isolated from local vineyards, was tested on different molds that cause food spoilage. M. pulcherrima UMY15 was a very effective biocontrol agent against Penicillium roqueforti, P. italicum, P. expansum, and Aspergillus oryzae in in-vitro plate tests. However, the inhibitory activity of M. pulcherrima UMY15 was less effective on Fusarium sp. and A. niger species in biocontrol assays. In addition, M. pulcherrima UMY15 strain completely inhibited the germination and mycelia growth of A. oryzae, A. parasiticus, and Fusarium sp. spores on artificial wounds of apples when they coinoculated with M. pulcherrima UMY15. Moreover, when coinoculated, M. pulcherrima UMY15 strain also inhibited the growth of P. roqueforti, P. italicum, P. expansum, A. oryzae, Fusarium sp., and Rhizopus sp. in grape juice, indicating that M. pulcherrima UMY15 can be used as a very effective biocontrol yeast against various species of postharvest pathogens, including Penicillium, Aspergillus, Fusarium, and Rhizopus.

Weed biocontrol in the EU: from serendipity to strategy

USDA-ARS?s Scientific Manuscript database

Biological control of weeds is a globally-recognized approach to the management of the worst invasive plants in the world. Unfortunately, accidental introduction of agents account for most weed biocontrol in the EU, but do include a number of current or emerging successes. From the redistribution of...

Wild Grape-Associated Yeasts as Promising Biocontrol Agents against Vitis vinifera Fungal Pathogens.

PubMed

Cordero-Bueso, Gustavo; Mangieri, Nicola; Maghradze, David; Foschino, Roberto; Valdetara, Federica; Cantoral, Jesús M; Vigentini, Ileana

2017-01-01

The increasing level of hazardous residues in the environment and food chains has led the European Union to restrict the use of chemical fungicides. Thus, exploiting new natural antagonistic microorganisms against fungal diseases could serve the agricultural production to reduce pre- and post-harvest losses, to boost safer practices for workers and to protect the consumers' health. The main aim of this work was to evaluate the antagonistic potential of epiphytic yeasts against Botrytis cinerea, Aspergillus carbonarius , and Penicillium expansum pathogen species. In particular, yeast isolation was carried out from grape berries of Vitis vinifera ssp sylvestris populations, of the Eurasian area, and V. vinifera ssp vinifera cultivars from three different farming systems (organic, biodynamic, and conventional). Strains able to inhibit or slow the growth of pathogens were selected by in vitro and in vivo experiments. The most effective antagonist yeast strains were subsequently assayed for their capability to colonize the grape berries. Finally, possible modes of action, such as nutrients and space competition, iron depletion, cell wall degrading enzymes, diffusible and volatile antimicrobial compounds, and biofilm formation, were investigated as well. Two hundred and thirty-one yeast strains belonging to 26 different species were isolated; 20 of them, ascribed to eight species, showed antagonistic action against all molds. Yeasts isolated from V. vinifera ssp sylvestris were more effective (up to 50%) against B. cinerea rather than those isolated from V. vinifera ssp vinifera. Six strains, all isolated from wild vines, belonging to four species ( Meyerozyma guilliermondii, Hanseniaspora uvarum, Hanseniaspora clermontiae , and Pichia kluyveri ) revealed one or more phenotypical characteristics associated to the analyzed modes of antagonistic action.

Wild Grape-Associated Yeasts as Promising Biocontrol Agents against Vitis vinifera Fungal Pathogens

PubMed Central

Cordero-Bueso, Gustavo; Mangieri, Nicola; Maghradze, David; Foschino, Roberto; Valdetara, Federica; Cantoral, Jesús M.; Vigentini, Ileana

2017-01-01

The increasing level of hazardous residues in the environment and food chains has led the European Union to restrict the use of chemical fungicides. Thus, exploiting new natural antagonistic microorganisms against fungal diseases could serve the agricultural production to reduce pre- and post-harvest losses, to boost safer practices for workers and to protect the consumers' health. The main aim of this work was to evaluate the antagonistic potential of epiphytic yeasts against Botrytis cinerea, Aspergillus carbonarius, and Penicillium expansum pathogen species. In particular, yeast isolation was carried out from grape berries of Vitis vinifera ssp sylvestris populations, of the Eurasian area, and V. vinifera ssp vinifera cultivars from three different farming systems (organic, biodynamic, and conventional). Strains able to inhibit or slow the growth of pathogens were selected by in vitro and in vivo experiments. The most effective antagonist yeast strains were subsequently assayed for their capability to colonize the grape berries. Finally, possible modes of action, such as nutrients and space competition, iron depletion, cell wall degrading enzymes, diffusible and volatile antimicrobial compounds, and biofilm formation, were investigated as well. Two hundred and thirty-one yeast strains belonging to 26 different species were isolated; 20 of them, ascribed to eight species, showed antagonistic action against all molds. Yeasts isolated from V. vinifera ssp sylvestris were more effective (up to 50%) against B. cinerea rather than those isolated from V. vinifera ssp vinifera. Six strains, all isolated from wild vines, belonging to four species (Meyerozyma guilliermondii, Hanseniaspora uvarum, Hanseniaspora clermontiae, and Pichia kluyveri) revealed one or more phenotypical characteristics associated to the analyzed modes of antagonistic action. PMID:29163377

Prevention of fungal spoilage in food products using natural compounds: A review.

PubMed

Ribes, Susana; Fuentes, Ana; Talens, Pau; Barat, Jose Manuel

2017-04-10

The kingdom Fungi is the most important group of microorganism contaminating food commodities, and chemical additives are commonly used in the food industry to prevent fungal spoilage. However, the increasing consumer concern about synthetic additives has led to their substitution by natural compounds in foods. The current review provides an overview of using natural agents isolated from different sources (plants, animals, and microorganisms) as promising antifungal compounds, including information about their mechanism of action and their use in foods to preserve and prolong shelf life. Compounds derived from plants, chitosan, lactoferrin, and biocontrol agents (lactic acid bacteria, antagonistic yeast, and their metabolites) are able to control the decay caused by fungi in a wide variety of foods. Several strategies are employed to reduce the drawbacks of some antifungal agents, like their incorporation into oil-in-water emulsions and nanoemulsions, edible films and active packaging, and their combination with other natural preservatives. These strategies facilitate the addition of volatile agents into food products and, improve their antifungal effectiveness. Moreover, biological agents have been investigated as one of the most promising options in the control of postharvest decay. Numerous mechanisms of action have been elucidated and different approaches have been studied to enhance their antifungal effectiveness.

Broad-spectrum inhibition of Phytophthora infestans by fungal endophytes

PubMed Central

von Dahlen, Janina K; Schnake, Anika; Ginschel, Sarah; Schulz, Barbara; Rose, Laura E

2018-01-01

ABSTRACT Phytophthora infestans is a devastating pathogen of tomato and potato. It readily overcomes resistance genes and applied agrochemicals and hence even today causes large yield losses. Fungal endophytes provide a largely unexplored avenue of control of Phy. infestans. Not only do endophytes produce a wide array of bioactive metabolites, they may also directly compete with and defeat pathogens in planta. Here, we tested 12 fungal endophytes isolated from different plant species in vitro for their production of metabolites with anti- Phytophthora activity. Four well-performing isolates were evaluated for their ability to suppress nine isolates of Phy. infestans on agar medium and in planta. Two endophytes reliably inhibited all Phy. infestans isolates on agar medium, of which Phoma eupatorii isolate 8082 was the most promising. It nearly abolished infection by Phy. infestans in planta. Our data indicate a role for the production of anti-Phytophthora compounds by the fungus and/or an enhanced plant defense response, as evident by an enhanced anthocyanin production. Here, we present a potential biocontrol agent, which can inhibit a broad-spectrum of Phy. infestans isolates. Such broadly acting inhibition is ideal, because it allows for effective control of genetically diverse isolates and may slow the adaptation of Phy. infestans. PMID:29528408

Selection rhizosphere-competent microbes for development of microbial products as biocontrol agents

NASA Astrophysics Data System (ADS)

Mashinistova, A. V.; Elchin, A. A.; Gorbunova, N. V.; Muratov, V. S.; Kydralieva, K. A.; Khudaibergenova, B. M.; Shabaev, V. P.; Jorobekova, Sh. J.

2009-04-01

Rhizosphere-borne microorganisms reintroduced to the soil-root interface can establish without inducing permanent disturbance in the microbial balance and effectively colonise the rhizosphere due to carbon sources of plant root exudates. A challenge for future development of microbial products for use in agriculture will be selection of rhizosphere-competent microbes that both protect the plant from pathogens and improve crop establishment and persistence. In this study screening, collection, identification and expression of stable and technological microbial strains living in soils and in the rhizosphere of abundant weed - couch-grass Elytrigia repens L. Nevski were conducted. A total of 98 bacteria isolated from the rhizosphere were assessed for biocontrol activity in vitro against phytopathogenic fungi including Fusarium culmorum, Fusarium heterosporum, Fusarium oxysporum, Drechslera teres, Bipolaris sorokiniana, Piricularia oryzae, Botrytis cinerea, Colletothrichum atramentarium and Cladosporium sp., Stagonospora nodorum. Biocontrol activity were performed by the following methods: radial and parallel streaks, "host - pathogen" on the cuts of wheat leaves. A culture collection comprising 64 potential biocontrol agents (BCA) against wheat and barley root diseases has been established. Of these, the most effective were 8 isolates inhibitory to at least 4 out of 5 phytopathogenic fungi tested. The remaining isolates inhibited at least 1 of 5 fungi tested. Growth stimulating activity of proposed rhizobacteria-based preparations was estimated using seedling and vegetative pot techniques. Seeds-inoculation and the tests in laboratory and field conditions were conducted for different agricultural crops - wheat and barley. Intact cells, liquid culture filtrates and crude extracts of the four beneficial bacterial strains isolated from the rhizosphere of weed were studied to stimulate plant growth. As a result, four bacterial strains selected from rhizosphere of weed

Integrated management of foot rot of lentil using biocontrol agents under field condition.

PubMed

Hannan, M A; Hasan, M M; Hossain, I; Rahman, S M E; Ismail, Alhazmi Mohammed; Oh, Deog-Hwan

2012-07-01

The efficacy of cowdung, Bangladesh Institute of Nuclear Agriculture (BINA)-biofertilizer, and Bangladesh Agricultural University (BAU)-biofungicide, alone or in combination, was evaluated for controlling foot rot disease of lentil. The results exhibited that BINA-biofertilizer and BAUbiofungicide (peat soil-based Rhizobium leguminosarum and black gram bran-based Trichoderma harzianum) are compatible and have combined effects in controlling the pathogenic fungi Fusarium oxysporum and Sclerotium rolfsii, which cause the root rot of lentil. Cowdung mixing with soil (at 5 t/ha) during final land preparation and seed coating with BINA-biofertilizer and BAU-biofungicide (at 2.5% of seed weight) before sowing recorded 81.50% field emergence of lentil, which showed up to 19.85% higher field emergence over the control. Post-emergence deaths of plants due to foot rot disease were significantly reduced after combined seed treatment with BINA-biofertilizer and BAU-biofungicide. Among the treatments used, only BAU-biofungicide as the seed treating agent resulted in higher plant stand (84.82%). Use of BINA-biofertilizer and BAU-biofungicide as seed treating biocontrol agents and application of cowdung in the soil as an organic source of nutrient resulted in higher shoot and root lengths, and dry shoot and root weights of lentil. BINA-biofertilizer significantly increased the number of nodules per plant and nodules weight of lentil. Seeds treating with BAUbiofungicide and BINA-biofertilizer and soil amendment with cowdung increased the biomass production of lentil up to 75.56% over the control.

Bacillus methylotrophicus Strain NKG-1, Isolated from Changbai Mountain, China, Has Potential Applications as a Biofertilizer or Biocontrol Agent.

PubMed

Ge, Beibei; Liu, Binghua; Nwet, Thinn Thinn; Zhao, Wenjun; Shi, Liming; Zhang, Kecheng

2016-01-01

Chemical pesticides are widely used in agriculture, which endangers both environmental health and food safety. Biocontrol is an environmentally-friendly and cost-effective green technique in environmental protection and agricultural production; it generally uses selected bioresources, including beneficial microorganisms. We isolated a novel bacterial strain (NKG-1) from the rare dormant volcanic soils of Changbai Mountain in China's Jilin Province. The strain was identified as Bacillus methylotrophicus using morphological, biochemical, physiological, and phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi on solid media. A greenhouse experiment showed that application of NKG-1 fermentation broth prior to inoculation of Botrytis cinerea, the cause of gray tomato mold, inhibited growth of the mold by 60%. Furthermore, application of a 100× dilution of NKG-1 fermentation broth to tomato seedlings yielded a significant increase in seedling fresh weight (27.4%), seedling length (12.5%), and root length (57.7%) compared to the control. When the same dosage was applied in the field, we observed increases in tomato plant height (14.7%), stem diameter (12.7%), crown width (16.3%), and maximum fruit diameter (11.5%). These results suggest that NKG-1 has potential commercial application as a biofertilizer or biocontrol agent.

Endemic plants harbour specific Trichoderma communities with an exceptional potential for biocontrol of phytopathogens.

PubMed

Zachow, Christin; Berg, Christian; Müller, Henry; Monk, Jana; Berg, Gabriele

2016-10-10

Trichoderma strains exhibit enormous potential for applications in biotechnology, in particular as biocontrol agents against pathogens. However, little is known about the diversity of plant-associated Trichoderma communities at a global scale and their antagonistic spectrum. In order to gather information about structure and function, we compared Trichoderma biomes of endemic (Aeonium, Diospyros, Hebe, Rhododendron) and cosmopolitan plants (Zea mays) in a global study encompassing the area Northwest Africa to New Zealand via the European Alps and Madagascar. At the quantitative level we found no differences between cosmopolitan and endemic plants. Statistically significant differences were detected at the qualitative level: Trichoderma populations of endemic plants were highly specific and diverse with hot spots appearing in Madagascar and New Zealand. By contrast, maize plants from all sites shared the majority of Trichoderma species (65.5%). Interestingly, the high above ground biodiversity in ecosystems containing endemic plants was confirmed by a high below ground Trichoderma diversity. Despite the differences, we found a global Trichoderma core community shared by all analysed plants, which was dominated by T. koningii and T. koningiopsis. Amplicon-based network analyses revealed a high similarity between maize Trichoderma grown world-wide and distinct populations of endemic plants. Furthermore, Trichoderma strains from endemic plants showed a higher antagonistic activity against fungal pathogens compared to maize-associated strains. Our results showed that endemic plants are associated with a specific Trichoderma microbiome which possesses a high antagonistic activity indicating that it has potential to be used for biocontrol purposes. Copyright © 2016 Elsevier B.V. All rights reserved.

Seed treatments to control seedborne fungal pathogens of vegetable crops.

PubMed

Mancini, Valeria; Romanazzi, Gianfranco

2014-06-01

Vegetable crops are frequently infected by fungal pathogens, which can include seedborne fungi. In such cases, the pathogen is already present within or on the seed surface, and can thus cause seed rot and seedling damping-off. Treatment of vegetable seeds has been shown to prevent plant disease epidemics caused by seedborne fungal pathogens. Furthermore, seed treatments can be useful in reducing the amounts of pesticides required to manage a disease, because effective seed treatments can eliminate the need for foliar application of fungicides later in the season. Although the application of fungicides is almost always effective, their non-target environmental impact and the development of pathogen resistance have led to the search for alternative methods, especially in the past few years. Physical treatments that have already been used in the past and treatments with biopesticides, such as plant extracts, natural compounds and biocontrol agents, have proved to be effective in controlling seedborne pathogens. These have been applied alone or in combination, and they are widely used owing to their broad spectrum in terms of disease control and production yield. In this review, the effectiveness of different seed treatments against the main seedborne pathogens of some important vegetable crops is critically discussed. © 2013 Society of Chemical Industry.

Phenylacetic acid-producing Rhizoctonia solani represses the biosynthesis of nematicidal compounds in vitro and influences biocontrol of Meloidogyne incognita in tomato by Pseudomonas fluorescens strain CHA0 and its GM derivatives.

PubMed

Siddiqui, I A; Shaukat, S S

2005-01-01

The aim of the present investigation was to determine the influence of Rhizoctonia solani and its pathogenicity factor on the production of nematicidal agent(s) by Pseudomonas fluorescens strain CHA0 and its GM derivatives in vitro and nematode biocontrol potential by bacterial inoculants in tomato. One (Rs7) of the nine R. solani isolates from infected tomato roots inhibited seedling emergence and caused root rot in tomato. Thin layer chromatography revealed that culture filtrates of two isolates (Rs3 and Rs7) produced brown spots at Rf-values closely similar to synthetic phenylacetic acid (PAA), a phytotoxic factor. Filtrates from isolate Rs7, amended with the growth medium of P. fluorescens, markedly repressed nematicidal activity and PhlA'-'LacZ reporter gene expression of the bacteria in vitro. On the contrary, isolate Rs4 enhanced nematicidal potential of a 2,4-diacetylphloroglucinol overproducing mutant, CHA0/pME3424, of P. fluorescens strain CHA0 in vitro. Therefore, R. solani isolates Rs4 and Rs7 were tested more rigorously for their potential to influence biocontrol effectiveness of the bacterial agents. Methanol extract of the culture filtrates of PAA-producing isolate Rs7 resulting from medium amended with phenylalanine enhanced fungal repression of the production of nematicidal agents by bacteria, while amendments with zinc or molybdenum eliminated such fungal repression, thereby restoring bacterial potential to cause nematode mortality in vitro. A pot experiment was carried out, 3-week-old tomato seedlings were infested with R. solani isolates Rs4 or Rs7 and/or inoculated with Meloidogyne incognita, the root-knot nematode. The infested soil was treated with aqueous cell suspensions (10(8) CFU) of P. fluorescens strain CHA0 or its GM derivatives or left untreated (as a control). Observations taken 45 days after nematode inoculation revealed that, irrespective of the bacterial treatments, galling intensity per gram of fresh tomato roots was markedly

Miconia biocontrol: Where are we going and when will we get there?

Treesearch

M.T. Johnson

2010-01-01

We have made much progress in evaluating potential agents for biocontrol of miconia, and several appear likely to be suitable for future introduction to Hawaiÿi. Unfortunately, none of them is an obvious silver bullet. We face the challenge of prioritizing the existing candidates and inventing the combination of agents that will achieve our goals. Now is an opportune...

Regulation of morphogenesis and biocontrol properties in Trichoderma virens by a VELVET protein, Vel1.

PubMed

Mukherjee, Prasun K; Kenerley, Charles M

2010-04-01

Mycoparasitic strains of Trichoderma are applied as commercial biofungicides for control of soilborne plant pathogens. Although the majority of commercial biofungicides are Trichoderma based, chemical pesticides, which are ecological and environmental hazards, still dominate the market. This is because biofungicides are not as effective or consistent as chemical fungicides. Efforts to improve these products have been limited by a lack of understanding of the genetic regulation of biocontrol activities. In this study, using gene knockout and complementation, we identified the VELVET protein Vel1 as a key regulator of biocontrol, as well as morphogenetic traits, in Trichoderma virens, a commercial biocontrol agent. Mutants with mutations in vel1 were defective in secondary metabolism (antibiosis), mycoparasitism, and biocontrol efficacy. In nutrient-rich media they also lacked two types of spores important for survival and development of formulation products: conidia (on agar) and chlamydospores (in liquid shake cultures). These findings provide an opportunity for genetic enhancement of biocontrol and industrial strains of Trichoderma, since Vel1 is very highly conserved across three Trichoderma species.

Two-photon microscopy of fungal keratitis-affected rabbit cornea ex vivo using moxifloxacin as a labeling agent.

PubMed

Lee, Jun Ho; Le, Viet-Hoan; Lee, Seunghun; Park, Jin Hyoung; Lee, Jin Ah; Tchah, Hungwon; Kim, Sungjee; Kim, Myoung Joon; Kim, Ki Hean

2018-05-19

Two-photon microscopy (TPM) is a three dimensional (3D) microscopic technique based on nonlinear two-photon fluorescence, which has been tested as an alternative to reflectance confocal microscopy (RCM) for detecting fungal keratitis via optical imaging. Although TPM provided images with better contrast than RCM for fungal keratitis, its imaging speed was relatively low because of weak intrinsic signal. Moxifloxacin, a Food and Drug Administration (FDA)-approved antibiotic, was recently used as a cell-labeling agent for TPM. In this study, moxifloxacin was used to label fungal cells for TPM imaging of fungal keratitis models. Fungal cell suspensions and ex vivo fungal keratitis-affected rabbit corneas were prepared using two types of fungal pathogens, Aspergillus fumigatus and Candida albicans, and TPM imaging was performed both with and without moxifloxacin treatment. Fungal cells with enhanced fluorescence were clearly visible by TPM of moxifloxacin-treated fungal cell suspensions. TPM of moxifloxacin-treated fungal keratitis rabbit corneas revealed both the infecting fungal cells and corneal cells similar to those observed in TPM without moxifloxacin treatment, albeit with approximately 10-times enhanced fluorescence. Fungal cells were distinguished from corneal cells on the basis of their distinct morphologies. Thus, TPM with moxifloxacin labeling might be useful for the detection of fungal keratitis at the improved imaging speed. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

50-plus years of fungal viruses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghabrial, Said A., E-mail: saghab00@email.uky.edu; Castón, José R.; Jiang, Daohong

2015-05-15

Mycoviruses are widespread in all major taxa of fungi. They are transmitted intracellularly during cell division, sporogenesis, and/or cell-to-cell fusion (hyphal anastomosis), and thus their life cycles generally lack an extracellular phase. Their natural host ranges are limited to individuals within the same or closely related vegetative compatibility groups, although recent advances have established expanded experimental host ranges for some mycoviruses. Most known mycoviruses have dsRNA genomes packaged in isometric particles, but an increasing number of positive- or negative-strand ssRNA and ssDNA viruses have been isolated and characterized. Although many mycoviruses do not have marked effects on their hosts, thosemore » that reduce the virulence of their phytopathogenic fungal hosts are of considerable interest for development of novel biocontrol strategies. Mycoviruses that infect endophytic fungi and those that encode killer toxins are also of special interest. Structural analyses of mycoviruses have promoted better understanding of virus assembly, function, and evolution. - Highlights: • Historical perspective of fungal virus research. • Description, classification and diversity of fungal virus families. • Structural features of fungal virus particles. • Hypovirulence and exploitation of mycoviruses in biological control of plant pathogenic fungi.« less

Physiological and biochemical characterization of Trichoderma harzianum, a biological control agent against soilborne fungal plant pathogens.

PubMed Central

Grondona, I; Hermosa, R; Tejada, M; Gomis, M D; Mateos, P F; Bridge, P D; Monte, E; Garcia-Acha, I

1997-01-01

Monoconidial cultures of 15 isolates of Trichoderma harzianum were characterized on the basis of 82 morphological, physiological, and biochemical features and 99 isoenzyme bands from seven enzyme systems. The results were subjected to numerical analysis which revealed four distinct groups. Representative sequences of the internal transcribed spacer 1 (ITS 1)-ITS 2 region in the ribosomal DNA gene cluster were compared between groups confirming this distribution. The utility of the groupings generated from the morphological, physiological, and biochemical data was assessed by including an additional environmental isolate in the electrophoretic analysis. The in vitro antibiotic activity of the T. harzianum isolates was assayed against 10 isolates of five different soilborne fungal plant pathogens: Aphanomyces cochlioides, Rhizoctonia solani, Phoma betae, Acremonium cucurbitacearum, and Fusarium oxysporum f. sp. radicis lycopersici. Similarities between levels and specificities of biological activity and the numerical characterization groupings are both discussed in relation to antagonist-specific populations in known and potential biocontrol species. PMID:9251205

The effect of entomopathogenic fungal culture filtrate on the immune response of the greater wax moth, Galleria mellonella.

PubMed

Mc Namara, Louise; Carolan, James C; Griffin, Christine T; Fitzpatrick, David; Kavanagh, Kevin

2017-07-01

Galleria mellonella is a well-established model species regularly employed in the study of the insect immune response at cellular and humoral levels to investigate fungal pathogenesis and biocontrol agents. A cellular and proteomic analysis of the effect of culture filtrate of three entomopathogenic fungi (EPF) species on the immune system of G. mellonella was performed. Treatment with Beauveria caledonica and Metarhizium anisopliae 96h culture filtrate facilitated a significantly increased yeast cell density in larvae (3-fold and 3.8-fold, respectively). Larvae co-injected with either M. anisopliae or B. caledonica culture filtrate and Candida albicans showed significantly increased mortality. The same was not seen for larvae injected with Beauveria bassiana filtrate. Together these results suggest that B. caledonica and M. anisopliae filtrate are modulating the insect immune system allowing a subsequent pathogen to proliferate. B. caledonica and M. anisopliae culture filtrates impact upon the larval prophenoloxidase (ProPO) cascade (e.g. ProPO activating factor 3 and proPO activating enzyme 3 were increased in abundance relative to controls), while B. bassiana treated larvae displayed higher abundances of alpha-esterase when compared to control larvae (2.4-fold greater) and larvae treated with M. anisopliae and B. caledonica. Treatment with EPF culture filtrate had a significant effect on antimicrobial peptide abundances particularly in M. anisopliae treated larvae where cecropin-D precursor, hemolin and gloverin were differentially abundant in comparison to controls. Differences in proteomic profiles for different treatments may reflect or even partially explain the differences in their immunomodulatory potential. Screening EPF for their ability to modulate the insect immune response represents a means of assessing EPF for use as biocontrol agents, particularly if the goal is to use them in combination with other control agents. Additionally EPF represent a

Mechanism of H₂O₂-induced oxidative stress regulating viability and biocontrol ability of Rhodotorula glutinis.

PubMed

Chen, Jian; Li, Boqiang; Qin, Guozheng; Tian, Shiping

2015-01-16

The use of antagonistic yeasts to control postharvest pathogens is a promising alternative to fungicides. The effectiveness of the antagonists against fungal pathogens is greatly dependent on their viability, which is usually mediated by reactive oxygen species (ROS). Here, we investigated the effects of H₂O₂-induced oxidative stress on the viability and biocontrol efficacy of Rhodotorula glutinis and, using flow cytometric analysis, observed the changes of ROS accumulation and apoptosis in the yeast cells with or without H₂O₂ treatment. We found that the viability of R. glutinis decreased in a time- and dose-dependent manner under H₂O₂-induced oxidative stress. Compared to the control, yeast cells exposed to oxidative stress exhibited more accumulation of ROS and higher levels of protein oxidative damage, but showed lower efficacy for biocontrol of Penicillium expansum causing blue mold rot on peach fruit. The results indicate that apoptosis is a main cause of the cell viability loss in R. glutinis, which is attributed to ROS accumulation under oxidative stress. These findings offer a plausible explanation that oxidative stress affects biocontrol efficacy of R. glutinis via regulating its viability and cell apoptosis. Copyright © 2014 Elsevier B.V. All rights reserved.

Linear Epitopes of Paracoccidioides brasiliensis and Other Fungal Agents of Human Systemic Mycoses As Vaccine Candidates

PubMed Central

Travassos, Luiz R.; Taborda, Carlos P.

2017-01-01

Dimorphic fungi are agents of systemic mycoses associated with significant morbidity and frequent lethality in the Americas. Among the pathogenic species are Paracoccidioides brasiliensis and Paracoccidioides lutzii, which predominate in South America; Histoplasma capsulatum, Coccidioides posadasii, and Coccidioides immitis, and the Sporothrix spp. complex are other important pathogens. Associated with dimorphic fungi other important infections are caused by yeast such as Candida spp. and Cryptococcus spp. or mold such as Aspergillus spp., which are also fungal agents of deadly infections. Nowadays, the actual tendency of therapy is the development of a pan-fungal vaccine. This is, however, not easy because of the complexity of eukaryotic cells and the particularities of different species and isolates. Albeit there are several experimental vaccines being studied, we will focus mainly on peptide vaccines or epitopes of T-cell receptors inducing protective fungal responses. These peptides can be carried by antibody inducing β-(1,3)-glucan oligo or polysaccharides, or be mixed with them for administration. The present review discusses the efficacy of linear peptide epitopes in the context of antifungal immunization and vaccine proposition. PMID:28344577

Trichoderma Biocontrol: Signal Transduction Pathways Involved in Host Sensing and Mycoparasitism

PubMed Central

Zeilinger, Susanne; Omann, Markus

2007-01-01

Fungi of the genus Trichoderma are used as biocontrol agents against several plant pathogenic fungi like Rhizoctonia spp., Pythium spp., Botrytis cinerea and Fusarium spp. which cause both soil-borne and leaf- or flower-borne diseases of agricultural plants. Plant disease control by Trichoderma is based on complex interactions between Trichoderma, the plant pathogen and the plant. Until now, two main components of biocontrol have been identified: direct activity of Trichoderma against the plant pathogen by mycoparasitism and induced systemic resistance in plants. As the mycoparasitic interaction is host-specific and not merely a contact response, it is likely that signals from the host fungus are recognised by Trichoderma and provoke transcription of mycoparasitism-related genes. In the last few years examination of signalling pathways underlying Trichoderma biocontrol started and it was shown that heterotrimeric G-proteins and mitogen-activated protein (MAP) kinases affected biocontrol-relevant processes such as the production of hydrolytic enzymes and antifungal metabolites and the formation of infection structures. MAPK signalling was also found to be involved in induction of plant systemic resistance in Trichoderma virens and in the hyperosmotic stress response in Trichoderma harzianum. Analyses of the function of components of the cAMP pathway during Trichoderma biocontrol revealed that mycoparasitism-associated coiling and chitinase production as well as secondary metabolism are affected by the internal cAMP level; in addition, a cross talk between regulation of light responses and the cAMP signalling pathway was found in Trichoderma atroviride. PMID:19936091

Trichoderma biocontrol: signal transduction pathways involved in host sensing and mycoparasitism.

PubMed

Zeilinger, Susanne; Omann, Markus

2007-11-08

Fungi of the genus Trichoderma are used as biocontrol agents against several plant pathogenic fungi like Rhizoctonia spp., Pythium spp., Botrytis cinerea and Fusarium spp. which cause both soil-borne and leaf- or flower-borne diseases of agricultural plants. Plant disease control by Trichoderma is based on complex interactions between Trichoderma, the plant pathogen and the plant. Until now, two main components of biocontrol have been identified: direct activity of Trichoderma against the plant pathogen by mycoparasitism and induced systemic resistance in plants. As the mycoparasitic interaction is host-specific and not merely a contact response, it is likely that signals from the host fungus are recognised by Trichoderma and provoke transcription of mycoparasitism-related genes. In the last few years examination of signalling pathways underlying Trichoderma biocontrol started and it was shown that heterotrimeric G-proteins and mitogen-activated protein (MAP) kinases affected biocontrol-relevant processes such as the production of hydrolytic enzymes and antifungal metabolites and the formation of infection structures. MAPK signalling was also found to be involved in induction of plant systemic resistance in Trichoderma virens and in the hyperosmotic stress response in Trichoderma harzianum. Analyses of the function of components of the cAMP pathway during Trichoderma biocontrol revealed that mycoparasitism-associated coiling and chitinase production as well as secondary metabolism are affected by the internal cAMP level; in addition, a cross talk between regulation of light responses and the cAMP signalling pathway was found in Trichoderma atroviride.

Bacillus methylotrophicus Strain NKG-1, Isolated from Changbai Mountain, China, Has Potential Applications as a Biofertilizer or Biocontrol Agent

PubMed Central

Ge, Beibei; Liu, Binghua; Nwet, Thinn Thinn; Zhao, Wenjun; Shi, Liming; Zhang, Kecheng

2016-01-01

Chemical pesticides are widely used in agriculture, which endangers both environmental health and food safety. Biocontrol is an environmentally-friendly and cost-effective green technique in environmental protection and agricultural production; it generally uses selected bioresources, including beneficial microorganisms. We isolated a novel bacterial strain (NKG-1) from the rare dormant volcanic soils of Changbai Mountain in China’s Jilin Province. The strain was identified as Bacillus methylotrophicus using morphological, biochemical, physiological, and phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi on solid media. A greenhouse experiment showed that application of NKG-1 fermentation broth prior to inoculation of Botrytis cinerea, the cause of gray tomato mold, inhibited growth of the mold by 60%. Furthermore, application of a 100× dilution of NKG-1 fermentation broth to tomato seedlings yielded a significant increase in seedling fresh weight (27.4%), seedling length (12.5%), and root length (57.7%) compared to the control. When the same dosage was applied in the field, we observed increases in tomato plant height (14.7%), stem diameter (12.7%), crown width (16.3%), and maximum fruit diameter (11.5%). These results suggest that NKG-1 has potential commercial application as a biofertilizer or biocontrol agent. PMID:27832162

Mining the Volatilomes of Plant-Associated Microbiota for New Biocontrol Solutions

PubMed Central

Bailly, Aurélien; Weisskopf, Laure

2017-01-01

Microbial lifeforms associated with land plants represent a rich source for crop growth- and health-promoting microorganisms and biocontrol agents. Volatile organic compounds (VOCs) produced by the plant microbiota have been demonstrated to elicit plant defenses and inhibit the growth and development of numerous plant pathogens. Therefore, these molecules are prospective alternatives to synthetic pesticides and the determination of their bioactivities against plant threats could contribute to the development of control strategies for sustainable agriculture. In our previous study we investigated the inhibitory impact of volatiles emitted by Pseudomonas species isolated from a potato field against the late blight-causing agent Phytophthora infestans. Besides the well-documented emission of hydrogen cyanide, other Pseudomonas VOCs impeded P. infestans mycelial growth and sporangia germination. Current advances in the field support the emerging concept that the microbial volatilome contains unexploited, eco-friendly chemical resources that could help select for efficient biocontrol strategies and lead to a greener chemical disease management in the field. PMID:28890716

Mining the Volatilomes of Plant-Associated Microbiota for New Biocontrol Solutions.

PubMed

Bailly, Aurélien; Weisskopf, Laure

2017-01-01

Microbial lifeforms associated with land plants represent a rich source for crop growth- and health-promoting microorganisms and biocontrol agents. Volatile organic compounds (VOCs) produced by the plant microbiota have been demonstrated to elicit plant defenses and inhibit the growth and development of numerous plant pathogens. Therefore, these molecules are prospective alternatives to synthetic pesticides and the determination of their bioactivities against plant threats could contribute to the development of control strategies for sustainable agriculture. In our previous study we investigated the inhibitory impact of volatiles emitted by Pseudomonas species isolated from a potato field against the late blight-causing agent Phytophthora infestans . Besides the well-documented emission of hydrogen cyanide, other Pseudomonas VOCs impeded P. infestans mycelial growth and sporangia germination. Current advances in the field support the emerging concept that the microbial volatilome contains unexploited, eco-friendly chemical resources that could help select for efficient biocontrol strategies and lead to a greener chemical disease management in the field.

Draft Genome Sequence of a Biocontrol Rhizobacterium, Chryseobacterium kwangjuense Strain KJ1R5, Isolated from Pepper (Capsicum annuum)

PubMed Central

Jeong, Jin-Ju; Park, Hongjae; Park, Byeong Hyeok; Mannaa, Mohamed; Sang, Mee Kyung

2016-01-01

Strain KJ1R5 of the rhizobacterium Chryseobacterium kwangjuense is an effective biocontrol agent against Phytophthora blight of pepper caused by a destructive soilborne oomycete, Phytophthora capsici. Here, we present the draft genome sequence of strain KJ1R5, which contains genes related to biocontrol, plant growth promotion, and environmental stress adaptation. PMID:27103726

Potential of a new strain of Bacillus amyloliquefaciens BUZ-14 as a biocontrol agent of postharvest fruit diseases.

PubMed

Calvo, H; Marco, P; Blanco, D; Oria, R; Venturini, M E

2017-05-01

The biocontrol potential of the Bacillus amyloliquefaciens strain BUZ-14 was tested against the main postharvest diseases of orange, apple, grape and stone fruit. After characterizing the temperature and pH growth curves of strain BUZ-14, its in vitro antifungal activity was determined against Botrytis cinerea, Monilinia fructicola, M. laxa, Penicillium digitatum, P. expansum and P. italicum. Subsequently, in vivo activity was tested against these pathogens by treating fruit with cells, endospores and cell-free supernatants. The in vitro results showed that BUZ-14 inhibited the growth of all the pathogens tested corresponding to the least susceptible species, P. italicum, and the most susceptible, M. laxa. In vivo tests corroborated these results as most of the treatments decreased the incidence of brown rot in stone fruit from 100% to 0%, establishing 10 7  CFU mL -1 as the minimum inhibitory concentration. For the Penicillium species a preventive treatment inhibited P. digitatum and P. italicum growth in oranges and reduced P. expansum incidence in apples from 100% to 20%. Finally, it has been demonstrated that BUZ-14 was able to survive and to control brown rot in peaches stored at cool temperatures, making it a very suitable biocontrol agent for application during the post-harvest storage and marketing of horticultural products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Testing the efficacy of eGFP-transformed Aspergillus flavus as biocontrol strains

USDA-ARS?s Scientific Manuscript database

Current biological control methods to prevent pre-harvest aflatoxin contamination of corn, cottonseed, and ground and tree nuts involve field inoculation of non-aflatoxigenic Aspergillus flavus. To date, the efficacy of this approach requires annual reapplication of the biocontrol agent. The reason ...

Potentialities of Mermithid Nematodes for the Biocontrol of Blackflies (Diptera: Simuliidae)--A Review,

DTIC Science & Technology

biocontrol agents of agricultural insect pests and medically important insect vectors. More specifically, mermithid nematodes appear to regulate natural...Mermithids comprise a family of nematodes which invariably kill/sterilize their insect host(s). These nematodes have considerable potential as

Biocontrol of the wheat pathogen Zymoseptoria tritici using cyclic lipopeptides from Bacillus subtilis.

PubMed

Mejri, Samara; Siah, Ali; Coutte, François; Magnin-Robert, Maryline; Randoux, Béatrice; Tisserant, Benoit; Krier, François; Jacques, Philippe; Reignault, Philippe; Halama, Patrice

2017-06-21

Innovation toward ecofriendly plant protection products compatible with sustainable agriculture and healthy food is today strongly encouraged. Here, we assessed the biocontrol activity of three cyclic lipopeptides from Bacillus subtilis (mycosubtilin, M; surfactin, S; fengycin, F) and two mixtures (M + S and M + S + F) on wheat against Zymoseptoria tritici, the main pathogen on this crop. Foliar application of these biomolecules at a 100-mg L -1 concentration on the wheat cultivars Dinosor and Alixan, 2 days before fungal inoculation, provided significant reductions of disease severity. The best protection levels were recorded with the M-containing formulations (up to 82% disease reduction with M + S on Dinosor), while S and F treatments resulted in lower but significant disease reductions. In vitro and in planta investigations revealed that M-based formulations inhibit fungal growth, with half-maximal inhibitory concentrations of 1.4 mg L -1 for both M and M + S and 4.5 mg L -1 for M + S + F, thus revealing that the observed efficacy of these products may rely mainly on antifungal property. By contrast, S and F had no direct activity on the pathogen, hence suggesting that these lipopeptides act on wheat against Z. tritici as resistance inducers rather than as biofungicides. This study highlighted the efficacy of several lipopeptides from B. subtilis to biocontrol Z. tritici through likely distinct and biomolecule-dependent modes of action.

Fungal endophytes of South China blueberry (Vaccinium dunalianum var. urophyllum).

PubMed

Li, Z-J; Shen, X-Y; Hou, C-L

2016-12-01

A total of 374 fungal endophyte strains were isolated from of Vaccinium dunalianum var. urophyllum (Ericaceae), a well-known cultivated blueberry in southern China. These fungal endophytes could be categorized into 25 morphotypes according to culture characteristics and molecular identification based on the internal transcribed spacer region. All of these isolates belonged to Ascomycota. Jaccard's (Jc) and Sorenson's similarity indices indicated that the species communities from the fruits and branches were closer to each other than to those from leaves. The leaves appeared to host the highest fungal biodiversity, and the fruits displayed the lowest diversity. This study is the first on endophytic fungi isolated from fruits, branches and leaves of blueberry plants. The results contribute to the body of knowledge on the biocontrol of pathogens associated with blueberry and develop the improvement of plant growth. By comparing with the different fungal communities, the leaves appeared to host the highest biodiversity. © 2016 The Society for Applied Microbiology.

Identification and characterization of a new Bacillus atrophaeus strain B5 as biocontrol agent of postharvest anthracnose disease in soursop (Annona muricata) and avocado (Persea americana).

PubMed

Guardado-Valdivia, Lizeth; Tovar-Pérez, Erik; Chacón-López, Alejandra; López-García, Ulises; Gutiérrez-Martínez, Porfirio; Stoll, Alexandra; Aguilera, Selene

2018-05-01

Anthracnose is a fungal disease caused by Colletotrichum species that is detrimental to numerous fruit, including soursop and avocado. The use of fungicides to maintain the high quality of fruit creates a potential health risk. One alternative to this problem is the biological control, which has been applied successfully during postharvest. The Bacillus species are one of the most studied biological agents against postharvest pathogens because accomplish their biocontrol performance by producing a variety of metabolites. In this study, we evaluated the activity of metabolites contained in the cell free supernatant, obtained from Bacillus strain B5 culture, against micelial growth and spore germination of two virulent strains of C. gloeosporioides isolated from soursop and avocado. On the basis of 16S rDNA gene sequence analysis, this strain was identified as Bacillus atrophaeus. A preventive treatment using cell free supernatant, reduced severity and incidence of anthracnose disease on harvested soursop and avocado fruit. B. atrophaeus strain B5 harbors genes involved in the production of antibiotics such as surfactin, bacillomycin and iturin, which could be contributing to the efficiency of the preventive treatment during postharvest. The antagonistic role of metabolites contained in the cell free supernatant against anthracnose disease, provide a new approach by which to attack this problem and can help reduce the use of chemical pesticides, environmental pollution, leading to the safer fruit preservation. Copyright © 2018 Elsevier GmbH. All rights reserved.

Isolation of Dickeya dadantii strains from potato disease and biocontrol by their bacteriophages.

PubMed

Soleimani-Delfan, Abbas; Etemadifar, Zahra; Emtiazi, Giti; Bouzari, Majid

2015-01-01

One of the most economically important bacterial pathogens of plants and plant products is Dickeya dadantii. This bacterium causes soft rot disease in tubers and other parts of the potato and other plants of the Solanaceae family. The application of restricted host range bacteriophages as biocontrol agents has recently gained widespread interest. This study purposed to isolate the infectious agent of the potato and evaluate its biocontrol by bacteriophages. Two phytopathogenic strains were isolated from infected potatoes, identified based on biochemical and 16S rRNA gene sequencing, and submitted to GenBank as D. dadantii strain pis3 (accession no. HQ423668) and D. dadantii strain sip4 (accession no. HQ423669). Their bacteriophages were isolated from Caspian Sea water by enriching the water filtrate with D. dadantii strains as hosts using spot or overlay methods. On the basis of morphotypes, the isolated bacteriophages were identified as members of the Myoviridae and Siphoviridae families and could inhibit the growth of antibiotic resistant D. dadantii strains in culture medium. Moreover, in Dickeya infected plants treated with bacteriophage, no disease progression was detected. No significant difference was seen between phage-treated and control plants. Thus, isolated bacteriophages can be suggested for the biocontrol of plant disease caused by Dickeya strains.

Role of 2-hexyl, 5-propyl resorcinol production by Pseudomonas chlororaphis PCL1606 in the multitrophic interactions in the avocado rhizosphere during the biocontrol process.

PubMed

Calderón, Claudia E; de Vicente, Antonio; Cazorla, Francisco M

2014-07-01

Different bacterial traits can contribute to the biocontrol of soilborne phytopathogenic fungus. Among others, (1) antagonism, (2) competition for nutrients and niches, (3) induction of systemic resistance of the plants and (4) predation and parasitism are the most studied. Pseudomonas chlororaphis PCL1606 is an antagonistic rhizobacterium that produces the antifungal metabolite 2-hexyl, 5-propyl resorcinol (HPR). This bacterium can biologically control the avocado white root rot caused by Rosellinia necatrix. Confocal laser scanning microscopy of the avocado rhizosphere revealed that this biocontrol bacterium and the fungal pathogen compete for the same niche and presumably also for root exudate nutrients. The use of derivative mutants in the geners related to HPR biosynthesis (dar genes) revealed that the lack of HPR production by P. chlororaphis PCL1606 negatively influences the bacterial colonisation of the avocado root surface. Microscopical analysis showed that P. chlororaphis PCL1606 closely interacts and colonises the fungal hyphae, which may represent a novel biocontrol mechanism in this pseudomonad. Additionally, the presence of HPR-producing biocontrol bacteria negatively affects the ability of the fungi to infect the avocado root. HPR production negatively affects hyphal growth, leading to alterations in the R. necatrix physiology visible under microscopy, including the curling, vacuolisation and branching of hyphae, which presumably affects the colonisation and infection abilities of the fungus. This study provides the first report of multitrophic interactions in the avocado rhizosphere, advancing our understanding of the role of HPR production in those interactions. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Investigating the compatibility of the biocontrol agent Clonostachys rosea IK726 with prodigiosin-producing Serratia rubidaea S55 and phenazine-producing Pseudomonas chlororaphis ToZa7.

PubMed

Kamou, Nathalie N; Dubey, Mukesh; Tzelepis, Georgios; Menexes, Georgios; Papadakis, Emmanouil N; Karlsson, Magnus; Lagopodi, Anastasia L; Jensen, Dan Funck

2016-05-01

This study was carried out to assess the compatibility of the biocontrol fungus Clonostachys rosea IK726 with the phenazine-producing Pseudomonas chlororaphis ToZa7 or with the prodigiosin-producing Serratia rubidaea S55 against Fusarium oxysporum f. sp. radicis-lycopersici. The pathogen was inhibited by both strains in vitro, whereas C. rosea displayed high tolerance to S. rubidaea but not to P. chlororaphis. We hypothesized that this could be attributed to the ATP-binding cassette (ABC) proteins. The results of the reverse transcription quantitative PCR showed an induction of seven genes (abcB1, abcB20, abcB26, abcC12, abcC12, abcG8 and abcG25) from subfamilies B, C and G. In planta experiments showed a significant reduction in foot and root rot on tomato plants inoculated with C. rosea and P. chlororaphis. This study demonstrates the potential for combining different biocontrol agents and suggests an involvement of ABC transporters in secondary metabolite tolerance in C. rosea.

Rare fungal infectious agents: a lurking enemy

PubMed Central

Skiada, Anna; Pavleas, Ioannis; Drogari-Apiranthitou, Maria

2017-01-01

In the expanding population of immunocompromised patients and those treated in intensive care units, rare fungal infectious agents have emerged as important pathogens, causing invasive infections associated with high morbidity and mortality. These infections may present either as de novo or as breakthrough invasive infections in high-risk patients with hematologic malignancies receiving prophylactic or empirical antifungal therapy or in patients with central venous catheters. Diagnosis and treatment are challenging. Physicians should have a high index of suspicion because early diagnosis is of paramount importance. Conventional diagnostic methods such as cultures and histopathology are still essential, but rapid and more specific molecular techniques for both detection and identification of the infecting pathogens are being developed and hopefully will lead to early targeted treatment. The management of invasive fungal infections is multimodal. Reversal of risk factors, if feasible, should be attempted. Surgical debridement is recommended in localized mold infections. The efficacy of various antifungal drugs is not uniform. Amphotericin B is active against most yeasts, except Trichosporon, as well as against Mucorales, Fusarium, and some species of Paecilomyces and dimorphic fungi. The use of voriconazole is suggested for the treatment of trichosporonosis and scedosporiosis. Combination treatment, though recommended as salvage therapy in some infections, is controversial in most cases. Despite the use of available antifungals, mortality remains high. The optimization of molecular-based techniques, with expansion of reference libraries and the possibility for direct detection of resistance mechanisms, is awaited with great interest in the near future. Further research is necessary, however, in order to find the best ways to confront and destroy these lurking enemies. PMID:29152230

Regulation of Morphogenesis and Biocontrol Properties in Trichoderma virens by a VELVET Protein, Vel1▿ †

PubMed Central

Mukherjee, Prasun K.; Kenerley, Charles M.

2010-01-01

Mycoparasitic strains of Trichoderma are applied as commercial biofungicides for control of soilborne plant pathogens. Although the majority of commercial biofungicides are Trichoderma based, chemical pesticides, which are ecological and environmental hazards, still dominate the market. This is because biofungicides are not as effective or consistent as chemical fungicides. Efforts to improve these products have been limited by a lack of understanding of the genetic regulation of biocontrol activities. In this study, using gene knockout and complementation, we identified the VELVET protein Vel1 as a key regulator of biocontrol, as well as morphogenetic traits, in Trichoderma virens, a commercial biocontrol agent. Mutants with mutations in vel1 were defective in secondary metabolism (antibiosis), mycoparasitism, and biocontrol efficacy. In nutrient-rich media they also lacked two types of spores important for survival and development of formulation products: conidia (on agar) and chlamydospores (in liquid shake cultures). These findings provide an opportunity for genetic enhancement of biocontrol and industrial strains of Trichoderma, since Vel1 is very highly conserved across three Trichoderma species. PMID:20154111

Identification of growth stage molecular markers in Trichoderma sp. 'atroviride type B' and their potential application in monitoring fungal growth and development in soil.

PubMed

Mendoza-Mendoza, Artemio; Steyaert, Johanna; Nieto-Jacobo, Maria Fernanda; Holyoake, Andrew; Braithwaite, Mark; Stewart, Alison

2015-11-01

Several members of the genus Trichoderma are biocontrol agents of soil-borne fungal plant pathogens. The effectiveness of biocontrol agents depends heavily on how they perform in the complex field environment. Therefore, the ability to monitor and track Trichoderma within the environment is essential to understanding biocontrol efficacy. The objectives of this work were to: (a) identify key genes involved in Trichoderma sp. 'atroviride type B' morphogenesis; (b) develop a robust RNA isolation method from soil; and (c) develop molecular marker assays for characterizing morphogenesis whilst in the soil environment. Four cDNA libraries corresponding to conidia, germination, vegetative growth and conidiogenesis were created, and the genes identified by sequencing. Stage specificity of the different genes was confirmed by either Northern blot or quantitative reverse-transcriptase PCR (qRT-PCR) analysis using RNA from the four stages. con10, a conidial-specific gene, was observed in conidia, as well as one gene also involved in subsequent stages of germination (L-lactate/malate dehydrogenase encoding gene). The germination stage revealed high expression rates of genes involved in amino acid and protein biosynthesis, while in the vegetative-growth stage, genes involved in differentiation, including the mitogen-activated protein kinase kinase similar to Kpp7 from Ustilago maydis and the orthologue to stuA from Aspergillus nidulans, were preferentially expressed. Genes involved in cell-wall synthesis were expressed during conidiogenesis. We standardized total RNA isolation from Trichoderma sp. 'atroviride type B' growing in soil and then examined the expression profiles of selected genes using qRT-PCR. The results suggested that the relative expression patterns were cyclic and not accumulative.

Biocontrol Potential of Streptomyces hydrogenans Strain DH16 toward Alternaria brassicicola to Control Damping Off and Black Leaf Spot of Raphanus sativus

PubMed Central

Manhas, Rajesh K.; Kaur, Talwinder

2016-01-01

Biocontrol agents and their bioactive metabolites provide one of the best alternatives to decrease the use of chemical pesticides. In light of this, the present investigation reports the biocontrol potential of Streptomyces hydrogenans DH16 and its metabolites towards Alternaria brassicicola, causal agent of black leaf spot and damping off of seedlings of crucifers. In vitro antibiosis of strain against pathogen revealed complete suppression of mycelial growth of pathogen, grown in potato dextrose broth supplemented with culture supernatant (20% v/v) of S. hydrogenans DH16. Microscopic examination of the fungal growth showed severe morphological abnormalities in the mycelium caused by antifungal metabolites. In vivo studies showed the efficacy of streptomycete cells and culture supernatant as seed dressings to control damping off of Raphanus sativus seedlings. Treatment of pathogen infested seeds with culture supernatant (10%) and streptomycete cells significantly improved seed germination (75–80%) and vigor index (1167–1538). Furthermore, potential of cells and culture supernatant as foliar treatment to control black leaf spot was also evaluated. Clearly visible symptoms of disease were observed in the control plants with 66.81% disease incidence and retarded growth of root system. However, disease incidence reduced to 6.78 and 1.47% in plants treated with antagonist and its metabolites, respectively. Additionally, treatment of seeds and plants with streptomycete stimulated various growth traits of plants over uninoculated control plants in the absence of pathogen challenge. These results indicate that S. hydrogenans and its culture metabolites can be developed as biofungicides as seed dressings to control seed borne pathogens, and as sprays to control black leaf spot of crucifers. PMID:28018402

Buying Time: Preliminary Assessment of Biocontrol in the Recovery of Native Forest Vegetation in the Aftermath of the Invasive Emerald Ash Borer

Treesearch

Elan Margulies; Leah Bauer; Inés Ibáñez

2017-01-01

Introduced forest pests have become one of the major threats to forests, and biological control is one of the few environmentally acceptable management practices. Assessing the impacts of a biocontrol program includes evaluating the establishment of biocontrol agents, the control of target pest, the impact on the affected organism, and the indirect impacts that the...

Indigenous bacteria may interfere with the biocontrol of plant diseases

NASA Astrophysics Data System (ADS)

Someya, Nobutaka; Akutsu, Katsumi

2009-06-01

Prodigiosin is a reddish antibiotic pigment that plays an important role in the biocontrol of plant diseases by the bacterium Serratia marcescens. However, its activity is unstable under agricultural conditions; further, it can be degraded by various environmental factors. To examine the effect of epiphytic microbes on the stability of prodigiosin used for biological control processes, we collected a total of 1,280 bacterial isolates from the phylloplane of cyclamen and tomato plants. Approximately 72% of the bacterial strains isolated from the cyclamen plants and 66% of those isolated from the tomato plants grew on minimal agar medium containing 100 μg ml-1 prodigiosin. Certain isolates obtained from both plant species exhibited prodigiosin-degrading activity. We compared the 16S rRNA gene sequences derived from the isolates with sequences in a database. The comparison revealed that the sequences determined for the prodigiosin-degrading isolates were homologous to those of the genera Pseudomonas, Caulobacter, Rhizobium, Sphingomonas, Janthinobacterium, Novosphingobium, and Rathayibacter. These results indicate that indigenous epiphytic microorganisms may interfere with the interaction between plant pathogens and biocontrol agents by degrading the antibiotics produced by the agents.

High-throughput synergy screening identifies microbial metabolites as combination agents for the treatment of fungal infections

PubMed Central

Zhang, Lixin; Yan, Kezhi; Zhang, Yu; Huang, Ren; Bian, Jiang; Zheng, Chuansen; Sun, Haixiang; Chen, Zhihui; Sun, Nuo; An, Rong; Min, Fangui; Zhao, Weibo; Zhuo, Ying; You, Jianlan; Song, Yongjie; Yu, Zhenyan; Liu, Zhiheng; Yang, Keqian; Gao, Hong; Dai, Huanqin; Zhang, Xiaoli; Wang, Jian; Fu, Chengzhang; Pei, Gang; Liu, Jintao; Zhang, Si; Goodfellow, Michael; Jiang, Yuanying; Kuai, Jun; Zhou, Guochun; Chen, Xiaoping

2007-01-01

The high mortality rate of immunocompromised patients with fungal infections and the limited availability of highly efficacious and safe agents demand the development of new antifungal therapeutics. To rapidly discover such agents, we developed a high-throughput synergy screening (HTSS) strategy for novel microbial natural products. Specifically, a microbial natural product library was screened for hits that synergize the effect of a low dosage of ketoconazole (KTC) that alone shows little detectable fungicidal activity. Through screening of ≈20,000 microbial extracts, 12 hits were identified with broad-spectrum antifungal activity. Seven of them showed little cytotoxicity against human hepatoma cells. Fractionation of the active extracts revealed beauvericin (BEA) as the most potent component, because it dramatically synergized KTC activity against diverse fungal pathogens by a checkerboard assay. Significantly, in our immunocompromised mouse model, combinations of BEA (0.5 mg/kg) and KTC (0.5 mg/kg) prolonged survival of the host infected with Candida parapsilosis and reduced fungal colony counts in animal organs including kidneys, lungs, and brains. Such an effect was not achieved even with the high dose of 50 mg/kg KTC. These data support synergism between BEA and KTC and thereby a prospective strategy for antifungal therapy. PMID:17360571

CsrB, a noncoding regulatory RNA, is required for BarA-dependent expression of biocontrol traits in Rahnella aquatilis HX2.

PubMed

Mei, Li; Xu, Sanger; Lu, Peng; Lin, Haiping; Guo, Yanbin; Wang, Yongjun

2017-01-01

Rahnella aquatilis is ubiquitous and its certain strains have the applicative potent as a plant growth-promoting rhizobacteria. R. aquatilis HX2 is a biocontrol agent to produce antibacterial substance (ABS) and showed efficient biocontrol against crown gall caused by Agrobacterium vitis on sunflower and grapevine plants. The regulatory network of the ABS production and biocontrol activity is still limited known. In this study, a transposon-mediated mutagenesis strategy was used to investigate the regulators that involved in the biocontrol activity of R. aquatilis HX2. A 366-nt noncoding RNA CsrB was identified in vitro and in vivo, which regulated ABS production and biocontrol activity against crown gall on sunflower plants, respectively. The predicted product of noncoding RNA CsrB contains 14 stem-loop structures and an additional ρ-independent terminator harpin, with 23 characteristic GGA motifs in the loops and other unpaired regions. CsrB is required for ABS production and biocontrol activity in the biocontrol regulation by a two-component regulatory system BarA/UvrY in R. aquatilis HX2. The noncoding RNA CsrB regulates BarA-dependent ABS production and biocontrol activity in R. aquatilis HX2. To the best of our knowledge, this is the first report of noncoding RNA as a regulator for biocontrol function in R. aquatilis.

CsrB, a noncoding regulatory RNA, is required for BarA-dependent expression of biocontrol traits in Rahnella aquatilis HX2

PubMed Central

Lu, Peng; Lin, Haiping; Guo, Yanbin

2017-01-01

Background Rahnella aquatilis is ubiquitous and its certain strains have the applicative potent as a plant growth-promoting rhizobacteria. R. aquatilis HX2 is a biocontrol agent to produce antibacterial substance (ABS) and showed efficient biocontrol against crown gall caused by Agrobacterium vitis on sunflower and grapevine plants. The regulatory network of the ABS production and biocontrol activity is still limited known. Methodology/Principal findings In this study, a transposon-mediated mutagenesis strategy was used to investigate the regulators that involved in the biocontrol activity of R. aquatilis HX2. A 366-nt noncoding RNA CsrB was identified in vitro and in vivo, which regulated ABS production and biocontrol activity against crown gall on sunflower plants, respectively. The predicted product of noncoding RNA CsrB contains 14 stem-loop structures and an additional ρ-independent terminator harpin, with 23 characteristic GGA motifs in the loops and other unpaired regions. CsrB is required for ABS production and biocontrol activity in the biocontrol regulation by a two-component regulatory system BarA/UvrY in R. aquatilis HX2. Conclusion/Significance The noncoding RNA CsrB regulates BarA-dependent ABS production and biocontrol activity in R. aquatilis HX2. To the best of our knowledge, this is the first report of noncoding RNA as a regulator for biocontrol function in R. aquatilis. PMID:29091941

Quorum signaling mycotoxins: A new risk strategy for bacterial biocontrol of Fusarium verticillioides and other endophytic fungal species?

USDA-ARS?s Scientific Manuscript database

Bacterial endophytes are used as biocontrol organisms for plant pathogens such as the maize endophyte Fusarium verticillioides and its production of fumonisin mycotoxins. However, such applications are not always predictable and efficient. All bacteria communicate via cell-dependent signals, which...

Indirect effects of biocontrol of an invasive riparian plant (Tamarix) alters habitat and reduces herpetofauna abundance

USGS Publications Warehouse

Bateman, H.L.; Merritt, D.M.; Glenn, E.P.; Nagler, P.L.

2014-01-01

The biological control agent (tamarisk leaf beetle, Diorhabda spp.) is actively being used to defoliate exotic saltcedar or tamarisk (Tamarix spp.) in riparian ecosystems in western USA. The Virgin River in Arizona and Nevada is a system where tamarisk leaf beetle populations are spreading. Saltcedar biocontrol, like other control methods, has the potential to affect non-target species. Because amphibians and reptiles respond to vegetation changes in habitat and forage in areas where beetles are active, herpetofauna are model taxa to investigate potential impacts of biocontrol defoliation. Our objectives related herpetofauna abundance to vegetation cover and indices (normalized difference vegetation index, NDVI; enhanced vegetation index, EVI) and timing of biocontrol defoliation. We captured herpetofauna and ground-dwelling arthropods in trap arrays and measured vegetation using remotely sensed images and on-the-ground measurements at 16–21 sites 2 years before (2009–2010) and 2 years following (2011–2012) biocontrol defoliation. Following defoliation, riparian stands (including stands mixed with native and exotic trees and stands of monotypic exotic saltcedar) had significantly lower NDVI and EVI values and fewer captures of marked lizards. Total captures of herpetofauna (toads, lizards, and snakes) were related to higher vegetation cover and sites with a lower proportion of saltcedar. Our results suggest that effects of biocontrol defoliation are likely to be site-specific and depend upon the proportion of native riparian trees established prior to biocontrol introduction and defoliation. The mechanisms by which habitat structure, microclimate, and ultimately vertebrate species are affected by exotic plant biocontrol riparian areas should be a focus of natural-resource managers.

Differential impact of some Aspergillus species on Meloidogyne javanica biocontrol by Pseudomonas fluorescens strain CHA0.

PubMed

Siddiqui, I A; Shaukat, S S; Khan, A

2004-01-01

The aim was to determine the influence of some Aspergillus species on the production of nematicidal agent(s) in vitro and biocontrol of Meloidogyne javanica in tomato by Pseudomonas fluorescens strains CHA0 and CHA0/pME3424. Six species of Aspergillus, isolated from the rhizosphere of certain crops, produced a variety of secondary metabolites in vitro. Culture filtrate (CF) obtained from Ps. fluorescens strain CHA0 and its2,4-diacetylphloroglucinol overproducing mutant CHA0/pME3424 grown in King's B liquid medium caused significant mortality of M. javanica juveniles in vitro. Bacterial growth medium amended with CF of A. niger enhanced nematicidal and beta-galactosidase activities of fluorescent pseudomonads while A. quadrilineatus repressed such activities. Methanol or ethyl acetate extracts of the CF of A. niger markedly optimized bacterial efficacy to cause nematode deaths while hexane extract of the fungus had no influence on the nematicidal activity of the bacterial strains. A. niger applied alone or in conjunction with the bacterial inoculants inhibited root-knot nematode galling in tomato. On the other hand, A. quadrilineatus used alone or together with CHA0 did not inhibit nematode galling but when used in combination with strain CHA0/pME3424 did reduce galling intensity. Aspergillus niger enhances the production of nematicidal compounds by Ps. fluorescensin vitro and improves biocontrol potential of the bacterial inoculants in tomato while A. quadrilineatus reduces bacterial performance to suppress root-knot nematodes. Rhizosphere harbours a variety of micro-organisms including bacteria, fungi and viruses. Aspergillus species are ubiquitous in most agricultural soils and generally produce a variety of secondary metabolites. Such metabolites synthesized by Aspergillus species may influence the production of nematicidal agents and subsequent biocontrol performance of the bacterial inoculants against plant-parasitic nematodes. This fact needs to be taken into

Recent Trends in Salmonella Outbreaks and Emerging Technology for Biocontrol of Salmonella Using Phages in Foods: A Review.

PubMed

Oh, Jun-Hyun; Park, Mi-Kyung

2017-12-28

Salmonella is one of the principal causes of foodborne outbreaks. As traditional control methods have shown less efficacy against emerging Salmonella serotypes or antimicrobialresistant Salmonella , new approaches have been attempted. The use of lytic phages for the biocontrol of Salmonella in the food industry has become an attractive method owing to the many advantages offered by the use of phages as biocontrol agents. Phages are natural alternatives to traditional antimicrobial agents; they have proven effective in the control of bacterial pathogens in the food industry, which has led to the development of different phage products. The treatment with specific phages in the food industry can prevent the decay of products and the spread of bacterial diseases, and ultimately promotes safe environments for animal and plant food production, processing, and handling. After an extensive investigation of the current literature, this review focuses predominantly on the efficacy of phages for the successful control of Salmonella spp. in foods. This review also addresses the current knowledge on the pathogenic characteristics of Salmonella , the prevalence of emerging Salmonella outbreaks, the isolation and characterization of Salmonella -specific phages, the effectiveness of Salmonella -specific phages as biocontrol agents, and the prospective use of Salmonella -specific phages in the food industry.

Research on Volatile Organic Compounds From Bacillus subtilis CF-3: Biocontrol Effects on Fruit Fungal Pathogens and Dynamic Changes During Fermentation

PubMed Central

Gao, Haiyan; Li, Peizhong; Xu, Xinxing; Zeng, Qing; Guan, Wenqiang

2018-01-01

The dynamic changes of the levels of volatile organic compounds (VOCs) produced by Bacillus subtilis CF-3 and their biocontrol effects on common fungal pathogens were researched in this study. The results showed that the VOCs in 24-h fermentation liquid (24hFL) of B. subtilis CF-3 inhibited mycelial growth of Botrytis cinerea, Colletotrichum gloeosporioides, Penicillium expansum, Monilinia fructicola, and Alternaria alternata, with a mean inhibition rate of 59.97%. The inhibitory effect on M. fructicola and C. gloeosporioides was the highest; they were therefore selected as target fungal pathogens for further experiments. Based on headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), 74 potential VOCs were identified during the fermentation: 15 alcohols, 18 ketones, 4 pyrazines, 4 esters, 10 acids, 5 phenols, 3 hydrocarbons, 3 amines, 2 aldehydes, 5 ethers, and 5 other components. At different fermentation times, the type and content of VOCs were different. Most of the potential VOCs (62 VOCs) were identified in the 48hFL. The inhibition rates of all VOCs reached their peaks (73.46% on M. fructicola and 63.63% on C. gloeosporioides) in the 24hFL. Among the identified VOCs, 2,4-di-tert-butylphenol, 1-octanol, and benzothiazole showed significant positive correlations with the rates of M. fructicola and C. gloeosporioides inhibition. Benzoic acid and benzaldehyde showed a significant positive correlation with the rates of M. fructicola inhibition, and anisole and 3-methylbutanal showed a significant positive correlation with the rates of C. gloeosporioides inhibition. In vitro, 2,4-di-tert-butylphenol showed a strong inhibitory effect on both M. fructicola and C. gloeosporioides. In vivo, benzothiazole showed the strongest inhibitory effect on the mycelial extensions of both M. fructicola and C. gloeosporioides, which also led to an increased rate of healthy fruit. The results of the present study clarified that 2

Evidence for Biotrophic Lifestyle and Biocontrol Potential of Dark Septate Endophyte Harpophora oryzae to Rice Blast Disease

PubMed Central

Su, Zhen-Zhu; Mao, Li-Juan; Li, Na; Feng, Xiao-Xiao; Yuan, Zhi-Lin; Wang, Li-Wei; Lin, Fu-Cheng; Zhang, Chu-Long

2013-01-01

The mutualism pattern of the dark septate endophyte (DSE) Harpophora oryzae in rice roots and its biocontrol potential in rice blast disease caused by Magnaporthe oryzae were investigated. Fluorescent protein-expressing H. oryzae was used to monitor the colonization pattern. Hyphae invaded from the epidermis to the inner cortex, but not into the root stele. Fungal colonization increased with root tissue maturation, showing no colonization in the meristematic zone, slight colonization in the elongation zone, and heavy colonization in the differentiation zone. H. oryzae adopted a biotrophic lifestyle in roots accompanied by programmed cell death. Real-time PCR facilitated the accurate quantification of fungal growth and the respective plant response. The biocontrol potential of H. oryzae was visualized by inoculation with eGFP-tagged M. oryzae in rice. H. oryzae protected rice from M. oryzae root invasion by the accumulation of H2O2 and elevated antioxidative capacity. H. oryzae also induced systemic resistance against rice blast. This systemic resistance was mediated by the OsWRKY45-dependent salicylic acid (SA) signaling pathway, as indicated by the strongly upregulated expression of OsWRKY45. The colonization pattern of H. oryzae was consistent with the typical characteristics of DSEs. H. oryzae enhanced local resistance by reactive oxygen species (ROS) and high antioxidative level and induced OsWRKY45-dependent SA-mediated systemic resistance against rice blast. PMID:23637814

Bio-protective microbial agents from rhizosphere eco-systems trigger plant defense responses provide protection against sheath blight disease in rice (Oryza sativa L.).

PubMed

Singh, Udai B; Malviya, Deepti; Wasiullah; Singh, Shailendra; Pradhan, Jatindra K; Singh, Bhanu P; Roy, Manish; Imram, Mohd; Pathak, Neelam; Baisyal, B M; Rai, Jai P; Sarma, B K; Singh, Rajiv K; Sharma, P K; Kaur, Saman Deep; Manna, M C; Sharma, Sushil K; Sharma, Arun K

2016-11-01

Sheath blight of rice (Oryza sativa L.) caused by Rhizoctonia solani is a major disease and attempts are being made to develop microbe based technologies for biocontrol of this pathogen. However, the mechanisms of biocontrol are not fully understood and still require indepth study in the backdrop of emerging concepts in biological systems. The present investigation was aimed at deciphering the mechanisms of biocontrol of sheath blight of rice employing Pseudomonas fluorescens and Trichoderma harzianum as model agents for biocontrol. Initially 25, 5 and 5 strains of P. fluorescens, T. viride and T. harzianum, respectively, were screened for their biocontrol potential. Out of which, six strains with higher value of percent inhibition of fungal mycelium in dual plate assay were selected. The role of P. fluorescens, T. viride and T. harzianum were investigated in induction and bioaccumulation of natural antioxidants, defence-related biomolecules and other changes in plant which lead not only to growth promotion but also protection from pathogenic stress conditions in rice. The two most promising strains, P. fluorescens PF-08 and T. harzianum UBSTH-501 selected on the basis of in planta evaluation, when applied individually or in combination, significantly enhanced the accumulation of defence-related biomolecules, enzymes and exhibited biocontrol potential against R. solani. A modified/newly developed delivery system was applied for the first time in the experiments involving inoculation of plants with both bioagents, viz. P. fluorescens PF-08 and T. harzianum UBSTH-501. Results suggested that application of P. fluorescens PF-08 and T. harzianum UBSTH-501 alone or in combination, not only helps in control of the disease but also increases plant growth along with reduction in application of toxic chemical pesticides. Copyright © 2016 Elsevier GmbH. All rights reserved.

Inhibition coefficient and molecular diversity of multi stress tolerant Trichoderma as potential biocontrol agent against Sclerotium rolfsii Sacc.

PubMed

Hirpara, Darshna G; Gajera, H P; Hirapara, Jaydeep G; Golakiya, B A

2017-11-01

Trichoderma is one of the most exploited biocontrol agent for the management of plant diseases. Twenty strains of Trichoderma (six of T. harzianum, four of T. viride, three of T. virens, three of T. koningii, each one of T. hamatum, T. reesei, T. parceramosum and Trichoderma spp.) subjected to in vitro antagonism up to 12days after inoculation against Sclerotium rolfsii Sacc. causing stem rot in groundnut. A new concept was developed to determine inhibition coefficient representing pathogen biology and biocontrol related biophysical variables. Results explained differential inhibition coefficient of test pathogen by Trichoderma antagonists. The inhibition coefficient of test pathogen was examined highest (91.13%) by T. virens NBAII Tvs12 followed by T. virens MTCC 794 (89.33%) and T. koningii MTCC 796 (62.39%). Microscopic study confirmed biocontrol mechanism as mycoparasitism for Tvs12 and antibiosis for T. koningii MTCC 796. The sclerotial biogenesis of test pathogen was elevated during weak antagonism and diminished in interactions with strong antagonists. The inhibition coefficient of S. rolfsii was significantly negatively correlated with sclerotia formation and lipid peroxidation during the antagonism. Trichoderma strains were screened for fungicides (carbendazim and tebuconazole, thiram and mancozeb) and abiotic stress (drought and salt) tolerance. Results indicated that T. koningii MTCC 796 efficiently grew better than the other strains with maximum radial growth under adverse conditions. The genetic variability among the Trichoderma was determined using 34 gene specific markers which amplified 146 alleles. The SSR similarities explained substantial diversity (15 to 87%) across Trichoderma strains and pathogen S. rolfsii. Principal coordinates analysis (PCA) were comparable to the cluster analysis and first three most informative PC components explained 64.45% of the total variation. In PCA, potent antagonists appear to be distinct from other strains. Five

Assessment of biocontrol strains for reduction of mycotoxins (aflatoxin and CPA) in maize

USDA-ARS?s Scientific Manuscript database

Aspergillus flavus strains K49, NRRL 21882 (from Afla-Guard®) and AF36 are being developed as biocontrol agents for the control of aflatoxin in maize. In this study, the three non-aflatoxigenic strains were compared to evaluate which is most effective in reducing aflatoxin. Also, we tested these st...

Trichodiene Production in a Trichoderma harzianum erg1-Silenced Strain Provides Evidence of the Importance of the Sterol Biosynthetic Pathway in Inducing Plant Defense-Related Gene Expression.

PubMed

Malmierca, M G; McCormick, S P; Cardoza, R E; Monte, E; Alexander, N J; Gutiérrez, S

2015-11-01

Trichoderma species are often used as biocontrol agents against plant-pathogenic fungi. A complex molecular interaction occurs among the biocontrol agent, the antagonistic fungus, and the plant. Terpenes and sterols produced by the biocontrol fungus have been found to affect gene expression in both the antagonistic fungus and the plant. The terpene trichodiene (TD) elicits the expression of genes related to tomato defense and to Botrytis virulence. We show here that TD itself is able to induce the expression of Botrytis genes involved in the synthesis of botrydial (BOT) and also induces terpene gene expression in Trichoderma spp. The terpene ergosterol, in addition to its role as a structural component of the fungal cell membranes, acts as an elicitor of defense response in plants. In the present work, using a transformant of T. harzianum, which is silenced in the erg1 gene and accumulates high levels of squalene, we show that this ergosterol precursor also acts as an important elicitor molecule of tomato defense-related genes and induces Botrytis genes involved in BOT biosynthesis, in both cases, in a concentration-dependent manner. Our data emphasize the importance of a balance of squalene and ergosterol in fungal interactions as well as in the biocontrol activity of Trichoderma spp.

Biological Control of Aflatoxin Contamination in U.S. Crops and the Use of Bioplastic Formulations of Aspergillus flavus Biocontrol Strains To Optimize Application Strategies.

PubMed

Abbas, Hamed K; Accinelli, Cesare; Shier, W Thomas

2017-08-23

Aflatoxin contamination has a major economic impact on crop production in the southern United States. Reduction of aflatoxin contamination in harvested crops has been achieved by applying nonaflatoxigenic biocontrol Aspergillus flavus strains that can out-compete wild aflatoxigenic A. flavus, reducing their numbers at the site of application. Currently, the standard method for applying biocontrol A. flavus strains to soil is using a nutrient-supplying carrier (e.g., pearled barley for Afla-Guard). Granules of Bioplastic (partially acetylated corn starch) have been investigated as an alternative nutritive carrier for biocontrol agents. Bioplastic granules have also been used to prepare a sprayable biocontrol formulation that gives effective reduction of aflatoxin contamination in harvested corn kernels with application of much smaller amounts to leaves later in the growing season. The ultimate goal of biocontrol research is to produce biocontrol systems that can be applied to crops only when long-range weather forecasting indicates they will be needed.

Polyamine is a critical determinant of Pseudomonas chlororaphis O6 for GacS-dependent bacterial cell growth and biocontrol capacity.

PubMed

Park, Ju Yeon; Kang, Beom Ryong; Ryu, Choong-Min; Anderson, Anne J; Kim, Young Cheol

2018-05-01

The Gac/Rsm network regulates, at the transcriptional level, many beneficial traits in biocontrol-active pseudomonads. In this study, we used Phenotype MicroArrays, followed by specific growth studies and mutational analysis, to understand how catabolism is regulated by this sensor kinase system in the biocontrol isolate Pseudomonas chlororaphis O6. The growth of a gacS mutant was decreased significantly relative to that of the wild-type on ornithine and arginine, and on the precursor of these amino acids, N-acetyl-l-glutamic acid. The gacS mutant also showed reduced production of polyamines. Expression of the genes encoding arginine decarboxylase (speA) and ornithine decarboxylases (speC) was controlled at the transcriptional level by the GacS sensor of P. chlororaphis O6. Polyamine production was reduced in the speC mutant, and was eliminated in the speAspeC mutant. The addition of exogenous polyamines to the speAspeC mutant restored the in vitro growth inhibition of two fungal pathogens, as well as the secretion of three biological control-related factors: pyrrolnitrin, protease and siderophore. These results extend our knowledge of the regulation by the Gac/Rsm network in a biocontrol pseudomonad to include polyamine synthesis. Collectively, our studies demonstrate that bacterial polyamines act as important regulators of bacterial cell growth and biocontrol potential. © 2017 BSPP AND JOHN WILEY & SONS LTD.

Antagonistic activity of Bacillus subtilis SB1 and its biocontrol effect on tomato bacterial wilt

USDA-ARS?s Scientific Manuscript database

A potential biocontrol agent of bacterial wilt, Bacillus subtilis SB1, isolated from tomato roots, showed a broad-spectrum of antimicrobial activity in in vitro experiments. It inhibited the growth of many plant pathogens, including Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, Fusarium ox...

Isolation of oxalic acid tolerating fungi and decipherization of its potential to control Sclerotinia sclerotiorum through oxalate oxidase like protein.

PubMed

Yadav, Shivani; Srivastava, Alok K; Singh, Dhanajay P; Arora, Dilip K

2012-11-01

Oxalic acid plays major role in the pathogenesis by Sclerotinia sclerotiorum; it lowers the pH of nearby environment and creates the favorable condition for the infection. In this study we examined the degradation of oxalic acid through oxalate oxidase and biocontrol of Sclerotinia sclerotiorum. A survey was conducted to collect the rhizospheric soil samples from Indo-Gangetic Plains of India to isolate the efficient fungal strains able to tolerate oxalic acid. A total of 120 fungal strains were isolated from root adhering soils of different vegetable crops. Out of 120 strains a total of 80 isolates were able to grow at 10 mM of oxalic acid whereas only 15 isolates were grow at 50 mM of oxalic acid concentration. Then we examined the antagonistic activity of the 15 isolates against Sclerotinia sclerotiorum. These strains potentially inhibit the growth of the test pathogen. A total of three potential strains and two standard cultures of fungi were tested for the oxalate oxidase activity. Strains S7 showed the maximum degradation of oxalic acid (23 %) after 60 min of incubation with fungal extract having oxalate oxidase activity. Microscopic observation and ITS (internally transcribed spacers) sequencing categorized the potential fungal strains into the Aspergillus, Fusarium and Trichoderma. Trichoderma sp. are well studied biocontrol agent and interestingly we also found the oxalate oxidase type activity in these strains which further strengthens the potentiality of these biocontrol agents.

Biocontrol potential of Trichoderma harzianum isolate T-aloe against Sclerotinia sclerotiorum in soybean.

PubMed

Zhang, Fuli; Ge, Honglian; Zhang, Fan; Guo, Ning; Wang, Yucheng; Chen, Long; Ji, Xiue; Li, Chengwei

2016-03-01

Sclerotinia stem rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary is a major disease of soybean (Glycine max (L.) Merr.). At present, we revealed the three-way interaction between Trichoderma harzianum T-aloe, pathogen S. sclerotiorum and soybean plants in order to demonstrate biocontrol mechanism and evaluate biocontrol potential of T-aloe against S. sclerotiorum in soybean. In our experiments, T-aloe inhibited the growth of S. sclerotiorum with an efficiency of 56.3% in dual culture tests. T-aloe hyphae grew in parallel or intertwined with S. sclerotiorum hyphae and produced hooked contact branches, indicating mycoparasitism. Plate tests showed that T-aloe culture filtrate inhibited S. sclerotiorum growth with an inhibition efficiency of 51.2% and sclerotia production. T-aloe pretreatment showed growth-promoting effect on soybean plants. The activities of peroxidase, superoxide dismutase, and catalase increased, and the hydrogen peroxide (H2O2) as well as the superoxide radical (O2(-)) content in soybean leaves decreased after T-aloe pretreatment in response to S. sclerotiorum pathogen challenge. T-aloe treatment diminished damage caused by pathogen stress on soybean leaf cell membrane, and increased chlorophyll as well as total phenol contents. The defense-related genes PR1, PR2, and PR3 were expressed in the leaves of T-aloe-treated plants. In summary, T-aloe displayed biocontrol potential against S. sclerotiorum. This is the first report of unraveling biocontrol potential of Trichoderma Spp. to soybean sclerotinia stem rot from the three-way interaction between the biocontrol agent, pathogen S. sclerotiorum and soybean plants. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Transcriptomic response of the mycoparasitic fungus Trichoderma atroviride to the presence of a fungal prey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seidl, Verena; Song, Lifu; Lindquist, Erika

2009-11-30

Background: Fungi of the genus Trichoderma are effective mycoparasites an for this reason used as biocontrol agents agents plant pathogenic fungi. The ability to recognize, combat and finally besiege and kill the prey are essential skills for this process. Only fragments of the biochemical processes related to this ability have been uncovered so far, however. This study aims at uncovering transcriptional responses occurring in the mycoparasite Trichoderma atroviride when being confronted with a potential prey. Results: T. atroviride was confronted with two fungal preys, Botrytis cinerea and Rhizoctonia solani, and cDNAs prepared from mycelia immediately before getting into physical contactmore » with them (“onset of mycoparasitism”), and compared with such prepared from mycelial and conidiating cultures, respectively. About 3000 ESTs, representing about 900 genes each, were obtained from each of these three conditions. 65 genes, represented by 439 ESTs, were specifically and significantly overexpressed during onset of mycoparasitism, and the expression of a subset thereof verified by expression analysis. They comprised 18 KOG groups, but were most abundant from those including posttranslational processing (159 from 183 ESTs), and amino acid metabolism (70 of 84 ESTs), respectively. Several heat shock factors and tRNA synthases were particularly abundant. Metabolic network analysis confirmed the upregulation of the amino acid biosynthesic and the lipid catabolic capacity. Conclusion: Analysis of the genes overexpressed during the onset of mycoparasitism in T. atroviride has revealed that the fungus reacts to this condition with several previously undetected physiological reactions including strong stress response, sensing of nitrogen shortage and lipid catabolism. The data enable a new and more comprehensive interpretation of the physiology of mycoparasitism, and will aid in the selection of traits for breeding of biocontrol strains by recombinant techniques.« less

Effect of bacterial antagonists on lettuce: active biocontrol of Rhizoctonia solani and negligible, short-term effects on nontarget microorganisms.

PubMed

Scherwinski, Katja; Grosch, Rita; Berg, Gabriele

2008-04-01

The aim of this study was to assess the biocontrol efficacy against Rhizoctonia solani of three bacterial antagonists introduced into naturally Rhizoctonia-infested lettuce fields and to analyse their impact on the indigenous plant-associated bacteria and fungi. Lettuce seedlings were inoculated with bacterial suspensions of two endophytic strains, Serratia plymuthica 3Re4-18 and Pseudomonas trivialis 3Re2-7, and with the rhizobacterium Pseudomonas fluorescens L13-6-12 7 days before and 5 days after planting in the field. Similar statistically significant biocontrol effects were observed for all applied bacterial antagonists compared with the uninoculated control. Single-strand conformation polymorphism analysis of 16S rRNA gene or ITS1 fragments revealed a highly diverse rhizosphere and a less diverse endophytic microbial community for lettuce. Representatives of several bacterial (Alpha-, Beta- and Gammaproteobacteria, Firmicutes, Bacteriodetes), fungal (Ascomycetes, Basidiomycetes) and protist (Oomycetes) groups were present inside or on lettuce plants. Surprisingly, given that lettuce is a vegetable that is eaten raw, species of genera such as Flavobacterium, Burkholderia, Staphylococcus, Cladosporium and Aspergillus, which contain potentially human pathogenic strains, were identified. Analysis of the indigenous bacterial and endophytic fungal populations revealed only negligible, short-term effects resulting from the bacterial treatments, and that they were more influenced by field site, plant growth stage and microenvironment.

Biocontrol Activity of Volatile-Producing Bacillus megaterium and Pseudomonas protegens against Aspergillus flavus and Aflatoxin Production on Stored Rice Grains

PubMed Central

Mannaa, Mohamed; Oh, Ji Yeon

2017-01-01

In our previous study, three bacterial strains, Bacillus megaterium KU143, Microbacterium testaceum KU313, and Pseudomonas protegens AS15, were selected as effective biocontrol agents against Aspergillus flavus on stored rice grains. In this study, we evaluated the inhibitory effects of the volatiles produced by the strains on A. flavus growth and aflatoxin production on stored rice grains. The three strains significantly reduced mycelial growth of A. flavus in dual-culture assays compared with the negative control strain, Sphingomonas aquatilis KU408, and an untreated control. Of these tested strains, volatiles produced by B. megaterium KU143 and P. protegens AS15 markedly inhibited mycelial growth, sporulation, and conidial germination of A. flavus on agar medium and suppressed the fungal populations in rice grains. Moreover, volatiles produced by these two strains significantly reduced aflatoxin production in the rice grains by A. flavus. To our knowledge, this is the first report of the suppression of A. flavus aflatoxin production in rice grains using B. megaterium and P. protegens volatiles. PMID:29138628

Aflatoxins: mechanisms of inhibition by antagonistic plants and microorganisms

USDA-ARS?s Scientific Manuscript database

Aflatoxins are a family of toxic fungal secondary metabolites. The rapid expansion in our knowledge about inhibition of aflatoxin biosynthesis by compounds from plants and microorganisms has enabled us to utilize them as potential biocontrol agents. Substantial efforts have been devoted to identify ...

Bacterial Seed Endophytes of Domesticated Cucurbits Antagonize Fungal and Oomycete Pathogens Including Powdery Mildew.

PubMed

Khalaf, Eman M; Raizada, Manish N

2018-01-01

The cucurbit vegetables, including cucumbers, melons and pumpkins, have been cultivated for thousands of years without fungicides. However, their seed germination stage is prone to be infected by soil-borne fungal and oomycete pathogens. Endophytes are symbionts that reside inside plant tissues including seeds. Seed endophytes are founders of the juvenile plant microbiome and can promote host defense at seed germination and later stages. We previously isolated 169 bacterial endophytes associated with seeds of diverse cultivated cucurbits. We hypothesized that these endophytes can antagonize major fungal and oomycete pathogens. Here we tested the endophytes for in vitro antagonism (dual culture assays) against important soil-borne pathogens ( Rhizoctonia solani , Fusarium graminearum , Phytophthora capsici , Pythium aphanideratum ). The endophytes were also assayed in planta (leaf disk and detached leaf bioassays) for antagonism against a foliar pathogen of global importance, Podosphaera fuliginea , the causative agent of cucurbit powdery mildew. The endophytes were further tested in vitro for secretion of volatile organic compounds (VOCs) known to induce plant defense. Extracellular ribonuclease activity was also tested, as a subset of pathogenesis-related (PR) proteins of plant hosts implicated in suppression of fungal pathogens, displays ribonuclease activity. An unexpected majority of the endophytes (70%, 118/169) exhibited antagonism to the five phytopathogens, of which 68% (50/73) of in vitro antagonists belong to the genera Bacillus and Paenibacillus . All Lactococcus and Pantoea endophytes exhibited anti-oomycete activity. However, amongst the most effective inoculants against Podosphaera fuliginea were Pediococcus and Pantoea endophytes. Interestingly, 67% (113/169) of endophytes emitted host defense inducing VOCs (acetoin/diacetyl) and 62% (104/169) secreted extracellular ribonucleases in vitro , respectively. These results show that seeds of cultivated

Bacterial Seed Endophytes of Domesticated Cucurbits Antagonize Fungal and Oomycete Pathogens Including Powdery Mildew

PubMed Central

Khalaf, Eman M.; Raizada, Manish N.

2018-01-01

The cucurbit vegetables, including cucumbers, melons and pumpkins, have been cultivated for thousands of years without fungicides. However, their seed germination stage is prone to be infected by soil-borne fungal and oomycete pathogens. Endophytes are symbionts that reside inside plant tissues including seeds. Seed endophytes are founders of the juvenile plant microbiome and can promote host defense at seed germination and later stages. We previously isolated 169 bacterial endophytes associated with seeds of diverse cultivated cucurbits. We hypothesized that these endophytes can antagonize major fungal and oomycete pathogens. Here we tested the endophytes for in vitro antagonism (dual culture assays) against important soil-borne pathogens (Rhizoctonia solani, Fusarium graminearum, Phytophthora capsici, Pythium aphanidermatum). The endophytes were also assayed in planta (leaf disk and detached leaf bioassays) for antagonism against a foliar pathogen of global importance, Podosphaera fuliginea, the causative agent of cucurbit powdery mildew. The endophytes were further tested in vitro for secretion of volatile organic compounds (VOCs) known to induce plant defense. Extracellular ribonuclease activity was also tested, as a subset of pathogenesis-related (PR) proteins of plant hosts implicated in suppression of fungal pathogens, displays ribonuclease activity. An unexpected majority of the endophytes (70%, 118/169) exhibited antagonism to the five phytopathogens, of which 68% (50/73) of in vitro antagonists belong to the genera Bacillus and Paenibacillus. All Lactococcus and Pantoea endophytes exhibited anti-oomycete activity. However, amongst the most effective inoculants against Podosphaera fuliginea were Pediococcus and Pantoea endophytes. Interestingly, 67% (113/169) of endophytes emitted host defense inducing VOCs (acetoin/diacetyl) and 62% (104/169) secreted extracellular ribonucleases in vitro, respectively. These results show that seeds of cultivated cucurbits

Dry formulations of the biocontrol agent Candida sake CPA-1 using fluidised bed drying to control the main postharvest diseases on fruits.

PubMed

Carbó, Anna; Torres, Rosario; Usall, Josep; Fons, Estanislau; Teixidó, Neus

2017-08-01

The biocontrol agent Candida sake CPA-1 is effective against several diseases. Consequently, the optimisation of a dry formulation of C. sake to improve its shelf life and manipulability is essential for increasing its potential with respect to future commercial applications. The present study aimed to optimise the conditions for making a dry formulation of C. sake using a fluidised bed drying system and then to determine the shelf life of the optimised formulation and its efficacy against Penicillium expansum on apples. The optimal conditions for the drying process were found to be 40 °C for 45 min and the use of potato starch as the carrier significantly enhanced the viability. However, none of the protective compounds tested increased the viability of the dried cells. A temperature of 25 °C for 10 min in phosphate buffer was considered as the optimum condition to recover the dried formulations. The dried formulations should be stored at 4 °C and air-packaged; moreover, shelf life assays indicated good results after 12 months of storage. The formulated products maintained their biocontrol efficacy. A fluidised bed drying system is a suitable process for dehydrating C. sake cells; moreover, the C. sake formulation is easy to pack, store and transport, and is a cost-effective process. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Trichoderma harzianum enhances the production of nematicidal compounds in vitro and improves biocontrol of Meloidogyne javanica by Pseudomonas fluorescens in tomato.

PubMed

Siddiqui, I A; Shaukat, S S

2004-01-01

To determine the influence of soil-borne fungus Trichoderma harzianum on the biocontrol performance of Pseudomonas fluorescens strain CHA0 and its 2,4-diacetylphloroglucinol (DAPG) overproducing derivative CHA0/pME3424 against Meloidogyne javanica. Amendment of the culture filtrate (CF) or methanol extract of the CF of a T. harzianum strain Th6 to P. fluorescens growth medium enhanced the production of nematicidal compound(s) by bacterial inoculants in vitro. In addition, bacteria overwhelmingly expressed phl'-'lacZ reporter gene when the medium was amended with CF of T. harzianum. Pseudomonas fluorescens and T. harzianum applied together in unsterilized sandy loam soil caused greater reduction in nematode population densities in tomato roots. Trichoderma harzianum improves root-knot nematode biocontrol by the antagonistic rhizobacterium P. fluorescens both in vitro and under glasshouse conditions. The synergistic effect of T. harzianum on the production of nematicidal compound(s) critical in biocontrol may improve the efficacy of biocontrol bacteria against plant-parasitic nematodes. Considering the inconsistent performance of the biocontrol agents under field conditions, application of a mixture of compatible T. harzianum and P. fluorescens would more closely mimic the natural situation and might broaden the spectrum of biocontrol activity with enhanced efficacy and reliability of control.

Burkholderia terrae BS001 migrates proficiently with diverse fungal hosts through soil and provides protection from antifungal agents

PubMed Central

Nazir, Rashid; Tazetdinova, Diana I.; van Elsas, Jan Dirk

2014-01-01

Soil bacteria can benefit from co-occurring soil fungi in respect of the acquisition of carbonaceous nutrients released by fungal hyphae and the access to novel territories in soil. Here, we investigated the capacity of the mycosphere-isolated bacterium Burkholderia terrae BS001 to comigrate through soil along with hyphae of the soil fungi Trichoderma asperellum, Rhizoctonia solani, Fusarium oxysporum, F. oxysporum pv lini, Coniochaeta ligniaria, Phanerochaete velutina, and Phallus impudicus. We used Lyophyllum sp. strain Karsten as the reference migration-inciting fungus. Bacterial migration through presterilized soil on the extending fungal hyphae was detected with six of the seven test fungi, with only Phallus impudicus not showing any bacterial transport. Much like with Lyophyllum sp. strain Karsten, intermediate (106–108 CFU g-1 dry soil) to high (>108 CFU g-1 dry soil) strain BS001 cell population sizes were found at the hyphal migration fronts of four fungi, i.e., T. asperellum, Rhizoctonia solani, F. oxysporum and F. oxysporum pv lini, whereas for two fungi, Coniochaeta ligniaria and Phanerochaete velutina, the migration responses were retarded and population sizes were lower (103–106 CFU g-1 dry soil). Consistent with previous data obtained with the reference fungus, migration with the migration-inciting fungi occurred only in the direction of the hyphal growth front. Remarkably, Burkholderia terrae BS001 provided protection from several antifungal agents to the canonical host Lyophyllum sp. strain Karsten. Specifically, this host was protected from Pseudomonas fluorescens strain CHA0 metabolites, as well as from the anti-fungal agent cycloheximide. Similar protection by strain BS001was observed for T. asperellum, and, to a lower extent, F. oxysporum and Rhizoctonia solani. The protective effect may be related to the consistent occurrence of biofilm-like cell layers or agglomerates at the surfaces of the protected fungi. The current study represents

Use of biocontrol organisms and compost amendments for improved control of soilborne diseases and increased potato production

USDA-ARS?s Scientific Manuscript database

Soilborne potato diseases are persistent problems in potato production and alternative management practices are needed. In this research, biocontrol agents (Bacillus subtilis GB03 and Rhizoctonia solani hypovirulent isolate Rhs1A1) and compost amendments (from different source material), were evalua...

Biocontrol of Bacterial Fruit Blotch by Bacillus subtilis 9407 via Surfactin-Mediated Antibacterial Activity and Colonization.

PubMed

Fan, Haiyan; Zhang, Zhanwei; Li, Yan; Zhang, Xun; Duan, Yongming; Wang, Qi

2017-01-01

In this study, Bacillus subtilis 9407 showed a strong antibacterial activity against Acidovorax citrulli in vitro and 61.7% biocontrol efficacy on melon seedlings 4 days post inoculation under greenhouse conditions. To understand the biocontrol mechanism of B. subtilis 9407, identify the primary antibacterial compound and determine its role in controlling bacterial fruit blotch (BFB), a srfAB deletion mutant (Δ srfAB ) was constructed. The Δ srfAB which was deficient in production of surfactin, not only showed almost no ability to inhibit growth of A. citrulli but also decreased biofilm formation and reduced swarming motility. Colonization assay demonstrated that B. subtilis 9407 could conlonize on melon roots and leaves in a large population, while Δ srfAB showed a four- to ten-fold reduction in colonization of melon roots and leaves. Furthermore, a biocontrol assay showed that Δ srfAB lost the biocontrol efficacy. In summary, our results indicated that surfactin, which consists of C13- to C16-surfactin A was the primary antibacterial compound of B. subtilis 9407, and it played a major role in biofilm formation, swarming motility, colonization and suppressing BFB. We propose that the biocontrol activity of B. subtilis 9407 is the results of the coordinated action of surfactin-mediated antibacterial activity and colonization. This study reveals for the first time that the use of a B. subtilis strain as a potential biological control agent could efficiently control BFB by producing surfactin.

Biocontrol of Bacterial Fruit Blotch by Bacillus subtilis 9407 via Surfactin-Mediated Antibacterial Activity and Colonization

PubMed Central

Fan, Haiyan; Zhang, Zhanwei; Li, Yan; Zhang, Xun; Duan, Yongming; Wang, Qi

2017-01-01

In this study, Bacillus subtilis 9407 showed a strong antibacterial activity against Acidovorax citrulli in vitro and 61.7% biocontrol efficacy on melon seedlings 4 days post inoculation under greenhouse conditions. To understand the biocontrol mechanism of B. subtilis 9407, identify the primary antibacterial compound and determine its role in controlling bacterial fruit blotch (BFB), a srfAB deletion mutant (ΔsrfAB) was constructed. The ΔsrfAB which was deficient in production of surfactin, not only showed almost no ability to inhibit growth of A. citrulli but also decreased biofilm formation and reduced swarming motility. Colonization assay demonstrated that B. subtilis 9407 could conlonize on melon roots and leaves in a large population, while ΔsrfAB showed a four- to ten-fold reduction in colonization of melon roots and leaves. Furthermore, a biocontrol assay showed that ΔsrfAB lost the biocontrol efficacy. In summary, our results indicated that surfactin, which consists of C13- to C16-surfactin A was the primary antibacterial compound of B. subtilis 9407, and it played a major role in biofilm formation, swarming motility, colonization and suppressing BFB. We propose that the biocontrol activity of B. subtilis 9407 is the results of the coordinated action of surfactin-mediated antibacterial activity and colonization. This study reveals for the first time that the use of a B. subtilis strain as a potential biological control agent could efficiently control BFB by producing surfactin. PMID:29075242

Quorum sensing is a key regulator for the antifungal and biocontrol activity of chitinase-producing Chromobacterium sp. C61.

PubMed

Kim, In Seon; Yang, Si Young; Park, Seur Kee; Kim, Young Cheol

2017-01-01

Chromobacterium sp. strain C61 has strong biocontrol activity; however, the genetic and biochemical determinants of its plant disease suppression activity are not well understood. Here, we report the identification and characterization of two new determinants of its biocontrol activity. Transposon mutagenesis was used to identify mutants that were deficient in fungal suppression. One of these mutants had an insertion in a homologue of depD, a structural gene in the dep operon, that encodes a protein involved in non-ribosomal peptide synthesis. In the second mutant, the insertion was in a homologue of the luxI gene, which encodes a homoserine lactone synthase. The luxI - and depD - mutants had no antifungal activity in vitro and a dramatically reduced capacity to suppress various plant diseases in planta. Antifungal production and biocontrol were restored by complementation of the luxI - mutant. Other phenotypes associated with effective biological control, including motility and lytic enzyme secretion, were also affected by the luxI mutation. Biochemical analysis of ethyl acetate extracts of culture filtrates of the mutant and wild-type strains showed that a key antifungal compound, chromobactomycin, was produced by wild-type C61 and the complemented luxI - mutant, but not by the luxI - or depD - mutant. These data suggest that multiple biocontrol-related phenotypes are regulated by homoserine lactones in C61. Thus, quorum sensing plays an essential role in the biological control potential of diverse bacterial lineages. © 2016 BSPP and John Wiley & Sons Ltd.

Improvement of a dry formulation of Pseudomonas fluorescens EPS62e for fire blight disease biocontrol by combination of culture osmoadaptation with a freeze-drying lyoprotectant.

PubMed

Cabrefiga, J; Francés, J; Montesinos, E; Bonaterra, A

2014-10-01

To study the effect of lyoprotectants and osmoadaptation on viability of Pseudomonas fluorescens EPS62e during freeze-drying and storage and to evaluate the formulation in terms of efficacy in biocontrol and fitness on pear flowers. A wettable powder formulation of a biocontrol agent of fire blight was optimized by means of lyoprotectants and culture osmoadaptation. Freeze-drying was used to obtain dehydrated cells, and the best viability (70% of survival) was obtained using lactose as lyoprotectant. Survival during lyophilization was additionally improved using physiological adaptation of cells during cultivation under salt-amended medium (osmoadaptation). The procedure increased the survival of cells after freeze-drying attaining viability values close to a 100% in the lactose-formulated product (3 × 10(11) CFU g(-1) ), and through the storage period of 1 year at 4°C. The dry formulation showed also an improved biocontrol efficacy and survival of EPS62e on pear flowers under low relative humidity conditions. Cell viability after freeze-drying was improved using lactose as lyoprotectant combined with a procedure of osmoadaptation during cultivation. The powder-formulated product remained active for 12 months and retained biocontrol levels similar to that of fresh cells. The formulation showed an improved survival of EPS62e on flowers and an increase of the efficacy of biocontrol of fire blight at low relative humidity. The results have a potential value for commercial application in biocontrol agents not only of fire blight but also of other plant diseases. © 2014 The Society for Applied Microbiology.

Potential of Burkholderia seminalis TC3.4.2R3 as Biocontrol Agent Against Fusarium oxysporum Evaluated by Mass Spectrometry Imaging

NASA Astrophysics Data System (ADS)

Araújo, Francisca Diana da Silva; Araújo, Welington Luiz; Eberlin, Marcos Nogueira

2017-05-01

Species of genus Burkholderia display different interaction profiles in the environment, causing either several diseases in plants and animals or being beneficial to some plants, promoting their growth, and suppressing phytopathogens. Burkholderia spp. also produce many types of biomolecules with antimicrobial activity, which may be commercially used to protect crops of economic interest, mainly against fungal diseases. Herein we have applied matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to investigate secondary metabolites produced by B. seminalis TC3.4.2R3 in monoculture and coculture with plant pathogen Fusarium oxysporum. The siderophore pyochelin and the rhamnolipid Rha-Rha-C15-C14 were detected in wild-type B. seminalis strain, and their productions were found to vary in mutant strains carrying disruptions in gene clusters associated with antimicrobial compounds. Two mycotoxins were detected in F. oxysporum. During coculture with B. seminalis, metabolites probably related to defense mechanisms of these microorganisms were observed in the interspecies interaction zone. Our findings demonstrate the effective application of MALDI-MSI in the detection of bioactive molecules involved in the defense mechanism of B. seminalis, and these findings suggest the potential use of this bacterium in the biocontrol of plant diseases caused by F. oxysporum.

Optimization of Culture Medium Enhances Viable Biomass Production and Biocontrol Efficacy of the Antagonistic Yeast, Candida diversa.

PubMed

Liu, Jia; Li, Guangkun; Sui, Yuan

2017-01-01

Viable biomass production is a key determinant of suitability of antagonistic yeasts as potential biocontrol agents. This study investigated the effects of three metal ions (magnesium, ferrous, and zinc) on biomass production and viability of the antagonistic yeast, Candida diversa . Using response surface methodology to optimize medium components, a maximum biomass was obtained, when the collective Mg 2+ , Fe 2+ , and Zn 2+ concentrations were adjusted in a minimal mineral (MM) medium. Compared with the unmodified MM, and three ion-deficient MM media, yeast cells cultured in the three ion-modified MM medium exhibited a lower level of cellular oxidative damage, and a higher level of antioxidant enzyme activity. A biocontrol assay indicated that C. diversa grown in the ion-modified MM exhibited the greatest level of control of gray mold on apple fruit. These results provide new information on culture medium optimization to grow yeast antagonists in order to improve biomass production and biocontrol efficacy.

Optimization of Culture Medium Enhances Viable Biomass Production and Biocontrol Efficacy of the Antagonistic Yeast, Candida diversa

PubMed Central

Liu, Jia; Li, Guangkun; Sui, Yuan

2017-01-01

Viable biomass production is a key determinant of suitability of antagonistic yeasts as potential biocontrol agents. This study investigated the effects of three metal ions (magnesium, ferrous, and zinc) on biomass production and viability of the antagonistic yeast, Candida diversa. Using response surface methodology to optimize medium components, a maximum biomass was obtained, when the collective Mg2+, Fe2+, and Zn2+ concentrations were adjusted in a minimal mineral (MM) medium. Compared with the unmodified MM, and three ion-deficient MM media, yeast cells cultured in the three ion-modified MM medium exhibited a lower level of cellular oxidative damage, and a higher level of antioxidant enzyme activity. A biocontrol assay indicated that C. diversa grown in the ion-modified MM exhibited the greatest level of control of gray mold on apple fruit. These results provide new information on culture medium optimization to grow yeast antagonists in order to improve biomass production and biocontrol efficacy. PMID:29089939

Pilot-scale production and liquid formulation of Rhodotorula minuta, a potential biocontrol agent of mango anthracnose.

PubMed

Patiño-Vera, M; Jiménez, B; Balderas, K; Ortiz, M; Allende, R; Carrillo, A; Galindo, E

2005-01-01

To develop a pilot-plant fermentation process for the production of the yeast Rhodotorula minuta, to be used as a biocontrol agent of mango anthracnose, using a low-cost culture medium. To develop a stable liquid formulation that preserve high viability of the yeast stored at 4 degrees C. Keeping constant the volumetric power input, a fermentation process was scaled-up from shake flasks to a 100 l bioreactor. Preharvest applications of the yeast resulted in postharvest anthracnose severity equal or lower than that observed with a chemical fungicide. Glycerol was added to the formulation as water activity reducer and xanthan gum as a viscosity-enhancing agent. Yeast initial concentration of 10(10) CFU ml(-1) resulted in 4-5 orders of magnitude decrease after 1 month of storage at 4 degrees C, whereas when it was formulated at 10(9) CFU ml(-1), the decrease was of two orders of magnitude in 6 months. The fermentation process was successfully scaled-up using a low-cost culture medium. Postharvest anthracnose severity could be considerably reduced using this yeast. Formulating the yeast at 10(9) CFU ml(-1) and adding glycerol (20%) and xanthan (5 g l(-1)) avoided both contamination and yeast sedimentation and it was able to preserve up to 10(7) CFU ml(-1) after 6 months at 4 degrees C. The yeast R. minuta is reported as a novel antagonistic micro-organism against the pathogen Colletotrichum gloeosporioides. Pilot plant production of this yeast allowed us to conduct field tests in commercial orchards during three harvest seasons. Yeast suspensions applied to mango trees reduced the fruit anthracnose severity in levels similar or better than chemical fungicides.

Biocontrol efficacy of different isolates of Trichoderma against soil borne pathogen Rhizoctonia solani.

PubMed

Asad, Saeed Ahmad; Ali, Naeem; Hameed, Abdul; Khan, Sabaz Ali; Ahmad, Rafiq; Bilal, Muhammad; Shahzad, Muhammad; Tabassum, Ayesha

2014-01-01

In this study, the biocontrol abilities of water-soluble and volatile metabolites of three different isolates of Trichoderma (T. asperellum, T. harzianum and Trichoderma spp.) against soil borne plant pathogen Rhizoctonia solani were investigated both in vitro and in vivo. The results showed for the first time that mycelial growth inhibition of the pathogen was 74.4-67.8% with water-soluble metabolites as compared to 15.3-10.6% with volatile metabolites in vitro. In vivo antagonistic activity of Trichoderma isolates against R. solani was evaluated on bean plants under laboratory and greenhouse conditions. We observed that T. asperellum was more effective and consistent, lowering disease incidence up to 19.3% in laboratory and 30.5% in green house conditions. These results showed that three isolates of Trichoderma could be used as effective biocontrol agents against R. solani.

Evaluation of atoxigenic isolates of Aspergillus flavus as potential biocontrol agents for aflatoxin in maize.

PubMed

Atehnkeng, J; Ojiambo, P S; Ikotun, T; Sikora, R A; Cotty, P J; Bandyopadhyay, R

2008-10-01

Aflatoxin contamination resulting from maize infection by Aspergillus flavus is both an economic and a public health concern. Therefore, strategies for controlling aflatoxin contamination in maize are being investigated. The abilities of eleven naturally occurring atoxigenic isolates in Nigeria to reduce aflatoxin contamination in maize were evaluated in grain competition experiments and in field studies during the 2005 and 2006 growing seasons. Treatments consisted of inoculation of either grains in vials or ears at mid-silking stage in field plots, with the toxigenic isolate (La3228) or atoxigenic isolate alone and co-inoculation of each atoxigenic isolate and La3328. Aflatoxin B(1) + B(2) concentrations were significantly (p < 0.05) lower in the co-inoculation treatments compared with the treatment in which the aflatoxin-producing isolate La3228 was inoculated alone. Relative levels of aflatoxin B(1) + B(2) reduction ranged from 70.1% to 99.9%. Among the atoxigenics, two isolates from Lafia, La3279 and La3303, were most effective at reducing aflatoxin B(1) + B(2) concentrations in both laboratory and field trials. These two isolates have potential value as agents for the biocontrol of aflatoxin contamination in maize. Because these isolates are endemic to West Africa, they are both more likely than introduced isolates to be well adapted to West African environments and to meet regulatory concerns over their use throughout that region.

Candida parapsilosis as a Potent Biocontrol Agent against Growth and Aflatoxin Production by Aspergillus Species

PubMed Central

Niknejad, F; Zaini, F; Faramarzi, MA; Amini, M; Kordbacheh, P; Mahmoudi, M; Safara, M

2012-01-01

Background: Aflatoxin contamination of food and feed stuff is a serious health problem and significant economic concerns. In the present study, the inhibitory effect of Candida parapsilosis IP1698 on mycelial growth and aflatoxin production in aflatoxigenic strains of Aspergillus species was investigated. Methods: Mycelial growth inhibitions of nine strains of aflatoxigenic and non-aflatoxigenic Aspergillus species in the presence of C. parapsilosis investigated by pour plate technique at different pH, temperature and time of incubation. Reduction of aflatoxin was evaluated in co-cultured fungi in yeast extract sucrose broth after seven days of incubation using HPLC method. The data were analyzed by SPSS 11.5. Results: The presence of the C. parapsilosis at different pH did not affect significantly the growth rate of Aspergillus isolates. On the other hand, temperature and time of incubation showed to be significantly effective when compared to controls without C. parapsilosis (P≤0.05). In aflatoxigenic strains, minimum percentage of reductions in total aflatoxin and B1, B2, G1, G2 fractions were 92.98, 92.54, 77.48, 54.54 and 72.22 and maximum percentage of reductions were 99.59, not detectable, 94.42, and not detectable in both G1 and G2, respectively. Conclusion: C. parapsilosis might employ as a good biocontrol agent against growth and aflatoxin production by aflatoxigenic Aspergillus species PMID:23308351

Intracellular trehalose and sorbitol synergistically promoting cell viability of a biocontrol yeast Pichia anomala for aflatoxin reduction

USDA-ARS?s Scientific Manuscript database

Pichia anomala WRL-076 was discovered by a visual screening bioassay for its antagonism against Aspergillus flavus. The yeast was shown to significantly inhibit aflatoxin production and the growth of A. flavus. P. anomala is a potential biocontrol agent for reduction of mycotoxin in the food chain...

Evolutionarily informative strain-typing for Beauveria bassiana: multilocus haplotype stability and a genetic context for the mycoinsecticide GHA

USDA-ARS?s Scientific Manuscript database

Beauveria bassiana strain GHA (ARSEF3620, ATCC74250), the active component of mycoinsecticide formulations BotaniGard® and Mycotrol® (Certis, Columbia, MD), is a leading fungal biocontrol agent used against pest insects. Due to its pathogenicity and virulence toward diverse insect taxa, GHA is often...

Rhizoctonia solani infection reduced by bacterial and fungal combination of biofertilizer inoculums on organic potato

NASA Astrophysics Data System (ADS)

Papp, Orsolya; Biro, Borbala; Abod, Eva; Jung, Timea; Tirczka, Imre; Drexler, Dora

2017-04-01

Soil biological functioning and proper agrotechnical management are of key importance in organic agriculture. Beneficial microbial inoculums are used either as plant strengthening products (psp) or also as plant protecting products (ppp). Question is, which type of microbes should be applied to certain soil-plant systems to improve yield or reduce the damage of soil-born plant pathogens? Objective of present study was to compare the effect of inoculums 1 (PPS) with plant growth promoting bacterium strains (PGPR) and inoculums 2 (TPB) with potential biocontrol-agents, including both fungi and bacteria in organic potato production. Field experiment was conducted at the Organic Research Station of the Szent István University (Babatpuszta, Hungary). Growth and quality of potato (Solanum tuberosum var. Demon) was studied in the two microbial treatments and control, in four replicates. The PPS inoculums included Pseudomonas protegens, Ps. jessenii and Strenotrophomonas maltophylia, with plant growth promoting (PGPR) effect. TPB inoculums consisted of Trichoderma hartianum, Pseudomonas putida and Bacillus subtilis strains with main biocontrol effects of fungal and bacterium combination. Strains were incubated for 24 hours at 28 oC in a rotary shaker (140 rpm/min) up till cell-number about 1010 cell.ml-1 in Nutrient broth substrate, and mixed to prepare combined inoculums. Each potato tuber was treated by 10 ml inoculums that was added to 100 ml water respectively with only water at the controls. Yield of potato (10 plants/plot) and tuber quality, i.e. the percentage ratio of scabbiness (Streptomyces scabies), Rhizoctonia solani, and Fusarium sp. infection was estimated. Abundance of total aerob and anaerob heterotrophs, total microscopic fungi, pseudomonads bacteria and some sporeforming microorganisms was assessed by the most probable number (MPN) method in soil samples, collected four times during vegetation. Soil enzyme, dehydrogenase (DH) and fluorescein diacetate

Fungal Endophyte Diversity and Bioactivity in the Indian Medicinal Plant Ocimum sanctum Linn

PubMed Central

Chowdhary, Kanika; Kaushik, Nutan

2015-01-01

Endophytic mycopopulation isolated from India’s Queen of herbs Tulsi (Ocimum sanctum) were explored and investigated for their diversity and antiphytopathogenic activity against widespread plant pathogens Botrytis cinerea, Sclerotinia sclerotiorum, Rhizoctonia solani and Fusarium oxysporum. 90 fungal isolates, representing 17 genera were recovered from 313 disease-free and surface sterilised plant segments (leaf and stem tissues) from three different geographic locations (Delhi, Hyderabad and Mukteshwar) during distinct sampling times in consequent years 2010 and 2011 in India. Fungal endophytes were subjected to molecular identification based on rDNA ITS sequence analysis. Plant pathogens such as F. verticillioides, B. maydis, C. coarctatum, R. bataticola, Hypoxylon sp., Diaporthe phaseolorum, Alternaria tenuissima and A. alternata have occurred as endophyte only during second sampling (second sampling in 2011) in the present study. Bi-plot generated by principal component analysis suggested tissue specificity of certain fungal endophytes. Dendrogram revealed species abundance as a function of mean temperature of the location at the time of sampling. Shannon diversity in the first collection is highest in Hyderabad leaf tissues (H' = 1.907) whereas in second collection it was highest from leaf tissues of Delhi (H' = 1.846). Mukteshwar (altitude: 7500 feet) reported least isolation rate in second collection. Nearly 23% of the total fungal isolates were considered as potent biocontrol agent. Hexane extract of M. phaseolina recovered from Hyderabad in first collection demonstrated highest activity against S. sclerotiorum with IC50 value of 0.38 mg/ml. Additionally, its components 2H-pyran-2-one, 5,6-dihydro-6-pentyl and palmitic acid, methyl ester as reported by GC-MS Chromatogram upon evaluation for their antiphytopathogenic activity exhibited IC50 value of 1.002 and 0.662 against respectively S. sclerotiorum indicating their significant role in

Towards a Cancer Drug of Fungal Origin

PubMed Central

Kornienko, Alexander; Evidente, Antonio; Vurro, Maurizio; Mathieu, Véronique; Cimmino, Alessio; Evidente, Marco; van Otterlo, Willem A. L.; Dasari, Ramesh; Lefranc, Florence; Kiss, Robert

2015-01-01

Although fungi produce highly structurally diverse metabolites, many of which have served as excellent sources of pharmaceuticals, no fungi-derived agent has been approved as a cancer drug so far. This is despite a tremendous amount of research being aimed at the identification of fungal metabolites with promising anticancer activities. This review discusses the results of clinical testing of fungal metabolites and their synthetic derivatives, with the goal to evaluate how far we are from an approved cancer drug of fungal origin. Also, because in vivo studies in animal models are predictive of the efficacy and toxicity of a given compound in a clinical situation, literature describing animal cancer testing of compounds of fungal origin is reviewed as well. Agents showing the potential to advance to clinical trials are also identified. Finally, the technological challenges involved in the exploitation of fungal biodiversity and procurement of sufficient quantities of clinical candidates are discussed and potential solutions that could be pursued by researchers are highlighted. PMID:25850821

POSSIBLE ROLE OF FUNGAL HEMOLYSINS IN SICK BUILDING SYNDROME

EPA Science Inventory

Many fungi produce proteinaceous hemolytic agents. Like bacterial hemolysins, fungal hemolysins create pores or holes in membranes. Depending on which membranes are damaged, fungal hemolysins can produce a variety of effects. Fungal hemolysins can cause histamine release from ...

Comparative transcriptome and gene co-expression network analysis reveal genes and signaling pathways adaptively responsive to varied adverse stresses in the insect fungal pathogen, Beauveria bassiana.

PubMed

He, Zhangjiang; Zhao, Xin; Lu, Zhuoyue; Wang, Huifang; Liu, Pengfei; Zeng, Fanqin; Zhang, Yongjun

2018-01-01

Sensing, responding, and adapting to the surrounding environment are crucial for all living organisms to survive, proliferate, and differentiate in their biological niches. Beauveria bassiana is an economically important insect-pathogenic fungus which is widely used as a biocontrol agent to control a variety of insect pests. The fungal pathogen unavoidably encounters a variety of adverse environmental stresses and defense response from the host insects during application of the fungal agents. However, few are known about the transcription response of the fungus to respond or adapt varied adverse stresses. Here, we comparatively analyzed the transcriptome of B. bassiana in globe genome under the varied stationary-phase stresses including osmotic agent (0.8 M NaCl), high temperature (32 °C), cell wall-perturbing agent (Congo red), and oxidative agents (H 2 O 2 or menadione). Total of 12,412 reads were obtained, and mapped to the 6767 genes of the B. bassiana. All of these stresses caused transcription responses involved in basal metabolism, cell wall construction, stress response or cell rescue/detoxification, signaling transduction and gene transcription regulation, and likely other cellular processes. An array of genes displayed similar transcription patterns in response to at least two of the five stresses, suggesting a shared transcription response to varied adverse stresses. Gene co-expression network analysis revealed that mTOR signaling pathway, but not HOG1 MAP kinase pathway, played a central role in regulation the varied adverse stress responses, which was verified by RNAi-mediated knockdown of TOR1. Our findings provided an insight of transcription response and gene co-expression network of B. bassiana in adaptation to varied environments. Copyright © 2017 Elsevier Inc. All rights reserved.

Prevalence of type III secretion system in effective biocontrol pseudomonads.

PubMed

Almario, Juliana; Gobbin, Davide; Défago, Geneviève; Moënne-Loccoz, Yvan; Rezzonico, Fabio

2014-05-01

Functional type III secretion system (T3SS) genes are needed for effective biocontrol of Pythium damping-off of cucumber by Pseudomonas fluorescens KD, but whether biocontrol Pseudomonas strains with T3SS genes display overall a higher plant-protecting activity is unknown. The assessment of 198 biocontrol fluorescent pseudomonads originating from 60 soils worldwide indicated that 32% harbour the ATPase-encoding T3SS gene hrcN, which was most often found in tomato isolates. The hrcN(+) biocontrol strains (and especially those also producing 2,4-diacetylphloroglucinol and displaying 1-aminocyclopropane-1-carboxylate deaminase activity) displayed higher plant-protecting ability in comparison with hrcN(-) biocontrol strains, both in the Pythium/cucumber and Fusarium/cucumber pathosystems. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Non-pathogenic Fusarium solani represses the biosynthesis of nematicidal compounds in vitro and reduces the biocontrol of Meloidogyne javanica by Pseudomonas fluorescens in tomato.

PubMed

Siddiqui, I A; Shaukat, S S

2003-01-01

The aim of the present investigation was to determine the influence of various Fusarium solani strains on the production of nematicidal agent(s) in vitro and biocontrol of Meloidogyne javanica in tomato by Pseudomonas fluorescens strains CHA0 and CHA0/pME3424. Culture filtrates (CF) of P. fluorescens strain CHA0 and its diacetylphloroglucinol-overproducing derivative CHA0/pME3424 caused substantial mortality of M. javanica juveniles in vitro. Bacterial growth medium amended with the growth medium of F. solani repressed the nematicidal activity of the bacteria. Methanol extract of F. solani CF resulting from Czapek's Dox liquid (CDL) medium without zinc amendment repressed the nematicidal activity of the bacteria while the CF obtained from CDL medium amended with zinc did not. Conidial suspension of F. solani strain Fs5 (repressor strain for the biosynthesis of nematicidal compounds in P. fluorescens) reduced biocontrol potential of the bacterial inoculants against M. javanica in tomato while strain Fs3 (non-repressor) did not. Fusarium solani strains with increased nematicidal activity repress the biosynthesis of nematicidal compounds by P. fluorescens strains in vitro and greatly alter its biocontrol efficacy against root-knot nematode under natural conditions. Fusarium solani strains are distributed worldwide and found in almost all the agricultural fields which suggest that some mycotoxin-producing strains will also be found in almost any soil sample taken. Besides the suppressive effect of these metabolite-producing strains on the production of nematicidal compound(s) critical in biocontrol, F. solani strains may also affect the performance of mycotoxin-sensitive biocontrol bacteria effective against plant-parasitic nematodes.

Potential role of exoglucanase genes (WaEXG1 and WaEXG2) in the biocontrol activity of Wickerhamomyces anomalous

USDA-ARS?s Scientific Manuscript database

The use of yeasts, including Wickerhamomyces anomalus, as biocontrol agents against fungi responsible for postharvest diseases of fruits and vegetables has been investigated for the past two decades. Among a variety of killer mechanisms, the production of glucanases coded by the genes WaEXG1 and Wa...

Wheat bran soil inoculant of sumateran nematode-trapping fungi as biocontrol agents of the root-knot nematode meloidogyne incognita on deli tobacco (nicotiana tabaccum l) cv. deli 4

NASA Astrophysics Data System (ADS)

Dwi Sri Hastuti, Liana; Faull, Jane

2018-03-01

A pot experiment was carried out to test the effectiveness of nematode-trapping fungi (NTF) isolated from Sumatera for controlling infection by the root-knot nematode (RKN) on Deli tobacco plant. Wheat bran soil containing 109 conidia of Arthrobotrys. oligospora, Candellabrella musiformis and Dactylella eudermata was added to the soil as a dry inoculum. Carbofuran was also applied as chemical agent and comparison treatment. Seedling tobacco (Nicotiana tabacum L.) cv. Deli 4 was inoculated with root knot (Meloidogyne incognita Chitwood.) seven days after the plant were transplanted to the pots. A. oligospora, C. musiformis and D. eudermata were found to be reliable as biocontrol agents, reducing the number of vermiform nematodes, swollen root, sausage shaped and galls in tobacco plant after 7, 15 and 30 days of infection with M. incognita. Treatment with NTF produced results that were comparable with Carbofuran® as a control agent in the reduction of the number of infections in tobacco plant caused by M. incognita in Nicotiana tabacum var. Deli 4. They also optimize the growth of the tobacco plants especially up to 15 days after infection.

Detection and quantification by PCR assay of the biocontrol agent Pantoea agglomerans CPA-2 on apples.

PubMed

Soto-Muñoz, Lourdes; Teixidó, Neus; Usall, Josep; Viñas, Inmaculada; Torres, Rosario

2014-04-03

The registration of biological control agents requires the development of monitoring systems to detect and quantify the agent in the environment. Pantoea agglomerans CPA-2 is an effective biocontrol agent for postharvest diseases of citrus and pome fruits. The monitoring of CPA-2 in postharvest semi-commercial trials was evaluated by Rodac impression plates and the colonies isolated were confirmed by conventional PCR using the SCAR primers PAGA1 and PAGB1. Samples were taken from different surfaces that had contact with CPA-2, the surrounding environment and working clothes worn by handlers. Moreover, population dynamics of the strain CPA-2 were determined on apple surfaces using both the classical plating technique and real-time quantitative PCR (qPCR). A qPCR assay using a 3'-minor groove-binding (MGB) probe was developed for the specific detection and quantification of P. agglomerans strain CPA-2. Based on the nucleotide sequence of a SCAR fragment of CPA-2, one primer set and TaqMan MGB probe were designed. The primers SP2-F/SP2-R and the TaqMan MGB probe showed a specific detection of strain CPA-2 on apple surfaces, which was verified tested against purified DNA from 17 strains of P. agglomerans, 4 related Pantoea species, and 21 bacterial strains from other genera isolated from whole and also freshly-cut fruit and vegetables. The detection level was approximately 10(3) cells per reaction, and the standard curve was linear within a range of 5log units. Results from semi-commercial trials showed that CPA-2 had a low impact. The maximum persistence of P. agglomerans CPA-2 was not longer than 5days in plastic boxes stored at 0°C. Significant differences in CPA-2 population level dynamics were observed in results obtained by qPCR and dilution plating. These differences may indicate the presence of non-degraded DNA from non-viable cells. In conclusion, qPCR is a novel potential tool to quickly and specifically monitor recent surface colonisation by CPA-2

Fungal antagonists of the plant pathogen Rhizoctonia solani: selection, control efficacy and influence on the indigenous microbial community.

PubMed

Grosch, Rita; Scherwinski, Katja; Lottmann, Jana; Berg, Gabriele

2006-12-01

A broad spectrum of fungal antagonists was evaluated as potential biocontrol agents (BCAs) against the soil-borne pathogen Rhizoctonia solani using a new combination of in vitro and in vivo assays. The in vitro characterisation of diverse parameters including the ability to parasitise mycelium and to inhibit the germination of Rhizoctonia sclerotia at different temperatures resulted in the selection of six potential fungal antagonists. These were genotypically characterised by their BOX-PCR fingerprints, and identified as Trichoderma reesei and T. viride by partial 18S rDNA sequencing. When potato sprouts were treated with Trichoderma, all isolates significantly reduced the incidence of Rhizoctonia symptoms. Evaluated under growth chamber conditions, the selected Trichoderma isolates either partly or completely controlled the dry mass loss of lettuce caused by R. solani. Furthermore, the antagonistic Trichoderma strains were active under field conditions. To analyse the effect of Trichoderma treatment on indigenous root-associated microbial communities, we performed a DNA-dependent SSCP (Single-Strand Conformation Polymorphism) analysis of 16S rDNA/ITS sequences. In this first assessment study for Trichoderma it was shown that the pathogen and the vegetation time had much more influence on the composition of the microbiota than the BCA treatment. After evaluation of all results, three Trichoderma strains originally isolated from Rhizoctonia sclerotia were selected as promising BCAs.

A Saccharomyces cerevisiae genome-wide mutant screen for sensitivity to 2,4-diacetylphloroglucinol, a biocontrol antibiotic produced by Pseudomonas fluorescens

USDA-ARS?s Scientific Manuscript database

Strains of Pseudomonas fluorescens that produce the antibiotic 2,4-diacetylphloroglucinol (DAPG) are biocontrol agents of a variety of soilborne pathogens. DAPG is active against a broad spectrum of organisms ranging from bacteria to higher plants. This suggests that the antibiotic may target basic...

Effects of alcohols and ciclopirox alamine, an anti-fungal agent, on the peripheral blood lymphocyte functions in vitro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prabhala, R.H.; Maxey, V.; Hicks, M.J.

1986-03-01

Effects of ethanol (1%), propanol (1%) and ciclopirox alamine, an anti-fungal agent, (4 ..mu..g/well), on the peripheral blood lymphocyte functions, including response to T- (Concanavalin A, ConA) and B-cell (Lipopolysaccharide, LPS) mitogens, and presence of functional T-lymphocyte subsets were determined in vitro. Purified human lymphocytes were incubated at 37/sup 0/C for 48 hours with or without test compounds in presence or absence of ConA and LPS. All three compounds suppress the response to T- or B-cell mitogens. The percentage of T-lymphocytes with T-helper characteristics in the presence of ethanol and ciclopirox alamine was increased. All three compounds suppressed the percentagemore » of T-lymphocytes with E-resetting characteristics. Alcohols enhanced the number of natural killer cells, whereas, ciclopirox alamine exhibited the reverse action. Although the alcohols and the anti-fungal agent enhanced the T-helper subpopulation, their response to mitogens was suppressed. This may be due to the suppression of T-cell activating lymphokines. Alcohol metabolite such as acetaldehyde also suppress the number of T-cells and their functions at 0.01% so may also be part of the explanation for immunoalteration.« less

Entomopathogenic nematodes in the European biocontrol market.

PubMed

Ehlers, R U

2003-01-01

In Europe total revenues in the biocontrol market have reached approximately 200 million Euros. The sector with the highest turn-over is the market for beneficial invertebrates with a 55% share, followed by microbial agents with approximately 25%. Annual growth rates of up to 20% have been estimated. Besides microbial plant protection products that are currently in the process of re-registration, several microbial products have been registered or are in the process of registration, following the EU directive 91/414. Entomopathogenic nematodes (EPN) are exceptionally safe biocontrol agents. Until today, they are exempted from registration in most European countries, the reason why SMEs were able to offer economically reasonable nematode-based products. The development of technology for mass production in liquid media significantly reduced the product costs and accelerated the introduction of nematode products in tree nurseries, ornamentals, strawberries, mushrooms, citrus and turf. Progress in storage and formulation technology has resulted in high quality products which are more resistant to environmental extremes occurring during transportation to the user. The cooperation between science, industry and extension within the EU COST Action 819 has supported the development of quality control methods. Today four companies produce EPN in liquid culture, offering 8 different nematode species. Problems with soil insects are increasing. Grubs, like Melolontha melolontha and other scarabaeidae cause damage in orchards and turf. Since the introduction of the Western Corn Rootworm Diabrotica virgifera into Serbia in 1992, this pests as spread all over the Balkan Region and has reached Italy, France and Austria. These soil insect pests are potential targets for EPN. The development of insecticide resistance has opened another sector for EPN. Novel adjuvants used to improve formulation of EPN have enabled the foliar application against Western Flower Thrips and Plutella

Growth kinetics and efficacy as parameters for ranking and selecting biocontrol agents that reduce pink rot in stored potatoes

USDA-ARS?s Scientific Manuscript database

Increased production of organic agricultural products and the relative ineffectiveness of traditional control measures support development of new biocontrol technologies for use against pink rot infections in storage. The microbiota of 84 different agricultural soils was individually transferred to...

Study of Pathogens of Fungal Keratitis and the Sensitivity of Pathogenic Fungi to Therapeutic Agents with the Disk Diffusion Method.

PubMed

Wang, Lulu; Wang, Liya; Han, Lei; Yin, Weijing

2015-01-01

To identify the causative fungi of fungal keratitis, test their susceptibility to antifungal agents with the disk diffusion method and study the relationship between the organisms, the inhibition zones and the clinical outcomes. 535 patients with fungal keratitis in one eye were included in this study. Pathogenic fungi were isolated by corneal scraping, identified by fungal cultivation and subjected to drug sensitivity tests conducted with the disk diffusion method. The patients were treated initially with voriconazole, terbinafine and natamycin eye drops for one week. Further treatment continued using the most effective drug according to the drug sensitivity results. The patients were followed up every week until three months after cured. The inhibition zones of fungi cultured with voriconazole, terbinafine and natamycin were compared. The relationship between inhibition zones and organism, organism and treatment results measure, and each treatment results measure and inhibition zones were evaluated. Of 535 patients, 53.84%, 19.25% and 26.91% were infected with Aspergillus, Fusarium and other fungi, respectively. Keratitis patients infected with Aspergillus keratitis had the worst outcome. The size of the inhibition zones of Aspergillus spp., Fusarium spp. and other fungal genera differed significantly in response to voriconazole, terbinafine and natamycin. The inhibition zone associated with natamycin correlated significantly with the clinical outcome of fungal keratitis (OR = 0.925), but no other such correlations were found for the other drugs tested. Aspergillus and Fusarium were the predominant pathogenic genera causing fungal keratitis in our patients. Among the causative fungi, infections due to Aspergillus spp. were associated with the worst outcomes. The inhibition zones of fungal isolates in response to natamycin significantly correlated with the treatment outcomes of keratitis. Specifically, the smaller the natamycin inhibition zone, the lower the

House fly (Musca domestica): a review of control strategies for a challenging pest.

PubMed

Malik, Anushree; Singh, Neena; Satya, Santosh

2007-05-01

Musca domestica L. (Diptera: Muscidae), commonly called the house fly, is a major domestic, medical and veterinary pest that causes irritation, spoils food and acts as a vector for many pathogenic organisms. In this paper, the social and health problems related to housefly are introduced with the associated need to control its population. Physical and chemical methods of house fly control are briefly discussed. The main focus of this review is on the biological control methods for house fly control, that comprise botanical, fungal, bacterial and parasitoid agents. Although several biocontrol agents are still in the nascent stage, some of them (especially fungal and parasitoid agents) have shown reliable field performance and seem to be suitable candidates for commercialization. However, the majority of these laboratory and field studies have been conducted in the temperate region. It remains to be seen whether the application of biocontrol agents would be feasible in tropical environments. The integrated pest management practices, which can provide more reliable field performance, have also been discussed. A multi-dimensional approach that exerts control on all the life stages of house fly, but simultaneously preserves the fly's natural enemies could be an ecologically sustainable way of maintaining the fly populations below maximally acceptable limits.

Transcriptome analysis of Brassica juncea var. tumida Tsen responses to Plasmodiophora brassicae primed by the biocontrol strain Zhihengliuella aestuarii.

PubMed

Luo, Yuanli; Dong, Daiwen; Su, Yu; Wang, Xuyi; Peng, Yumei; Peng, Jiang; Zhou, Changyong

2018-05-01

Mustard clubroot, caused by Plasmodiophora brassicae, is a serious disease that affects Brassica juncea var. tumida Tsen, a mustard plant that is the raw material for a traditional fermented food manufactured in Chongqing, China. In our laboratory, we screened the antagonistic bacteria Zhihengliuella aestuarii against P. brassicae. To better understand the biocontrol mechanism, three transcriptome analyses of B. juncea var. tumida Tsen were conducted using Illumina HiSeq 4000, one from B. juncea only inoculated with P. brassicae (P), one inoculated with P. brassica and the biocontrol agent Z. aestuarii at the same time (P + B), and the other was the control (H), in which P. brassicae was replaced by sterile water. A total of 19.94 Gb was generated by Illumina HiSeq sequencing. The sequence data were de novo assembled, and 107,617 unigenes were obtained. In total, 5629 differentially expressed genes between biocontrol-treated (P + B) and infected (P) samples were assigned to 126 KEGG pathways. Using multiple testing corrections, 20 pathways were significantly enriched with Qvalue ≤ 0.05. The resistance-related genes, involved in the production of pathogenesis-related proteins, pathogen-associated molecular pattern-triggered immunity, and effector-triggered immunity signaling pathways, calcium influx, salicylic acid pathway, reactive oxygen intermediates, and mitogen-activated protein kinase cascades, and cell wall modification, were obtained. The various defense responses induced by the biocontrol strain combatted the P. brassicae infection. The genes and pathways involved in plant resistance were induced by a biocontrol strain. The transcriptome data explained the molecular mechanism of the potential biocontrol strain against P. brassicae. The data will also serve as an important public information platform to study B. juncea var. tumida Tsen and will be useful for breeding mustard plants resistant to P. brassicae.

Biocontrol of the toxigenic plant pathogen Fusarium culmorum by soil fauna in an agroecosystem.

PubMed

Meyer-Wolfarth, Friederike; Schrader, Stefan; Oldenburg, Elisabeth; Weinert, Joachim; Brunotte, Joachim

2017-08-01

In 2011 and 2013, a field experiment was conducted in a winter wheat field at Adenstedt (northern Germany) to investigate biocontrol and interaction effects of important members of the soil food web (Lumbricus terrestris, Annelida; Folsomia candida, Collembola and Aphelenchoides saprophilus, Nematoda) on the phytopathogenic fungus Fusarium culmorum in wheat straw. Therefore, soil fauna was introduced in mesocosms in defined numbers and combinations and exposed to either Fusarium-infected or non-infected wheat straw. L. terrestris was introduced in all faunal treatments and combined either with F. candida or A. saprophilus or both. Mesocosms filled with a Luvisol soil, a cover of different types of wheat straw and respective combinations of faunal species were established outdoors in the topsoil of a winter wheat field after harvest of the crop. After a time span of 4 and 8 weeks, the degree of wheat straw coverage of mesocosms was quantified to assess its attractiveness for the soil fauna. The content of Fusarium biomass in residual wheat straw and soil was determined using a double-antibody sandwich (DAS)-ELISA method. In both experimental years, the infected wheat straw was incorporated more efficiently into the soil than the non-infected control straw due to the presence of L. terrestris in all faunal treatments than the non-infected control straw. In addition, Fusarium biomass was reduced significantly in all treatments after 4 weeks (2011: 95-99%; 2013:15-54%), whereupon the decline of fungal biomass was higher in faunal treatments than in non-faunal treatments and differed significantly from them. In 2011, Fusarium biomass of the faunal treatments was below the quantification limit after 8 weeks. In 2013, a decline of Fusarium biomass was observed, but the highest content of Fusarium biomass was still found in the non-faunal treatments after 8 weeks. In the soil of all treatments, Fusarium biomass was below the quantification limit. The earthworm species

[Antagonistic interactions between saprotrophic fungi and geohelminths. 2. Saprotrophic fungi in biocontrol of parasitic geohelminths of humans and animals].

PubMed

Jaborowska-Jarmoluk, Magdalena; Mazurkiewicz-Zapałowicz, Kinga; Kołodziejczyk, Lidia

2009-01-01

The soils ecosystem plays an important role in the epidemiology of geohelminth diseases of humans and animals. Soil contamination with ova of the parasitic geohelminths represents a global public health-hazard issue. Biological agents have been thought to control the infective forms of parasites present in the soil. Biocontrol of geohelminths represents an alternative to pesticides (i.e., nematicides), which are not efficient in killing infective nematode forms and, additionally, result in the environment pollution and long-term disturbances in the soil ecosystem homeostasis. The degree of the inhibiting effect of soil saprotrophic fungi on geohelminth embryonic development varies and depends on the species. A number of fungi cause various morphological disorders in the embryos of developing parasitic nematodes, but also have an ovicidal effect. Although the nature of the antagonism between fungi and other living organisms has not been fully explained, it is certain that mycotoxins and fungal enzymes constitute its important components. Considering the studies carried out so far, the antagonistic effect of mold fungi against the infective stages of geohelminths can be fully recommended as a real control factor, especially as these saprotrophs represent a natural factor within the soil environment, that is of particular biochemical activity.

Exploring the evolutionary ecology of fungal endophytes in agricultural systems: using functional traits to reveal mechanisms in community processes

PubMed Central

Saunders, Megan; Glenn, Anthony E; Kohn, Linda M

2010-01-01

All plants, including crop species, harbor a community of fungal endophyte species, yet we know little about the biotic factors that are important in endophyte community assembly. We suggest that the most direct route to understanding the mechanisms underlying community assembly is through the study of functional trait variation in the host and its fungal consortium. We review studies on crop endophytes that investigate plant and fungal traits likely to be important in endophyte community processes. We focus on approaches that could speed detection of general trends in endophyte community assembly: (i) use of the ‘assembly rules’ concept to identify specific mechanisms that influence endophyte community dynamics, (ii) measurement of functional trait variation in plants and fungi to better understand endophyte community processes and plant–fungal interactions, and (iii) investigation of microbe–microbe interactions, and fungal traits that mediate them. This approach is well suited for research in agricultural systems, where pair-wise host–fungus interactions and mechanisms of fungal–fungal competition have frequently been described. Areas for consideration include the possibility that human manipulation of crop phenotype and deployment of fungal biocontrol species can significantly influence endophyte community assembly. Evaluation of endophyte assembly rules may help to fine-tune crop management strategies. PMID:25567944

Involvement of phenazines and biosurfactants in biocontrol of Pythium myriotylum root rot on cocoyam by Pseudomonas sp. CMR12A

USDA-ARS?s Scientific Manuscript database

Pseudomonas sp. CMR12a was isolated from the rhizosphere of the tropical tuber crop cocoyam and produces both phenazines and cyclic lipopeptide (CLP) biosurfactants. CMR12a was shown to be an efficient biocontrol agent of P. myriotylum on cocoyam. To assess the importance of phenazine and biosurfact...

An alternative anionic bio-sustainable anti-fungal agent: Investigation of its mode of action on the fungal cell membrane.

PubMed

Stenbæk, Jonas; Löf, David; Falkman, Peter; Jensen, Bo; Cárdenas, Marité

2017-07-01

The potential of a lactylate (the sodium caproyl lactylate or C10 lactylate), a typical food grade emulsifier, as an anionic environmental friendly anti-fungal additive was tested in growth medium and formulated in a protective coating for exterior wood. Different laboratory growth tests on the blue stain fungus Aureobasidium pullulans were performed and its interactions on a model fungal cell membrane were studied. Promising short term anti-fungal effects in growth tests were observed, although significant but less dramatic effects took place in coating test on wood panels. Scanning electron microscope analysis shows clear differences in the amount of fungal slime on the mycelium of Aureobasidium pullulans when the fungus was exposed of C10 lactylate. This could indicate an effect on the pullulan and melanin production by the fungus. Moreover, the interaction studies on model fungal cell membranes show that C10 lactylate affects the phospholipid bilayer in a similar manner to other negative charged detergents. Copyright © 2017 Elsevier Inc. All rights reserved.

Potential of osmoadaptation for improving Pantoea agglomerans E325 as biocontrol agent for fire blight of apple and pear

USDA-ARS?s Scientific Manuscript database

Pantoea agglomerans biocontrol strain E325 is the active ingredient in a commercial product for fire blight, a destructive disease of apple and pear initiated by Erwinia amylovora in flowers. Osmoadaptation, involving the combination of saline osmotic stress and osmolyte amendment to growth media, w...

Fungal Infections and New Biologic Therapies.

PubMed

Vallabhaneni, Snigdha; Chiller, Tom M

2016-05-01

The development of biologic therapies targeting proinflammatory mediators has led to significant advances in the treatment of immune-mediated inflammatory diseases (IMIDs). Blocking undesired inflammatory effects also has the potential to disrupt the body's immune response and increase the risk for infections, including fungal infections. This review summarizes the published data on the frequency and risk for fungal infections among patients treated with biologics, with a focus on the newer therapies approved for use with IMIDs in the last 10 years. The use of biologics is associated with a small but important risk of fungal infections. Pneumocystis jirovecii pneumonia, histoplasmosis, and candidiasis are some of the most common fungal infections associated with biologics. Providers should be vigilant for fungal infection among patients taking biologics, be aware that biologic agents may alter the typical presentation of fungal infections, and take timely steps to diagnose and treat fungal infection to reduce resultant morbidity and mortality.

Production and characterization of rhamnolipids produced by Serratia rubidaea SNAU02 under solid-state fermentation and its application as biocontrol agent.

PubMed

Nalini, S; Parthasarathi, R

2014-12-01

The present study aimed at exploring mahua (Madhuca indica) oil cake as a novel substrate for the production of biosurfactant by Serratia rubidaea SNAU02 under solid-state fermentation (SSF). Response surface methodology showed followings as the optimal conditions for the production of biosurfactant: mahua oil cake 7.48 g, 2.5 ml inoculum size (1×10(8) cells/ml), and pH 7.22 and 31 °C temperature. The characterization of the biosurfactant by TLC, FT-IR and GC-MS revealed the presence of rhamnolipid. The presence of rhamnosyl transferase gene responsible for biosynthesis of rhamnolipid was identified. The strain SNAU02 exhibited antifungal activity and demonstrated no toxicity against the seeds of Brassica oleracea and Artemia salina employed as a bio-indicator. The present findings indicated the potential of mahua oil cake as suitable substrate for the production of rhamnolipids in SSF by S. rubidaea SNAU02 and application potential of the biosurfactant produced as biocontrol agent against plant pathogens. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fungal endophytes of turmeric (Curcuma longa L.) and their biocontrol potential against pathogens Pythium aphanidermatum and Rhizoctonia solani.

PubMed

Vinayarani, G; Prakash, H S

2018-03-14

Endophytic fungi have been isolated from the healthy turmeric (Curcuma longa L.) rhizomes from South India. Thirty-one endophytes were identified based on morphological and ITS-rDNA sequence analysis. The isolated endophytes were screened for antagonistic activity against Pythium aphanidermatum (Edson) Fitzp., and Rhizoctonia solani Kuhn., causing rhizome rot and leaf blight diseases in turmeric respectively. Results revealed that only six endophytes showed > 70% suppression of test pathogens in antagonistic dual culture assays. The endophyte T. harzianum TharDOB-31 showed significant in vitro mycelial growth inhibition of P. aphanidermatum (76.0%) and R. solani (76.9%) when tested by dual culture method. The SEM studies of interaction zone showed morphological abnormalities like parasitism, shriveling, breakage and lysis of hyphae of the pathogens by endophyte TharDOB-31. Selected endophytic isolates recorded multiple plant growth promoting traits in in vitro studies. The rhizome bacterization followed by soil application of endophyte TharDOB-31 showed lowest Percent Disease Incidence of rhizome rot and leaf blight, 13.8 and 11.6% respectively. The treatment of TharDOB-31 exhibited significant increase in plant height (85 cm) and fresh rhizome yield/plant (425 g) in comparison with untreated control under greenhouse condition. The confocal microscopy validates the colonization of the TharDOB-31 in turmeric rhizomes. The secondary metabolites in ethyl acetate extract of TharDOB-31 were found to contain higher number of antifungal compounds by high resolution liquid chromatograph mass spectrometer analysis. Thereby, endophyte T. harzianum isolate can be exploited as a potential biocontrol agent for suppressing rhizome rot and leaf blight diseases in turmeric.

Relationship between mycoparasites lifestyles and biocontrol behaviors against Fusarium spp. and mycotoxins production.

PubMed

Kim, Seon Hwa; Vujanovic, Vladimir

2016-06-01

Global food security research is seeking eco-friendly solutions to control mycotoxins in grain infected by fungi (molds). In particular, mycotoxigenic Fusarium spp. outbreak is a chronic threat for cereal grain production, human, and animal health. In this review paper, we discuss up-to-date biological control strategies in applying mycoparasites as biological control agents (BCA) to prevent plant diseases in crops and mycotoxins in grain, food, and feed. The aim is to increase food safety and to minimize economic losses due to the reduced grain yield and quality. However, recent papers indicate that the study of the BCA specialists with biotrophic lifestyle lags behind our understanding of the BCA generalists with necrotrophic lifestyle. We examine critical behavioral traits of the two BCA groups of mycoparasites. The goal is to highlight their major characteristics in the context of future research towards an efficient biocontrol strategy against mycotoxin-producing Fusarium species. The emphasis is put on biocontrol of Fusarium graminearum, F. avenaceum, and F. culmorum causing Fusarium head blight (FHB) in cereals and their mycotoxins.

Grouper as a natural biocontrol of invasive lionfish.

PubMed

Mumby, Peter J; Harborne, Alastair R; Brumbaugh, Daniel R

2011-01-01

Lionfish (Pterois volitans/miles) have invaded the majority of the Caribbean region within five years. As voracious predators of native fishes with a broad habitat distribution, lionfish are poised to cause an unprecedented disruption to coral reef diversity and function. Controls of lionfish densities within its native range are poorly understood, but they have been recorded in the stomachs of large-bodied Caribbean groupers. Whether grouper predation of lionfish is sufficient to act as a biocontrol of the invasive species is unknown, but pest biocontrol by predatory fishes has been reported in other ecosystems. Groupers were surveyed along a chain of Bahamian reefs, including one of the region's most successful marine reserves which supports the top one percentile of Caribbean grouper biomass. Lionfish biomass exhibited a 7-fold and non-linear reduction in relation to the biomass of grouper. While Caribbean grouper appear to be a biocontrol of invasive lionfish, the overexploitation of their populations by fishers, means that their median biomass on Caribbean reefs is an order of magnitude less than in our study. Thus, chronic overfishing will probably prevent natural biocontrol of lionfishes in the Caribbean.

Grouper as a Natural Biocontrol of Invasive Lionfish

PubMed Central

Mumby, Peter J.; Harborne, Alastair R.; Brumbaugh, Daniel R.

2011-01-01

Lionfish (Pterois volitans/miles) have invaded the majority of the Caribbean region within five years. As voracious predators of native fishes with a broad habitat distribution, lionfish are poised to cause an unprecedented disruption to coral reef diversity and function. Controls of lionfish densities within its native range are poorly understood, but they have been recorded in the stomachs of large-bodied Caribbean groupers. Whether grouper predation of lionfish is sufficient to act as a biocontrol of the invasive species is unknown, but pest biocontrol by predatory fishes has been reported in other ecosystems. Groupers were surveyed along a chain of Bahamian reefs, including one of the region's most successful marine reserves which supports the top one percentile of Caribbean grouper biomass. Lionfish biomass exhibited a 7-fold and non-linear reduction in relation to the biomass of grouper. While Caribbean grouper appear to be a biocontrol of invasive lionfish, the overexploitation of their populations by fishers, means that their median biomass on Caribbean reefs is an order of magnitude less than in our study. Thus, chronic overfishing will probably prevent natural biocontrol of lionfishes in the Caribbean. PMID:21731769

Isolation of fungi from dead arthropods and identification of a new mosquito natural pathogen.

PubMed

Jaber, Sana; Mercier, Alex; Knio, Khouzama; Brun, Sylvain; Kambris, Zakaria

2016-09-05

Insects are well known vectors of human and animal pathogens and millions of people are killed by mosquito-borne diseases every year. The use of insecticides to target insect vectors has been hampered by the issues of toxicity to the environment and by the selection of resistant insects. Therefore, biocontrol strategies based on naturally occurring microbial pathogens emerged as a promising control alternative. The entomopathogenic fungus Beauveria bassiana is well characterized and have been approved by the United States Environmental Protection Agency as a pest biological control method. However, thousands of other fungi are unexploited and it is important to identify and use different fungi for biocontrol with possibly some vector specific strains. The aim of this study was to identify new fungal entomopathogens that may be used as potential mosquito biocontrol agents. Cadavers of arthropods were collected from pesticide free areas and the fungi associated isolated, cultured and identified. Then the ability of each isolate to kill laboratory insects was assayed and compared to that of B. bassiana. In total we have isolated and identified 42 fungal strains from 17 different arthropod cadavers. Twenty four fungal isolates were cultivated in the laboratory and were able to induce sporulation. When fungal spores were microinjected into Drosophila melanogaster, eight isolates proved to be highly pathogenic while the remaining strains showed moderate or no pathogenicity. Then a selection of isolates was tested against Aedes mosquitoes in a model mimicking natural infections. Only one fungus (Aspergillus nomius) was as pathogenic as B. bassiana and able to kill 100 % of the mosquitoes. The obtained results are encouraging and demonstrate the feasibility of this simple approach for the identification of new potential mosquito killers. Indeed, it is essential to anticipate and prepare biocontrol methods to fight the expansion of mosquitoes' habitat predicted in certain

Wheat seeds harbour bacterial endophytes with potential as plant growth promoters and biocontrol agents of Fusarium graminearum.

PubMed

Díaz Herrera, Silvana; Grossi, Cecilia; Zawoznik, Myriam; Groppa, María Daniela

2016-01-01

The role of endophytic communities of seeds is still poorly characterised. The purpose of this work was to survey the presence of bacterial endophytes in the seeds of a commercial wheat cultivar widely sown in Argentina and to look for plant growth promotion features and biocontrol abilities against Fusarium graminearum among them. Six isolates were obtained from wheat seeds following a culture-dependent protocol. Four isolates were assignated to Paenibacillus genus according to their 16S rRNA sequencing. The only gammaproteobacteria isolated, presumably an Enterobactereaceae of Pantoea genus, was particularly active as IAA and siderophore producer, and also solubilised phosphate and was the only one that grew on N-free medium. Several of these isolates demonstrated ability to restrain F. graminearum growth on dual culture and in a bioassay using barley and wheat kernels. An outstanding ability to form biofilm on an inert surface was corroborated for those Paenibacillus which displayed greater biocontrol of F. graminearum, and the inoculation with one of these isolates in combination with the Pantoea isolate resulted in greater chlorophyll content in barley seedlings. Our results show a significant ecological potential of some components of the wheat seed endophytic community. Copyright © 2016 Elsevier GmbH. All rights reserved.

Weed-biocontrol insects reduce native-plant recruitment through second-order apparent competition.

PubMed

Pearson, Dean E; Callaway, Ragan M

2008-09-01

Small-mammal seed predation is an important force structuring native-plant communities that may also influence exotic-plant invasions. In the intermountain West, deer mice (Peromyscus maniculatus) are prominent predators of native-plant seeds, but they avoid consuming seeds of certain widespread invasives like spotted knapweed (Centaurea maculosa). These mice also consume the biological-control insects Urophora spp. introduced to control C. maculosa, and this food resource substantially increases deer mouse populations. Thus, mice may play an important role in the invasion and management of C. maculosa through food-web interactions. We examined deer mouse seed predation and its effects on seedling emergence and establishment of a dominant native grass, Pseudoroegneria spicata, and forb, Balsamorhiza sagittata, in C. maculosa-invaded grasslands that were treated with herbicide to suppress C. maculosa or left untreated as controls. Deer mice readily took seeds of both native plants but removed 2-20 times more of the larger B. sagittata seeds than the smaller P. spicata seeds. Seed predation reduced emergence and establishment of both species but had greater impacts on B. sagittata. The intensity of seed predation corresponded with annual and seasonal changes in deer mouse abundance, suggesting that abundance largely determined mouse impacts on native-plant seeds. Accordingly, herbicide treatments that reduced mouse abundance by suppressing C. maculosa and its associated biocontrol food subsidies to mice also reduced seed predation and decreased the impact of deer mice on B. sagittata establishment. These results provide evidence that Urophora biocontrol agents may exacerbate the negative effects of C. maculosa on native plants through a form of second-order apparent competition-a biocontrol indirect effect that has not been previously documented. Herbicide suppressed C. maculosa and Urophora, reducing mouse populations and moderating seed predation on native plants

Species-Specific Detection of Mycosphaerella polygoni-cuspidati as a Biological Control Agent for Fallopia japonica by PCR Assay.

PubMed

Kurose, Daisuke; Furuya, Naruto; Saeki, Tetsuya; Tsuchiya, Kenichi; Tsushima, Seiya; Seier, Marion K

2016-10-01

The ascomycete fungus Mycosphaerella polygoni-cuspidati has been undergoing evaluation as a potential classical biological control agent for the invasive weed Fallopia japonica (Japanese knotweed), which has become troublesome in Europe and North America. In advance of the potential release of a biocontrol agent into a new environment, it is crucial to develop an effective monitoring system to enable the evaluation of agent establishment and dispersal within the target host population, as well as any potential attacks on non-target species. Therefore, a primer pair was designed for direct, rapid, and specific detection of the Japanese knotweed pathogen M. polygoni-cuspidati based on the sequences of the internal transcribed spacer regions including the 5.8S rDNA. A PCR product of approximately 298 bp was obtained only when the DNA extracted from mycelial fragments of M. polygoni-cuspidati was used. The lower limit of detection of the PCR method was 100 fg of genomic DNA. Using the specific primer pair, M. polygoni-cuspidati could be detected from both naturally and artificially infected Japanese knotweed plants. No amplification was observed for other Mycosphaerella spp. or fungal endophytes isolated from F. japonica. The designed primer pair is thus effective for the specific detection of M. polygoni-cuspidati in planta.

Interaction of media on production and biocontrol efficacy of Pseudomonas fluorescens and Bacillus subtilis against grey mould of apple.

PubMed

Peighamy-Ashnaei, S; Sharifi-Tehrani, A; Ahmadzadeh, M; Behboudi, K

2008-01-01

The medium has a profound effect on biocontrol agents, including ability to grow and effectiveness in disease control. In this study, growth and antagonistic efficacy of strains P-5 and P-35 (P. fluorescens), B-3 and B-16 (B. subtilis) were evaluated in combinations of two carbon (sucrose and molasses) and two nitrogen (urea and yeast extract) sources to optimize control of Botrytis cinerea on apple. All of the strains were grown in different liquid media (pH = 6.9) including: sucrose + yeast extract, molasses of sugar beet + yeast extract in 2:1 and 1:1 w/w ratios, molasses of sugar beet + urea, molasses, malt extract and nutrient broth. Apples (Golden Delicious) were inoculated by a 25-microl suspension of 10(6) spores of B. cinerea per ml, wounding each fruit (in two sites separately). Then a 25-microl suspension of each strain, containing 2 x 10(8) cfu ml(-1) grown in each of the above culture media, was applied to each wound. Results indicated that Molasses + Yeast extract (1:1 w/w) medium supported rapid growth in all of the strains. The final growth of B. subtilis B-16 in Molasses + Yeast extract (1:1 w/w) medium was 5 x 10(9) cfu ml(-1). After ten days, all of the strains significantly inhibited pathogenicity of B. cinerea on apples. The biocontrol efficacy of B. subtilis B-3 in Molasses + Yeast extract (1:1 w/w) medium reduced the severity of grey mould from 100% (inoculated control) to less than 26.9%. After 20 days, Strain B-3 showed a considerable biocontrol efficacy in Molasses medium and reduced the severity of grey mould from 100% (inoculated control) to less than 38.2%. The results obtained in this study could be used to provide a reliable basis for the increase of population of biocontrol agents in fermentation process.

Tissue age and plant genotype affect the microbiota of apple and pear bark.

PubMed

Arrigoni, Elena; Antonielli, Livio; Pindo, Massimo; Pertot, Ilaria; Perazzolli, Michele

2018-06-01

Plant tissues host complex fungal and bacterial communities, and their composition is determined by host traits such as tissue age, plant genotype and environmental conditions. Despite the importance of bark as a possible reservoir of plant pathogenic microorganisms, little is known about the associated microbial communities. In this work, we evaluated the composition of fungal and bacterial communities in the pear (Abate and Williams cultivars) and apple (Golden Delicious and Gala cultivars) bark of three/four-year-old shoots (old bark) or one-year-old shoots (young bark), using a meta-barcoding approach. The results showed that both fungal and bacterial communities are dominated by genera with ubiquitous attitudes, such as Aureobasidium, Cryptococcus, Deinococcus and Hymenobacter, indicating intense microbial migration to surrounding environments. The shoot age, plant species and plant cultivar influenced the composition of bark fungal and bacterial communities. In particular, bark communities included potential biocontrol agents that could maintain an equilibrium with potential plant pathogens. The abundance of fungal (e.g. Alternaria, Penicillium, Rosellinia, Stemphylium and Taphrina) and bacterial (e.g. Curtobacterium and Pseudomonas) plant pathogens was affected by bark age and host genotype, as well as those of fungal genera (e.g. Arthrinium, Aureobasidium, Rhodotorula, Sporobolomyces) and bacterial genera (e.g. Bacillus, Brevibacillus, Methylobacterium, Sphingomonas and Stenotrophomonas) with possible biocontrol and plant growth promotion properties. Copyright © 2018 Elsevier GmbH. All rights reserved.

Endophytic fungi associated with Monarda citriodora, an aromatic and medicinal plant and their biocontrol potential.

PubMed

Katoch, Meenu; Pull, Shipra

2017-12-01

The Food and Agriculture Organization has estimated that every year considerable losses of the food crops occur due to plant diseases. Although fungicides are extensively used for management of plant diseases, they are expensive and hazardous to the environment and human health. Alternatively, biological control is the safe way to overcome the effects of plant diseases and to sustain agriculture. Since Monarda citriodora Cerv. ex Lag. (Lamiaceae/Labiatae) is known for its antifungal properties, it was chosen for the study. The isolation of endophytic fungi from M. citriodora and assessing their biocontrol potential. The isolated endophytes were characterized using ITS-5.8 S rDNA sequencing. Their biocontrol potential was assessed using different antagonistic assays against major plant pathogens. Twenty-eight endophytes representing 11 genera were isolated, of which, around 82% endophytes showed biocontrol potential against plant pathogens. MC-2 L (Fusarium oxysporum), MC-14 F (F. oxysporum), MC-22 F (F. oxysporum) and MC-25 F (F. redolens) displayed significant antagonistic activity against all the tested pathogens. Interestingly, MC-10 L (Muscodor yucatanensis) completely inhibited the growth of Sclerotinia sp., Colletotrichum capsici, Aspergillus flavus and A. fumigatus in dual culture assay, whereas MC-8 L (A. oryzae) and MC-9 L (Penicillium commune) completely inhibited the growth of the Sclerotinia sp. in fumigation assay. Endophytes MC-2 L, MC-14 F, MC-22 F and MC-25 F could effectively be used to control broad range of phytopathogens, while MC-10 L, MC-8 L and MC-9 L could be used to control specific pathogens. Secondly, endophytes showing varying degrees of antagonism in different assays represented the chemo-diversity not only as promising biocontrol agents but also as a resource of defensive and bioactive metabolites.

Mechanisms of Bacterial (Serratia marcescens) Attachment to, Migration along, and Killing of Fungal Hyphae

PubMed Central

Hover, Tal; Maya, Tal; Ron, Sapir; Sandovsky, Hani; Shadkchan, Yana; Kijner, Nitzan; Mitiagin, Yulia; Fichtman, Boris; Harel, Amnon; Shanks, Robert M. Q.; Bruna, Roberto E.; García-Véscovi, Eleonora

2016-01-01

We have found a remarkable capacity for the ubiquitous Gram-negative rod bacterium Serratia marcescens to migrate along and kill the mycelia of zygomycete molds. This migration was restricted to zygomycete molds and several basidiomycete species. No migration was seen on any molds of the phylum Ascomycota. S. marcescens migration did not require fungal viability or surrounding growth medium, as bacteria migrated along aerial hyphae as well. S. marcescens did not exhibit growth tropism toward zygomycete mycelium. Bacterial migration along hyphae proceeded only when the hyphae grew into the bacterial colony. S. marcescens cells initially migrated along the hyphae, forming attached microcolonies that grew and coalesced to generate a biofilm that covered and killed the mycelium. Flagellum-defective strains of S. marcescens were able to migrate along zygomycete hyphae, although they were significantly slower than the wild-type strain and were delayed in fungal killing. Bacterial attachment to the mycelium does not necessitate type 1 fimbrial adhesion, since mutants defective in this adhesin migrated equally well as or faster than the wild-type strain. Killing does not depend on the secretion of S. marcescens chitinases, as mutants in which all three chitinase genes were deleted retained wild-type killing abilities. A better understanding of the mechanisms by which S. marcescens binds to, spreads on, and kills fungal hyphae might serve as an excellent model system for such interactions in general; fungal killing could be employed in agricultural fungal biocontrol. PMID:26896140

Genome Sequencing and Comparative Analysis of the Biocontrol Agent Trichoderma harzianum sensu stricto TR274

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steindorff, Andrei S.; Noronha, Elilane F.; Ulhoa, Cirano J.

2015-03-17

Biological control is a complex process which requires many mechanisms and a high diversity of biochemical pathways. The species of Trichoderma harzianum are well known for their biocontrol activity against many plant pathogens. To gain new insights into the biocontrol mechanism used by T. harzianum, we sequenced the isolate TR274 genome using Illumina. The assembly was performed using AllPaths-LG with a maximum coverage of 100x. The assembly resulted in 2282 contigs with a N50 of 37033bp. The genome size generated was 40.8 Mb and the GC content was 47.7%, similar to other Trichoderma genomes. Using the JGI Annotation Pipeline wemore » predicted 13,932 genes with a high transcriptome support. CEGMA tests suggested 100% genome completeness and 97.9% of RNA-SEQ reads were mapped to the genome. The phylogenetic comparison using orthologous proteins with all Trichoderma genomes sequenced at JGI, corroborates the Trichoderma (T. asperellum and T. atroviride), Longibrachiatum (T. reesei and T. longibrachiatum) and Pachibasium (T. harzianum and T. virens) section division described previously. The comparison between two Trichoderma harzianum species suggests a high genome similarity but some strain-specific expansions. Analyses of the secondary metabolites, CAZymes, transporters, proteases, transcription factors were performed. The Pachybasium section expanded virtually all categories analyzed compared with the other sections, specially Longibrachiatum section, that shows a clear contraction. These results suggests that these proteins families have an important role in their respective phenotypes. Future analysis will improve the understanding of this complex genus and give some insights about its lifestyle and the interactions with the environment.« less

Immune Recognition of Fungal Polysaccharides.

PubMed

Snarr, Brendan D; Qureshi, Salman T; Sheppard, Donald C

2017-08-28

The incidence of fungal infections has dramatically increased in recent years, in large part due to increased use of immunosuppressive medications, as well as aggressive medical and surgical interventions that compromise natural skin and mucosal barriers. There are relatively few currently licensed antifungal drugs, and rising resistance to these agents has led to interest in the development of novel preventative and therapeutic strategies targeting these devastating infections. One approach to combat fungal infections is to augment the host immune response towards these organisms. The polysaccharide-rich cell wall is the initial point of contact between fungi and the host immune system, and therefore, represents an important target for immunotherapeutic approaches. This review highlights the advances made in our understanding of the mechanisms by which the immune system recognizes and interacts with exopolysaccharides produced by four of the most common fungal pathogens: Aspergillus fumigatus , Candida albicans , Cryptococcus neoformans , and Histoplasma capsulatum . Work to date suggests that inner cell wall polysaccharides that play an important structural role are the most conserved across diverse members of the fungal kingdom, and elicit the strongest innate immune responses. The immune system senses these carbohydrates through receptors, such as lectins and complement proteins. In contrast, a greater diversity of polysaccharides is found within the outer cell walls of pathogenic fungi. These glycans play an important role in immune evasion, and can even induce anti-inflammatory host responses. Further study of the complex interactions between the host immune system and the fungal polysaccharides will be necessary to develop more effective therapeutic strategies, as well as to explore the use of immunosuppressive polysaccharides as therapeutic agents to modulate inflammation.

Evaluation of yeasts from Tibetan fermented products as agents for biocontrol of blue mold of Nashi pear fruits*

PubMed Central

Hu, Hao; Xu, Yang; Lu, Huang-ping; Xiao, Rui; Zheng, Xiao-dong; Yu, Ting

2015-01-01

A total of 20 strains of yeast isolated from Tibetan fermented products were screened for antagonism against blue mold of pear caused by Penicillium expansum. Six isolates that inhibited incidence of postharvest decay by 35% or more were selected for further screening. Among them, the most effective was Rhodotorula mucilaginosa. The results showed that washed cell suspensions of R. mucilaginosa yielded better antagonistic efficacy than unwashed cell-culture mixtures, cell-free culture filtrates, and autoclaved cell cultures. Biocontrol activity improved with increasing concentrations of incubated cells. The best concentration was 1×108 cells/ml, at which the incidence of decay was only 16.7% after 6 d of incubation. The germination of conidia of P. expansum in vitro was significantly inhibited by both washed cell-suspensions and unwashed cell-culture mixtures. Rapid colonization by yeast at different concentrations showed a relationship between yeast-cell concentration and biocontrol activity. Although the titratable acidity of pear fruits increased after treatment, R. mucilaginosa did not affect the total soluble solids or ascorbic acid content. This is the first study to report that the yeast R. mucilaginosa from Tibet Autonomous Region of China may have potential as an antagonist to control the postharvest decay of pear fruits. PMID:25845361

Evaluation of yeasts from Tibetan fermented products as agents for biocontrol of blue mold of Nashi pear fruits.

PubMed

Hu, Hao; Xu, Yang; Lu, Huang-ping; Xiao, Rui; Zheng, Xiao-dong; Yu, Ting

2015-04-01

A total of 20 strains of yeast isolated from Tibetan fermented products were screened for antagonism against blue mold of pear caused by Penicillium expansum. Six isolates that inhibited incidence of postharvest decay by 35% or more were selected for further screening. Among them, the most effective was Rhodotorula mucilaginosa. The results showed that washed cell suspensions of R. mucilaginosa yielded better antagonistic efficacy than unwashed cell-culture mixtures, cell-free culture filtrates, and autoclaved cell cultures. Biocontrol activity improved with increasing concentrations of incubated cells. The best concentration was 1×10(8) cells/ml, at which the incidence of decay was only 16.7% after 6 d of incubation. The germination of conidia of P. expansum in vitro was significantly inhibited by both washed cell-suspensions and unwashed cell-culture mixtures. Rapid colonization by yeast at different concentrations showed a relationship between yeast-cell concentration and biocontrol activity. Although the titratable acidity of pear fruits increased after treatment, R. mucilaginosa did not affect the total soluble solids or ascorbic acid content. This is the first study to report that the yeast R. mucilaginosa from Tibet Autonomous Region of China may have potential as an antagonist to control the postharvest decay of pear fruits.

Augmenting the efficacy of fungal and mycotoxin control via chemosensitization

USDA-ARS?s Scientific Manuscript database

Antimycotic chemosensitization could serve as an effective method for control of fungal pathogens. In a chemo-biological platform to enhance antimycotic susceptibility of fungi or to overcome fungal tolerance to conventional antimycotic agents, the model yeast S. cerevisiae could be a functional too...

[Fungal population structure and its biological effect in rhizosphere soil of continuously cropped potato].

PubMed

Meng, Pin-Pin; Liu, Xing; Qiu, Hui-Zhen; Zhang, Wen-Ming; Zhang, Chun-Hong; Wang, Di; Zhang, Jun-Lian; Shen, Qi-Rong

2012-11-01

Continuous cropping obstacle is one of the main restriction factors in potato industry. In order to explore the mechanisms of potato's continuous cropping obstacle and to reduce the impact on potato's tuber yield, a field experiment combined with PCR-DGGE molecular fingerprinting was conducted to investigate the fungal population structure and its biological effect in rhizosphere soil of continuously cropped potato. With the increasing year of potato' s continuous cropping, the numbers of visible bands in rhizosphere fungal DGGE profiles increased obviously. As compared with that of CK (rotation cropping), the operational taxonomic unit (OTU) in treatments of one to five years continuous cropping was increased by 38.5%, 38.5%, 30.8%, 46.2%, and 76.9% respectively, indicating that potato's continuous cropping caused an obvious increase in the individual numbers of dominant fungal populations in rhizosphere soil. Also with the increasing year of potato's continuous cropping, the similarity of the fungal population structure among the treatments had a gradual decrease. The sequencing of the fungal DGGE bands showed that with the increasing year of continuous cropping, the numbers of the potato's rhizosphere soil-borne pathogens Fusarium oxysporum and F. solani increased obviously, while the number of Chaetomium globosum, as a biocontrol species, had a marked decrease in the fifth year of continuous cropping. It was suggested that potato' s continuous cropping caused the pathogen fungal populations become the dominant microbial populations in rhizosphere soil, and the rhizosphere micro-ecological environment deteriorated, which in turn affected the root system, making the root vigor and its absorption area reduced, and ultimately, the tuber yield decreased markedly.

Exogenous trehalose enhanced the biocontrol efficacy of Hanseniaspora uvarum against grape berry rots caused by Aspergillus tubingensis and Penicillium commune.

PubMed

Apaliya, Maurice Tibiru; Zhang, Hongyin; Zheng, Xiangfeng; Yang, Qiya; Mahunu, Gustav K; Kwaw, Emmanuel

2018-03-13

Primarily, chemical pesticides are commonly used to control preharvest and postharvest diseases of fruits and vegetables. However, there is strong public concern regarding the human and environmental health problems that might emanate from the residues of these chemical pesticides. As a result, biocontrol is often preferred due to its safety for humans and animals. The microbial antagonists employed often encounter variable climatic conditions, which affect their efficacy. In this study, the biocontrol efficacy of Hanseniaspora uvarum enhanced with trehalose against Aspergillus tubingensis and Penicillium commune in grapes was investigated. H. uvarum Y3 pretreated with 2.0% w/v trehalose in nutrient yeast dextrose broth (NYDB) before used significantly inhibited the incidence of decay and lesion diameter without affecting the sensory qualities of the grapes stored at either 4 °C or 20 °C. There was also a significant (P < 0.05) increase in the population dynamics of H. uvarum that was pretreated with 2% trehalose compared to that of H. uvarum alone. The in vitro assay on spore germination revealed an inhibition of A. tubingensis and P. commune by 85.6% and 87.0% respectively. Scanning electron microscopy results showed that both untreated H. uvarum and H. uvarum pre-treated with the 2% w/v trehalose before use inhibited fungal mycelium and development of grape rot. The biocontrol efficacy of H. uvarum was enhanced against grape rot caused by A. tubingensis and P. commune. The findings indicate the potential applicability of trehalose in the enhancement of H. uvarum. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Studies of plant colonisation by closely related Bacillus amyloliquefaciens biocontrol agents using strain specific quantitative PCR assays.

PubMed

Johansson, Anna H; Bejai, Sarosh; Niazi, Adnan; Manzoor, Shahid; Bongcam-Rudloff, Erik; Meijer, Johan

2014-12-01

Certain strains of Bacillus amyloliquefaciens can colonize plants and improve growth and stress management. In order to study these effects, bacterial growth dynamics on plants and in the rhizosphere are of interest calling for specific analytical tools. For that purpose, quantitative real-time PCR (qPCR) assays were developed in order to differentiate among three closely related B. amyloliquefaciens subsp. plantarum strains (UCMB5033, UCMB5036, UCMB5113) and to determine their levels with high accuracy. Oligonucleotide primers were designed for strain unique gene sequences and used for SYBR green based qPCR analysis. Standard curves covered a wide linear range (10(6)) of DNA amounts with the lowest detection level at 50 fg. Post-reaction melting curve analysis showed only a single product. Accurate threshold cycles were obtained, even in the presence of high excess of related Bacillus strains and total bacterial DNA from soil. Analysis of Bacillus colonisation after seed treatment of two oilseed rape cultivars (Oase and Ritz) grown on agar support showed a time dependent effect but that the bacteria mostly were found on root tissues and little on green tissues. The colonisation on plants grown in soil varied among the Bacillus strains where Oase seemed to house more bacteria than Ritz. Applied as a mixture, all three Bacillus strains co-existed on the roots of plants grown in soil. The qPCR assay in combination with other techniques will be a powerful tool to study plant interactions of these B. amyloliquefaciens biocontrol agents to further understand the requirements for successful interactions and improvement of plant properties.

Environmental fate and behaviour of the biocontrol agent Bacillus amyloliquefaciens CPA-8 after preharvest application to stone fruit.

PubMed

Vilanova, Laura; Teixidó, Neus; Usall, Josep; Balsells-Llauradó, Marta; Gotor-Vila, Amparo; Torres, Rosario

2018-02-01

Bacillus amyloliquefaciens strain CPA-8 has been described as an effective biocontrol agent to control brown rot in stone fruit for both preharvest and postharvest applications. However, no information about the environmental fate and behaviour of this strain under field conditions is available. The dispersion of the CPA-8 application was evaluated using water-sensitive papers, and complete coverage was observed on the leaves of treated trees, while <1% of non-treated tree leaves had CPA-8. CPA-8 persisted on the fruit of treated trees during preharvest and postharvest conditions, while a significant decrease on leaves and weeds was observed 21 days after treatment. On non-treated trees, CPA-8 was detected on leaves until 180 days after treatment, and on weeds, the CPA-8 population was dependent on the distance from the treated trees. A high persistence of CPA-8 was detected on inert materials, such as clothes and gloves worn by handlers and plastic harvesting boxes. More than 99% of the samples with a CPA-8 phenotype were confirmed as CPA-8 using polymerase chain reaction (PCR). This work demonstrated a good distribution, persistence and adaptation of the CPA-8 strain to field and postharvest conditions. Monitoring of dispersion and persistence is an excellent tool to determine the time of application and provides valuable information for registering issues. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Co-culturing of Fungal Strains Against Botrytis cinerea as a Model for the Induction of Chemical Diversity and Therapeutic Agents

PubMed Central

Serrano, Rachel; González-Menéndez, Víctor; Rodríguez, Lorena; Martín, Jesús; Tormo, José R.; Genilloud, Olga

2017-01-01

New fungal SMs (SMs) have been successfully described to be produced by means of in vitro-simulated microbial community interactions. Co-culturing of fungi has proved to be an efficient way to induce cell–cell interactions that can promote the activation of cryptic pathways, frequently silent when the strains are grown in laboratory conditions. Filamentous fungi represent one of the most diverse microbial groups known to produce bioactive natural products. Triggering the production of novel antifungal compounds in fungi could respond to the current needs to fight health compromising pathogens and provide new therapeutic solutions. In this study, we have selected the fungus Botrytis cinerea as a model to establish microbial interactions with a large set of fungal strains related to ecosystems where they can coexist with this phytopathogen, and to generate a collection of extracts, obtained from their antagonic microbial interactions and potentially containing new bioactive compounds. The antifungal specificity of the extracts containing compounds induced after B. cinerea interaction was determined against two human fungal pathogens (Candida albicans and Aspergillus fumigatus) and three phytopathogens (Colletotrichum acutatum, Fusarium proliferatum, and Magnaporthe grisea). In addition, their cytotoxicity was also evaluated against the human hepatocellular carcinoma cell line (HepG2). We have identified by LC-MS the production of a wide variety of known compounds induced from these fungal interactions, as well as novel molecules that support the potential of this approach to generate new chemical diversity and possible new therapeutic agents. PMID:28469610

Co-culturing of Fungal Strains Against Botrytis cinerea as a Model for the Induction of Chemical Diversity and Therapeutic Agents.

PubMed

Serrano, Rachel; González-Menéndez, Víctor; Rodríguez, Lorena; Martín, Jesús; Tormo, José R; Genilloud, Olga

2017-01-01

New fungal SMs (SMs) have been successfully described to be produced by means of in vitro -simulated microbial community interactions. Co-culturing of fungi has proved to be an efficient way to induce cell-cell interactions that can promote the activation of cryptic pathways, frequently silent when the strains are grown in laboratory conditions. Filamentous fungi represent one of the most diverse microbial groups known to produce bioactive natural products. Triggering the production of novel antifungal compounds in fungi could respond to the current needs to fight health compromising pathogens and provide new therapeutic solutions. In this study, we have selected the fungus Botrytis cinerea as a model to establish microbial interactions with a large set of fungal strains related to ecosystems where they can coexist with this phytopathogen, and to generate a collection of extracts, obtained from their antagonic microbial interactions and potentially containing new bioactive compounds. The antifungal specificity of the extracts containing compounds induced after B. cinerea interaction was determined against two human fungal pathogens ( Candida albicans and Aspergillus fumigatus ) and three phytopathogens ( Colletotrichum acutatum , Fusarium proliferatum , and Magnaporthe grisea ). In addition, their cytotoxicity was also evaluated against the human hepatocellular carcinoma cell line (HepG2). We have identified by LC-MS the production of a wide variety of known compounds induced from these fungal interactions, as well as novel molecules that support the potential of this approach to generate new chemical diversity and possible new therapeutic agents.

Mapping the Flowering of an Invasive Plant Using Unmanned Aerial Vehicles: Is There Potential for Biocontrol Monitoring?

PubMed

de Sá, Nuno C; Castro, Paula; Carvalho, Sabrina; Marchante, Elizabete; López-Núñez, Francisco A; Marchante, Hélia

2018-01-01

Invasion by alien species is a worldwide phenomenon with negative consequences at both natural and production areas. Acacia longifolia is an invasive shrub/small tree well known for its negative ecological impacts in several places around the world. The recent introduction of a biocontrol agent ( Trichilogaster acaciaelongifoliae ), an Australian bud-galling wasp which decreases flowering of A. longifolia , in Portugal, demands the development of a cost-efficient method to monitor its establishment. We tested how unmanned aerial vehicles (UAV) can be used to map A. longifolia flowering. Our core assumption is as the population of the biocontrol agent increases, its impacts on the reduction of A. longifolia flowering will be increasingly visible. Additionally, we tested if there is a simple linear correlation between the number of flowers of A. longifolia counted in field and the area covered by flowers in the UAV imagery. UAV imagery was acquired over seven coastal areas including frontal dunes, interior sand dunes and pine forests considering two phenological stages: peak and off-peak flowering season. The number of flowers of A. longifolia was counted, in a minimum of 60 1 m 2 quadrats per study area. For each study area, flower presence/absence maps were obtained using supervised Random Forest. The correlation between the number of flowers and the area covered by flowering plants could then be tested. The flowering of A. longifolia was mapped using UAV mounted with RGB and CIR Cannon IXUS/ELPH cameras (Overall Accuracy > 0.96; Cohen's Kappa > 0.85) varying according to habitat type and flowering season. The correlation between the number of flowers counted and the area covered by flowering was weak ( r 2 between 0.0134 and 0.156). This is probably explained, at least partially, by the high variability of A. longifolia in what regards flowering morphology and distribution. The very high accuracy of our approach to map A. longifolia flowering proved to be cost

Four-trophic level food webs reveal the cascading impacts of an invasive plant targeted for biocontrol.

PubMed

López-Núñez, Francisco A; Heleno, Ruben H; Ribeiro, Sérgio; Marchante, Hélia; Marchante, Elizabete

2017-03-01

Biological invasions are a major threat to biodiversity and as such understanding their impacts is a research priority. Ecological networks provide a valuable tool to explore such impacts at the community level, and can be particularly insightful for planning and monitoring biocontrol programmes, including the potential for their seldom evaluated indirect non-target effects. Acacia longifolia is among the worst invasive species in Portugal, and has been recently targeted for biocontrol by a highly specific gall-wasp. Here we use an ambitious replicated network approach to: (1) identify the mechanisms by which direct and indirect impacts of A. longifolia can cascade from plants to higher trophic levels, including gallers, their parasitoids and inquilines; (2) reveal the structure of the interaction networks between plants, gallers, parasitoids and inquilines before the biocontrol; and (3) explore the potential for indirect interactions among gallers, including those established with the biocontrol agent, via apparent competition. Over a 15-month period, we collected 31,737 galls from native plants and identified all emerging insects, quantifying the interactions between 219 plant-, 49 galler-, 65 parasitoid- and 87 inquiline-species-one of the largest ecological networks to date. No galls were found on any of the 16 alien plant species. Invasion by A. longifolia caused an alarming simplification of plant communities, with cascading effects to higher trophic levels, namely: a decline of overall gall biomass, and on the richness, abundance and biomass of galler insects, their parasitoids, and inquilines. Correspondingly, we detected a significant decline in the richness of interactions between plants and galls. The invasion tended to increase overall interaction evenness by promoting the local extinction of the native plants that sustained more gall species. However, highly idiosyncratic responses hindered the detection of further consistent changes in network

Mechanisms of Bacterial (Serratia marcescens) Attachment to, Migration along, and Killing of Fungal Hyphae.

PubMed

Hover, Tal; Maya, Tal; Ron, Sapir; Sandovsky, Hani; Shadkchan, Yana; Kijner, Nitzan; Mitiagin, Yulia; Fichtman, Boris; Harel, Amnon; Shanks, Robert M Q; Bruna, Roberto E; García-Véscovi, Eleonora; Osherov, Nir

2016-05-01

We have found a remarkable capacity for the ubiquitous Gram-negative rod bacterium Serratia marcescens to migrate along and kill the mycelia of zygomycete molds. This migration was restricted to zygomycete molds and several basidiomycete species. No migration was seen on any molds of the phylum Ascomycota. S. marcescens migration did not require fungal viability or surrounding growth medium, as bacteria migrated along aerial hyphae as well.S. marcescens did not exhibit growth tropism toward zygomycete mycelium. Bacterial migration along hyphae proceeded only when the hyphae grew into the bacterial colony. S. marcescens cells initially migrated along the hyphae, forming attached microcolonies that grew and coalesced to generate a biofilm that covered and killed the mycelium. Flagellum-defective strains of S. marcescens were able to migrate along zygomycete hyphae, although they were significantly slower than the wild-type strain and were delayed in fungal killing. Bacterial attachment to the mycelium does not necessitate type 1 fimbrial adhesion, since mutants defective in this adhesin migrated equally well as or faster than the wild-type strain. Killing does not depend on the secretion of S. marcescens chitinases, as mutants in which all three chitinase genes were deleted retained wild-type killing abilities. A better understanding of the mechanisms by which S. marcescens binds to, spreads on, and kills fungal hyphae might serve as an excellent model system for such interactions in general; fungal killing could be employed in agricultural fungal biocontrol. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Bridgehead Effect in the Worldwide Invasion of the Biocontrol Harlequin Ladybird

PubMed Central

Lombaert, Eric; Guillemaud, Thomas; Cornuet, Jean-Marie; Malausa, Thibaut; Facon, Benoît; Estoup, Arnaud

2010-01-01

Recent studies of the routes of worldwide introductions of alien organisms suggest that many widespread invasions could have stemmed not from the native range, but from a particularly successful invasive population, which serves as the source of colonists for remote new territories. We call here this phenomenon the invasive bridgehead effect. Evaluating the likelihood of such a scenario is heuristically challenging. We solved this problem by using approximate Bayesian computation methods to quantitatively compare complex invasion scenarios based on the analysis of population genetics (microsatellite variation) and historical (first observation dates) data. We applied this approach to the Harlequin ladybird Harmonia axyridis (HA), a coccinellid native to Asia that was repeatedly introduced as a biocontrol agent without becoming established for decades. We show that the recent burst of worldwide invasions of HA followed a bridgehead scenario, in which an invasive population in eastern North America acted as the source of the colonists that invaded the European, South American and African continents, with some admixture with a biocontrol strain in Europe. This demonstration of a mechanism of invasion via a bridgehead has important implications both for invasion theory (i.e., a single evolutionary shift in the bridgehead population versus multiple changes in case of introduced populations becoming invasive independently) and for ongoing efforts to manage invasions by alien organisms (i.e., heightened vigilance against invasive bridgeheads). PMID:20305822

Biocontrol mechanism by root-associated Bacillus amyloliquefaciens FZB42 - a review.

PubMed

Chowdhury, Soumitra Paul; Hartmann, Anton; Gao, XueWen; Borriss, Rainer

2015-01-01

Bacillus amyloliquefaciens subsp. plantarum FZB42 is a Gram-positive model bacterium for unraveling plant-microbe interactions in Bacilli. In addition, FZB42 is used commercially as biofertilizer and biocontrol agent in agriculture. Genome analysis of FZB42 revealed that nearly 10% of the FZB42 genome is devoted to synthesizing antimicrobial metabolites and their corresponding immunity genes. However, recent investigations in planta demonstrated that - except surfactin - the amount of such compounds found in vicinity of plant roots is relatively low, making doubtful a direct function in suppressing competing microflora including plant pathogens. These metabolites have been also suspected to induce changes within the rhizosphere microbial community, which might affect environment and plant health. However, sequence analysis of rhizosphere samples revealed only marginal changes in the root microbiome, suggesting that secondary metabolites are not the key factor in protecting plants from pathogenic microorganisms. On the other hand, adding FZB42 to plants compensate, at least in part, changes in the community structure caused by the pathogen, indicating an interesting mechanism of plant protection by beneficial Bacilli. Sub-lethal concentrations of cyclic lipopeptides and volatiles produced by plant-associated Bacilli trigger pathways of induced systemic resistance (ISR), which protect plants against attacks of pathogenic microbes, viruses, and nematodes. Stimulation of ISR by bacterial metabolites is likely the main mechanism responsible for biocontrol action of FZB42.

A method of multiplex PCR for detection of field released Beauveria bassiana, a fungal entomopathogen applied for pest management in jute (Corchorus olitorius).

PubMed

Biswas, Chinmay; Dey, Piyali; Gotyal, B S; Satpathy, Subrata

2015-04-01

The fungal entomopathogen Beauveria bassiana is a promising biocontrol agent for many pests. Some B. bassiana strains have been found effective against jute pests. To monitor the survival of field released B. bassiana a rapid and efficient detection technique is essential. Conventional methods such as plating method or direct culture method which are based on cultivation on selective media followed by microscopy are time consuming and not so sensitive. PCR based methods are rapid, sensitive and reliable. A single primer PCR may fail to amplify some of the strains. However, multiplex PCR increases the possibility of detection as it uses multiple primers. Therefore, in the present investigation a multiplex PCR protocol was developed by multiplexing three primers SCA 14, SCA 15 and SCB 9 to detect field released B. bassiana strains from soil as well as foliage of jute field. Using our multiplex PCR protocol all the five B. bassiana strains could be detected from soil and three strains viz., ITCC 6063, ITCC 4563 and ITCC 4796 could be detected even from the crop foliage after 45 days of spray.

Potential Alternatives to Classical Biocontrol: Using Native Agents in Invaded Habitats and Genetically Engineered Sterile Cultivars for Invasive Plant Management

Treesearch

ShiLi Miao; Yi Li; Qinfeng Guo; Hua Yu; JiangQing Ding; et al.

2012-01-01

The development of an effective approach to control and eradication of invasive species has become a major challenge to scientists, managers, and society. Biocontrol has been widely utilized to control exotic plants in the past few decades with some degree of sucess. However, there have been an increasing number of controversies pertaining to this approach, largely...

Development of a population-based threshold model of conidial germination for analysing the effects of physiological manipulation on the stress tolerance and infectivity of insect pathogenic fungi.

PubMed

Andersen, M; Magan, N; Mead, A; Chandler, D

2006-09-01

Entomopathogenic fungi are being used as biocontrol agents of insect pests, but their efficacy can be poor in environments where water availability is reduced. In this study, the potential to improve biocontrol by physiologically manipulating fungal inoculum was investigated. Cultures of Beauveria bassiana, Lecanicillium muscarium, Lecanicillium longisporum, Metarhizium anisopliae and Paecilomyces fumosoroseus were manipulated by growing them under conditions of water stress, which produced conidia with increased concentrations of erythritol. The time-course of germination of conidia at different water activities (water activity, aw) was described using a generalized linear model, and in most cases reducing the water activity of the germination medium delayed the onset of germination without affecting the distribution of germination times. The germination of M. anisopliae, L. muscarium, L. longisporum and P. fumosoroseus was accelerated over a range of aw levels as a result of physiological manipulation. However, the relationship between the effect of physiological manipulation on germination and the osmolyte content of conidia varied according to fungal species. There was a linear relationship between germination rate, expressed as the reciprocal of germination time, and aw of the germination medium, but there was no significant effect of fungal species or physiological manipulation on the aw threshold for germination. In bioassays with M. anisopliae, physiologically manipulated conidia germinated more rapidly on the surface of an insect host, the melon cotton aphid Aphis gossypii, and fungal virulence was increased even when relative humidity was reduced after an initial high period. It is concluded that physiological manipulation may lead to improvements in biocontrol in the field, but choice of fungal species/isolate will be critical. In addition, the population-based threshold model used in this study, which considered germination in terms of physiological

Comparative analysis of the repertoire of G protein-coupled receptors of three species of the fungal genus Trichoderma.

PubMed

Gruber, Sabine; Omann, Markus; Zeilinger, Susanne

2013-05-16

Eukaryotic organisms employ cell surface receptors such as the seven-transmembrane G protein-coupled receptors (GPCRs) as sensors to connect to the environment. GPCRs react to a variety of extracellular cues and are considered to play central roles in the signal transduction in fungi. Several species of the filamentous ascomycete Trichoderma are potent mycoparasites, i.e. can attack and parasitize other fungi, which turns them into successful bio-fungicides for the protection of plants against fungal phytopathogens. The identification and characterization of GPCRs will provide insights into how Trichoderma communicates with its environment and senses the presence of host fungi. We mined the recently published genomes of the two mycoparasitic biocontrol agents Trichoderma atroviride and Trichoderma virens and compared the identified GPCR-like proteins to those of the saprophyte Trichoderma reesei. Phylogenetic analyses resulted in 14 classes and revealed differences not only among the three Trichoderma species but also between Trichoderma and other fungi. The class comprising proteins of the PAQR family was significantly expanded both in Trichoderma compared to other fungi as well as in the two mycoparasites compared to T. reesei. Expression analysis of the PAQR-encoding genes of the three Trichoderma species revealed that all except one were actually transcribed. Furthermore, the class of receptors with a DUF300 domain was expanded in T. atroviride, and T. virens showed an expansion of PTH11-like receptors compared to T. atroviride and T. reesei. Comparative genome analyses of three Trichoderma species revealed a great diversity of putative GPCRs with genus- and species- specific differences. The expansion of certain classes in the mycoparasites T. atroviride and T. virens is likely to reflect the capability of these fungi to establish various ecological niches and interactions with other organisms such as fungi and plants. These GPCRs consequently represent

Characterization of fungal antagonistic bacilli isolated from aerial roots of banyan (Ficus benghalensis) using intact-cell MALDI-TOF mass spectrometry (ICMS).

PubMed

Pathak, K V; Keharia, H

2013-05-01

To characterize fungal antagonistic bacilli isolated from aerial roots of banyan tree and identify the metabolites responsible for their antifungal activity. Seven gram positive, endospore-forming, rod-shaped endophytic bacterial strains exhibiting a broad-spectrum antifungal activity were isolated from the surface-sterilized aerial roots of banyan tree. The isolates designated as K1, A2, A4 and A12 were identified as Bacillus subtilis, whereas isolates A11 and A13 were identified as Bacillus amyloliquefaciens using Biolog Microbial Identification System. The antifungal lipopeptides, surfactins, iturins and fengycins with masses varying in the range from m/z 900 to m/z 1550 could be detected using intact-cell MALDI-TOF mass spectrometry (ICMS). On the basis of mass spectral and carbon source utilization profile, all seven endophytes could be distinguished from each other. Furthermore, ICMS analysis revealed higher extent of heterogeneity among iturins and fengycins produced by B. subtilis K1, correlating well with its higher antifungal activity in comparison with other isolates. Seven fungal antagonistic bacilli were isolated from aerial roots of banyan tree, exhibiting broad spectrum of antifungal activity, among which B. subtilis K1 isolate was found to be most potent. The ICMS analysis revealed that all these isolates produced cyclic lipopeptides belonging to surfactin, iturin and fengycin families and exhibited varying degree of heterogeneity. The endophytes are considered as a potential source of novel bioactive metabolites, and this study describes the potent fungal antagonistic bacilli from aerial roots of banyan tree. The isolates described in this study have a prospective application as biocontrol agents. Also ICMS analysis described in this study for characterization of antifungal metabolites produced by banyan endophytic bacilli may be used as a high throughput tool for screening of microbes producing novel cyclic lipopeptides. © 2013 The Society for

Involvement of the Transcriptional Coactivator ThMBF1 in the Biocontrol Activity of Trichoderma harzianum.

PubMed

Rubio, M Belén; Pardal, Alonso J; Cardoza, Rosa E; Gutiérrez, Santiago; Monte, Enrique; Hermosa, Rosa

2017-01-01

Trichoderma harzianum is a filamentous fungus well adapted to different ecological niches. Owing to its ability to antagonize a wide range of plant pathogens, it is used as a biological control agent in agriculture. Selected strains of T. harzianum are also able to increase the tolerance of plants to biotic and abiotic stresses. However, little is known about the regulatory elements of the T. harzianum transcriptional machinery and their role in the biocontrol by this species. We had previously reported the involvement of the transcription factor THCTF1 in the T. harzianum production of the secondary metabolite 6-pentyl-pyrone, an important volatile compound related to interspecies cross-talk. Here, we performed a subtractive hybridization to explore the genes regulated by THCTF1, allowing us to identify a multiprotein bridging factor 1 ( mbf1 ) homolog. The gene from T. harzianum T34 was isolated and characterized, and the generated Thmbf1 overexpressing transformants were used to investigate the role of this gene in the biocontrol abilities of the fungus against two plant pathogens. The transformants showed a reduced antifungal activity against Fusarium oxysporum f. sp. lycopersici race 2 (FO) and Botrytis cinerea (BC) in confrontation assays on discontinuous medium, indicating that the Thmbf1 gene could affect T. harzianum production of volatile organic compounds (VOC) with antifungal activity. Moreover, cellophane and dialysis membrane assays indicated that Thmbf1 overexpression affected the production of low molecular weight secreted compounds with antifungal activity against FO. Intriguingly, no correlation in the expression profiles, either in rich or minimal medium, was observed between Thmbf1 and the master regulator gene cross-pathway control ( cpc1 ). Greenhouse assays allowed us to evaluate the biocontrol potential of T. harzianum strains against BC and FO on susceptible tomato plants. The wild type strain T34 significantly reduced the necrotic leaf

Involvement of the Transcriptional Coactivator ThMBF1 in the Biocontrol Activity of Trichoderma harzianum

PubMed Central

Rubio, M. Belén; Pardal, Alonso J.; Cardoza, Rosa E.; Gutiérrez, Santiago; Monte, Enrique; Hermosa, Rosa

2017-01-01

Trichoderma harzianum is a filamentous fungus well adapted to different ecological niches. Owing to its ability to antagonize a wide range of plant pathogens, it is used as a biological control agent in agriculture. Selected strains of T. harzianum are also able to increase the tolerance of plants to biotic and abiotic stresses. However, little is known about the regulatory elements of the T. harzianum transcriptional machinery and their role in the biocontrol by this species. We had previously reported the involvement of the transcription factor THCTF1 in the T. harzianum production of the secondary metabolite 6-pentyl-pyrone, an important volatile compound related to interspecies cross-talk. Here, we performed a subtractive hybridization to explore the genes regulated by THCTF1, allowing us to identify a multiprotein bridging factor 1 (mbf1) homolog. The gene from T. harzianum T34 was isolated and characterized, and the generated Thmbf1 overexpressing transformants were used to investigate the role of this gene in the biocontrol abilities of the fungus against two plant pathogens. The transformants showed a reduced antifungal activity against Fusarium oxysporum f. sp. lycopersici race 2 (FO) and Botrytis cinerea (BC) in confrontation assays on discontinuous medium, indicating that the Thmbf1 gene could affect T. harzianum production of volatile organic compounds (VOC) with antifungal activity. Moreover, cellophane and dialysis membrane assays indicated that Thmbf1 overexpression affected the production of low molecular weight secreted compounds with antifungal activity against FO. Intriguingly, no correlation in the expression profiles, either in rich or minimal medium, was observed between Thmbf1 and the master regulator gene cross-pathway control (cpc1). Greenhouse assays allowed us to evaluate the biocontrol potential of T. harzianum strains against BC and FO on susceptible tomato plants. The wild type strain T34 significantly reduced the necrotic leaf lesions

Aureobasidium pullulansas a biocontrol agent of blue mold in "Rocha" pear.

PubMed

Ferreira-Pinto, M M; Moura-Guedes, M C; Barreiro, M G; Pais, I; Santos, M R; Silva, M J

2006-01-01

The blue mold of "Rocha" pear caused by Penicillium expansum is an important postharvest disease which is adequately controlled by application of synthetic fungicides. In recent years, strategies like biological control have been considered a desirable alternative to chemicals. Several studies have demonstrated the potential of the yeast-like fungus Aureobasidium pullulans for control of postharvest decay of pear. A Portuguese isolate of Aureobasidium pullulans was characterized and evaluated for its activity in reducing postharvest blue mold decay of "Rocha" pear caused by Penicillium expansum. Study of optimal conditions for antagonist growth was carried out in six different culture media. The effect of four maturity stages of fruits in the development of A. pullulans was also studied. Biocontrol studies were performed with two concentrations of the antagonist (3 x 10(8) and 4 x 10(9) CFU/ml). A. pullulans growth was significantly different (P < or = 0.001) according to the various media and time of incubation. Best results were obtained in Corn Meal Agar (CMA) and Potato Dextrose Agar (PDA) media which contains the higher concentration of glucose (20 mg/l). Medium resulted from fruits of the first harvest date presented lower colony diameter. Inoculation of A. pullulans at 3 x 10(8) and 4 x 10(9) CFU/ml reduced the incidence of the disease by 23 and 63%, and reduced the lesion diameter by 36 and 46%, respectively.

Novel Routes for Improving Biocontrol Activity of Bacillus Based Bioinoculants

PubMed Central

Wu, Liming; Wu, Hui-Jun; Qiao, Junqing; Gao, Xuewen; Borriss, Rainer

2015-01-01

Biocontrol (BC) formulations prepared from plant-growth-promoting bacteria are increasingly applied in sustainable agriculture. Especially inoculants prepared from endospore-forming Bacillus strains have been proven as efficient and environmental-friendly alternative to chemical pesticides due to their long shelf life, which is comparable with that of agrochemicals. However, these formulations of the first generation are sometimes hampered in their action and do not fulfill in each case the expectations of the appliers. In this review we use the well-known plant-associated Bacillus amyloliquefaciens type strain FZB42 as example for the successful application of different techniques offered today by comparative, evolutionary and functional genomics, site-directed mutagenesis and strain construction including marker removal, for paving the way for preparing a novel generation of BC agents. PMID:26696998

Ecological activity for mycotoxin beyond toxicity: screening mycotoxins for quorum inhibition

USDA-ARS?s Scientific Manuscript database

ABSTRACT: Biocontrol organisms are becoming essential features of several agricultural based crops, and bacterial endophytes are important components of several biocontrol systems. We are developing bacterial endophytes for use as biocontrol organisms for the corn fungal endophyte Fusarium verticil...

Cytokinin production by Pseudomonas fluorescens G20-18 determines biocontrol activity against Pseudomonas syringae in Arabidopsis

PubMed Central

Großkinsky, Dominik K.; Tafner, Richard; Moreno, María V.; Stenglein, Sebastian A.; García de Salamone, Inés E.; Nelson, Louise M.; Novák, Ondřej; Strnad, Miroslav; van der Graaff, Eric; Roitsch, Thomas

2016-01-01

Plant beneficial microbes mediate biocontrol of diseases by interfering with pathogens or via strengthening the host. Although phytohormones, including cytokinins, are known to regulate plant development and physiology as well as plant immunity, their production by microorganisms has not been considered as a biocontrol mechanism. Here we identify the ability of Pseudomonas fluorescens G20-18 to efficiently control P. syringae infection in Arabidopsis, allowing maintenance of tissue integrity and ultimately biomass yield. Microbial cytokinin production was identified as a key determinant for this biocontrol effect on the hemibiotrophic bacterial pathogen. While cytokinin-deficient loss-of-function mutants of G20-18 exhibit impaired biocontrol, functional complementation with cytokinin biosynthetic genes restores cytokinin-mediated biocontrol, which is correlated with differential cytokinin levels in planta. Arabidopsis mutant analyses revealed the necessity of functional plant cytokinin perception and salicylic acid-dependent defence signalling for this biocontrol mechanism. These results demonstrate microbial cytokinin production as a novel microbe-based, hormone-mediated concept of biocontrol. This mechanism provides a basis to potentially develop novel, integrated plant protection strategies combining promotion of growth, a favourable physiological status and activation of fine-tuned direct defence and abiotic stress resilience. PMID:26984671

Cytokinin production by Pseudomonas fluorescens G20-18 determines biocontrol activity against Pseudomonas syringae in Arabidopsis.

PubMed

Großkinsky, Dominik K; Tafner, Richard; Moreno, María V; Stenglein, Sebastian A; García de Salamone, Inés E; Nelson, Louise M; Novák, Ondřej; Strnad, Miroslav; van der Graaff, Eric; Roitsch, Thomas

2016-03-17

Plant beneficial microbes mediate biocontrol of diseases by interfering with pathogens or via strengthening the host. Although phytohormones, including cytokinins, are known to regulate plant development and physiology as well as plant immunity, their production by microorganisms has not been considered as a biocontrol mechanism. Here we identify the ability of Pseudomonas fluorescens G20-18 to efficiently control P. syringae infection in Arabidopsis, allowing maintenance of tissue integrity and ultimately biomass yield. Microbial cytokinin production was identified as a key determinant for this biocontrol effect on the hemibiotrophic bacterial pathogen. While cytokinin-deficient loss-of-function mutants of G20-18 exhibit impaired biocontrol, functional complementation with cytokinin biosynthetic genes restores cytokinin-mediated biocontrol, which is correlated with differential cytokinin levels in planta. Arabidopsis mutant analyses revealed the necessity of functional plant cytokinin perception and salicylic acid-dependent defence signalling for this biocontrol mechanism. These results demonstrate microbial cytokinin production as a novel microbe-based, hormone-mediated concept of biocontrol. This mechanism provides a basis to potentially develop novel, integrated plant protection strategies combining promotion of growth, a favourable physiological status and activation of fine-tuned direct defence and abiotic stress resilience.

Biocontrol of Burkholderia cepacia complex bacteria and bacterial phytopathogens by Bdellovibrio bacteriovorus.

PubMed

McNeely, Damian; Chanyi, Ryan M; Dooley, James S; Moore, John E; Koval, Susan F

2017-04-01

Bdellovibrio and like organisms are predatory bacteria that have the unusual property of using the cytoplasmic constituents of other Gram-negative bacteria as nutrients. These predators may thus provide an alternative approach to the biocontrol of human and plant pathogens. Predators were isolated on Burkholderia cenocepacia K56-2 and J2315 as prey cells, in enrichment cultures with soil and sewage. Three isolates (DM7C, DM8A, and DM11A) were identified as Bdellovibrio bacteriovorus on the basis of morphology, a periplasmic life cycle, and 16S rRNA gene sequencing. The prey range of these isolates was tested on Burkholderia cepacia complex bacteria and several phytopathogenic bacteria of agricultural importance. Of 31 strains of the Burkholderia cepacia complex tested, only 4 were resistant to predation by strain DM7C. A subset of 9 of the prey tested were also susceptible to strains DM8A and DM11A. Of 12 phytopathogens tested, 4 were resistant to strains DM7C and DM8A, and only 2 were resistant to strain DM11A. Thus, Bdellovibrio bacteriovorus strains retrieved from environmental samples on 2 Burkholderia cenocepacia isolates from cystic fibrosis patients did not distinguish in their prey range between other isolates of that pathogen or phytopathogens. Such strains hold promise as potential wide-spectrum biocontrol agents.

Biocontrol mechanism by root-associated Bacillus amyloliquefaciens FZB42 – a review

PubMed Central

Chowdhury, Soumitra Paul; Hartmann, Anton; Gao, XueWen; Borriss, Rainer

2015-01-01

Bacillus amyloliquefaciens subsp. plantarum FZB42 is a Gram-positive model bacterium for unraveling plant–microbe interactions in Bacilli. In addition, FZB42 is used commercially as biofertilizer and biocontrol agent in agriculture. Genome analysis of FZB42 revealed that nearly 10% of the FZB42 genome is devoted to synthesizing antimicrobial metabolites and their corresponding immunity genes. However, recent investigations in planta demonstrated that – except surfactin – the amount of such compounds found in vicinity of plant roots is relatively low, making doubtful a direct function in suppressing competing microflora including plant pathogens. These metabolites have been also suspected to induce changes within the rhizosphere microbial community, which might affect environment and plant health. However, sequence analysis of rhizosphere samples revealed only marginal changes in the root microbiome, suggesting that secondary metabolites are not the key factor in protecting plants from pathogenic microorganisms. On the other hand, adding FZB42 to plants compensate, at least in part, changes in the community structure caused by the pathogen, indicating an interesting mechanism of plant protection by beneficial Bacilli. Sub-lethal concentrations of cyclic lipopeptides and volatiles produced by plant-associated Bacilli trigger pathways of induced systemic resistance (ISR), which protect plants against attacks of pathogenic microbes, viruses, and nematodes. Stimulation of ISR by bacterial metabolites is likely the main mechanism responsible for biocontrol action of FZB42. PMID:26284057

Phenotypic and genetic characterization of Paecilomyces lilacinus strains with biocontrol activity against root-knot nematodes.

PubMed

Gunasekera, T S; Holland, R J; Gillings, M R; Briscoe, D A; Neethling, D C; Williams, K L; Nevalainen, K M

2000-09-01

Efficient selection of fungi for biological control of nematodes requires a series of screening assays. Assessment of genetic diversity in the candidate species maximizes the variety of the isolates tested and permits the assignment of a particular genotype with high nematophagous potential using a rapid novel assay. Molecular analyses also facilitate separation between isolates, allowing the identification of proprietary strains and trace biocontrol strains in the environment. The resistance of propagules to UV radiation is an important factor in the survival of a biocontrol agent. We have analyzed 15 strains of the nematophagous fungus Paecilomyces lilacinus using these principles. Arbitrarily primed DNA and allozyme assays were applied to place the isolates into genetic clusters, and demonstrated that some genetically related P. lilacinus strains exhibit widespread geographic distributions. When exposed to UV radiation, some weakly nematophagous strains were generally more susceptible than effective isolates. A microtitre tray-based assay used to screen the pathogenic activity of each isolate to Meloidogyne javanica egg masses revealed that the nematophagous ability varied between 37%-100%. However, there was no clear relationship between nematophagous ability and genetic clusters. Molecular characterizations revealed sufficient diversity to allow tracking of strains released into the environment.

Exploring the life cycles of three South American rusts that have potential as biocontrol agents of the stipoid grass Nassella neesiana in Australasia.

PubMed

Anderson, Freda E; Díaz, Marina L; Barton, Jane; Flemmer, Andrea C; Hansen, Paula V; McLaren, David A

2011-01-01

Three rusts, Puccinia nassellae, Uromyces pencanus, and Puccinia graminella, are being studied as potential biological control agents for Nassella neesiana (Chilean needle grass) in Australia and New Zealand. An understanding of the life cycle of a pathogen is desirable before its release as a biocontrol agent is considered, to enable the assessment of the risks involved in such a release. Field observations and experiments have been carried out to elucidate the life cycles of these three pathogens. Puccinia nassellae cycles as urediniospores and produces dormant teliospores. Dormancy of teliospores has been broken through manipulation in the laboratory, but resulting basidiospores have failed to infect N. neesiana plants under the conditions tested. Uromyces pencanus cycles as urediniospores and its telia appear to have lost the capacity to produce basidiospores. Aecia have been reported for this rust in the literature. However, evidence is provided that these aecia in fact belong to the life cycle of P. graminella. Puccinia graminella produces only aecia and telia. The aeciospores have been shown to be repetitive (aecidioid urediniospores). Teliospores germinate directly without a dormant phase, but resulting basidiospores failed to infect N. neesiana plants under the conditions tested. The role of teliospores in the life cycle of all three rusts remains unknown. Although the autoecious nature of their life cycles has not been proven experimentally, neither is there any evidence that they are heteroecious. Practical and theoretical implications of these findings are discussed. Copyright © 2011 The British Mycological Society. All rights reserved.

Characterization of the Biosynthetic Operon for the Antibacterial Peptide Herbicolin in Pantoea vagans Biocontrol Strain C9-1 and Incidence in Pantoea Species

PubMed Central

Kamber, Tim; Lansdell, Theresa A.; Stockwell, Virginia O.; Ishimaru, Carol A.; Smits, Theo H. M.

2012-01-01

Pantoea vagans C9-1 is a biocontrol strain that produces at least two antibiotics inhibiting the growth of Erwinia amylovora, the causal agent of fire blight disease of pear and apple. One antibiotic, herbicolin I, was purified from culture filtrates of P. vagans C9-1 and determined to be 2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine, also known as Nß-epoxysuccinamoyl-DAP-valine. A plasposon library was screened for mutants that had lost the ability to produce herbicolin I. It was shown that mutants had reduced biocontrol efficacy in immature pear assays. The biosynthetic gene cluster in P. vagans C9-1 was identified by sequencing the flanking regions of the plasposon insertion sites. The herbicolin I biosynthetic gene cluster consists of 10 coding sequences (CDS) and is located on the 166-kb plasmid pPag2. Sequence comparisons identified orthologous gene clusters in Pantoea agglomerans CU0119 and Serratia proteamaculans 568. A low incidence of detection of the biosynthetic cluster in a collection of 45 Pantoea spp. from biocontrol, environmental, and clinical origins showed that this is a rare trait among the tested strains. PMID:22504810

[Invasive fungal disease due to Scedosporium, Fusarium and mucorales].

PubMed

Pemán, Javier; Salavert, Miguel

2014-01-01

The number of emerging organisms causing invasive fungal infections has increased in the last decades. These etiological agents include Scedosporium, Fusarium and mucorales. All of them can cause disseminated, virulent, and difficult-to treat infections in immunosuppressed patients, the most affected, due to their resistance to most available antifungal agents. Current trends in transplantation including the use of new immunosuppressive treatments, the common prescription of antifungal agents for prophylaxis, and new ecological niches could explain the emergence of these fungal pathogens. These pathogens can also affect immunocompetent individuals, especially after natural disasters (earthquakes, floods, tsunamis), combat wounds or near drowning. All the invasive infections caused by Scedosporium, Fusarium, and mucorales are potentially lethal and a favourable outcome is associated with rapid diagnosis by direct microscopic examination of the involved tissue, wide debridement of infected material, early use of antifungal agents including combination therapy, and an improvement in host defenses, especially neutropenia. Copyright © 2014. Published by Elsevier Espana.

Biocontrol ability and action mechanism of food-isolated yeast strains against Botrytis cinerea causing post-harvest bunch rot of table grape.

PubMed

Parafati, Lucia; Vitale, Alessandro; Restuccia, Cristina; Cirvilleri, Gabriella

2015-05-01

Strains belonging to the species Saccharomyces cerevisiae, Wickerhamomyces anomalus, Metschnikowia pulcherrima and Aureobasidium pullulans, isolated from different food sources, were tested in vitro as biocontrol agents (BCAs) against the post-harvest pathogenic mold Botrytis cinerea. All yeast strains demonstrated antifungal activity at different levels depending on species and medium. Killer strains of W. anomalus and S. cerevisiae showed the highest biocontrol in vitro activity, as demonstrated by largest inhibition halos. The competition for iron and the ability to form biofilm and to colonize fruit wounds were hypothesized as the main action mechanisms for M. pulcherrima. The production of hydrolytic enzymes and the ability to colonize the wounds were the most important mechanisms for biocontrol activity in A. pullulans and W. anomalus, which also showed high ability to form biofilm. The production of volatile organic compounds (VOCs) with in vitro and in vivo inhibitory effect on pathogen growth was observed for the species W. anomalus, S. cerevisiae and M. pulcherrima. Our study clearly indicates that multiple modes of action may explain as M. pulcherrima provide excellent control of postharvest botrytis bunch rot of grape. Copyright © 2014 Elsevier Ltd. All rights reserved.

Diversity of endophytic fungal community of cacao (Theobroma cacao L.) and biological control of Crinipellis perniciosa, causal agent of Witches' Broom Disease

PubMed Central

2005-01-01

The basidiomycete fungus Crinipellis perniciosa (Stahel) Singer is the causal agent of Witches' Broom Disease of Cacao (Theobroma cacao L.) which is the main factor limiting cacao production in the Americas. Pod losses of up to 90% are experienced in affected areas as evidenced by the 50% drop in production in Bahia province, Brazil following the arrival of the C. perniciosa in the area in 1989. The disease has proven particularly difficult to control and many farmers in affected areas have given up cacao cultivation. In order to evaluate the potential of endophytes as a biological control agent of this phytopathogen, the endophytic fungal community of resistant and susceptible cacao plants as well as affected branches was studied between 2001 and 2002. The fungal community was identified by morphological traits and rDNA sequencing as belonging to the genera Acremonium, Blastomyces, Botryosphaeria, Cladosporium, Colletotrichum, Cordyceps, Diaporthe, Fusarium, Geotrichum, Gibberella, Gliocladium, Lasiodiplodia, Monilochoetes, Nectria, Pestalotiopsis, Phomopsis, Pleurotus, Pseudofusarium, Rhizopycnis, Syncephalastrum, Trichoderma, Verticillium and Xylaria. These fungi were evaluated both in vitro and in vivo by their ability to inhibit C. perniciosa. Among these, some were identified as potential antagonists, but only one fungus (Gliocladium catenulatum) reduced the incidence of Witches' Broom Disease in cacao seedlings to 70%. PMID:15951847

Diversity of endophytic fungal community of cacao (Theobroma cacao L.) and biological control of Crinipellis perniciosa, causal agent of Witches' Broom Disease.

PubMed

Rubini, Marciano R; Silva-Ribeiro, Rute T; Pomella, Alan W V; Maki, Cristina S; Araújo, Welington L; Dos Santos, Deise R; Azevedo, João L

2005-01-01

The basidiomycete fungus Crinipellis perniciosa (Stahel) Singer is the causal agent of Witches' Broom Disease of Cacao (Theobromacacao L.) which is the main factor limiting cacao production in the Americas. Pod losses of up to 90% are experienced in affected areas as evidenced by the 50% drop in production in Bahia province, Brazil following the arrival of the C. perniciosa in the area in 1989. The disease has proven particularly difficult to control and many farmers in affected areas have given up cacao cultivation. In order to evaluate the potential of endophytes as a biological control agent of this phytopathogen, the endophytic fungal community of resistant and susceptible cacao plants as well as affected branches was studied between 2001 and 2002. The fungal community was identified by morphological traits and rDNA sequencing as belonging to the genera Acremonium, Blastomyces, Botryosphaeria, Cladosporium, Colletotrichum, Cordyceps, Diaporthe, Fusarium, Geotrichum, Gibberella, Gliocladium, Lasiodiplodia, Monilochoetes, Nectria, Pestalotiopsis, Phomopsis, Pleurotus, Pseudofusarium, Rhizopycnis, Syncephalastrum, Trichoderma, Verticillium and Xylaria. These fungi were evaluated both in vitro and in vivo by their ability to inhibit C. perniciosa. Among these, some were identified as potential antagonists, but only one fungus (Gliocladium catenulatum) reduced the incidence of Witches' Broom Disease in cacao seedlings to 70%.

Nontarget herbivory by a weed biocontrol insect is limited to spillover, reducing the chance of population-level impacts.

PubMed

Catton, Haley A; Lalonde, Robert G; De Clerck-Floate, Rosemarie A

2015-03-01

recommendations for monitoring and management of biocontrol systems with similar attributes, such as removing target plants around nontarget populations of interest. Because M. crucifer is among the least host-specific of the modern weed biocontrol agents, and H. micrantha is likely one of its most highly preferred nontargets, these conclusions are, arguably, generally applicable to other nontarget plants and biocontrol systems.

Selection of Streptomyces against soil borne fungal pathogens by a standardized dual culture assay and evaluation of their effects on seed germination and plant growth.

PubMed

Kunova, Andrea; Bonaldi, Maria; Saracchi, Marco; Pizzatti, Cristina; Chen, Xiaoyulong; Cortesi, Paolo

2016-11-09

In the search for new natural resources for crop protection, streptomycetes are gaining interest in agriculture as plant growth promoting bacteria and/or biological control agents. Because of their peculiar life cycle, in which the production of secondary metabolites is synchronized with the development of aerial hyphae and sporulation, the commonly used methods to screen for bacterial antagonists need to be adapted. The dual culture assay was standardized in terms of inoculation timing of Streptomyces antagonist and pathogen, and growth rate of different fungal pathogens. In case of fast-growing fungi, inoculation of the antagonist 2 or 3 days prior to the pathogen resulted in significantly stronger inhibition of mycelium growth. One hundred and thirty Streptomyces strains were evaluated against six destructive soil borne pathogens. The activity of strains varied from broad-spectrum to highly specific inhibition of individual pathogens. All strains inhibited at least one tested pathogen. Three strains, which combined the largest broad-spectrum with the highest inhibition activity, were selected for further characterization with four vegetable species. All of them were able to colonize seed surface of all tested vegetable crops. They mostly improved radicle and hypocotyl growth in vitro, although no statistically significant enhancement of biomass weight was observed in vivo. Occasionally, transient negative effects on germination and plant growth were observed. The adapted dual culture assay allowed us to compare the inhibition of individual Streptomyces strains against six fungal soil borne pathogens. The best selected strains were able to colonize the four vegetable crops and have a potential to be developed into biocontrol products. Although they occasionally negatively influenced plant growth, these effects did not persist during the further development. Additional in vivo studies are needed to confirm their potential as biological control or plant growth

Fate of biological control introductions: monitoring an Australian fungal pathogen of grasshoppers in North America.

PubMed Central

Bidochka, M J; Walsh, S R; Ramos, M E; St Leger, R J; Silver, J C; Roberts, D W

1996-01-01

In North America there are two generally recognized pathotypes (pathotypes 1 and 2) of the fungus Entomophaga grylli which show host-preferential infection of grasshopper subfamilies. Pathotype 3, discovered in Australia, has a broader grasshopper host range and was considered to be a good biocontrol agent. Between 1989 and 1991 pathotype 3 was introduced at two field sites in North Dakota. Since resting spores are morphologically indistinguishable among pathotypes, we used pathotype-specific DNA probes to confirm pathotype identification in E. grylli-infected grasshoppers collected at the release sites in 1992, 1993, and 1994. In 1992, up to 23% of E. grylli-infected grasshoppers of the subfamilies Melanoplinae, Oedipodinae, and Gomphocerinae were infected by pathotype 3, with no infections > 1 km from the release sites. In 1993, pathotype 3 infections declined to 1.7%. In 1994 grasshopper populations were low and no pathotype 3 infections were found. The frequency of pathotype 3 infection has declined to levels where its long-term survival in North America is questionable. Analyses of biocontrol releases are critical to evaluating the environmental risks associated with these ecological manipulations, and molecular probes are powerful tools for monitoring biocontrol releases. Images Fig. 1 PMID:8570660

Releasing biocontrol agents: Risk assessment and overdue reform

Treesearch

Bob Peterson; Sharlene Sing

2007-01-01

Although the need for universally instituting formal risk assessment (RA) in the screening and approval process for non-native biological control (BC) agent releases has been widely acknowledged for the past several years, little seems to have been accomplished in terms of codifying this practice within a regulatory framework. Given the low success rate of classical BC...

Emerging microbial biocontrol strategies for plant pathogens.

PubMed

Syed Ab Rahman, Sharifah Farhana; Singh, Eugenie; Pieterse, Corné M J; Schenk, Peer M

2018-02-01

To address food security, agricultural yields must increase to match the growing human population in the near future. There is now a strong push to develop low-input and more sustainable agricultural practices that include alternatives to chemicals for controlling pests and diseases, a major factor of heavy losses in agricultural production. Based on the adverse effects of some chemicals on human health, the environment and living organisms, researchers are focusing on potential biological control microbes as viable alternatives for the management of pests and plant pathogens. There is a growing body of evidence that demonstrates the potential of leaf and root-associated microbiomes to increase plant efficiency and yield in cropping systems. It is important to understand the role of these microbes in promoting growth and controlling diseases, and their application as biofertilizers and biopesticides whose success in the field is still inconsistent. This review focusses on how biocontrol microbes modulate plant defense mechanisms, deploy biocontrol actions in plants and offer new strategies to control plant pathogens. Apart from simply applying individual biocontrol microbes, there are now efforts to improve, facilitate and maintain long-term plant colonization. In particular, great hopes are associated with the new approaches of using "plant-optimized microbiomes" (microbiome engineering) and establishing the genetic basis of beneficial plant-microbe interactions to enable breeding of "microbe-optimized crops". Copyright © 2017 Elsevier B.V. All rights reserved.

Intracellular trehalose and sorbitol synergistically promoting cell viability of a biocontrol yeast, Pichia anomala, for aflatoxin reduction.

PubMed

Hua, Sui Sheng T; Hernlem, Bradley J; Yokoyama, Wallace; Sarreal, Siov Bouy L

2015-05-01

Pichia anomala (Wickerhamomyces anomalus) WRL-076 was discovered by a visual screening bioassay for its antagonism against Aspergillus flavus. The yeast was shown to significantly inhibit aflatoxin production and the growth of A. flavus. P. anomala is a potential biocontrol agent for reduction of aflatoxin in the food chain. Maintaining the viability of biocontrol agents in formulated products is a great challenge for commercial applications. Four media, NYG, NYGS, NYGT and NYGST are described which support good growth of yeast cells and were tested as storage formulations. Post growth supplement of 5 % trehalose to NYGST resulted in 83 % viable yeast cells after 12 months in cold storage. Intracellular sorbitol and trehalose concentrations were determined by HPLC analysis at the beginning of the storage and at the end of 12 month. Correlation of cell viability to both trehalose and sorbitol suggested a synergistic effect. Bonferroni (Dunn) t Test, Tukey's Studentized Range (HSD) Test and Duncan's Multiple Range Test, all showed that yeast cell viability in samples with both intracellular trehalose and sorbitol were significantly higher than those with either or none, at a 95 % confidence level. DiBAC4(5) and CFDA-AM were used as the membrane integrity fluorescent stains to create a two-color vital staining scheme with red and green fluorescence, respectively. Yeast cells stored in formulations NYG and NYGS with no detectable trehalose, displayed mostly red fluorescence. Yeast cells in NYGST+5T showed mostly green fluorescence.

Augmentative Biocontrol in Natural Marine Habitats: Persistence, Spread and Non-Target Effects of the Sea Urchin Evechinus chloroticus

PubMed Central

Atalah, Javier; Hopkins, Grant A.; Forrest, Barrie M.

2013-01-01

Augmentative biocontrol aims to control established pest populations through enhancement of their indigenous enemies. To our knowledge, this approach has not been applied at an operational scale in natural marine habitats, in part because of the perceived risk of adverse non-target effects on native ecosystems. In this paper, we focus on the persistence, spread and non-target effects of the sea urchin Evechinus chloroticus when used as biocontrol agent to eradicate an invasive kelp from Fiordland, New Zealand. Rocky reef macrobenthic assemblages were monitored over 17 months in areas where the indigenous algal canopy was either removed or left intact prior to the translocation of a large number of urchins (>50 ind.·m−2). Urchin densities in treated areas significantly declined ∼9 months after transplant, and began spreading to adjacent sites. At the end of the 17-month study, densities had declined to ∼5 ind.·m−2. Compared to controls, treatment sites showed persistent shifts from kelp forest to urchin barrens, which were accompanied by significant reductions in taxa richness. Although these non-target effects were pronounced, they were considered to be localised and reversible, and arguably outweigh the irreversible and more profound ecological impacts associated with the establishment of an invasive species in a region of high conservation value. Augmentative biocontrol, used in conjunction with traditional control methods, represents a promising tool for the integrated management of marine pests. PMID:24260376

Bacteriophages as biocontrol agents of food pathogens.

PubMed

Mahony, Jennifer; McAuliffe, Olivia; Ross, R Paul; van Sinderen, Douwe

2011-04-01

Bacteriophages have long been recognized for their potential as biotherapeutic agents. The recent approval for the use of phages of Listeria monocytogenes for food safety purposes has increased the impetus of phage research to uncover phage-mediated applications with activity against other food pathogens. Areas of emerging and growing significance, such as predictive modelling and genomics, have shown their potential and impact on the development of new technologies to combat food pathogens. This review will highlight recent advances in the research of phages that target food pathogens and that promote their use in biosanitation, while it will also discuss its limitations. Copyright © 2010 Elsevier Ltd. All rights reserved.

Growth of chitinolytic dune soil beta-subclass Proteobacteria in response to invading fungal hyphae.

PubMed

De Boer, W; Klein Gunnewiek, P J; Kowalchuk, G A; Van Veen, J A

2001-08-01

It has frequently been reported that chitinolytic soil bacteria, in particular biocontrol strains, can lyse living fungal hyphae, thereby releasing potential growth substrate. However, the conditions used in such assays (high bacterial density, rich media, fragmented hyphae) make it difficult to determine whether mycolytic activity is actually of importance for the growth and survival of chitinolytic bacteria in soils. An unidentified group of beta-subclass Proteobacteria (CbetaPs) was most dominant among the culturable nonfilamentous chitinolytic bacteria isolated from Dutch sand dune soils. Here we demonstrate that the CbetaPs grew at the expense of extending fungal mycelium of three dune soil fungi (Chaetomium globosum, Fusarium culmorum, and Mucor hiemalis) under nutrient-limiting, soil-like conditions. Aggregates of CbetaPs were also often found attached to fungal hyphae. The growth of a control group of dominant nonchitinolytic dune soil bacteria (beta- and gamma-subclass Proteobacteria) was not stimulated in the mycelial zone, indicating that growth-supporting materials were not independently released in appreciable amounts by the extending hyphae. Therefore, mycolytic activities of CbetaPs have apparently been involved in allowing them to grow after exposure to living hyphae. The chitinase inhibitor allosamidin did not, in the case of Mucor, or only partially, in the cases of Chaetomium and Fusarium, repress mycolytic growth of the CbetaPs, indicating that chitinase activity alone could not explain the extent of bacterial proliferation. Chitinolytic Stenotrophomonas-like and Cytophaga-like bacteria, isolated from the same dune soils, were only slightly stimulated by exposure to fungal hyphae.

A proteomics approach to study synergistic and antagonistic interactions of the fungal-bacterial consortium Fusarium oxysporum wild-type MSA 35.

PubMed

Moretti, Marino; Grunau, Alexander; Minerdi, Daniela; Gehrig, Peter; Roschitzki, Bernd; Eberl, Leo; Garibaldi, Angelo; Gullino, Maria Lodovica; Riedel, Kathrin

2010-09-01

Fusarium oxysporum is an important plant pathogen that causes severe damage of many economically important crop species. Various microorganisms have been shown to inhibit this soil-borne plant pathogen, including non-pathogenic F. oxysporum strains. In this study, F. oxysporum wild-type (WT) MSA 35, a biocontrol multispecies consortium that consists of a fungus and numerous rhizobacteria mainly belonging to gamma-proteobacteria, was analyzed by two complementary metaproteomic approaches (2-DE combined with MALDI-Tof/Tof MS and 1-D PAGE combined with LC-ESI-MS/MS) to identify fungal or bacterial factors potentially involved in antagonistic or synergistic interactions between the consortium members. Moreover, the proteome profiles of F. oxysporum WT MSA 35 and its cured counter-part CU MSA 35 (WT treated with antibiotics) were compared with unravel the bacterial impact on consortium functioning. Our study presents the first proteome mapping of an antagonistic F. oxysporum strain and proposes candidate proteins that might play an important role for the biocontrol activity and the close interrelationship between the fungus and its bacterial partners.

Comparative genomics of the major fungal agents of human and animal Sporotrichosis: Sporothrix schenckii and Sporothrix brasiliensis.

PubMed

Teixeira, Marcus M; de Almeida, Luiz G P; Kubitschek-Barreira, Paula; Alves, Fernanda L; Kioshima, Erika S; Abadio, Ana K R; Fernandes, Larissa; Derengowski, Lorena S; Ferreira, Karen S; Souza, Rangel C; Ruiz, Jeronimo C; de Andrade, Nathalia C; Paes, Hugo C; Nicola, André M; Albuquerque, Patrícia; Gerber, Alexandra L; Martins, Vicente P; Peconick, Luisa D F; Neto, Alan Viggiano; Chaucanez, Claudia B; Silva, Patrícia A; Cunha, Oberdan L; de Oliveira, Fabiana F M; dos Santos, Tayná C; Barros, Amanda L N; Soares, Marco A; de Oliveira, Luciana M; Marini, Marjorie M; Villalobos-Duno, Héctor; Cunha, Marcel M L; de Hoog, Sybren; da Silveira, José F; Henrissat, Bernard; Niño-Vega, Gustavo A; Cisalpino, Patrícia S; Mora-Montes, Héctor M; Almeida, Sandro R; Stajich, Jason E; Lopes-Bezerra, Leila M; Vasconcelos, Ana T R; Felipe, Maria S S

2014-10-29

The fungal genus Sporothrix includes at least four human pathogenic species. One of these species, S. brasiliensis, is the causal agent of a major ongoing zoonotic outbreak of sporotrichosis in Brazil. Elsewhere, sapronoses are caused by S. schenckii and S. globosa. The major aims on this comparative genomic study are: 1) to explore the presence of virulence factors in S. schenckii and S. brasiliensis; 2) to compare S. brasiliensis, which is cat-transmitted and infects both humans and cats with S. schenckii, mainly a human pathogen; 3) to compare these two species to other human pathogens (Onygenales) with similar thermo-dimorphic behavior and to other plant-associated Sordariomycetes. The genomes of S. schenckii and S. brasiliensis were pyrosequenced to 17x and 20x coverage comprising a total of 32.3 Mb and 33.2 Mb, respectively. Pair-wise genome alignments revealed that the two species are highly syntenic showing 97.5% average sequence identity. Phylogenomic analysis reveals that both species diverged about 3.8-4.9 MYA suggesting a recent event of speciation. Transposable elements comprise respectively 0.34% and 0.62% of the S. schenckii and S. brasiliensis genomes and expansions of Gypsy-like elements was observed reflecting the accumulation of repetitive elements in the S. brasiliensis genome. Mitochondrial genomic comparisons showed the presence of group-I intron encoding homing endonucleases (HE's) exclusively in S. brasiliensis. Analysis of protein family expansions and contractions in the Sporothrix lineage revealed expansion of LysM domain-containing proteins, small GTPases, PKS type1 and leucin-rich proteins. In contrast, a lack of polysaccharide lyase genes that are associated with decay of plants was observed when compared to other Sordariomycetes and dimorphic fungal pathogens, suggesting evolutionary adaptations from a plant pathogenic or saprobic to an animal pathogenic life style. Comparative genomic data suggest a unique ecological shift in the

Elucidation of biocontrol mechanisms of Trichoderma harzianum against different plant fungal pathogens: Universal yet host specific response.

PubMed

Sharma, Vivek; Salwan, Richa; Sharma, Prem N; Kanwar, S S

2017-02-01

In the present study, different transcripts of Trichoderma harzianum ThHP-3 were evaluated for their response against four fungal pathogens Fusarium oxysporum, Colletotrichum capsici, Colletotrichum truncatum and Gloesercospora sorghi using RT-qPCR. The time course study of T. harzianum transcripts related to signal transduction, lytic enzymes, secondary metabolites and various transporters revealed variation in expression against four fungal pathogens. In a broader term, the transcripts were upregulated at various time intervals but the optimum expression of cyp3, abc, nrp, tga1, pmk, ech42 and glh20 varied with respect to host fungi. Additionally, the expression of transcripts related to transporters/cytochromes was also observed against Fusarium oxysporum after 96h whereas transcripts related to secondary metabolites and lytic enzymes showed significant difference in expression against Colletotrichum spp. from 72 to 96h. This is first study on transcriptomic response of T. harzianum against pathogenic fungi which shows their host specific response. Copyright © 2016 Elsevier B.V. All rights reserved.

Growth Promoting Rhizospheric and Endophytic Bacteria from Curcuma longa L. as Biocontrol Agents against Rhizome Rot and Leaf Blight Diseases.

PubMed

Vinayarani, G; Prakash, H S

2018-06-01

Plant growth promoting rhizobacteria and endophytic bacteria were isolated from different varieties of turmeric ( Curcuma longa L.) from South India. Totally 50 strains representing, 30 PGPR and 20 endophytic bacteria were identified based on biochemical assays and 16S rDNA sequence analysis. The isolates were screened for antagonistic activity against Pythium aphanidermatum (Edson) Fitzp., and Rhizoctonia solani Kuhn., causing rhizome rot and leaf blight diseases in turmeric, by dual culture and liquid culture assays. Results revealed that only five isolates of PGPR and four endophytic bacteria showed more than 70% suppression of test pathogens in both assays. The SEM studies of interaction zone showed significant ultrastructural changes of the hyphae like shriveling, breakage and desication of the pathogens by PGPR B. cereus (RBac-DOB-S24) and endophyte P. aeruginosa (BacDOB-E19). Selected isolates showed multiple Plant growth promoting traits. The rhizome bacterization followed by soil application of B. cereus (RBacDOB-S24) showed lowest Percent Disease Incidence (PDI) of rhizome rot and leaf blight, 16.4% and 15.5% respectively. Similarly, P. aeruginosa (BacDOB-E19) recorded PDI of rhizome rot (17.5%) and leaf blight (17.7%). The treatment of these promising isolates exhibited significant increase in plant height and fresh rhizome yield/plant in comparison with untreated control under greenhouse condition. Thereby, these isolates can be exploited as a potential biocontrol agent for suppressing rhizome rot and leaf blight diseases in turmeric.

Biocontrol of verticillium wilt and colonization of cotton plants by an endophytic bacterial isolate.

PubMed

Li, C-H; Shi, L; Han, Q; Hu, H-L; Zhao, M-W; Tang, C-M; Li, S-P

2012-09-01

To explore biocontrol potential of 39 DAEB isolates (doubly antagonistic towards both Verticillium dahliae Kleb and Fusarium oxysporum) against verticillium wilt of cotton and to elucidate colonization and category characteristics of an endophytic bacterium with significant biocontrol activity. Thirty-nine antagonistic endophytic bacteria strains were tested for their ability to control verticillium wilt in cotton plants caused by a defoliating pathotype of V. dahliae 107 in cotton under controlled conditions. The biocontrol trial revealed that an endophytic bacterium, designated HA02, showed a significant biocontrol activity to V. dahliae 107. After cotton seedlings were inoculated with a gfp gene-tagged HA02 (HA02-gfp), HA02-gfp populations were higher in the root than in the stem; in addition, the HA02-gfp was distributed in the maturation zone of cotton root. Furthermore, HA02-gfp also colonized seedlings of maize, rape and soybean after the bacteria inoculation. Phylogenetic trees based on 16S rDNA sequences combined with morphological, physiological and identification showed that the bacterium belongs to the Enterobacter genus. Our results showed that only 1 of 39 DAEB isolates demonstrated more efficient biocontrol potential towards V. dahliae 107 in greenhouse and field trials. HA02-gfp mainly colonized cotton in roots. In addition, we quantitatively observed HA02 colonization in other hosts. HA02 belongs to the Enterobacter genus. This is the first study on biocontrol to defoliating pathotype of V. dahliae Kleb by endophytic bacteria. The HA02 showed effective biocontrol to V. dahliae 107 in greenhouse and field trials. Furthermore, we assessed the quantitative and qualitative colonization of HA02 in cotton seedlings. Our study provides basic information to further explore managing strategies to control this critical disease. © 2012 The Authors Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

Oryctes virus--time for a new look at a useful biocontrol agent.

PubMed

Jackson, Trevor A; Crawford, Allan M; Glare, Travis R

2005-05-01

The introduction of Oryctes virus into outbreak areas of the rhinoceros beetle, Oryctes rhinoceros (Coleoptera: Scarabaeidae), has been a major success for "classical" biocontrol with a virus and has led to a dramatic reduction in palm damage in many areas of the Asia/Pacific region. In recent years, however, there have been new reports of high levels of rhinoceros beetle damage to palms. Damage has been especially intense in SE Asia following the introduction of no-burn polices for land clearance and replanting, but outbreaks have also been reported from some Pacific Islands where control seems to have diminished over time. SE Asian studies show that there is considerable genetic variation among endemic Oryctes virus isolates and studies in new island release areas have shown rapid evolution of the virus. The consequences of such genetic variation are in need of further study. Furthermore, the taxonomic position of the virus is unclear, with its removal from the Baculoviridae to an "unassigned' virus, reflecting its novel characteristics. Genomic sequencing could help resolve the taxonomy of the virus and provide a basis for studying strain variation. Oryctes virus has achieved wide success in the past without the benefit of molecular analysis and identification techniques. In order to fully take advantage of this unique pathogen for protection of palms, a renewed, coordinated effort centered on genetic selection and distribution of effective strains is required.

Impact of mild heat treatments on induction of thermotolerance in the biocontrol yeast Candida sake CPA-1 and viability after spray-drying.

PubMed

Cañamás, T P; Viñas, I; Usall, J; Magan, N; Solsona, C; Teixidó, N

2008-03-01

The objective of this study was to examine the induction of thermotolerance in the biocontrol agent Candida sake CPA-1 cells by mild heat treatments to enhanced survival of formulations using spray-drying. The possible role of heat-shock proteins (HSPs) biosynthesis in induced thermotolerance and the role of sugars and sugar alcohols were also determined. Studies were conducted on C. sake cells grown in molasses medium and exposed to mild temperatures of 30 and 33 degrees C during mid- (16 h), late-exponential (24 h), early- (30 h) and mid-stationary (36 h) growth phases. The effect on viability was determined both before and after spray-drying. Cycloheximide and chloramphenicol were used to examine the role of HSPs and HPLC was used to analyse the accumulation of sugar and sugar alcohols. The results indicate that both temperatures induced thermotolerance in cells of C. sake. Mild heat-adapted cells at 33 degrees C in the early- or mid-stationary phases had survival values after spray-drying significantly higher (P biocontrol yeasts such as C. sake. However, this does not improve survival of cells exposed to spray-drying sufficiently to consider this a suitable formulation method for this biocontrol agent. HSPs, sugars and sugar polyols were not directly responsible for induced thermotolerance in yeast cells. This type of information can be effectively applied to improve the viability of cells in the process of formulation.

Indigenous Pseudomonas spp. Strains from the Olive (Olea europaea L.) Rhizosphere as Effective Biocontrol Agents against Verticillium dahliae: From the Host Roots to the Bacterial Genomes

PubMed Central

Gómez-Lama Cabanás, Carmen; Legarda, Garikoitz; Ruano-Rosa, David; Pizarro-Tobías, Paloma; Valverde-Corredor, Antonio; Niqui, José L.; Triviño, Juan C.; Roca, Amalia; Mercado-Blanco, Jesús

2018-01-01

The use of biological control agents (BCA), alone or in combination with other management measures, has gained attention over the past decades, driven by the need to seek for sustainable and eco-friendly alternatives to confront plant pathogens. The rhizosphere of olive (Olea europaea L.) plants is a source of bacteria with potential as biocontrol tools against Verticillium wilt of olive (VWO) caused by Verticillium dahliae Kleb. A collection of bacterial isolates from healthy nursery-produced olive (cultivar Picual, susceptible to VWO) plants was generated based on morphological, biochemical and metabolic characteristics, chemical sensitivities, and on their in vitro antagonistic activity against several olive pathogens. Three strains (PIC25, PIC105, and PICF141) showing high in vitro inhibition ability of pathogens' growth, particularly against V. dahliae, were eventually selected. Their effectiveness against VWO caused by the defoliating pathotype of V. dahliae was also demonstrated, strain PICF141 being the rhizobacteria showing the best performance as BCA. Genotypic and phenotypic traits traditionally associated with plant growth promotion and/or biocontrol abilities were evaluated as well (e.g., phytase, xylanase, catalase, cellulase, chitinase, glucanase activities, and siderophore and HCN production). Multi-locus sequence analyses of conserved genes enabled the identification of these strains as Pseudomonas spp. Strain PICF141 was affiliated to the “Pseudomonas mandelii subgroup,” within the “Pseudomonas fluorescens group,” Pseudomonas lini being the closest species. Strains PIC25 and PIC105 were affiliated to the “Pseudomonas aeruginosa group,” Pseudomonas indica being the closest relative. Moreover, we identified P. indica (PIC105) for the first time as a BCA. Genome sequencing and in silico analyses allowed the identification of traits commonly associated with plant-bacteria interactions. Finally, the root colonization ability of these olive

Indigenous Pseudomonas spp. Strains from the Olive (Olea europaea L.) Rhizosphere as Effective Biocontrol Agents against Verticillium dahliae: From the Host Roots to the Bacterial Genomes.

PubMed

Gómez-Lama Cabanás, Carmen; Legarda, Garikoitz; Ruano-Rosa, David; Pizarro-Tobías, Paloma; Valverde-Corredor, Antonio; Niqui, José L; Triviño, Juan C; Roca, Amalia; Mercado-Blanco, Jesús

2018-01-01

The use of biological control agents (BCA), alone or in combination with other management measures, has gained attention over the past decades, driven by the need to seek for sustainable and eco-friendly alternatives to confront plant pathogens. The rhizosphere of olive ( Olea europaea L.) plants is a source of bacteria with potential as biocontrol tools against Verticillium wilt of olive (VWO) caused by Verticillium dahliae Kleb. A collection of bacterial isolates from healthy nursery-produced olive (cultivar Picual, susceptible to VWO) plants was generated based on morphological, biochemical and metabolic characteristics, chemical sensitivities, and on their in vitro antagonistic activity against several olive pathogens. Three strains (PIC25, PIC105, and PICF141) showing high in vitro inhibition ability of pathogens' growth, particularly against V. dahliae , were eventually selected. Their effectiveness against VWO caused by the defoliating pathotype of V. dahliae was also demonstrated, strain PICF141 being the rhizobacteria showing the best performance as BCA. Genotypic and phenotypic traits traditionally associated with plant growth promotion and/or biocontrol abilities were evaluated as well (e.g., phytase, xylanase, catalase, cellulase, chitinase, glucanase activities, and siderophore and HCN production). Multi-locus sequence analyses of conserved genes enabled the identification of these strains as Pseudomonas spp. Strain PICF141 was affiliated to the " Pseudomonas mandelii subgroup," within the " Pseudomonas fluorescens group," Pseudomonas lini being the closest species. Strains PIC25 and PIC105 were affiliated to the " Pseudomonas aeruginosa group," Pseudomonas indica being the closest relative. Moreover, we identified P. indica (PIC105) for the first time as a BCA. Genome sequencing and in silico analyses allowed the identification of traits commonly associated with plant-bacteria interactions. Finally, the root colonization ability of these olive

Production of Gentisyl Alcohol from Phoma herbarum Endophytic in Curcuma longa L. and Its Antagonistic Activity Towards Leaf Spot Pathogen Colletotrichum gloeosporioides.

PubMed

Gupta, Suruchi; Kaul, Sanjana; Singh, Baljinder; Vishwakarma, Ram A; Dhar, Manoj K

2016-11-01

Endophytes from medicinal plants represent a potential source of bioactive compounds. During the present investigation, fungal endophytes were isolated from turmeric (Curcuma longa), an important medicinal plant. A total of 207 endophytic fungal isolates were obtained from the rhizome of C. longa L. They were grouped into seven genera based on morphological and molecular data. The fungal endophytes of C. longa were evaluated for antifungal activity against Colletotrichum gloeosporioides, the causal organism of leaf spot of turmeric. The disease is a major cause for economic loss in turmeric cultivation. Endophytic Phoma herbarum showed significant activity against C. gloeosporioides and was therefore selected for further studies. A compound gentisyl alcohol was isolated from P. herbarum which showed effective antagonism against C. gloeosporioides. The organism could therefore be used as a biocontrol agent against C. gloeosporioides.

Bacterial and fungal keratitis in Upper Egypt: In vitro screening of enzymes, toxins and antifungal activity

PubMed Central

Gharamah, Abdullah A; Moharram, Ahmed M; Ismail, Mady A; AL-Hussaini, Ashraf K

2014-01-01

Purpose: This work was conducted to study the ability of bacterial and fungal isolates from keratitis cases in Upper Egypt to produce enzymes, toxins, and to test the isolated fungal species sensitivity to some therapeutic agents. Materials and Methods: One hundred and fifteen patients clinically diagnosed to have microbial keratitis were investigated. From these cases, 37 bacterial isolates and 25 fungal isolates were screened for their ability to produce extra-cellular enzymes in solid media. In addition, the ability of fungal isolates to produce mycotoxins and their sensitivity to 4 antifungal agents were tested. Results: Protease, lipase, hemolysins, urease, phosphatase, and catalase were detected respectively in 48.65%, 37.84%, 59.46%, 43.24%, 67.57%, and 100% out of 37 bacterial isolates tested. Out of 25 fungal isolates tested during the present study, 80% were positive for protease, 84% for lipase and urease, 28% for blood hemolysis, and 100% for phosphatase and catalase enzymes. Thirteen fungal isolates were able to produce detectable amounts of 7 mycotoxins in culture medium (aflatoxins (B1, B2, G1, and G2), sterigmatocystin, fumagillin, diacetoxyscirpenol, zearalenone, T-2 toxin, and trichodermin). Among the antifungal agents tested in this study, terbinafine showed the highest effect against most isolates in vitro. Conclusion: In conclusion, the ability of bacterial and fungal isolates to produce extracellular enzymes and toxins may be aid in the invasion and destruction of eye tissues, which, in turn, lead to vision loss. PMID:24008795

Nutrient Effects on Biocontrol of Penicillium roqueforti by Pichia anomala J121 during Airtight Storage of Wheat

PubMed Central

Druvefors, Ulrika Ädel; Passoth, Volkmar; Schnürer, Johan

2005-01-01

The biocontrol yeast Pichia anomala inhibits the growth of a variety of mold species. We examined the mechanism underlying the inhibition of the grain spoilage mold Penicillium roqueforti by the biocontrol yeast P. anomala J121 during airtight storage. The biocontrol effect in a model grain silo with moist wheat (water activity of 0.96) was enhanced when complex medium, maltose, or glucose was added. Supplementation with additional nitrogen or vitamin sources did not affect the biocontrol activity of the yeast. The addition of complex medium or glucose did not significantly influence the yeast cell numbers in the silos, whether in the presence or absence of P. roqueforti. Mold growth was not influenced by the addition of nutrients, if cultivated without yeast. The products of glucose metabolism, mainly ethanol and ethyl acetate, increased after glucose addition to P. anomala-inoculated treatments. Our results suggest that neither competition for nutrients nor production of a glucose-repressible cell wall lytic enzyme is the main mode of action of biocontrol by P. anomala in this grain system. Instead, the mold-inhibiting effect probably is due to the antifungal action of metabolites, most likely a combination of ethyl acetate and ethanol, derived from glycolysis. The discovery that sugar amendments enhance the biocontrol effect of P. anomala suggests novel ways of formulating biocontrol yeasts. PMID:15812013

Use of Endophytic and Rhizosphere Actinobacteria from Grapevine Plants To Reduce Nursery Fungal Graft Infections That Lead to Young Grapevine Decline

PubMed Central

Álvarez-Pérez, José Manuel; González-García, Sandra; Cobos, Rebeca; Olego, Miguel Ángel; Ibañez, Ana; Díez-Galán, Alba; Garzón-Jimeno, Enrique

2017-01-01

/or the root system. Although different strategies have recently been developed to protect pruning wounds using antifungal compounds (natural or synthetic) or biocontrol agents, no tools are yet available for controlling soil pathogens that infect plants through their root system. This study shows that different actinobacterial isolates, when applied to grafts in a nursery, can significantly reduce the infection rate caused by fungal pathogens that enter through the root system. This is a new, promising, and green alternative for preventing the decline of young grapevines in nurseries and vineyards. PMID:28986378

Use of Endophytic and Rhizosphere Actinobacteria from Grapevine Plants To Reduce Nursery Fungal Graft Infections That Lead to Young Grapevine Decline.

PubMed

Álvarez-Pérez, José Manuel; González-García, Sandra; Cobos, Rebeca; Olego, Miguel Ángel; Ibañez, Ana; Díez-Galán, Alba; Garzón-Jimeno, Enrique; Coque, Juan José R

2017-12-15

root system. Although different strategies have recently been developed to protect pruning wounds using antifungal compounds (natural or synthetic) or biocontrol agents, no tools are yet available for controlling soil pathogens that infect plants through their root system. This study shows that different actinobacterial isolates, when applied to grafts in a nursery, can significantly reduce the infection rate caused by fungal pathogens that enter through the root system. This is a new, promising, and green alternative for preventing the decline of young grapevines in nurseries and vineyards. Copyright © 2017 American Society for Microbiology.

Potential of genes and gene products from Trichoderma sp. and Gliocladium sp. for the development of biological pesticides.

PubMed

Lorito, M; Hayes, C K; Zoina, A; Scala, F; Del Sorbo, G; Woo, S L; Harman, G E

1994-12-01

Fungal cell wall degrading enzymes produced by the biocontrol fungi Trichoderma harzianum and Gliocladium virens are strong inhibitors of spore germination and hyphal elongation of a number of phytopathogenic fungi. The purified enzymes include chitinolytic enzymes with different modes of action or different substrate specificity and glucanolytic enzymes with exo-activity. A variety of synergistic interactions were found when different enzymes were combined or associated with biotic or abiotic antifungal agents. The levels of inhibition obtained by using enzyme combinations were, in some cases, comparable with commercial fungicides. Moreover, the antifungal interaction between enzymes and common fungicides allowed the reduction of the chemical doses up to 200-fold. Chitinolytic and glucanolytic enzymes from T. harzianum were able to improve substantially the antifungal ability of a biocontrol strain of Enterobacter cloacae. DNA fragments containing genes encoding for different chitinolytic enzymes were isolated from a cDNA library of T. harzianum and cloned for mechanistic studies and biocontrol purposes. Our results provide additional information on the role of lytic enzymes in processes of biocontrol and strongly suggest the use of lytic enzymes and their genes for biological control of plant diseases.

Genomic Encyclopedia of Fungi

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grigoriev, Igor

Genomes of fungi relevant to energy and environment are in focus of the Fungal Genomic Program at the US Department of Energy Joint Genome Institute (JGI). Its key project, the Genomics Encyclopedia of Fungi, targets fungi related to plant health (symbionts, pathogens, and biocontrol agents) and biorefinery processes (cellulose degradation, sugar fermentation, industrial hosts), and explores fungal diversity by means of genome sequencing and analysis. Over 150 fungal genomes have been sequenced by JGI to date and released through MycoCosm (www.jgi.doe.gov/fungi), a fungal web-portal, which integrates sequence and functional data with genome analysis tools for user community. Sequence analysis supportedmore » by functional genomics leads to developing parts list for complex systems ranging from ecosystems of biofuel crops to biorefineries. Recent examples of such parts suggested by comparative genomics and functional analysis in these areas are presented here.« less

Hintoniamine, a new calmodulin inhibitor from the endophytic fungal species 39140-2

USDA-ARS?s Scientific Manuscript database

A new fungal endophytic species (39140-2) was isolated from the medicinal plant Hintonia latiflora (Sessé et Mociño ex DC.) Bullock, a Rubiaceae widely used in Mexico as antidiabetic agent. Sequencing of the 28S fraction of the rDNA of this fungal strain and comparing with similar sequences for all ...

Biocontrol strategies for Mediterranean-style fermented sausages.

PubMed

Oliveira, Márcia; Ferreira, Vânia; Magalhães, Rui; Teixeira, Paula

2018-01-01

Naturally fermented meat sausages have a long tradition in Mediterranean countries and are one of the most important groups of traditional foods consumed throughout Europe. Despite all the advances in food science and technology and increased regulatory requirements and concerns for safety and quality during the last decades, the challenge to control important foodborne pathogens in this type of meat products still persists. Simultaneously, growing consumer interest in safe, high quality and minimal processed products, with less additives/preservatives have driven the food industry and scientists in a crusade for innovative technologies to maintain the safety of these products by natural means. Biological control (biocontrol) fits well within this tendency. This review summarizes the latest achievements on biocontrol strategies applied to Mediterranean-style fermented sausages, namely: (i) bioprotective cultures; (ii) bacteriocins; and, (iii) essential oils (EOs). Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparative analysis of the repertoire of G protein-coupled receptors of three species of the fungal genus Trichoderma

PubMed Central

2013-01-01

Background Eukaryotic organisms employ cell surface receptors such as the seven-transmembrane G protein-coupled receptors (GPCRs) as sensors to connect to the environment. GPCRs react to a variety of extracellular cues and are considered to play central roles in the signal transduction in fungi. Several species of the filamentous ascomycete Trichoderma are potent mycoparasites, i.e. can attack and parasitize other fungi, which turns them into successful bio-fungicides for the protection of plants against fungal phytopathogens. The identification and characterization of GPCRs will provide insights into how Trichoderma communicates with its environment and senses the presence of host fungi. Results We mined the recently published genomes of the two mycoparasitic biocontrol agents Trichoderma atroviride and Trichoderma virens and compared the identified GPCR-like proteins to those of the saprophyte Trichoderma reesei. Phylogenetic analyses resulted in 14 classes and revealed differences not only among the three Trichoderma species but also between Trichoderma and other fungi. The class comprising proteins of the PAQR family was significantly expanded both in Trichoderma compared to other fungi as well as in the two mycoparasites compared to T. reesei. Expression analysis of the PAQR-encoding genes of the three Trichoderma species revealed that all except one were actually transcribed. Furthermore, the class of receptors with a DUF300 domain was expanded in T. atroviride, and T. virens showed an expansion of PTH11-like receptors compared to T. atroviride and T. reesei. Conclusions Comparative genome analyses of three Trichoderma species revealed a great diversity of putative GPCRs with genus- and species- specific differences. The expansion of certain classes in the mycoparasites T. atroviride and T. virens is likely to reflect the capability of these fungi to establish various ecological niches and interactions with other organisms such as fungi and plants. These

A mathematical model of nutrient influence on fungal competition.

PubMed

Jabed A Choudhury, M; M J Trevelyan, Philip; P Boswell, Graeme

2018-02-07

Fungi have a well-established role in nutrient cycling and are widely used as agents in biological control and in the remediation of polluted landscapes. Competition for resources between different fungal communities is common in these contexts and its outcome impacts on the success of such biotechnological applications. In this investigation a mathematical model is constructed to represent competition between two fungal colonies that have access to different resources. It is shown that the model equations display a multitude of travelling wave solutions and that the outcome of competition between two fungal biomasses can be controlled through the simple manipulation of the nutrient resources available to each. The model equations are also numerically integrated to illustrate the range of outcomes arising from fungal competition and these results are placed in context of established experimental observations. Copyright © 2017 Elsevier Ltd. All rights reserved.

A nationwide survey of deep fungal infections and fungal prophylaxis after hematopoietic stem cell transplantation in Japan.

PubMed

Imataki, O; Kami, M; Kim, S-W; Gotoh, M; Komaba, S; Kasai, M; Hashino, S; Naito, K; Masuda, M; Anan, K; Teshima, H; Togitani, K; Inoue, T; Nishimura, M; Adachi, Y; Fukuhara, T; Yamashita, T; Uike, N; Kobayashi, Y; Hamaguchi, M; Higuchi, M; Kawakami, K; Takaue, Y

2004-06-01

We conducted a nationwide survey to define incidence of deep fungal infections and fungal prophylaxis practices after HSCT. In all, 63 institutions responded. Total number of in-patient transplantations was 935: 367 autologous, 414 allogeneic myeloablative, and 154 allogeneic reduced-intensity (RIST) (n=154). Number of patients who were cared for in a clean room at transplant was 261 (71%) in autologous, 409 (99%) in conventional and 93 (66%) in RIST, respectively. All patients received prophylactic antifungal agents; 89% fluconazole. Number of patients who received the dosage recommended in the CDC guidelines (400 mg/day) was 135 (42%) in conventional transplant and 34 (30%) in RIST (P=0.037). Number of patients who received fluconazole until engraftment and beyond day 75 in conventional transplant vs RIST was, respectively, 324 (100%) vs 109 (97%), and 39 (12%) vs 18 (16%), with no significant difference between the two groups. A total of 37 patients (4.0%) were diagnosed with deep fungal infections; autologous transplantation (0.03%), conventional transplantation (6.0%) and RIST (7.1%). Wide variations in antifungal prophylaxis practice according to the type of transplant and the institutions, and deep fungal infection remain significant problems in RIST.

The lipid language of plant-fungal interactions.

PubMed

Christensen, Shawn A; Kolomiets, Michael V

2011-01-01

Lipid mediated cross-kingdom communication between hosts and pathogens is a rapidly emerging field in molecular plant-fungal interactions. Amidst our growing understanding of fungal and plant chemical cross-talk lies the distinct, yet little studied, role for a group of oxygenated lipids derived from polyunsaturated fatty acids, termed oxylipins. Endogenous fungal oxylipins are known for their roles in carrying out pathogenic strategies to successfully colonize their host, reproduce, and synthesize toxins. While plant oxylipins also have functions in reproduction and development, they are largely recognized as agents that facilitate resistance to pathogen attack. Here we review the composition and endogenous functions of oxylipins produced by both plants and fungi and introduce evidence which suggests that fungal pathogens exploit host oxylipins to facilitate their own virulence and pathogenic development. Specifically, we describe how fungi induce plant lipid metabolism to utilize plant oxylipins in order to promote G-protein-mediated regulation of sporulation and mycotoxin production in the fungus. The use of host-ligand mimicry (i.e. coronatine) to manipulate plant defense responses that benefit the fungus are also implicated. Published by Elsevier Inc.

Commercialization of postharvest biocontrol: barriers and opportunities

USDA-ARS?s Scientific Manuscript database

The past twenty years has seen the field of postharvest biocontrol evolve from an unknown entity with one or two novel reports in the literature to a sophisticated science with strong research programs worldwide, hundreds of publications, patented technologies, and now several commercial products. ...

Effects of biological control agents and exotic plant invasion on deer mouse populations

Treesearch

Yvette K. Ortega; Dean E. Pearson; Kevin S. McKelvey

2004-01-01

Exotic insects are commonly introduced as biological control agents to reduce densities of invasive exotic plants. Although current biocontrol programs for weeds take precautions to minimize ecological risks, little attention is paid to the potential nontarget effects of introduced food subsidies on native consumers. Previous research demonstrated that two gall flies (...

Trans-Kingdom RNA Silencing in Plant-Fungal Pathogen Interactions.

PubMed

Hua, Chenlei; Zhao, Jian-Hua; Guo, Hui-Shan

2018-02-05

Fungal pathogens represent a major group of plant invaders that are the causative agents of many notorious plant diseases. Large quantities of RNAs, especially small RNAs involved in gene silencing, have been found to transmit bidirectionally between fungal pathogens and their hosts. Although host-induced gene silencing (HIGS) technology has been developed and applied to protect crops from fungal infections, the mechanisms of RNA transmission, especially small RNAs regulating trans-kingdom RNA silencing in plant immunity, are largely unknown. In this review, we summarize and discuss recent important findings regarding trans-kingdom sRNAs and RNA silencing in plant-fungal pathogen interactions compared with the well-known RNAi mechanisms in plants and fungi. We focus on the interactions between plant and fungal pathogens with broad hosts, represented by the vascular pathogen Verticillium dahliae and non-vascular pathogen Botrytis cinerea, and discuss the known instances of natural RNAi transmission between fungal pathogens and host plants. Given that HIGS has been developed and recently applied in controlling Verticillium wilt diseases, we propose an ideal research system exploiting plant vasculature-Verticillium interaction to further study trans-kingdom RNA silencing. Copyright © 2017 The Author. Published by Elsevier Inc. All rights reserved.

Discovery of secondary metabolites from Bacillus spp. biocontrol strains using genome mining and mass spectroscopy

USDA-ARS?s Scientific Manuscript database

Genome sequencing, data mining and mass spectrometry were used to identify secondary metabolites produced by several Bacillus spp. biocontrol strains. These biocontrol strains have shown promise in managing Fusarium head blight in wheat. Draft genomes were produced and screened in silico using genom...

What magnitude are observed non-target impacts from weed biocontrol?

PubMed

Suckling, David Maxwell; Sforza, René François Henri

2014-01-01

A systematic review focused by plant on non-target impacts from agents deliberately introduced for the biological control of weeds found significant non-target impacts to be rare. The magnitude of direct impact of 43 biocontrol agents on 140 non-target plants was retrospectively categorized using a risk management framework for ecological impacts of invasive species (minimal, minor, moderate, major, massive). The vast majority of agents introduced for classical biological control of weeds (>99% of 512 agents released) have had no known significant adverse effects on non-target plants thus far; major effects suppressing non-target plant populations could be expected to be detectable. Most direct non-target impacts on plants (91.6%) were categorized as minimal or minor in magnitude with no known adverse long-term impact on non-target plant populations, but a few cacti and thistles are affected at moderate (n = 3), major (n = 7) to massive (n = 1) scale. The largest direct impacts are from two agents (Cactoblastis cactorum on native cacti and Rhinocyllus conicus on native thistles), but these introductions would not be permitted today as more balanced attitudes exist to plant biodiversity, driven by both society and the scientific community. Our analysis shows (as far as is known), weed biological control agents have a biosafety track record of >99% of cases avoiding significant non-target impacts on plant populations. Some impacts could have been overlooked, but this seems unlikely to change the basic distribution of very limited adverse effects. Fewer non-target impacts can be expected in future because of improved science and incorporation of wider values. Failure to use biological control represents a significant opportunity cost from the certainty of ongoing adverse impacts from invasive weeds. It is recommended that a simple five-step scale be used to better communicate the risk of consequences from both action (classical biological control) and no

What Magnitude Are Observed Non-Target Impacts from Weed Biocontrol?

PubMed Central

Suckling, David Maxwell; Sforza, René François Henri

2014-01-01

A systematic review focused by plant on non-target impacts from agents deliberately introduced for the biological control of weeds found significant non-target impacts to be rare. The magnitude of direct impact of 43 biocontrol agents on 140 non-target plants was retrospectively categorized using a risk management framework for ecological impacts of invasive species (minimal, minor, moderate, major, massive). The vast majority of agents introduced for classical biological control of weeds (>99% of 512 agents released) have had no known significant adverse effects on non-target plants thus far; major effects suppressing non-target plant populations could be expected to be detectable. Most direct non-target impacts on plants (91.6%) were categorized as minimal or minor in magnitude with no known adverse long-term impact on non-target plant populations, but a few cacti and thistles are affected at moderate (n = 3), major (n = 7) to massive (n = 1) scale. The largest direct impacts are from two agents (Cactoblastis cactorum on native cacti and Rhinocyllus conicus on native thistles), but these introductions would not be permitted today as more balanced attitudes exist to plant biodiversity, driven by both society and the scientific community. Our analysis shows (as far as is known), weed biological control agents have a biosafety track record of >99% of cases avoiding significant non-target impacts on plant populations. Some impacts could have been overlooked, but this seems unlikely to change the basic distribution of very limited adverse effects. Fewer non-target impacts can be expected in future because of improved science and incorporation of wider values. Failure to use biological control represents a significant opportunity cost from the certainty of ongoing adverse impacts from invasive weeds. It is recommended that a simple five-step scale be used to better communicate the risk of consequences from both action (classical biological control) and no

Detection of two fungal biocontrol agents against root-knot nematodes by RAPD markers.

PubMed

Zhu, Ming Liang; Mo, Ming He; Xia, Zhen Yuan; Li, Yun Hua; Yang, Shu Jun; Li, Tian Fei; Zhang, Ke Qin

2006-05-01

The strain ZK7 of Pochonia chlamydosporia var. chlamydosporia and IPC of Paecilomyces lilacinus are highly effective in the biological control against root-knot nematodes infecting tobacco. When applied, they require a specific monitoring method to evaluate the colonization and dispersal in soil. In this work, the randomly amplified polymorphic DNA (RAPD) technique was used to differentiate between the two individual strains and 95 other isolates, including isolates of the same species and common soil fungi. This approach allowed the selection of specific fragments of 1.2 kb (Vc1200) and 2.0 kb (Vc2000) specific for ZK7, 1.4 kb (P1400) and 0.85 kb (P850) specific for IPC, using the random Primers OPL-02, OPD-05, OPD-05 and OPC-11, respectively. These fragments were cloned, sequenced, and used to design sequence-characterized amplification region (SCAR) primers specific for the two strains. In classical polymerase chain reaction (PCR), with serial dilution of ZK7 and IPC pure culture DNAs template, the detection limits of these oligonucleotide SCAR-PCR primers were found to be 10, 1000, 500, 100 pg, respectively. In the dot blotting, digoxigenin (DIG)-labeled amplicons from these four primers specifically recognized the corresponding fragments in the DNAs template of these two strains. The detection limit of these amplicons were 0.2, 0.2, 0.5, 0.5 mug, respectively.

DISSEMINATED FUNGAL INFECTION WITH ADRENAL INVOLVEMENT: REPORT OF TWO HIV NEGATIVE BRAZILIAN PATIENTS.

PubMed

Pereira, Graziella Hanna; Lanzoni, Valéria Pereira Barbosa; Beirão, Elisa Maria; Timerman, Artur; Melhem, Marcia de Souza Carvalho

2015-12-01

Paracoccidioidomycosis and histoplasmosis are systemic fungal infections endemic in Brazil. Disseminated clinical forms are uncommon in immunocompetent individuals. We describe two HIV-negative patients with disseminated fungal infections, paracoccidioidomycosis and histoplasmosis, who were diagnosed by biopsies of suprarenal lesions. Both were treated for a prolonged period with oral antifungal agents, and both showed favorable outcomes.

Fungal infections in burns: a comprehensive review

PubMed Central

Struck, M.F.; Gille, J.

2013-01-01

Summary Burn wound infections remain the most important factor limiting survival in burn intensive care units. Large wound surface, impaired immune systems, and broad-spectrum antibiotic therapy contribute to the growth of opportunistic fungal species. Faced with challenging fluid resuscitation, wound excision and cardiopulmonary stabilization, mycosis in burns are likely to be underestimated. Diagnostic performance can sometimes be delayed because clinical signs are unspecific and differentiation between colonization and infection is difficult. Therapeutic measures range from infection prophylaxis over treatment with antifungal agents towards radical amputation of infected limbs. New methods of early and reliable detection of fungal organisms, as well as the use of novel antifungal substances, are promising but require wider establishment to confirm the beneficial effects in burn patients. This review aims to highlight the main important aspects of fungal infections in burns including incidence, infection control, diagnostic and therapeutic approaches, prognosis and outcomes. PMID:24563641

Selection and characterization of Argentine isolates of Trichoderma harzianum for effective biocontrol of Septoria leaf blotch of wheat.

PubMed

Stocco, Marina C; Mónaco, Cecilia I; Abramoff, Cecilia; Lampugnani, Gladys; Salerno, Graciela; Kripelz, Natalia; Cordo, Cristina A; Consolo, Verónica F

2016-03-01

Species of the genus Trichoderma are economically important as biocontrol agents, serving as a potential alternative to chemical control. The applicability of Trichoderma isolates to different ecozones will depend on the behavior of the strains selected from each zone. The present study was undertaken to isolate biocontrol populations of Trichoderma spp. from the Argentine wheat regions and to select and characterize the best strains of Trichoderma harzianum by means of molecular techniques. A total of 84 out of the 240 strains of Trichoderma were able to reduce the disease severity of the leaf blotch of wheat. Thirty-seven strains were selected for the reduction equal to or greater than 50% of the severity, compared with the control. The percentage values of reduction of the pycnidial coverage ranged between 45 and 80%. The same last strains were confirmed as T. harzianum by polymerase chain reaction amplification of internal transcribed spacers, followed by sequencing. Inter-simple sequence repeat was used to examine the genetic variability among isolates. This resulted in a total of 132 bands. Further numerical analysis revealed 19 haplotypes, grouped in three clusters (I, II, III). Shared strains, with different geographical origins and isolated in different years, were observed within each cluster. The origin of the isolates and the genetic group were partially related. All isolates from Paraná were in cluster I, all isolates from Lobería were in cluster II, and all isolates from Pergamino and Santa Fe were in cluster III. Our results suggest that the 37 native strains of T. harzianum are important in biocontrol programs and could be advantageous for the preparation of biopesticides adapted to the agroecological conditions of wheat culture.

Enhancement of commercial antifungal agents by kojic acid

USDA-ARS?s Scientific Manuscript database

Kojic acid (KA), a natural by-product of fungal fermentation, is a commonly used food and cosmetic additive. We show that KA increases activity of amphotericin B and strobilurin, medical and agricultural antifungal agents, respectively, possibly targeting the fungal antioxidative system. KA shows pr...

Response of Vitis vinifera cell cultures to Eutypa lata and Trichoderma atroviride culture filtrates: expression of defence-related genes and phenotypes.

PubMed

Mutawila, C; Stander, C; Halleen, F; Vivier, M A; Mostert, L

2017-03-01

Cell suspension cultures of Vitis vinifera cv. Dauphine berries were used to study the response to the vascular pathogen, Eutypa lata, in comparison with a biological control agent, Trichoderma atroviride, that was previously shown to be effective in pruning wound protection. The expression of genes coding for enzymes of the phenylpropanoid pathway and pathogenesis-related (PR) proteins was profiled over a 48-h period using quantitative reverse transcriptase PCR. The cell cultures responded to elicitors of both fungi with a hypersensitive-like response that lead to a decrease in cell viability. Similar genes were triggered by both the pathogen and biocontrol agent, but the timing patterns and magnitude of expression was dependent on the specific fungal elicitor. Culture filtrates of both fungi caused upregulation of phenylalanine ammonia-lyase (PAL), 4-coumaroyl Co-A ligase (CCo-A) and stilbene synthase (STS), and a downregulation of chalcone synthase (CHS) genes. The pathogen filtrate caused a biphasic pattern in the upregulation of PAL and STS genes which was not observed in cells treated with filtrates of the biocontrol agent. Analytical assays showed significantly higher total phenolic content and chitinolytic enzyme activity in the cell cultures treated with the T. atroviride filtrate compared to the pathogen filtrate. These results corresponded well to the higher expression of PAL and chitinase class IV genes. The response of the cell cultures to T. atroviride filtrate provides support for the notion that the wound protection by the biocontrol agent at least partially relies on the induction of grapevine resistance mechanisms.

Trichoderma virens as a biocontrol of Toxocara canis: In vivo evaluation.

PubMed

de Souza Maia Filho, Fernando; da Silva Fonseca, Anelise Oliveira; Persici, Beatriz Maroneze; de Souza Silveira, Julia; Braga, Caroline Quintana; Pötter, Luciana; de Avila Botton, Sônia; Brayer Pereira, Daniela Isabel

Microorganisms have been widely studied as biological control agents of parasites of medical and veterinary importance. Coprophagous arthropods, bacteria and fungi are among the different organisms evaluated as potential biological control agents. Nematophagous fungi capture and digest the free forms of nematodes in the soil. Due to its zoonotic potential, Toxocara canis have been brought to the attention of researchers. The aim of the present study was to determine whether the administration of embryonated T. canis eggs exposed to the nematophagous fungus Trichoderma virens reduces parasite infection in experimental animals. Embryonated T. canis eggs were exposed to T. virens mycelium for 15 days at 25°C. Subsequently, 100 fungus-exposed eggs were orally administered to 20 Swiss mice. As a positive control, another 20 mice received 100 embryonated eggs that were not exposed to the fungus. After 48h, the animals were killed, and heart, lungs and liver were harvested for the recovery of larvae. The organs of the animals that received embryonated T. canis eggs exposed to the fungus showed a lower mean larval recovery when compared with the animals that received embryonated eggs without fungus exposure (p<0.05). The exposure of T. canis eggs to T. virens reduces the experimental infection, demonstrating the potential of this nematophagous fungus as a biocontrol agent. Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture

PubMed Central

Álvarez, Belén; Biosca, Elena G.

2017-01-01

Bacterial wilt diseases caused by Ralstonia solanacearum, R. pseudosolanacearum, and R. syzygii subsp. indonesiensis (former R. solanacearum species complex) are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the advantage of being environmentally friendly. Advances in bacterial wilt biocontrol include an increasing interest in bacteriophage-based treatments as a promising re-emerging strategy. Bacteriophages against the bacterial wilt pathogens have been described with either lytic or lysogenic effect but, they were proved to be active against strains belonging to R. pseudosolanacearum and/or R. syzygii subsp. indonesiensis, not to the present R. solanacearum species, and only two of them demonstrated successful biocontrol potential in planta. Despite the publication of three patents on the topic, until now no bacteriophage-based product is commercially available. Therefore, there is still much to be done to incorporate valid bacteriophages in an integrated management program to effectively fight bacterial wilt in the field. PMID:28769942

Bacteriophage-Based Bacterial Wilt Biocontrol for an Environmentally Sustainable Agriculture.

PubMed

Álvarez, Belén; Biosca, Elena G

2017-01-01

Bacterial wilt diseases caused by Ralstonia solanacearum , R. pseudosolanacearum , and R. syzygii subsp. indonesiensis (former R. solanacearum species complex) are among the most important plant diseases worldwide, severely affecting a high number of crops and ornamentals. Difficulties of bacterial wilt control by non-biological methods are related to effectiveness, bacterial resistance and environmental impact. Alternatively, a great many biocontrol strategies have been carried out, with the advantage of being environmentally friendly. Advances in bacterial wilt biocontrol include an increasing interest in bacteriophage-based treatments as a promising re-emerging strategy. Bacteriophages against the bacterial wilt pathogens have been described with either lytic or lysogenic effect but, they were proved to be active against strains belonging to R. pseudosolanacearum and/or R. syzygii subsp. indonesiensis , not to the present R. solanacearum species, and only two of them demonstrated successful biocontrol potential in planta . Despite the publication of three patents on the topic, until now no bacteriophage-based product is commercially available. Therefore, there is still much to be done to incorporate valid bacteriophages in an integrated management program to effectively fight bacterial wilt in the field.

Stress tolerance and biocontrol performance of the yeast antagonist, Candida diversa, change with morphology transition.

PubMed

Li, Guangkun; Chi, Mengshan; Chen, Huizhen; Sui, Yuan; Li, Yan; Liu, Yongsheng; Zhang, Xiaojing; Sun, Zhiqiang; Liu, Guoqing; Wang, Qi; Liu, Jia

2016-02-01

As an eco-friendly management method, biological control of postharvest diseases, utilizing antagonistic yeasts, is a research topic receiving considerable attention. Detailed knowledge on the biology of yeast antagonists is crucial when considering their potential application and development as biocontrol products. Changes in the growth form, such as single-cell to pseudohyphae, have been associated with the mode of action in postharvest biocontrol yeasts. In this study, the antagonistic yeast, Candida diversa, reversibly shifted from a single-cell morphology on yeast peptone dextrose (YPD) medium with 2 % agar to a pseudohyphal morphology on YPD with 0.3 % agar. The tolerance of the pseudohyphal form to heat and oxidative stresses, as well as the biocontrol efficacy against Botrytis cinerea on apple and kiwifruit stored at 25 and 4 °C, was significantly higher as compared to the single-cell form. This study provides new information on the ability of C. diversa to change its morphology and the impact of the morphology shift on stress tolerance and biocontrol performance.

DISSEMINATED FUNGAL INFECTION WITH ADRENAL INVOLVEMENT: REPORT OF TWO HIV NEGATIVE BRAZILIAN PATIENTS

PubMed Central

PEREIRA, Graziella Hanna; LANZONI, Valéria Pereira Barbosa; BEIRÃO, Elisa Maria; TIMERMAN, Artur; MELHEM, Marcia de Souza Carvalho

2015-01-01

Paracoccidioidomycosis and histoplasmosis are systemic fungal infections endemic in Brazil. Disseminated clinical forms are uncommon in immunocompetent individuals. We describe two HIV-negative patients with disseminated fungal infections, paracoccidioidomycosis and histoplasmosis, who were diagnosed by biopsies of suprarenal lesions. Both were treated for a prolonged period with oral antifungal agents, and both showed favorable outcomes. PMID:27049710

Aflatoxin-producing fungi in maize field soils from sea level to over 2000 masl: a three year study in Sonora, Mexico.

PubMed

Ortega-Beltran, Alejandro; Jaime, Ramon; Cotty, Peter J

2015-04-01

Aflatoxins, highly toxic carcinogens produced by several members of Aspergillus section Flavi, contaminate crops in temperate zones. In the state of Sonora, Mexico, maize is cultivated from 0 to 2100 masl with diverse cultivation practices. This is typical of the nation. In order to design better sampling strategies across Mexico, aflatoxin-producing fungal communities associated with maize production during 2006, 2007, and 2008 in Sonora were investigated in four agro-ecological zones (AEZ) at varying elevation. Fungal communities were dominated by the Aspergillus flavus L strain morphotype (46%), but variation occurred between years and among AEZ. Several atoxigenic isolates with potential to be used as biocontrol agents for aflatoxin mitigation were detected in all AEZ. The characteristics of each AEZ had minimal influences on fungal community structure and should not be a major consideration for future sampling designs for Mexico. Insights into the dynamics and stability of aflatoxin-producing fungal communities across AEZ are discussed. Published by Elsevier Ltd.

Fonsecaea Pedrosoi: A Rare Etiology in Fungal Keratitis

PubMed Central

Sangwan, Jyoti; Lathwal, Sumit; Juyal, Deepak; Sharma, Neelam

2013-01-01

Fungal corneal ulcer is common in India due to tropical climate and a large agrarian population that is at risk. Fonsecaea pedrosoi is the most common agent of chromoblastomycosis, a chronic localized fungal infection of the skin and subcutaneous tissues mainly involving lower extremities. We report a rare case of corneal chromoblastomycosis caused by F.pedrosoi, which was successfully treated with topical Amphotericin B followed by a long course of oral antifungal therapy. To the best of our knowledge, this is the first case of mycotic keratitis caused by F.pedrosoi, from the foothills of Himalayas. PMID:24298496

Miscellaneous fungal diseases

USGS Publications Warehouse

Friend, M.

1999-01-01

As for other types of disease, fungal infections probably are more common causes of disease in wild birds than is currently recognized. Also, the similarity in gross lesions produced by some fungi mask the detection of less common fungi as disease agents. Numerous types of disease-causing fungi in addition to Aspergillus fumigatus and Candida albicans have been isolated from birds; most isolations have been from poultry and wild birds being maintained in captivity. Enhanced disease surveillance that is often associated with privately owned birds and greater opportunity to detect disease in confined birds are reasons for these findings rather than any known differences in the occurrence of fungal diseases in free-ranging and captive birds. Many of the reported infections appear to have been opportunistic invasions by the fungi involved. The important points are that many fungi are capable of causing disease in birds but their collective impacts do not rival A. fumigatus as a single cause of disease in wild birds. Nevertheless, it is important to be aware of the diversity of pathogenic or disease causing fungi.

Identification and Characterization of Lipopeptides from Bacillus subtilis B1 Against Sapstain Fungus of Rubberwood Through MALDI-TOF-MS and RT-PCR.

PubMed

Sajitha, K L; Dev, Suma Arun; Maria Florence, E J

2016-07-01

Bacillus subtilis is a potent biocontrol agent producing a wide array of antifungal lipopeptides for the inhibition of fungal growth. B. subtilis B1 isolated from market-available compost provided an efficient control of rubberwood sapstain fungus, Lasiodiplodia theobromae. The current study is aimed to identify and characterize the lipopeptides responsible for the biocontrol of rubberwood sapstain fungus by Bacillus subtilis B1. The bacterial whole-cell surface extract from the dual culture of B. subtilis B1 and sapstain fungus (L. theobromae) was analysed using MALDI-TOF-MS. The protonated as well as sodium, potassium adducts of homologues of iturin C, surfactin, bacillomycin D and fengycin A and B were identified and expression of the lipopeptide biosynthetic genes could be confirmed through RT-PCR. This is the first report of mycobacillin and trimethylsilyl derivative of bacilysin during antagonism through MALDI-TOF-MS. MALDI-TOF-MS with RT-PCR offered easy platforms to characterize the antifungal lipopeptides. The identification of antifungal lipopeptides can lead to the formulation of prospective biocontrol by-products which have wide-scale utility.

Biocontrol of tomato wilt disease by Bacillus subtilis isolates from natural environments depends on conserved genes mediating biofilm formation

PubMed Central

Liu, Hongxia; Kolter, Roberto; Losick, Richard; Guo, Jian-hua

2014-01-01

Summary Bacillus subtilis and other Bacilli have long been used as biological control agents against plant bacterial diseases but the mechanisms by which the bacteria confer protection are not well understood. Our goal in this study was to isolate strains of B. subtilis that exhibit high levels of biocontrol efficacy from natural environments and to investigate the mechanisms by which these strains confer plant protection. We screened a total of sixty isolates collected from various locations across China and obtained six strains that exhibited above 50% biocontrol efficacy on tomato plants against the plant pathogen Ralstonia solanacearum under greenhouse conditions. These wild strains were able to form robust biofilms both in defined medium and on tomato plant roots and exhibited strong antagonistic activities against various plant pathogens in plate assays. We show that plant protection by those strains depended on widely conserved genes required for biofilm formation, including regulatory genes and genes for matrix production. We provide evidence suggesting that matrix production is critical for bacterial colonization on plant root surfaces. Finally, we have established a model system for studies of B. subtilis-tomato plant interactions in protection against a plant pathogen. PMID:22934631

Auxin as a player in the biocontrol of Fusarium head blight disease of barley and its potential as a disease control agent.

PubMed

Petti, Carloalberto; Reiber, Kathrin; Ali, Shahin S; Berney, Margaret; Doohan, Fiona M

2012-11-22

Mechanisms involved in the biological control of plant diseases are varied and complex. Hormones, including the auxin indole acetic acid (IAA) and abscisic acid (ABA), are essential regulators of a multitude of biological functions, including plant responses to biotic and abiotic stressors. This study set out to determine what hormones might play a role in Pseudomonas fluorescens -mediated control of Fusarium head blight (FHB) disease of barley and to determine if biocontrol-associated hormones directly affect disease development. A previous study distinguished bacterium-responsive genes from bacterium-primed genes, distinguished by the fact that the latter are only up-regulated when both P. fluorescens and the pathogen Fusarium culmorum are present. In silico analysis of the promoter sequences available for a subset of the bacterium-primed genes identified several hormones, including IAA and ABA as potential regulators of transcription. Treatment with the bacterium or pathogen resulted in increased IAA and ABA levels in head tissue; both microbes had additive effects on the accumulation of IAA but not of ABA. The microbe-induced accumulation of ABA preceded that of IAA. Gene expression analysis showed that both hormones up-regulated the accumulation of bacterium-primed genes. But IAA, more than ABA up-regulated the transcription of the ABA biosynthesis gene NCED or the signalling gene Pi2, both of which were previously shown to be bacterium-responsive rather than primed. Application of IAA, but not of ABA reduced both disease severity and yield loss caused by F. culmorum, but neither hormone affect in vitro fungal growth. Both IAA and ABA are involved in the P. fluorescens-mediated control of FHB disease of barley. Gene expression studies also support the hypothesis that IAA plays a role in the primed response to F. culmorum. This hypothesis was validated by the fact that pre-application of IAA reduced both symptoms and yield loss asssociated with the disease

Auxin as a player in the biocontrol of Fusarium head blight disease of barley and its potential as a disease control agent

PubMed Central

2012-01-01

Background Mechanisms involved in the biological control of plant diseases are varied and complex. Hormones, including the auxin indole acetic acid (IAA) and abscisic acid (ABA), are essential regulators of a multitude of biological functions, including plant responses to biotic and abiotic stressors. This study set out to determine what hormones might play a role in Pseudomonas fluorescens –mediated control of Fusarium head blight (FHB) disease of barley and to determine if biocontrol-associated hormones directly affect disease development. Results A previous study distinguished bacterium-responsive genes from bacterium-primed genes, distinguished by the fact that the latter are only up-regulated when both P. fluorescens and the pathogen Fusarium culmorum are present. In silico analysis of the promoter sequences available for a subset of the bacterium-primed genes identified several hormones, including IAA and ABA as potential regulators of transcription. Treatment with the bacterium or pathogen resulted in increased IAA and ABA levels in head tissue; both microbes had additive effects on the accumulation of IAA but not of ABA. The microbe-induced accumulation of ABA preceded that of IAA. Gene expression analysis showed that both hormones up-regulated the accumulation of bacterium-primed genes. But IAA, more than ABA up-regulated the transcription of the ABA biosynthesis gene NCED or the signalling gene Pi2, both of which were previously shown to be bacterium-responsive rather than primed. Application of IAA, but not of ABA reduced both disease severity and yield loss caused by F. culmorum, but neither hormone affect in vitro fungal growth. Conclusions Both IAA and ABA are involved in the P. fluorescens-mediated control of FHB disease of barley. Gene expression studies also support the hypothesis that IAA plays a role in the primed response to F. culmorum. This hypothesis was validated by the fact that pre-application of IAA reduced both symptoms and yield loss

Comparative transcriptome analysis of the biocontrol strain Bacillus amyloliquefaciens FZB42 as response to biofilm formation analyzed by RNA sequencing.

PubMed

Kröber, Magdalena; Verwaaijen, Bart; Wibberg, Daniel; Winkler, Anika; Pühler, Alfred; Schlüter, Andreas

2016-08-10

The strain Bacillus amyloliquefaciens FZB42 is a plant growth promoting rhizobacterium (PGPR) and biocontrol agent known to keep infections of lettuce (Lactuca sativa) by the phytopathogen Rhizoctonia solani down. Several mechanisms, including the production of secondary metabolites possessing antimicrobial properties and induction of the host plant's systemic resistance (ISR), were proposed to explain the biocontrol effect of the strain. B. amyloliquefaciens FZB42 is able to form plaques (biofilm-like structures) on plant roots and this feature was discussed to be associated with its biocontrol properties. For this reason, formation of B. amyloliquefaciens biofilms was studied at the transcriptional level using high-throughput sequencing of whole transcriptome cDNA libraries from cells grown under biofilm-forming conditions vs. planktonic growth. Comparison of the transcriptional profiles of B. amyloliquefaciens FZB42 under these growth conditions revealed a common set of highly transcribed genes mostly associated with basic cellular functions. The lci gene, encoding an antimicrobial peptide (AMP), was among the most highly transcribed genes of cells under both growth conditions suggesting that AMP production may contribute to biocontrol. In contrast, gene clusters coding for synthesis of secondary metabolites with antimicrobial properties were only moderately transcribed and not induced in biofilm-forming cells. Differential gene expression revealed that 331 genes were significantly up-regulated and 230 genes were down-regulated in the transcriptome of B. amyloliquefaciens FZB42 under biofilm-forming conditions in comparison to planktonic cells. Among the most highly up-regulated genes, the yvqHI operon, coding for products involved in nisin (class I bacteriocin) resistance, was identified. In addition, an operon whose products play a role in fructosamine metabolism was enhanced in its transcription. Moreover, genes involved in the production of the extracellular

Cow dung extract: a medium for the growth of pseudomonads enhancing their efficiency as biofertilizer and biocontrol agent in rice.

PubMed

Srivastava, Rashmi; Aragno, Michel; Sharma, A K

2010-09-01

Some pseudomands are being utilized as biofertilizers and biopesticides because of their role in plant growth promotion and plant protection against root parasites, respectively. Two strains of Pseudomonas, P. jessenii LHRE62 and P. synxantha HHRE81, recovered from wheat rhizosphere, have shown their potential in field bioinoculation tests under rice-wheat and pulse-wheat rotation systems. Normally, pseudomonads are cultivated on synthetic media-like King's B and used for inoculation on seeds/soil drench with talcum or charcoal as carrier material. Cow dung is being used for different purposes from the ancient time and has a significant role in crop growth because of the content in humic compounds and fertilizing bioelements available in it. Here, cow dung extract was tested as a growth medium for strains LHRE62 and HHRE81, in comparison with growth in King's B medium. The log phase was delayed by 2 h as compared to growth in King's B medium. The bacterial growth yield, lower in plain cow dung extract as compared to King's B medium, was improved upon addition of different carbon substrates. Growth of rice var. Pant Dhan 4 in pot cultures was increased using liquid formulation of cow dung extract and bacteria as foliar spray, compared to their respective controls. Biocontrol efficacy of the bioagents was assessed by challenging rice crop with Rhizoctonia solani, a sheath blight pathogen. The growth promotion and biocontrol efficiencies were more pronounced in the case of mixed inocula of strains LHRE62 and HHRE81.

Antifungal Activity of Isolated Bacillus amyloliquefaciens SYBC H47 for the Biocontrol of Peach Gummosis.

PubMed

Li, Xunhang; Zhang, Yanzhou; Wei, Zhiwen; Guan, Zhengbing; Cai, Yujie; Liao, Xiangru

2016-01-01

and the growth of mycelia from B. dothidea; therefore, this strain behaves as a potential biocontrol agent against the gummosis disease.

Bacterial and fungal endophthalmitis in upper Egypt: related species and risk factors.

PubMed

Gharamah, A A; Moharram, A M; Ismail, M A; Al-Hussaini, A K

2012-08-01

To study risk factors, contributing factors of bacterial and fungal endophthalmitis in Upper Egypt, test the isolated species sensitive to some therapeutic agents, and to investigate the air-borne bacteria and fungi in opthalmology operating rooms. Thirty one cases of endophthalmitis were clinically diagnosed and microbiologically studied. Indoor air-borne bacteria and fungi inside four air-conditioned operating rooms in the Ophthalmology Department at Assiut University Hospitals were also investigated. The isolated microbes from endophthalmitis cases were tested for their ability to produce some extracellular enzymes including protease, lipase, urease, phosphatase and catalase. Also the ability of 5 fungal isolates from endophthalmitis origin to produce mycotoxins and their sensitivity to some therapeutic agents were studied. Results showed that bacteria and fungi were responsihle for infection in 10 and 6 cases of endophthalmitis, respectively and only 2 cases produced a mixture of bacteria and fungi. Trauma was the most prevalent risk factor of endophthalmitis where 58.1% of the 31 cases were due to trauma. In ophthalmology operating rooms, different bacterial and fungal species were isolated. 8 bacterial and 5 fungal isolates showed their ability to produce enzymes while only 3 fungal isolates were able to produce mycotoxins. Terbinafine showed the highest effect against most isolates in vitro. The ability of bacterial and fungal isolates to produce extracellular enzymes and mycotoxins may be aid in the invasion and destruction of eye tissues. Microbial contamination of operating rooms with air-borne bacteria and fungi in the present work may be a source of postoperative endophthalmitis.

Single-kernel analysis of fumonisins and other fungal metabolites in maize from South African subsistence farmers.

PubMed

Mogensen, J M; Sørensen, S M; Sulyok, M; van der Westhuizen, L; Shephard, G S; Frisvad, J C; Thrane, U; Krska, R; Nielsen, K F

2011-12-01

Fumonisins are important Fusarium mycotoxins mainly found in maize and derived products. This study analysed maize from five subsistence farmers in the former Transkei region of South Africa. Farmers had sorted kernels into good and mouldy quality. A total of 400 kernels from 10 batches were analysed; of these 100 were visually characterised as uninfected and 300 as infected. Of the 400 kernels, 15% were contaminated with 1.84-1428 mg kg(-1) fumonisins, and 4% (n=15) had a fumonisin content above 100 mg kg(-1). None of the visually uninfected maize had detectable amounts of fumonisins. The total fumonisin concentration was 0.28-1.1 mg kg(-1) for good-quality batches and 0.03-6.2 mg kg(-1) for mouldy-quality batches. The high fumonisin content in the batches was apparently caused by a small number (4%) of highly contaminated kernels, and removal of these reduced the average fumonisin content by 71%. Of the 400 kernels, 80 were screened for 186 microbial metabolites by liquid chromatography-tandem mass spectrometry, detecting 17 other fungal metabolites, including fusaric acid, equisetin, fusaproliferin, beauvericin, cyclosporins, agroclavine, chanoclavine, rugulosin and emodin. Fusaric acid in samples without fumonisins indicated the possibility of using non-toxinogenic Fusaria as biocontrol agents to reduce fumonisin exposure, as done for Aspergillus flavus. This is the first report of mycotoxin profiling in single naturally infected maize kernels. © 2011 Taylor & Francis

De novo transcriptome analyses of host-fungal interactions in oil palm (Elaeis guineensis Jacq.).

PubMed

Ho, Chai-Ling; Tan, Yung-Chie; Yeoh, Keat-Ai; Ghazali, Ahmad-Kamal; Yee, Wai-Yan; Hoh, Chee-Choong

2016-01-19

Basal stem rot (BSR) is a fungal disease in oil palm (Elaeis guineensis Jacq.) which is caused by hemibiotrophic white rot fungi belonging to the Ganoderma genus. Molecular responses of oil palm to these pathogens are not well known although this information is crucial to strategize effective measures to eradicate BSR. In order to elucidate the molecular interactions between oil palm and G. boninense and its biocontrol fungus Trichoderma harzianum, we compared the root transcriptomes of untreated oil palm seedlings with those inoculated with G. boninense and T. harzianum, respectively. Differential gene expression analyses revealed that jasmonate (JA) and salicylate (SA) may act in an antagonistic manner in affecting the hormone biosynthesis, signaling, and downstream defense responses in G. boninense-treated oil palm roots. In addition, G. boninense may compete with the host to control disease symptom through the transcriptional regulation of ethylene (ET) biosynthesis, reactive oxygen species (ROS) production and scavenging. The strengthening of host cell walls and production of pathogenesis-related proteins as well as antifungal secondary metabolites in host plants, are among the important defense mechanisms deployed by oil palm against G. boninense. Meanwhile, endophytic T. harzianum was shown to improve the of nutrition status and nutrient transportation in host plants. The findings of this analysis have enhanced our understanding on the molecular interactions of G. boninense and oil palm, and also the biocontrol mechanisms involving T. harzianum, thus contributing to future formulations of better strategies for prevention and treatment of BSR.

Biocontrol in an impulsive predator-prey model.

PubMed

Terry, Alan J

2014-10-01

We study a model for biological pest control (or "biocontrol") in which a pest population is controlled by a program of periodic releases of a fixed yield of predators that prey on the pest. Releases are represented as impulsive increases in the predator population. Between releases, predator-pest dynamics evolve according to a predator-prey model with some fairly general properties: the pest population grows logistically in the absence of predation; the predator functional response is either of Beddington-DeAngelis type or Holling type II; the predator per capita birth rate is bounded above by a constant multiple of the predator functional response; and the predator per capita death rate is allowed to be decreasing in the predator functional response and increasing in the predator population, though the special case in which it is constant is permitted too. We prove that, when the predator functional response is of Beddington-DeAngelis type and the predators are not sufficiently voracious, then the biocontrol program will fail to reduce the pest population below a particular economic threshold, regardless of the frequency or yield of the releases. We prove also that our model possesses a pest-eradication solution, which is both locally and globally stable provided that predators are sufficiently voracious and that releases occur sufficiently often. We establish, curiously, that the pest-eradication solution can be locally stable whilst not being globally stable, the upshot of which is that, if we delay a biocontrol response to a new pest invasion, then this can change the outcome of the response from pest eradication to pest persistence. Finally, we state a number of specific examples for our model, and, for one of these examples, we corroborate parts of our analysis by numerical simulations. Copyright © 2014 Elsevier Inc. All rights reserved.

Living fungal hyphae-templated porous gold microwires using nanoparticles as building blocks

NASA Astrophysics Data System (ADS)

Rehman, Asma; Majeed, Muhammad Irfan; Ihsan, Ayesha; Hussain, Syed Zajif; Saif-ur-Rehman; Ghauri, Muhammad Afzal; Khalid, Zafar M.; Hussain, Irshad

2011-12-01

A simple and environmentally benign green method is reported to decorate growing fungal hyphae with high loading of gold nanoparticles, which were initially produced using aqueous tea extract as a sole reducing/stabilizing agent. Inoculation of fungal spores in aqueous suspension of nanoparticles led to the growth of intensely red-coloured fungal hyphae due to the accumulation of gold nanoparticles. Heat treatment of these hybrid materials led to the formation of porous gold microwires. This report is thus an interesting example of using green and sustainable approach to produce nanostructured materials which have potential applications in catalysis, sensing and electronics.

Attachment Capability of Antagonistic Yeast Rhodotorula glutinis to Botrytis cinerea Contributes to Biocontrol Efficacy.

PubMed

Li, Boqiang; Peng, Huaimin; Tian, Shiping

2016-01-01

Rhodotorula glutinis as an antagonism show good biocontrol performance against various post-harvest diseases in fruits. In the present study, strong attachment capability of R. glutinis to spores and hyphae of Botrytis cinerea was observed. Further analysis showed that certain protein components on the yeast cell surface played critical role during the interaction between R. glutinis and B. cinerea. The components mainly distributed at the poles of yeast cells and might contain glycosylation modification, as tunicamycin treated yeast cells lost attachment capability to B. cinerea. To investigate contributions of attachment capability of R. glutinis to its biocontrol efficacy, yeast cells were mutagenized with 3% methane-sulfonic acid ethyl ester (EMS), and a mutant CE4 with stable non-attaching phenotype was obtained. No significant difference was found on colony, cell morphology, reproductive ability, and capsule formation between the mutant and wild-type. However, there was a distinct difference in India ink positive staining patterns between the two strains. Moreover, wild-type strain of R. glutinis showed better performance on inhibiting spore germination and mycelial growth of B. cinerea than CE4 strain when yeast cells and B. cinerea were co-cultured in vitro. In biocontrol assay, both wild-type and CE4 strains showed significant biocontrol efficacy against gray mold caused by B. cinerea in apple fruit, whereas, control effect of CE4 strain was lower than that of wild-type. Our findings provided new evidences that attachment capability of R. glutinis to B. cinerea contributed to its biocontrol efficacy.

Attachment Capability of Antagonistic Yeast Rhodotorula glutinis to Botrytis cinerea Contributes to Biocontrol Efficacy

PubMed Central

Li, Boqiang; Peng, Huaimin; Tian, Shiping

2016-01-01

Rhodotorula glutinis as an antagonism show good biocontrol performance against various post-harvest diseases in fruits. In the present study, strong attachment capability of R. glutinis to spores and hyphae of Botrytis cinerea was observed. Further analysis showed that certain protein components on the yeast cell surface played critical role during the interaction between R. glutinis and B. cinerea. The components mainly distributed at the poles of yeast cells and might contain glycosylation modification, as tunicamycin treated yeast cells lost attachment capability to B. cinerea. To investigate contributions of attachment capability of R. glutinis to its biocontrol efficacy, yeast cells were mutagenized with 3% methane-sulfonic acid ethyl ester (EMS), and a mutant CE4 with stable non-attaching phenotype was obtained. No significant difference was found on colony, cell morphology, reproductive ability, and capsule formation between the mutant and wild-type. However, there was a distinct difference in India ink positive staining patterns between the two strains. Moreover, wild-type strain of R. glutinis showed better performance on inhibiting spore germination and mycelial growth of B. cinerea than CE4 strain when yeast cells and B. cinerea were co-cultured in vitro. In biocontrol assay, both wild-type and CE4 strains showed significant biocontrol efficacy against gray mold caused by B. cinerea in apple fruit, whereas, control effect of CE4 strain was lower than that of wild-type. Our findings provided new evidences that attachment capability of R. glutinis to B. cinerea contributed to its biocontrol efficacy. PMID:27199931

The ABC transporter ABCG29 is involved in H2O2 tolerance and biocontrol traits in the fungus Clonostachys rosea.

PubMed

Dubey, Mukesh; Jensen, Dan Funck; Karlsson, Magnus

2016-04-01

For successful biocontrol interactions, biological control organisms must tolerate toxic metabolites produced by themselves or plant pathogens during mycoparasitic/antagonistic interactions, by host plant during colonization of the plant, and xenobiotics present in the environment. ATP-binding cassette (ABC) transporters can play a significant role in tolerance of toxic compounds by mediating active transport across the cellular membrane. This paper reports on functional characterization of an ABC transporter ABCG29 in the biocontrol fungus Clonostachys rosea strain IK726. Gene expression analysis showed induced expression of abcG29 during exposure to the Fusarium spp. mycotoxin zearalenone (ZEA) and the fungicides Cantus, Chipco Green and Apron. Expression of abcG29 in C. rosea was significantly higher during C. rosea-C. rosea (Cr-Cr) interaction or in exposure to C. rosea culture filtrate for 2 h, compared to interaction with Fusarium graminearum or 2 h exposure to F. graminearum culture filtrate. In contrast with gene expression data, ΔabcG29 strains did not display reduced tolerance towards ZEA, fungicides or chemical agents known for inducing oxidative, cell wall or osmotic stress, compared to C. rosea WT. The exception was a significant reduction in tolerance to H2O2 (10 mM) in ΔabcG29 strains when conidia were used as an inoculum. The antagonistic ability of ΔabcG29 strains towards F. graminearum, Fusarium oxysporum or Botrytis cinerea in dual plate assays were not different compared with WT. However, in biocontrol assays ΔabcG29 strains displayed reduced ability to protect Arabidopsis thaliana leaves from B. cinerea, and barley seedling from F. graminearum as measured by an A. thaliana detached leaf assay and a barley foot rot disease assay, respectively. These data show that the ABCG29 is dispensable for ZEA and fungicides tolerance, and antagonism but not H2O2 tolerance and biocontrol effects in C. rosea.

Efficacy of fungal and bacterial antagonists for controlling growth, FUM1 gene expression and fumonisin B1 production by Fusarium verticillioides on maize cobs of different ripening stages.

PubMed

Samsudin, Nik Iskandar Putra; Rodriguez, Alicia; Medina, Angel; Magan, Naresh

2017-04-04

This study was carried out to examine the efficacy of two biocontrol agents (Clonostachys rosea 016, BCA1; Gram-negative bacterium, BCA5) for control of FUM1 gene expression and fumonisin B 1 (FB 1 ) production by F. verticillioides FV1 on maize cobs of different ripening stages: R 3 , Milk (0.985 a w ); R 4 , Dough (0.976 a w ); R 5 , Dent (0.958 a w ). Initially, temporal studies on FUM1 gene expression and FB 1 production were performed on maize kernels for up to 14days. This revealed that day 10 was optimum for both parameters, and was used in the biocontrol studies. Maize cobs were inoculated with 50:50 mixtures of the pathogen:antagonist inoculum and incubated in environmental chambers to maintain the natural a w conditions for ten days at 25 and 30°C. The growth rates of F. verticillioides FV1, the relative expression of the FUM1 gene and FB 1 production were quantified. It was found that, a w ×temp had significant impacts on growth, FUM1 gene expression and FB 1 production by F. verticillioides FV1 on maize cobs of different maturities. The fungal antagonist (BCA1) significantly reduced FB 1 contamination on maize cobs by >70% at 25°C, and almost 60% at 30°C regardless of maize ripening stage. For the bacterial antagonist (BCA5) however, FB 1 levels on maize cobs were significantly decreased only in some treatments. These results suggest that efficacy of antagonists to control mycotoxin production in ripening maize cobs needs to take account of the ecophysiology of the pathogen and the antagonists, as well as the physiological status of the maize during silking to ensure effective control. Copyright © 2017 Elsevier B.V. All rights reserved.

The use of wavelength-selective plastic cladding materials in horticulture: understanding of crop and fungal responses through the assessment of biological spectral weighting functions.

PubMed

Paul, Nigel D; Jacobson, Rob J; Taylor, Anna; Wargent, Jason J; Moore, Jason P

2005-01-01

Plant responses to light spectral quality can be exploited to deliver a range of agronomically desirable end points in protected crops. This can be achieved using plastics with specific spectral properties as crop covers. We have studied the responses of a range of crops to plastics that have either (a) increased transmission of UV compared with standard horticultural covers, (b) decreased transmission of UV or (c) increased the ratio of red (R) : far-red (FR) radiation. Both the UV-transparent and R : FR increasing films reduced leaf area and biomass, offering potential alternatives to chemical growth regulators. The UV-opaque film increased growth, but while this may be useful in some crops, there were trade-offs with elements of quality, such as pigmentation and taste. UV manipulation may also influence disease control. Increasing UV inhibited not only the pathogenic fungus Botrytis cinerea but also the disease biocontrol agent Trichoderma harzianum. Unlike B. cinerea, T. harzianum was highly sensitive to UV-A radiation. These fungal responses and those for plant growth in the growth room and the field under different plastics are analyzed in terms of alternative biological spectral weighting functions (BSWF). The role of BSWF in assessing general patterns of response to UV modification in horticulture is also discussed.

Cost modeling of pseudomonoas fluorescens and pseudomonoas chlororphis biocontrol for competitive exclusion of salmonella enterica on tomatoes

USDA-ARS?s Scientific Manuscript database

Biocontrol measures may enhance postharvest interventions, however; published research on process-based models for biocontrol of foodborne pathogens on produce is limited. The aim of this research was to develop cost model estimates for competitive exclusion process using Pseudomonas fluorescens and...

Isolation and Characterization of phiLLS, a Novel Phage with Potential Biocontrol Agent against Multidrug-Resistant Escherichia coli

PubMed Central

Amarillas, Luis; Rubí-Rangel, Lucia; Chaidez, Cristobal; González-Robles, Arturo; Lightbourn-Rojas, Luis; León-Félix, Josefina

2017-01-01

Foodborne diseases are a serious and growing problem, and the incidence and prevalence of antimicrobial resistance among foodborne pathogens is reported to have increased. The emergence of antibiotic-resistant bacterial strains demands novel strategies to counteract this epidemic. In this regard, lytic bacteriophages have reemerged as an alternative for the control of pathogenic bacteria. However, the effective use of phages relies on appropriate biological and genomic characterization. In this study, we present the isolation and characterization of a novel bacteriophage named phiLLS, which has shown strong lytic activity against generic and multidrug-resistant Escherichia coli strains. Transmission electron microscopy of phiLLS morphology revealed that it belongs to the Siphoviridae family. Furthermore, this phage exhibited a relatively large burst size of 176 plaque-forming units per infected cell. Phage phiLLS significantly reduced the growth of E. coli under laboratory conditions. Analyses of restriction profiles showed the presence of submolar fragments, confirming that phiLLS is a pac-type phage. Phylogenetic analysis based on the amino acid sequence of large terminase subunits confirmed that this phage uses a headful packaging strategy to package their genome. Genomic sequencing and bioinformatic analysis showed that phiLLS is a novel bacteriophage that is most closely related to T5-like phages. In silico analysis indicated that the phiLLS genome consists of 107,263 bp (39.0 % GC content) encoding 160 putative ORFs, 16 tRNAs, several potential promoters and transcriptional terminators. Genome analysis suggests that the phage phiLLS is strictly lytic without carrying genes associated with virulence factors and/or potential immunoreactive allergen proteins. The bacteriophage isolated in this study has shown promising results in the biocontrol of bacterial growth under in vitro conditions, suggesting that it may prove useful as an alternative agent for the

Isolation and Characterization of phiLLS, a Novel Phage with Potential Biocontrol Agent against Multidrug-Resistant Escherichia coli.

PubMed

Amarillas, Luis; Rubí-Rangel, Lucia; Chaidez, Cristobal; González-Robles, Arturo; Lightbourn-Rojas, Luis; León-Félix, Josefina

2017-01-01

Foodborne diseases are a serious and growing problem, and the incidence and prevalence of antimicrobial resistance among foodborne pathogens is reported to have increased. The emergence of antibiotic-resistant bacterial strains demands novel strategies to counteract this epidemic. In this regard, lytic bacteriophages have reemerged as an alternative for the control of pathogenic bacteria. However, the effective use of phages relies on appropriate biological and genomic characterization. In this study, we present the isolation and characterization of a novel bacteriophage named phiLLS, which has shown strong lytic activity against generic and multidrug-resistant Escherichia coli strains. Transmission electron microscopy of phiLLS morphology revealed that it belongs to the Siphoviridae family. Furthermore, this phage exhibited a relatively large burst size of 176 plaque-forming units per infected cell. Phage phiLLS significantly reduced the growth of E. coli under laboratory conditions. Analyses of restriction profiles showed the presence of submolar fragments, confirming that phiLLS is a pac -type phage. Phylogenetic analysis based on the amino acid sequence of large terminase subunits confirmed that this phage uses a headful packaging strategy to package their genome. Genomic sequencing and bioinformatic analysis showed that phiLLS is a novel bacteriophage that is most closely related to T5-like phages. In silico analysis indicated that the phiLLS genome consists of 107,263 bp (39.0 % GC content) encoding 160 putative ORFs, 16 tRNAs, several potential promoters and transcriptional terminators. Genome analysis suggests that the phage phiLLS is strictly lytic without carrying genes associated with virulence factors and/or potential immunoreactive allergen proteins. The bacteriophage isolated in this study has shown promising results in the biocontrol of bacterial growth under in vitro conditions, suggesting that it may prove useful as an alternative agent for the

Increasing corn for biofuel production reduces biocontrol services in agricultural landscapes

PubMed Central

Landis, Douglas A.; Gardiner, Mary M.; van der Werf, Wopke; Swinton, Scott M.

2008-01-01

Increased demand for corn grain as an ethanol feedstock is altering U.S. agricultural landscapes and the ecosystem services they provide. From 2006 to 2007, corn acreage increased 19% nationally, resulting in reduced crop diversity in many areas. Biological control of insects is an ecosystem service that is strongly influenced by local landscape structure. Here, we estimate the value of natural biological control of the soybean aphid, a major pest in agricultural landscapes, and the economic impacts of reduced biocontrol caused by increased corn production in 4 U.S. states (Iowa, Michigan, Minnesota, and Wisconsin). For producers who use an integrated pest management strategy including insecticides as needed, natural suppression of soybean aphid in soybean is worth an average of $33 ha−1. At 2007–2008 prices these services are worth at least $239 million y−1 in these 4 states. Recent biofuel-driven growth in corn planting results in lower landscape diversity, altering the supply of aphid natural enemies to soybean fields and reducing biocontrol services by 24%. This loss of biocontrol services cost soybean producers in these states an estimated $58 million y−1 in reduced yield and increased pesticide use. For producers who rely solely on biological control, the value of lost services is much greater. These findings from a single pest in 1 crop suggest that the value of biocontrol services to the U.S. economy may be underestimated. Furthermore, we suggest that development of cellulosic ethanol production processes that use a variety of feedstocks could foster increased diversity in agricultural landscapes and enhance arthropod-mediated ecosystem services. PMID:19075234

Tamarisk biocontrol using tamarisk beetles: Potential consequences for riparian birds in the southwestern United States

USGS Publications Warehouse

Paxton, Eben H.; Theimer, Tad C.; Sogge, Mark K.

2011-01-01

The tamarisk beetle (Diorhabda spp.), a non-native biocontrol agent, has been introduced to eradicate tamarisk (Tamarix spp.), a genus of non-native tree that has become a dominant component of riparian woodlands in the southwestern United States. Tamarisk beetles have the potential to spread widely and defoliate large expanses of tamarisk habitat, but the effects of such a widespread loss of riparian vegetation on birds remains unknown. We reviewed literature on the effects of other defoliating insects on birds to investigate the potential for tamarisk beetles to affect birds positively or negatively by changing food abundance and vegetation structure. We then combined data on the temporal patterns of tamarisk defoliation by beetles with nest productivity of a well-studied riparian obligate, the Southwestern Willow Flycatcher (Empidonax traillii extimus), to simulate the potential demographic consequences of beetle defoliation on breeding riparian birds in both the short and long term. Our results highlight that the effects of tamarisk biocontrol on birds will likely vary by species and population, depending upon its sensitivity to seasonal defoliation by beetles and net loss of riparian habitat due to tamarisk mortality. Species with restricted distributions that include areas dominated by tamarisk may be negatively affected both in the short and long term. The rate of regeneration and/or restoration of native cottonwoods (Populus spp.) and willows (Salix spp.) relative to the rate of tamarisk loss will be critical in determining the long-term effect of this large-scale ecological experiment.

Evaluation of recycled bioplastic pellets and a sprayable formulation for application of an Aspergillus flavus biocontrol strain

USDA-ARS?s Scientific Manuscript database

Biocontrol of Aspergillus flavus using inoculated bioplastic granules has been proven to be effective under laboratory and field conditions. In the present study, the use of low-density pellets from recycled bioplastic as a biocontrol strain carrier was evaluated. Applying recycled bioplastic pell...

Proteomics of survival structures of fungal pathogens.

PubMed

Loginov, Dmitry; Šebela, Marek

2016-09-25

Fungal pathogens are causal agents of numerous human, animal, and plant diseases. They employ various infection modes to overcome host defense systems. Infection mechanisms of different fungi have been subjected to many comprehensive studies. These investigations have been facilitated by the development of various '-omics' techniques, and proteomics has one of the leading roles in this regard. Fungal conidia and sclerotia could be considered the most important structures for pathogenesis as their germination is one of the first steps towards a host infection. They represent interesting objects for proteomic studies because of the presence of unique proteins with unexplored biotechnological potential required for pathogen viability, development and the subsequent host infection. Proteomic peculiarities of survival structures of different fungi, including those of biotechnological significance (e.g., Asperillus fumigatus, A. nidulans, Metarhizium anisopliae), in a dormant state, as well as changes in the protein production during early stages of fungal development are the subjects of the present review. We focused on biological aspects of proteomic studies of fungal survival structures rather than on an evaluation of proteomic approaches. For that reason, proteins that have been identified in this context are discussed from the point of view of their involvement in different biological processes and possible functions assigned to them. This is the first review paper summarizing recent advances in proteomics of fungal survival structures. Copyright © 2016 Elsevier B.V. All rights reserved.

Biocontrol interventions for inactivation of foodborne pathogens on produce

USDA-ARS?s Scientific Manuscript database

Post-harvest interventions for control of foodborne pathogens on minimally processed foods are crucial for food safety. Biocontrol interventions have the primary objective of developing novel antagonists in combinations with physical and chemical interventions to inactivate pathogenic microbes. Ther...

Mycobiome of Cysts of the Soybean Cyst Nematode Under Long Term Crop Rotation

PubMed Central

Hu, Weiming; Strom, Noah; Haarith, Deepak; Chen, Senyu; Bushley, Kathryn E.

2018-01-01

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe (Phylum Nematoda), is a major pathogen of soybean. It causes substantial yield losses worldwide and is difficult to control because the cyst protects the eggs which can remain viable for nearly a decade. Crop rotation with non-host crops and use of biocontrol organisms such as fungi and bacteria offer promising approaches, but remain hampered by lack of knowledge of the biology of nematode parasitic organisms. We used a high-throughput metabarcoding approach to characterize fungal communities associated with the SCN cyst, a microenvironment in soil that may harbor both nematode parasites and plant pathogens. SCN cysts were collected from a long-term crop rotation experiment in Southeastern Minnesota at three time points over two growing seasons to characterize diversity of fungi inhabiting cysts and to examine how crop rotation and seasonal variation affects fungal communities. A majority of fungi in cysts belonged to Ascomycota and Basidiomycota, but the presence of several early diverging fungal subphyla thought to be primarily plant and litter associated, including Mortierellomycotina and Glomeromycotina (e.g., arbuscular mycorrhizal fungi), suggests a possible role as nematode egg parasites. Species richness varied by both crop rotation and season and was higher in early years of crop rotation and in fall at the end of the growing season. Crop rotation and season also impacted fungal community composition and identified several classes of fungi, including Eurotiomycetes, Sordariomycetes, and Orbiliomycetes (e.g., nematode trapping fungi), with higher relative abundance in early soybean rotations. The relative abundance of several genera was correlated with increasing years of soybean. Fungal communities also varied by season and were most divergent at midseason. The percentage of OTUs assigned to Mortierellomycotina_cls_Incertae_sedis and Sordariomycetes increased at midseason, while Orbiliomycetes

Mycobiome of Cysts of the Soybean Cyst Nematode Under Long Term Crop Rotation.

PubMed

Hu, Weiming; Strom, Noah; Haarith, Deepak; Chen, Senyu; Bushley, Kathryn E

2018-01-01

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe (Phylum Nematoda), is a major pathogen of soybean. It causes substantial yield losses worldwide and is difficult to control because the cyst protects the eggs which can remain viable for nearly a decade. Crop rotation with non-host crops and use of biocontrol organisms such as fungi and bacteria offer promising approaches, but remain hampered by lack of knowledge of the biology of nematode parasitic organisms. We used a high-throughput metabarcoding approach to characterize fungal communities associated with the SCN cyst, a microenvironment in soil that may harbor both nematode parasites and plant pathogens. SCN cysts were collected from a long-term crop rotation experiment in Southeastern Minnesota at three time points over two growing seasons to characterize diversity of fungi inhabiting cysts and to examine how crop rotation and seasonal variation affects fungal communities. A majority of fungi in cysts belonged to Ascomycota and Basidiomycota, but the presence of several early diverging fungal subphyla thought to be primarily plant and litter associated, including Mortierellomycotina and Glomeromycotina (e.g., arbuscular mycorrhizal fungi), suggests a possible role as nematode egg parasites. Species richness varied by both crop rotation and season and was higher in early years of crop rotation and in fall at the end of the growing season. Crop rotation and season also impacted fungal community composition and identified several classes of fungi, including Eurotiomycetes, Sordariomycetes, and Orbiliomycetes (e.g., nematode trapping fungi), with higher relative abundance in early soybean rotations. The relative abundance of several genera was correlated with increasing years of soybean. Fungal communities also varied by season and were most divergent at midseason. The percentage of OTUs assigned to Mortierellomycotina_cls_Incertae_sedis and Sordariomycetes increased at midseason, while Orbiliomycetes

Detection of fungal DNA in human body fluids and tissues during a multistate outbreak of fungal meningitis and other infections.

PubMed

Gade, Lalitha; Scheel, Christina M; Pham, Cau D; Lindsley, Mark D; Iqbal, Naureen; Cleveland, Angela Ahlquist; Whitney, Anne M; Lockhart, Shawn R; Brandt, Mary E; Litvintseva, Anastasia P

2013-05-01

Exserohilum rostratum was the major cause of an outbreak of fungal infections linked to injections of contaminated methylprednisolone acetate. Because almost 14,000 persons were exposed to product that was possibly contaminated with multiple fungal pathogens, there was unprecedented need for a rapid throughput diagnostic test that could detect both E. rostratum and other unusual agents of fungal infection. Here we report development of a novel PCR test that allowed for rapid and specific detection of fungal DNA in cerebrospinal fluid (CSF), other body fluids and tissues of infected individuals. The test relied on direct purification of free-circulating fungal DNA from fluids and subsequent PCR amplification and sequencing. Using this method, we detected Exserohilum rostratum DNA in 123 samples from 114 case-patients (28% of 413 case-patients for whom 627 samples were available), and Cladosporium DNA in one sample from one case-patient. PCR with novel Exserohilum-specific ITS-2 region primers detected 25 case-patients with samples that were negative using broad-range ITS primers. Compared to fungal culture, this molecular test was more sensitive: of 139 case-patients with an identical specimen tested by culture and PCR, E. rostratum was recovered in culture from 19 (14%), but detected by PCR in 41 (29%), showing a diagnostic sensitivity of 29% for PCR compared to 14% for culture in this patient group. The ability to rapidly confirm the etiologic role of E. rostratum in these infections provided an important contribution in the public health response to this outbreak.

Pathology smorgasboard: Biocontrol, pathogen movement, and recent fumigation results

USDA-ARS?s Scientific Manuscript database

Research on soilborne pathogens, disease control, and new forest diseases of interest were presented at the Western Forest and Conservation Nursery Association meeting in 2016. Research topics included reduced-rate soil fumigation, Pythium diversity and biocontrol, pathogen movement among nurseries,...

Subseafloor basalts as fungal habitats

NASA Astrophysics Data System (ADS)

Ivarsson, M.; Bengtson, S.

2013-12-01

The oceanic crust makes up the largest potential habitat for life on Earth, yet next to nothing is known about the abundance, diversity and ecology of its biosphere. Our understanding of the deep biosphere of subseafloor crust is, with a few exceptions, based on a fossil record. Surprisingly, a majority of the fossilized microorganisms have been interpreted or recently re-interpreted as remnants of fungi rather than prokaryotes. Even though this might be due to a bias in fossilization the presence of fungi in these settings can not be neglected. We have examined fossilized microorganisms in drilled basalt samples collected at the Emperor Seamounts in the Pacific Ocean. Synchrotron-radiation X-ray tomography microscopy (SRXTM) studies has revealed a complex morphology and internal structure that corresponds to characteristic fungal morphology. Chitin was detected in the fossilized hyphae, which is another strong argument in favour of a fungal interpretation. Chitin is absent in prokaryotes but a substantial constituent in fungal cell walls. The fungal colonies consist of both hyphae and yeast-like growth states as well as resting structures and possible fruit bodies, thus, the fungi exist in vital colonies in subseafloor basalts. The fungi have also been involved in extensive weathering of secondary mineralisations. In terrestrial environments fungi are known as an important geobiological agent that promotes mineral weathering and decomposition of organic matter, and they occur in vital symbiosis with other microorganisms. It is probable to assume that fungi would play a similar role in subseafloor basalts and have great impact on the ecology and on biogeochemical cycles in such environments.

Morphology of the female reproductive system and physiological age-grading of Megamelus scutellaris (Hemiptera: Delphacidae), a biological control agent of water hyacinth

USDA-ARS?s Scientific Manuscript database

The morphology of the female reproductive system in Megamelus scutellaris Berg (Hemiptera:Delphacidae), a biocontrol agent of Eichhornia crassipes (Mart.) Solms, was examined using standard light microscopy techniques. Ovaries extracted from individuals dissected in phosphate buffered saline were ex...

Novel Biocontrol Methods for Listeria monocytogenes Biofilms in Food Production Facilities.

PubMed

Gray, Jessica A; Chandry, P Scott; Kaur, Mandeep; Kocharunchitt, Chawalit; Bowman, John P; Fox, Edward M

2018-01-01

High mortality and hospitalization rates have seen Listeria monocytogenes as a foodborne pathogen of public health importance for many years and of particular concern for high-risk population groups. Food manufactures face an ongoing challenge in preventing the entry of L. monocytogenes into food production environments (FPEs) due to its ubiquitous nature. In addition to this, the capacity of L. monocytogenes strains to colonize FPEs can lead to repeated identification of L. monocytogenes in FPE surveillance. The contamination of food products requiring product recall presents large economic burden to industry and is further exacerbated by damage to the brand. Poor equipment design, facility layout, and worn or damaged equipment can result in Listeria hotspots and biofilms where traditional cleaning and disinfecting procedures may be inadequate. Novel biocontrol methods may offer FPEs effective means to help improve control of L. monocytogenes and decrease cross contamination of food. Bacteriophages have been used as a medical treatment for many years for their ability to infect and lyse specific bacteria. Endolysins, the hydrolytic enzymes of bacteriophages responsible for breaking the cell wall of Gram-positive bacteria, are being explored as a biocontrol method for food preservation and in nanotechnology and medical applications. Antibacterial proteins known as bacteriocins have been used as alternatives to antibiotics for biopreservation and food product shelf life extension. Essential oils are natural antimicrobials formed by plants and have been used as food additives and preservatives for many years and more recently as a method to prevent food spoilage by microorganisms. Competitive exclusion occurs naturally among bacteria in the environment. However, intentionally selecting and applying bacteria to effect competitive exclusion of food borne pathogens has potential as a biocontrol application. This review discusses these novel biocontrol methods and their

Cannibalism in invasive, native and biocontrol populations of the harlequin ladybird.

PubMed

Tayeh, Ashraf; Estoup, Arnaud; Lombaert, Eric; Guillemaud, Thomas; Kirichenko, Natalia; Lawson-Handley, Lori; De Clercq, Patrick; Facon, Benoît

2014-02-05

Cannibalism is widespread in both vertebrates and invertebrates but its extent is variable between and within species. Cannibalism depends on population density and nutritional conditions, and could be beneficial during colonisation of new environments. Empirical studies are needed to determine whether this trait might facilitate invasion of a new area in natural systems. We investigated whether the propensity for cannibalism in H. axyridis differs both between native and invasive populations and between invasive populations from the core and from the front of the invasive area in Western Europe. We also compared the propensity for cannibalism of these natural populations with that of laboratory-reared biocontrol populations. We measured the cannibalism rates of eggs by first instar larvae and adult females at two different individual densities of ladybirds from three types of population (invasive, native and biocontrol), in laboratory-controlled conditions. Cannibalism was significantly greater in larvae from invasive populations compared to native or biocontrol populations, but there was no difference in cannibalism rates between populations from the core or front of the invaded range. Cannibalism was significantly lower in larvae from biocontrol populations compared to wild (invasive and native) populations. No differences in cannibalism rates of adult females were found between any populations. While high population density significantly increased cannibalism in both larvae and adults, the norm of reaction of cannibalism to individual density did not change significantly during the invasion and/or laboratory rearing processes. This study is the first to provide evidence for a higher propensity for cannibalism in invasive populations compared to native ones. Our experiments also shed light on the difference in cannibalism evolution with respect to life stages. However, we are still at an early stage in understanding the underlying mechanisms and several

Challenges and opportunities for the commercialization of postharvest biocontrol

USDA-ARS?s Scientific Manuscript database

The past twenty years has seen the field of postharvest biocontrol evolve into a sophisticated science with global research programs worldwide, numerous yearly publications, patented technologies, and the development of new commercial products. The use of these products, however, still remains limi...

Fungal peritonitis by Thermoascus crustaceus in a peritoneal dialysis patient from Chile.

PubMed

Alvarez, Eduardo; Castillo, Alvaro; Iturrieta, Isabel

Fungal peritonitis is a relatively uncommon infection in peritoneal dialysis patients. However, it can be associated with significant morbimortality. In recent reports, Candida species and other filamentous fungi have been reported as being aetiological agents. Thermoascus species are ubiquitous, thermophilic fungi, with an anamorph in the Paecilomyces genus. Here we present the first report of fungal peritonitis by Thermoascus crustaceus from Chile. We present the case of an 83-year-old female patient, with a history of cholecystectomy, hernia repair, severe arterial hypertension, hip and knee osteoarthritis and several episodes of peritoneal dialysis with a cloudy exudate. Bacterial cultures were negative. In addition, a history of two months with intermittent fever peaks mainly in the evening was reported. Blood culture bottles inoculated with peritoneal fluid revealed the presence of fungal growth. Morphological and molecular studies allowed us to identify the aetiological agent as Thermoascus crustaceus. An antifungal susceptibility test was performed using the M38-A2 method, developed by the Clinical and Laboratory Standards Institute (CLSI). The MIC values to amphotericin B, itraconazole, voriconazole and echinochandins were 0.5, 0.25, 0.25 and 0.125μg/ml, respectively. Antifungal treatment with amphotericin B was prescribed, with good patient progress. Fungal peritonitis is a very rare entity. Moreover, the spectrum of fungal pathogens continues to expand, a reason for which morphological and molecular studies are necessary for a rapid diagnosis. Copyright © 2017 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

Biocontrol of Phytophthora Blight and Anthracnose in Pepper by Sequentially Selected Antagonistic Rhizobacteria against Phytophthora capsici.

PubMed

Sang, Mee Kyung; Shrestha, Anupama; Kim, Du-Yeon; Park, Kyungseok; Pak, Chun Ho; Kim, Ki Deok

2013-06-01

We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107) among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P < 0.05) reduced Phytophthora blight without influencing rhizosphere microbial populations; they showed similar or better levels of disease suppressions than in metalaxyl treatment in the 2007 and 2009 tests, but not in the 2008 test. In the 2-year plastic house tests, all the selected strains significantly (P < 0.05) reduced anthracnose incidence in at least one of the test years, but their biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit.

Virulence and site of infection of the fungus, Hirsutella thompsonii, to the honey bee ectoparasitic mite, Varroa destructor.

PubMed

Peng, Christine Y S; Zhou, Xinsheng; Kaya, Harry K

2002-11-01

The Varroa mite, Varroa destructor, is recognized as the most serious pest of both managed and feral Western honey bee (Apis mellifera) in the world. The mite has developed resistance to fluvalinate, an acaricide used to control it in beehives, and fluvalinate residues have been found in the beeswax, necessitating an urgent need to find alternative control measures to suppress this pest. Accordingly, we investigated the possibility of using the fungus, Hirsutella thompsonii, as a biocontrol agent of the Varroa mite. Among the 9 isolates of H. thompsonii obtained from the University of Florida and the USDA, only the 3 USDA isolates (ARSEF 257, 1947 and 3323) were infectious to the Varroa mite in laboratory tests. The mite became infected when it was allowed to walk on a sporulating H. thompsonii culture for 5 min. Scanning electron micrographs revealed that the membranous arolium of the mite leg sucker is the focus of infection where the fungal conidia adhered and germinated. The infected mites died from mycosis, with the lethal times to kill 50% (LT(50)s) dependent on the fungal isolates. Thus, the LT(50)s were 52.7, 77.2, and 96.7h for isolates 3323, 257, and 1947, respectively. Passage of H. thompsonii through Varroa mite three times significantly reduced the LT(50)s of isolates 257 and 1947 (P<0.05) but not the LT(50) of isolate 3323. The fungus did not infect the honey bee in larval, prepupal, pupal, and adult stages under our laboratory rearing conditions. Our encouraging results suggest that some isolates of H. thompsonii have the potential to be developed as a biocontrol agent for V. destructor. However, fungal infectivity against the mites under beehive conditions needs to be studied before any conclusion can be made.

The plant pathogenic fungus Gaeumannomyces graminis var. tritici improves bacterial growth and triggers early gene regulations in the biocontrol strain Pseudomonas fluorescens Pf29Arp.

PubMed

Barret, M; Frey-Klett, P; Boutin, M; Guillerm-Erckelboudt, A-Y; Martin, F; Guillot, L; Sarniguet, A

2009-01-01

In soil, some antagonistic rhizobacteria contribute to reduce root diseases caused by phytopathogenic fungi. Direct modes of action of these bacteria have been largely explored; however, commensal interaction also takes place between these microorganisms and little is known about the influence of filamentous fungi on bacteria. An in vitro confrontation bioassay between the pathogenic fungus Gaeumannomyces graminis var. tritici (Ggt) and the biocontrol bacterial strain Pseudomonas fluorescens Pf29Arp was set up to analyse bacterial transcriptional changes induced by the fungal mycelium at three time-points of the interaction before cell contact and up until contact. For this, a Pf29Arp shotgun DNA microarray was constructed. Specifity of Ggt effect was assessed in comparison with one of two other filamentous fungi, Laccaria bicolor and Magnaporthe grisea. During a commensal interaction, Ggt increased the growth rate of Pf29Arp. Before contact, Ggt induced bacterial genes involved in mycelium colonization. At contact, genes encoding protein of stress response and a patatin-like protein were up-regulated. Among all the bacterial genes identified, xseB was specifically up-regulated at contact by Ggt but down-regulated by the other fungi. Data showed that the bacterium sensed the presence of the fungus early, but the main gene alteration occurred during bacterial-fungal cell contact.

[Specifics of bio-controlled training in directed relaxation].

PubMed

Baranov, V M; Sentiabrev, N N; Solopov, I N

2005-01-01

Studies of personal and general patterns of acquisition of skills in biocontrolled relaxation based on biological feedback (EMG) permitted classification of human subjects by the ability to relax voluntarily muscles. In the process of skill acquisition changes were minimal at the beginning, grew progressively further on and stabilized on completion of the course of training.

Fusarium oxysporum f. sp. dianthi virus 1 accumulation is correlated with changes in virulence and other phenotypic traits of its fungal host.

PubMed

Lemus-Minor, Carlos German; Cañizares-Nolasco, Carmen; García-Pedrajas, Maria D D; Pérez-Artés, Encarnación

2018-03-08

Fusarium oxysporum f. sp. dianthi virus 1 (FodV1) was detected in isolate Fod 116 (Fod 116V + ) of Fusarium oxysporum f. sp. dianthi (Fod), reaching such a high accumulation level that it was clearly visible after agarose gel electrophoresis of total DNA extracts. FodV1 consists of four double-stranded RNA segments, that correspond to a new mycovirus in the Chrysoviridae family. We obtained an isolate of Fod 116 (Fod 116V - ) with only a residual level of FodV1 RNA accumulation by single-conidia selection. Compared to the Fod 116V - , isolate Fod 116V + showed significant phenotypic alterations in vegetative growth and virulence. The presence of a high titer of mycovirus FodV1 thus associated with a modified morphology and a reduced growth of the colonies on solid medium, and with a diminished conidiation in liquid medium. Inoculation of four susceptible carnation cultivars with either Fod 116V - or Fod 116V + showed that the presence of a high titer of FodV1 was also correlated with a significantly reduced virulence of its fungal host. All the results suggest that FodV1 could be associated with hypovirulence, identifying it as a potential biocontrol agent against Fusarium wilt of carnation. This is the first report of a mycovirus potentially associated to the induction of hypovirulence in the species Fusarium oxysporum.

A novel, image analysis-based method for the evaluation of in vitro antagonism.

PubMed

Szekeres, András; Leitgeb, Balázs; Kredics, László; Manczinger, László; Vágvölgyi, Csaba

2006-06-01

A novel method is proposed for the accurate evaluation of in vitro antagonism. Based on the measurement of areas of the fungal colonies, biocontrol indices were calculated, which are characteristic to the antagonistic Trichoderma strains. These indices provide a useful tool to describe the biocontrol abilities of fungi.

Evaluation of nested PCR in diagnosis of fungal rhinosinusitis.

PubMed

Badiee, Parisa; Gandomi, Behrooz; Sabz, Gholamabbass; Khodami, Bijan; Choopanizadeh, Maral; Jafarian, Hadis

2015-02-01

Given the importance of rapid diagnosis for fungal rhinosinusitis, this study aimed to evaluate the use of nested PCR to identify Aspergillus and Mucor species in clinical samples from patients with suspected fungal rhinosinusitis. Functional endoscopic sinus surgery specimens were collected from 98 patients with rhinosinusitis from 2012 to 2013. All samples were ground and cultured on sabouraud dextrose agar. The isolated fungi were identified based on their macroscopic and microscopic features. Fungal DNA was extracted from the tissue samples and nested PCR was performed with two sets of primers for Mucor and Aspergillus. Direct microscopic showed that 5.1% contained fungal components and 9.2% exhibited growth of fungi in culture. The most common agents isolated were Aspergillus fumigatus (n= 3), Aspergillus flavus (n=2), Penicillium sp (n=3) and Alternaria sp. (n=1). Mucor sp. was identified in the pathology smear from 1 patient. Positive results for fungal rhinosinusitis were obtained for a total of 10.2% by culture or pathology smear. Positive PCR results were obtained in 72 samples for Aspergillus and 31 samples for Mucor. Our results suggest that endoscopic sinus surgery specimens are not suitable for nested PCR, probably because of the accumulation of fungi that contaminate the environmental air. This drawback is a limiting factor for diagnosis with nasal cavity specimens. Therefore, molecular methods and conventional culture techniques are helpful complementary diagnostic methods to detect fungal rhinosinusitis and determine appropriate management for these patients.

Fungal endophytes isolated from Protium heptaphyllum and Trattinnickia rhoifolia as antagonists of Fusarium oxysporum.

PubMed

Fierro-Cruz, Juan E; Jiménez, Pedro; Coy-Barrera, Ericsson

Control of fungal pathogens is mainly addressed by the use of chemically synthesized fungicides which result in environmental pollution, developing resistance after prolonged use. In this context, endophytes have been recognized as potential biocontrollers, and also as a promising source of antifungal metabolites. Therefore, as part of our research on phytopathogen controllers, 355 fungal endophytes were isolated from Protium heptaphyllum and Trattinnickia rhoifolia (Burseraceae), both ethnobotanically important tree species that produce secondary metabolites of agronomic and industrial interest. Endophytes were tested by in vitro dual culture against Fusarium oxysporum, a phytopathogen of agronomic importance. Five endophytes exerted at least 40% inhibition on F. oxysporum growth. Ethyl acetate (EtOAc) extracts were obtained from the most active antagonistic fungi, after growing them in three different liquid media. The extracts were tested against a conidial suspension of F. oxysporum by direct bioautography. Two extracts derived from fungi identified as Chaetomium globosum, F211_UMNG and Meyerozima sp. F281_UMNG showed inhibition of pathogen growth. Isolate C. globosum, F211_UMNG was selected for a chemical analysis by RP-HPLC-DAD-ESI-MS and antifungal molecules such as cladosporin, chaetoatrosin A and chaetoviridin A were annotated and identified based on their MS data. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Anthracnose of lucky bamboo Dracaena sanderiana caused by the fungus Colletotrichum dracaenophilum in Egypt.

PubMed

Morsy, Ahmed A; Elshahawy, Ibrahim E

2016-05-01

Dracaena sanderiana, of the family Liliaceae, is among the ornamental plants most frequently imported into Egypt. Typical anthracnose symptoms were observed on the stems of imported D. sanderiana samples. The pathogen was isolated, demonstrated to be pathogenic based on Koch's rule and identified as Colletotrichum dracaenophilum. The optimum temperature for its growth ranges from 25 to 30 °C, maintained for 8 days. Kemazed 50% wettable powder (WP) was the most effective fungicide against the pathogen, as no fungal growth was observed over 100 ppm. The biocontrol agents Trichoderma harzianum and Trichoderma viride followed by Bacillus subtilis and Bacillus pumilus caused the highest reduction in fungal growth. To the best of our knowledge, this report describes the first time that this pathogen was observed on D. sanderiana in Egypt.

Anthracnose of lucky bamboo Dracaena sanderiana caused by the fungus Colletotrichum dracaenophilum in Egypt

PubMed Central

Morsy, Ahmed A.; Elshahawy, Ibrahim E.

2016-01-01

Dracaena sanderiana, of the family Liliaceae, is among the ornamental plants most frequently imported into Egypt. Typical anthracnose symptoms were observed on the stems of imported D. sanderiana samples. The pathogen was isolated, demonstrated to be pathogenic based on Koch’s rule and identified as Colletotrichum dracaenophilum. The optimum temperature for its growth ranges from 25 to 30 °C, maintained for 8 days. Kemazed 50% wettable powder (WP) was the most effective fungicide against the pathogen, as no fungal growth was observed over 100 ppm. The biocontrol agents Trichoderma harzianum and Trichoderma viride followed by Bacillus subtilis and Bacillus pumilus caused the highest reduction in fungal growth. To the best of our knowledge, this report describes the first time that this pathogen was observed on D. sanderiana in Egypt. PMID:27222738

Tamarisk biocontrol using tamarisk beetles: Potential consequences for riparian birds in the southwestern United States

USGS Publications Warehouse

Paxton, E.H.; Theimer, T.C.; Sogge, M.K.

2011-01-01

The tamarisk beetle (Diorhabda spp.), a non-native biocontrol agent, has been introduced to eradicate tamarisk (Tamarix spp.), a genus of non-native tree that has become a dominant component of riparian woodlands in the southwestern United States. Tamarisk beetles have the potential to spread widely and defoliate large expanses of tamarisk habitat, but the effects of such a widespread loss of riparian vegetation on birds remains unknown. We reviewed literature on the effects of other defoliating insects on birds to investigate the potential for tamarisk beetles to affect birds positively or negatively by changing food abundance and vegetation structure. We then combined data on the temporal patterns of tamarisk defoliation by beetles with nest productivity of a wellstudied riparian obligate, the Southwestern Willow Flycatcher (Empidonax traillii extimus), to simulate the potential demographic consequences of beetle defoliation on breeding riparian birds in both the short and long term. Our results highlight that the effects of tamarisk biocontrol on birds will likely vary by species and population, depending upon its sensitivity to seasonal defoliation by beetles and net loss of riparian habitat due to tamarisk mortality. Species with restricted distributions that include areas dominated by tamarisk may be negatively affected both in the short and long term. The rate of regeneration and/or restoration of native cottonwoods (Populus spp.) and willows (Salix spp.) relative to the rate of tamarisk loss will be critical in determining the long-term effect of this large-scale ecological experiment. ?? The Cooper Ornithological Society 2011.

Gene expression profile of the plant pathogen Fusarium graminearum under the antagonistic effect of Pantoea agglomerans.

PubMed

Pandolfi, V; Jorge, E C; Melo, C M R; Albuquerque, A C S; Carrer, H

2010-07-06

The pathogenic fungus Fusarium graminearum is an ongoing threat to agriculture, causing losses in grain yield and quality in diverse crops. Substantial progress has been made in the identification of genes involved in the suppression of phytopathogens by antagonistic microorganisms; however, limited information regarding responses of plant pathogens to these biocontrol agents is available. Gene expression analysis was used to identify differentially expressed transcripts of the fungal plant pathogen F. graminearum under antagonistic effect of the bacterium Pantoea agglomerans. A macroarray was constructed, using 1014 transcripts from an F. graminearum cDNA library. Probes consisted of the cDNA of F. graminearum grown in the presence and in the absence of P. agglomerans. Twenty-nine genes were either up (19) or down (10) regulated during interaction with the antagonist bacterium. Genes encoding proteins associated with fungal defense and/or virulence or with nutritional and oxidative stress responses were induced. The repressed genes coded for a zinc finger protein associated with cell division, proteins containing cellular signaling domains, respiratory chain proteins, and chaperone-type proteins. These data give molecular and biochemical evidence of response of F. graminearum to an antagonist and could help develop effective biocontrol procedures for pathogenic plant fungi.

Biocontrol of Phytophthora Blight and Anthracnose in Pepper by Sequentially Selected Antagonistic Rhizobacteria against Phytophthora capsici

PubMed Central

Sang, Mee Kyung; Shrestha, Anupama; Kim, Du-Yeon; Park, Kyungseok; Pak, Chun Ho; Kim, Ki Deok

2013-01-01

We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107) among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P < 0.05) reduced Phytophthora blight without influencing rhizosphere microbial populations; they showed similar or better levels of disease suppressions than in metalaxyl treatment in the 2007 and 2009 tests, but not in the 2008 test. In the 2-year plastic house tests, all the selected strains significantly (P < 0.05) reduced anthracnose incidence in at least one of the test years, but their biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit. PMID:25288942

Change of growth promotion and disease resistant of wheat seedling by application of biocontrol bacterium Pseudochrobactrum kiredjianiae A4 under simulated microgravity

NASA Astrophysics Data System (ADS)

Fu, Yuming; Gao, Han; Li, Hongyan; Qin, Youcai; Tang, Wen; Lu, Jinying; Li, Ming; Shao, Lingzhi; Liu, Hong

2017-10-01

Plant disease control and prevention in microgravity are critical for space plant cultivation. This study investigated the effects of a biocontrol bacterium Pseudochrobactrum kiredjianiae A4 on growth development and antifungal potential of wheat seedlings under simulated microgravity. The growth, antioxidant status and plant immune hormone of both non-infected and infected wheat seedlings were detected before and after inoculation of A4 strains under simulated microgravity condition (μG) and ground condition (1G). Our results showed that bacteria A4 promoted wheat growth by increasing root length and biomass accumulation and meanwhile enhancing fungal disease resistance through improving the antioxidant enzyme activities and plant hormone secretion. Moreover, A4 exhibited a weaker promotion ability on wheat biomass accumulation and disease resistance under μG condition compared to that under 1G. These results not only expand our understanding of the impact of microgravity on plant-microbe interaction, but also provide valuable insights into using plant beneficial microbes for plant cultivation and crop protection in space.

Biological interactions to select biocontrol agents against toxigenic strains of Aspergillus flavus and Fusarium verticillioides from maize.

PubMed

Etcheverry, Miriam G; Scandolara, Andrea; Nesci, Andrea; Vilas Boas Ribeiro, Marta Sofia; Pereira, Paola; Battilani, Paola

2009-05-01

Biological control represent an alternative to the use of pesticides in crop protection. A key to progress in biological control to protect maize against Fusarium verticillioides and Aspergillus flavus maize pathogens are, to select in vitro, the best agent to be applied in the field. The aim of this study was to examine the antagonistic activity of bacterial and yeast isolates against F.verticillioides and A. flavus toxigenic strains. The first study showed the impact of Bacillus amyloliquefaciens BA-S13, Microbacterium oleovorans DMS 16091, Enterobacter hormomaechei EM-562T, and Kluyveromyces spp. L14 and L16 isolates on mycelial growth of two strains of A. flavus MPVPA 2092, 2094 and three strains of F. verticillioides MPVPA 285, 289, and 294 on 3% maize meal extract agar at different water activities (0.99, 0.97, 0.95, and 0.93). From this first assay antagonistics isolates M. oleovorans, B. amyloliquefaciens and Kluyveromyces sp. (L16) produced an increase of lag phase of growth and decreased a growth rate of all fungal strains. These isolates were selected for futher studies. In vitro non-rhizospheric maize soil (centrally and sprayed inoculated) and in vitro maize (ears apex and base inoculated) were treated with antagonistics and pathogenic strains alone in co-inoculated cultures. Bacillus amyloliquefaciens significantly reduced F. verticillioides and A. flavus count in maize soil inoculated centrally. Kluyveromyces sp. L16 reduced F. verticillioides and A. flavus count in maize soil inoculated by spray. Kluyveromyces sp. L16 was the most effective treatment limiting percent infections by F. verticillioides on the maize ears.

Potential of endophytic fungi as biocontrol agents of Duponchelia fovealis (Zeller) (Lepidoptera:Crambidae).

PubMed

Amatuzzi, R F; Cardoso, N; Poltronieri, A S; Poitevin, C G; Dalzoto, P; Zawadeneak, M A; Pimentel, I C

2017-11-09

This study reports the first assessment of endophytic fungi isolated from strawberry leaves and selection of isolates for the control of Duponchelia fovealis, a new pest of strawberries. A total of 400 strawberry leaves of the cultivar 'Albion' were collected in four commercial farms. Leaves were disinfected, cut in fragments, and placed on Petri dishes containing potato dextrose agar media with tetracycline and incubated for 30 days. Following this time, 517 fungal colonies were isolated, and thirteen genera were identified: Cladosporium, Aspergillus, Nigrospora, Fusarium, Trichoderma, Chaetomium, Alternaria, Paecilomyces, Penicillium, Ulocladium, Bipolaris, Diaporthe, and Phoma. Eight isolates belonging to the genera Aspergillus, Diaporthe, Paecilomyces, and Cladosporium were selected for pathogenicity bioassays against third instar larvae of D. fovealis. Isolates of Paecilomyces induced the highest mortality rates.

Bacillus amyloliquefaciens GA1 as a source of potent antibiotics and other secondary metabolites for biocontrol of plant pathogens

PubMed Central

2009-01-01

Background Phytopathogenic fungi affecting crop and post-harvested vegetables are a major threat to food production and food storage. To face these drawbacks, producers have become increasingly dependent on agrochemicals. However, intensive use of these compounds has led to the emergence of pathogen resistance and severe negative environmental impacts. There are also a number of plant diseases for which chemical solutions are ineffective or non-existent as well as an increasing demand by consumers for pesticide-free food. Thus, biological control through the use of natural antagonistic microorganisms has emerged as a promising alternative to chemical pesticides for more rational and safe crop management. Results The genome of the plant-associated B. amyloliquefaciens GA1 was sample sequenced. Several gene clusters involved in the synthesis of biocontrol agents were detected. Four gene clusters were shown to direct the synthesis of the cyclic lipopeptides surfactin, iturin A and fengycin as well as the iron-siderophore bacillibactin. Beside these non-ribosomaly synthetised peptides, three additional gene clusters directing the synthesis of the antibacterial polyketides macrolactin, bacillaene and difficidin were identified. Mass spectrometry analysis of culture supernatants led to the identification of these secondary metabolites, hence demonstrating that the corresponding biosynthetic gene clusters are functional in strain GA1. In addition, genes encoding enzymes involved in synthesis and export of the dipeptide antibiotic bacilysin were highlighted. However, only its chlorinated derivative, chlorotetaine, could be detected in culture supernatants. On the contrary, genes involved in ribosome-dependent synthesis of bacteriocin and other antibiotic peptides were not detected as compared to the reference strain B. amyloliquefaciens FZB42. Conclusion The production of all of these antibiotic compounds highlights B. amyloliquefaciens GA1 as a good candidate for the

Bacillus amyloliquefaciens GA1 as a source of potent antibiotics and other secondary metabolites for biocontrol of plant pathogens.

PubMed

Arguelles-Arias, Anthony; Ongena, Marc; Halimi, Badre; Lara, Yannick; Brans, Alain; Joris, Bernard; Fickers, Patrick

2009-11-26

Phytopathogenic fungi affecting crop and post-harvested vegetables are a major threat to food production and food storage. To face these drawbacks, producers have become increasingly dependent on agrochemicals. However, intensive use of these compounds has led to the emergence of pathogen resistance and severe negative environmental impacts. There are also a number of plant diseases for which chemical solutions are ineffective or non-existent as well as an increasing demand by consumers for pesticide-free food. Thus, biological control through the use of natural antagonistic microorganisms has emerged as a promising alternative to chemical pesticides for more rational and safe crop management. The genome of the plant-associated B. amyloliquefaciens GA1 was sample sequenced. Several gene clusters involved in the synthesis of biocontrol agents were detected. Four gene clusters were shown to direct the synthesis of the cyclic lipopeptides surfactin, iturin A and fengycin as well as the iron-siderophore bacillibactin. Beside these non-ribosomaly synthetised peptides, three additional gene clusters directing the synthesis of the antibacterial polyketides macrolactin, bacillaene and difficidin were identified. Mass spectrometry analysis of culture supernatants led to the identification of these secondary metabolites, hence demonstrating that the corresponding biosynthetic gene clusters are functional in strain GA1. In addition, genes encoding enzymes involved in synthesis and export of the dipeptide antibiotic bacilysin were highlighted. However, only its chlorinated derivative, chlorotetaine, could be detected in culture supernatants. On the contrary, genes involved in ribosome-dependent synthesis of bacteriocin and other antibiotic peptides were not detected as compared to the reference strain B. amyloliquefaciens FZB42. The production of all of these antibiotic compounds highlights B. amyloliquefaciens GA1 as a good candidate for the development of biocontrol agents.

Screening mycotoxins for quorum inhibition in a biocontrol bacterial endophyte

USDA-ARS?s Scientific Manuscript database

Bacterial endophytes are used as biocontrol organisms for plant pathogens such as the maize endophyte Fusarium verticillioides and its production of fumonisin mycotoxins. However, such applications are not always predictable and efficient. Bacteria communicate via cell-dependent signals, which are r...

Cannibalism in invasive, native and biocontrol populations of the harlequin ladybird

PubMed Central

2014-01-01

Background Cannibalism is widespread in both vertebrates and invertebrates but its extent is variable between and within species. Cannibalism depends on population density and nutritional conditions, and could be beneficial during colonisation of new environments. Empirical studies are needed to determine whether this trait might facilitate invasion of a new area in natural systems. We investigated whether the propensity for cannibalism in H. axyridis differs both between native and invasive populations and between invasive populations from the core and from the front of the invasive area in Western Europe. We also compared the propensity for cannibalism of these natural populations with that of laboratory-reared biocontrol populations. We measured the cannibalism rates of eggs by first instar larvae and adult females at two different individual densities of ladybirds from three types of population (invasive, native and biocontrol), in laboratory-controlled conditions. Results Cannibalism was significantly greater in larvae from invasive populations compared to native or biocontrol populations, but there was no difference in cannibalism rates between populations from the core or front of the invaded range. Cannibalism was significantly lower in larvae from biocontrol populations compared to wild (invasive and native) populations. No differences in cannibalism rates of adult females were found between any populations. While high population density significantly increased cannibalism in both larvae and adults, the norm of reaction of cannibalism to individual density did not change significantly during the invasion and/or laboratory rearing processes. Conclusion This study is the first to provide evidence for a higher propensity for cannibalism in invasive populations compared to native ones. Our experiments also shed light on the difference in cannibalism evolution with respect to life stages. However, we are still at an early stage in understanding the underlying

Novel Biocontrol Methods for Listeria monocytogenes Biofilms in Food Production Facilities

PubMed Central

Gray, Jessica A.; Chandry, P. Scott; Kaur, Mandeep; Kocharunchitt, Chawalit; Bowman, John P.; Fox, Edward M.

2018-01-01

High mortality and hospitalization rates have seen Listeria monocytogenes as a foodborne pathogen of public health importance for many years and of particular concern for high-risk population groups. Food manufactures face an ongoing challenge in preventing the entry of L. monocytogenes into food production environments (FPEs) due to its ubiquitous nature. In addition to this, the capacity of L. monocytogenes strains to colonize FPEs can lead to repeated identification of L. monocytogenes in FPE surveillance. The contamination of food products requiring product recall presents large economic burden to industry and is further exacerbated by damage to the brand. Poor equipment design, facility layout, and worn or damaged equipment can result in Listeria hotspots and biofilms where traditional cleaning and disinfecting procedures may be inadequate. Novel biocontrol methods may offer FPEs effective means to help improve control of L. monocytogenes and decrease cross contamination of food. Bacteriophages have been used as a medical treatment for many years for their ability to infect and lyse specific bacteria. Endolysins, the hydrolytic enzymes of bacteriophages responsible for breaking the cell wall of Gram-positive bacteria, are being explored as a biocontrol method for food preservation and in nanotechnology and medical applications. Antibacterial proteins known as bacteriocins have been used as alternatives to antibiotics for biopreservation and food product shelf life extension. Essential oils are natural antimicrobials formed by plants and have been used as food additives and preservatives for many years and more recently as a method to prevent food spoilage by microorganisms. Competitive exclusion occurs naturally among bacteria in the environment. However, intentionally selecting and applying bacteria to effect competitive exclusion of food borne pathogens has potential as a biocontrol application. This review discusses these novel biocontrol methods and their

United States Department of Agriculture-Agricultural Research Service research programs in biological control of plant diseases.

PubMed

Roberts, Daniel P; Lohrke, Scott M

2003-01-01

A number of USDA-ARS programs directed at overcoming impediments to the use of biocontrol agents on a commercial scale are described. These include improvements in screening techniques, taxonomic studies to identify beneficial strains more precisely, and studies on various aspects of the large-scale production of biocontrol agents. Another broad area of studies covers the ecological aspects of biocontrol agents-their interaction with the pathogen, with the plant and with other aspects of the environmental complex. Examples of these studies are given and their relevance to the further development and expansion of biocontrol agents is discussed.

Saccharomyces cerevisiae: A novel and efficient biological control agent for Colletotrichum acutatum during pre-harvest.

PubMed

Lopes, Marcos Roberto; Klein, Mariana Nadjara; Ferraz, Luriany Pompeo; da Silva, Aline Caroline; Kupper, Katia Cristina

2015-06-01

In this study, we evaluated the efficiency of six isolates of Saccharomyces cerevisiae in controlling Colletotrichum acutatum, the causal agent of postbloom fruit drop that occur in pre-harvest citrus. We analyzed the mechanisms of action involved in biological control such as: production of antifungal compounds, nutrient competition, detection of killer activity, and production of hydrolytic enzymes of the isolates of S. cerevisiae on C. acutatum and their efficiency in controlling postbloom fruit drop on detached citrus flowers. Our results showed that all six S. cerevisiae isolates produced antifungal compounds, competed for nutrients, inhibited pathogen germination, and produced killer activity and hydrolytic enzymes when in contact with the fungus wall. The isolates were able to control the disease when detached flowers were artificially inoculated, both preventively and curatively. In this work we identified a novel potential biological control agent for C. acutatum during pre-harvest. This is the first report of yeast efficiency for the biocontrol of postbloom fruit drop, which represents an important contribution to the field of biocontrol of diseases affecting citrus populations worldwide. Copyright © 2015 Elsevier GmbH. All rights reserved.

Linking habitat management and conservation biocontrol through gut-content analysis

USDA-ARS?s Scientific Manuscript database

Increasing the habitat diversity of agricultural fields can lead to more effective biocontrol of arthropod pests. Annual cropping systems are exposed to frequent disturbance and lack habitat diversity; therefore it is important to develop strategies that can improve ecosystem services such as bioco...

Draft Genome Sequence of Chryseobacterium sp. Strain GSE06, a Biocontrol Endophytic Bacterium Isolated from Cucumber (Cucumis sativus)

PubMed Central

Jeong, Jin-Ju; Park, Byeong Hyeok; Park, Hongjae

2016-01-01

Chryseobacterium sp. strain GSE06 is a biocontrol endophytic bacterium against the destructive soilborne oomycete Phytophthora capsici, which causes Phytophthora blight of pepper. Here, we present its draft genome sequence, which contains genes related to biocontrol traits, such as colonization, antimicrobial activity, plant growth promotion, and abiotic or biotic stress adaptation. PMID:27313310

Composition of fungal soil communities varies with plant abundance and geographic origin

PubMed Central

Reininger, Vanessa; Martinez-Garcia, Laura B.; Sanderson, Laura; Antunes, Pedro M.

2015-01-01

Interactions of belowground fungal communities with exotic and native plant species may be important drivers of plant community structure in invaded grasslands. However, field surveys linking plant community structure with belowground fungal communities are missing. We investigated whether a selected number of abundant and relatively rare plants, either native or exotic, from an old-field site associate with different fungal communities. We also assessed whether these plants showed different symbiotic relationships with soil biota through their roots. We characterized the plant community and collected roots to investigate fungal communities using 454 pyrosequencing and assessed arbuscular mycorrhizal colonization and enemy-induced lesions. Differences in fungal communities were considered based on the assessment of α- and β diversity depending on plant ‘abundance’ and ‘origin’. Plant abundance and origin determined the fungal community. Fungal richness was higher for native abundant as opposed to relatively rare native plant species. However, this was not observed for exotics of contrasting abundance. Regardless of their origin, β diversity was higher for rare than for abundant species. Abundant exotics in the community, which happen to be grasses, were the least mycorrhizal whereas rare natives were most susceptible to enemy attack. Our results suggest that compared with exotics, the relative abundance of remnant native plant species in our old-field site is still linked to the structure of belowground fungal communities. In contrast, exotic species may act as a disturbing agent contributing towards the homogenization of soil fungal communities, potentially changing feedback interactions. PMID:26371291

The toolbox of Trichoderma spp. in the biocontrol of Botrytis cinerea disease.

PubMed

Vos, Christine M F; De Cremer, Kaat; Cammue, Bruno P A; De Coninck, Barbara

2015-05-01

Botrytis cinerea is a necrotrophic fungal pathogen causing disease in many plant species, leading to economically important crop losses. So far, fungicides have been widely used to control this pathogen. However, in addition to their detrimental effects on the environment and potential risks for human health, increasing fungicide resistance has been observed in the B. cinerea population. Biological control, that is the application of microbial organisms to reduce disease, has gained importance as an alternative or complementary approach to fungicides. In this respect, the genus Trichoderma constitutes a promising pool of organisms with potential for B. cinerea control. In the first part of this article, we review the specific mechanisms involved in the direct interaction between the two fungi, including mycoparasitism, the production of antimicrobial compounds and enzymes (collectively called antagonism), and competition for nutrients and space. In addition, biocontrol has also been observed when Trichoderma is physically separated from the pathogen, thus implying an indirect systemic plant defence response. Therefore, in the second part, we describe the consecutive steps leading to induced systemic resistance (ISR), starting with the initial Trichoderma-plant interaction and followed by the activation of downstream signal transduction pathways and, ultimately, the defence response resulting in ISR (ISR-prime phase). Finally, we discuss the ISR-boost phase, representing the effect of ISR priming by Trichoderma spp. on plant responses after additional challenge with B. cinerea. © 2014 BSPP AND JOHN WILEY & SONS LTD.

Trichodiene production in a Trichoderma harzianum erg1-silenced strain provides evidence of the importance of the sterol biosynthetic pathway in inducing plant defense-related gene expression

USDA-ARS?s Scientific Manuscript database

Trichoderma species are often used as biocontrol agents against plant-pathogenic fungi. A complex molecular interaction occurs among the biocontrol agent, the antagonistic fungus, and the plant. Terpenes and sterols produced by the biocontrol fungus have been found to affect gene expression in both ...

Metacridamides A and B from the biocontrol fungus metarhizium acridum

USDA-ARS?s Scientific Manuscript database

Metarhizium acridum, an entomopathogenic fungus, has been commercialized and used successfully for biocontrol of grasshopper pests in Africa and Australia. As part of an effort to catalog the secondary metabolites of this fungus we discovered that its conidia produce two novel 17-membered macrocycl...

Heat-Killed Yeast as a Pan-Fungal Vaccine.

PubMed

Martinez, Marife; Clemons, Karl V; Stevens, David A

2017-01-01

Fungal infections continue to rise worldwide. Antifungal therapy has long been a mainstay for the treatment of these infections, but often can fail for a number of reasons. These include acquired or innate drug resistance of the causative agent, poor drug penetration into the affected tissues, lack of cidal activity of the drug and drug toxicities that limit therapy. In some instances, such as coccidioidal meningitis, therapy is life-long. In addition, few new antifungal drugs are under development. In light of this information a preventative vaccine is highly desirable. Although numerous investigators have worked toward the development of fungal vaccines, none have become commercially available for use in humans. In the course of our studies, we have discovered that heat-killed yeast (HKY) of Saccharomyces cerevisiae can be used as a vaccine and have shown that it has efficacy in the prevention and reduction of five different fungal infections when used experimentally in mice, which raises the possibility of a pan-fungal vaccine preparation. In our studies we grow S. cerevisiae in broth and heat-kill the organism at 70 ° C for 3 h. The number of dead yeast cells is adjusted and mice are vaccinated subcutaneously beginning 3-7 weeks prior to infection. After infection, efficacy is assessed on the basis of survival and residual burden of the fungus in the target organs. Alternatively, efficacy can be assessed solely on fungal burden at a predetermined time postinfection. Although itself it is unlikely to be moved toward commercialization, HKY can be used a positive control vaccine for studies on specific molecular entities as vaccines, and as a guidepost for the key elements of potential, more purified, pan-fungal vaccine preparations.

Clinically Significant Enhancement of Voriconazole Efficacy by Moxifloxacin and Gentamicin in Fungal Keratitis.

PubMed

Matoba, Alice Y; Divatia, Mukul K; Arguello, Robert A; Chevez-Barrios, Paty

2018-05-01

To report the effect of topical antibiotics moxifloxacin 0.3% and gentamicin 0.3% on the clinical efficacy of topical antifungal agent voriconazole 1% in cases of culture- or biopsy-proven fungal keratitis. Two cases of fungal keratitis in which the addition of topical moxifloxacin or moxifloxacin and gentamicin led to an improved clinical response to topical voriconazole were reviewed retrospectively. One patient with clinical resistance of his fungal keratitis to both topical voriconazole and natamycin had resolution of his keratitis with the addition of topical moxifloxacin and gentamicin to voriconazole. One patient who had a poor response to topical voriconazole had a dramatic response to the increase of the voriconazole regimen and addition of moxifloxacin. In a subset of patients with fungal keratitis, the addition of topical moxifloxacin 0.3% or moxifloxacin 0.3% and gentamicin 0.3% may enhance the therapeutic effect of topical voriconazole 1%.

The Cerato-Platanin protein Epl-1 from Trichoderma harzianum is involved in mycoparasitism, plant resistance induction and self cell wall protection

PubMed Central

Gomes, Eriston Vieira; Costa, Mariana do Nascimento; de Paula, Renato Graciano; Ricci de Azevedo, Rafael; da Silva, Francilene Lopes; Noronha, Eliane F.; José Ulhoa, Cirano; Neves Monteiro, Valdirene; Elena Cardoza, Rosa; Gutiérrez, Santiago; Nascimento Silva, Roberto

2015-01-01

Trichoderma harzianum species are well known as biocontrol agents against important fungal phytopathogens. Mycoparasitism is one of the strategies used by this fungus in the biocontrol process. In this work, we analyzed the effect of Epl-1 protein, previously described as plant resistance elicitor, in expression modulation of T. harzianum genes involved in mycoparasitism process against phytopathogenic fungi; self cell wall protection and recognition; host hyphae coiling and triggering expression of defense-related genes in beans plants. The results indicated that the absence of Epl-1 protein affects the expression of all mycoparasitism genes analyzed in direct confrontation assays against phytopathogen Sclerotinia sclerotiorum as well as T. harzianum itself; the host mycoparasitic coiling process and expression modulation of plant defense genes showing different pattern compared with wild type strain. These data indicated the involvement T. harzianum Epl-1 in self and host interaction and also recognition of T. harzianum as a symbiotic fungus by the bean plants. PMID:26647876

The Cerato-Platanin protein Epl-1 from Trichoderma harzianum is involved in mycoparasitism, plant resistance induction and self cell wall protection.

PubMed

Gomes, Eriston Vieira; Costa, Mariana do Nascimento; de Paula, Renato Graciano; de Azevedo, Rafael Ricci; da Silva, Francilene Lopes; Noronha, Eliane F; Ulhoa, Cirano José; Monteiro, Valdirene Neves; Cardoza, Rosa Elena; Gutiérrez, Santiago; Silva, Roberto Nascimento

2015-12-09

Trichoderma harzianum species are well known as biocontrol agents against important fungal phytopathogens. Mycoparasitism is one of the strategies used by this fungus in the biocontrol process. In this work, we analyzed the effect of Epl-1 protein, previously described as plant resistance elicitor, in expression modulation of T. harzianum genes involved in mycoparasitism process against phytopathogenic fungi; self cell wall protection and recognition; host hyphae coiling and triggering expression of defense-related genes in beans plants. The results indicated that the absence of Epl-1 protein affects the expression of all mycoparasitism genes analyzed in direct confrontation assays against phytopathogen Sclerotinia sclerotiorum as well as T. harzianum itself; the host mycoparasitic coiling process and expression modulation of plant defense genes showing different pattern compared with wild type strain. These data indicated the involvement T. harzianum Epl-1 in self and host interaction and also recognition of T. harzianum as a symbiotic fungus by the bean plants.

Universal fungal vaccines

PubMed Central

Hamad, Mawieh

2012-01-01

The complex nature of fungal pathogens, the intricate host-pathogen relationship and the health status of subjects in need of antifungal vaccination continue to hamper efforts to develop fungal vaccines for clinical use. That said, the rise of the universal vaccine concept is hoped to revive fungal vaccine research by expanding the pool of vaccine candidates worthy of clinical evaluation. It can do so through antigenic commonality-based screening for vaccine candidates from a wide range of pathogens and by reassessing the sizable collection of already available experimental and approved vaccines. Development of experimental vaccines protective against multiple fungal pathogens is evidence of the utility of this concept in fungal vaccine research. However, universal fungal vaccines are not without difficulties; for instance, development of vaccines with differential effectiveness is an issue that should be addressed. Additionally, rationalizing the development of universal fungal vaccines on health or economic basis could be contentious. Herein, universal fungal vaccines are discussed in terms of their potential usefulness and possible drawbacks. PMID:22922769

Canada thistle biological control agents on two South Dakota wildlife refuges

USGS Publications Warehouse

Reed, C.C.; Larson, D.L.; Larson, J.L.

2006-01-01

We monitored populations of Canada thistle biocontrol agents Cassida rubiginosa, Ceutorhynchus litura, Larinus (= Hadroplantus) planus, Urophora cardui, Orellia (= Terellia) ruficauda, and Rhinocyllus conicus on Canada thistle (Cirsium arvense) at two national wildlife refuges in South Dakota from 1999 through 2003. C. litura, U. cardui, O. ruficauda, and R. conicus were present on both refuges. Agent populations were low except for C. litura, which was present in up to 90% of stems in some plots. C. litura infestation did not reduce thistle flowering, stem length, or over-winter survival. There was no change in thistle stem numbers over the study period and no difference in stem numbers in areas of high C. litura populations compared to areas of low C. litura populations. Our results suggest that insect biological control agents are inadequate for reduction of Canada thistle in southern South Dakota.

Mass-Rearing Hydrellia Pakistanae Deonier and H. balciunasi Bock for the Management of Hydrilla verticillata

DTIC Science & Technology

2009-06-01

capability. Mass Rearing: The ability to mass-produce large numbers of high quality insect biocontrol agents can be a tremendous asset when...implementing a biocontrol program. Common sense would dictate that releasing a high number of agents allows for higher establishment success, more rapid...varying densities of biocontrol agent (costs estimated using a constant weight). Table 1. Hypothetical calculation of Hydrellia pakistanae production cost

Fungal Endocarditis.

PubMed

Yuan, Shi-Min

2016-01-01

Fungal endocarditis is a rare and fatal condition. The Candida and Aspergillus species are the two most common etiologic fungi found responsible for fungal endocarditis. Fever and changing heart murmur are the most common clinical manifestations. Some patients may have a fever of unknown origin as the onset symptom. The diagnosis of fungal endocarditis is challenging, and diagnosis of prosthetic valve fungal endocarditis is extremely difficult. The optimum antifungal therapy still remains debatable. Treating Candida endocarditis can be difficult because the Candida species can form biofilms on native and prosthetic heart valves. Combined treatment appears superior to monotherapy. Combination of antifungal therapy and surgical debridement might bring about better prognosis.

Effect of thermoneutral housing on fungal-induced respiratory allergic disease in mice

EPA Science Inventory

Climate change is projected to increase the number of fungal, bacterial, and pollen agents both indoors and outdoors and may become a significant health impact. Combined with the thermal stress from a rise in global temperatures, it is important to consider how respiratory allerg...

Gamma irradiation inactivates honey bee fungal, microsporidian, and viral pathogens and parasites

USDA-ARS?s Scientific Manuscript database

Managed honey bee (Apis mellifera) populations are currently facing unsustainable losses due to a variety of factors. Colonies are challenged with brood pathogens, such as the fungal agent of chalkbrood disease, the microsporidian gut parasite Nosema sp., and several viruses. These pathogens may be ...

Biomimicry of volatile-based microbial control for managing emerging fungal pathogens.

PubMed

Gabriel, K T; Joseph Sexton, D; Cornelison, C T

2018-05-01

Volatile organic compounds (VOCs) are known to be produced by a wide range of micro-organisms and for a number of purposes. Volatile-based microbial inhibition in environments such as soil is well-founded, with numerous antimicrobial VOCs having been identified. Inhibitory VOCs are of interest as microbial control agents, as low concentrations of gaseous VOCs can elicit significant antimicrobial effects. Volatile organic compounds are organic chemicals typically characterized as having low molecular weight, low solubility in water, and high vapour pressure. Consequently, VOCs readily evaporate to the gaseous phase at standard temperature and pressure. This contact-independent antagonism presents unique advantages over traditional, contact-dependent microbial control methods, including increased surface exposure and reduced environmental persistence. This approach has been the focus of our recent research, with positive results suggesting it may be particularly promising for the management of emerging fungal pathogens, such as the causative agents of white-nose syndrome of bats and snake fungal disease, which are difficult or impossible to treat using traditional approaches. Here, we review the history of volatile-based microbial control, discuss recent progress in formulations that mimic naturally antagonistic VOCs, outline the development of a novel treatment device, and highlight areas where further work is needed to successfully deploy VOCs against existing and emerging fungal pathogens. © 2017 The Society for Applied Microbiology.

Fungal diversity in oil palm leaves showing symptoms of Fatal Yellowing disease

PubMed Central

de Assis Costa, Ohana Yonara; Tupinambá, Daiva Domenech; Bergmann, Jessica Carvalho; Barreto, Cristine Chaves

2018-01-01

Oil palm (Elaeis guineensis Jacq.) is an excellent source of vegetable oil for biodiesel production; however, there are still some limitations for its cultivation in Brazil such as Fatal Yellowing (FY) disease. FY has been studied for many years, but its causal agent has never been determined. In Colombia and nearby countries, it was reported that the causal agent of Fatal Yellowing (Pudrición del Cogollo) is the oomycete Phytophthora palmivora, however, several authors claim that Fatal Yellowing and Pudrición del Cogollo (PC) are different diseases. The major aims of this work were to test, using molecular biology tools, Brazilian oil palm trees for the co-occurrence of the oomycete Phytophthora and FY symptoms, and to characterize the fungal diversity in FY diseased and healthy leaves by next generation sequencing. Investigation with specific primers for the genus Phytophthora showed amplification in only one of the samples. Analysis of the fungal ITS region demonstrated that, at the genus level, different groups predominated in all symptomatic samples, while Pyrenochaetopsis and unclassified fungi predominated in all asymptomatic samples. Our results show that fungal communities were not the same between samples at the same stage of the disease or among all the symptomatic samples. This is the first study that describes the evolution of the microbial community in the course of plant disease and also the first work to use high throughput next generation sequencing to evaluate the fungal community associated with leaves of oil palm trees with and without symptoms of FY. PMID:29370299

Interactions of liposome carriers with infectious fungal hyphae reveals the role of β-glucans.

PubMed

Chavan, Neelam L; Young, Joseph K; Drezek, Rebekah A; Lewis, Russell; Bikram, Malavosklish

2012-09-04

Relatively little is known about how liposomal formulations modulate drug delivery to fungal pathogens. We compared patterns of hyphal cell wall binding for empty rhodmine-labeled liposomes and the clinically available amphotericin B-containing liposomal formulation (AmBisome) in Aspergillus fumigatus and Candida albicans. Following 0.5 h of coincubation with A. fumigatus , empty liposomes concentrated primarily in fungal septae along at the surface of the cell wall, suggesting that liposome uptake is concentrated in areas of the cell wall where linear glucan is exposed on the cell surface, which was confirmed by aniline blue staining. Consistent with this hypothesis, pretreatment of liposomes with soluble linear glucan (laminarin) decreased liposome binding in both Aspergillus and Candida fungal hyphae, while growth of Aspergillus hyphae in the presence of an agent that increases fungal cell wall surface exposure of linear β-glucans without cell death (caspofungin) increased liposome uptake throughout the Aspergillus fungal cell wall. Increasing the polyethylene glycol (PEG) concentration in liposomes from 0 to 30% significantly increased fungal uptake of liposomes that was only modestly attenuated when fungal cells were incubated in serum concentrations ranging from 10 to 100%. The presence of β-glucans on the fungal hyphae cell walls of Aspergillus fumigatus is one of the factors responsible for mediating the binding of liposome carriers to the hyphae and could explain possible synergy reported between liposomal amphotericin B and echinocanins.

A study of the suppression of body odour in elderly subjects by anti-fungal agents.

PubMed

Ozeki, C; Moro, O

2016-06-01

The suppression of body odour following the use of shampoos or soaps containing the anti-fungal agent miconazole nitrate (MCZ) has been recognized anecdotally. To determine whether MCZ could play a role in the suppression of body odour through inhibiting squalene oxidation. A prospective study recruited 54 elderly subjects residing in a nursing facility who needed bathing assistance. Subjects bathed with three types of body soap over a 6-week study period (regular soap, sample soap (soap containing MCZ), control soap; 2 weeks per type of soap). Body odour was evaluated based on olfactory assessment of the subjects and their clothing. The subjects and the examiners were blinded to the type of soap (sample or control) being used during the study. An analysis using GC/MS was also carried out to identify the volatile compounds associated with body odour. Suppression of unpleasant body odour of the neck and axilla was reported in subjects who used the sample soap. Three common volatile compounds were detected from the T-shirts worn by the subjects: 2-ethylbutanal, 6-methyl-5-hepten-2-one, and geranylacetone. The occurrence of these compounds was reduced using the sample soap. Our findings suggest that MCZ could play a role in the suppression of body odour. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Production, Survival, and Evaluation of Solid-Substrate Inocula of Penicillium oxalicum, a Biocontrol Agent Against Fusarium Wilt of Tomato.

PubMed

Larena, I; Melgarejo, P; De Cal, A

2002-08-01

ABSTRACT Production of conidia of Penicillium oxalicum (ATCC number pending), a biocontrol agent of Fusarium oxysporum f. sp. lycopersici, was tested in liquid and solid fermentation. P. oxalicum produced 250-fold more conidia in solid than in liquid fermentation at 30 days after inoculation of substrate. Solid fermentation was carried out in plastic bags (600 cm(3)) especially designed for solid fermentation (VALMIC) containing 50 g of peat/vermiculite (PV) (1:1, wt/wt) with 40% moisture, sealed, sterilized, and then inoculated with 1 ml of a conidial suspension of P. oxalicum (10(5) conidia g(-1) dry substrate), sealed again, and incubated in darkness at 20 to 25 degrees C for 30 days. Addition of amendments to PV in a proportion of 0.5 (wt/wt) significantly increased conidial production of P. oxalicum. The best production was obtained on PV plus meal of cereal grains (barley) or leguminous seeds (lentil) (100-fold higher). Conidial production obtained after 5 days of inoculation was similar to that obtained at 30 days. However, viability of conidia produced in PV plus lentil meal was 35% higher than that of conidia produced in PV plus barley meal. Changes in proportions (1:1:0.5, wt/wt/wt; 1:1:1, wt/wt/wt; 1:0.5:0.5, wt/wt/wt; 1:1:0.5, vol/vol/vol) of components of the substrate (peat/vermiculite/lentil meal) did not enhance production or viability of conidia. Optimal initial moisture in the substrate was 30 to 40%. At lower moistures, significant reductions of production of conidia were observed, particularly at 10%. There was a general decline in the number of conidia in bags with time of storage at -80, -20, 4, and 25 degrees C, or at room temperature (range from 30 to 15 degrees C), with the highest decline occurring from 60 to 180 days. Conidial viability also was reduced with time, except for conidia stored at -20 degrees C. Fresh conidia produced in solid fermentation system or those conidia stored at -20 degrees C for 180 days reduced Fusarium wilt of

Lipopeptides as main ingredients for inhibition of fungal phytopathogens by Bacillus subtilis/amyloliquefaciens

PubMed Central

Cawoy, Hélène; Debois, Delphine; Franzil, Laurent; De Pauw, Edwin; Thonart, Philippe; Ongena, Marc

2015-01-01

Some isolates of the Bacillus subtilis/amyloliquefaciens species are known for their plant protective activity against fungal phytopathogens. It is notably due to their genetic potential to form an impressive array of antibiotics including non-ribosomal lipopeptides (LPs). In the work presented here, we wanted to gain further insights into the relative role of these LPs in the global antifungal activity of B. subtilis/amyloliquefaciens. To that end, a comparative study was conducted involving multiple strains that were tested against four different phytopathogens. We combined various approaches to further exemplify that secretion of those LPs is a crucial trait in direct pathogen ward off and this can actually be generalized to all members of these species. Our data illustrate that for each LP family, the fungitoxic activity varies in function of the target species and that the production of iturins and fengycins is modulated by the presence of pathogens. Our data on the relative involvement of these LPs in the biocontrol activity and modulation of their production are discussed in the context of natural conditions in the rhizosphere. PMID:25529983

Cyprinid herpesvirus 3 as a potential biological control agent for carp (Cyprinus carpio) in Australia: susceptibility of non-target species.

PubMed

McColl, K A; Sunarto, A; Slater, J; Bell, K; Asmus, M; Fulton, W; Hall, K; Brown, P; Gilligan, D; Hoad, J; Williams, L M; Crane, M St J

2017-09-01

Carp (Cyprinus carpio L.) is a pest species in Australian waterways, and cyprinid herpesvirus 3 (CyHV-3) is being considered as a potential biological control (biocontrol) agent. An important consideration for any such agent is its target specificity. In this study, the susceptibility to CyHV-3 of a range of non-target species (NTS) was tested. The NTS were as follows: 13 native Australian, and one introduced, fish species; a lamprey species; a crustacean; two native amphibian species (tadpole and mature stages); two native reptilian species; chickens; and laboratory mice. Animals were exposed to 100-1000 times the approximate minimum amount of CyHV-3 required to cause disease in carp by intraperitoneal and/or bath challenge, and then examined clinically each day over the course of 28 days post-challenge. There were no clinical signs, mortalities or histological evidence consistent with a viral infection in a wide taxonomic range of NTS. Furthermore, there was no molecular evidence of infection with CyHV-3, and, in particular, all RT-PCRs for viral mRNA were negative. As a consequence, the results encourage further investigation of CyHV-3 as a potential biocontrol agent that is specific for carp. © 2016 John Wiley & Sons Ltd.

Rhizosphere Competence and Biocontrol Effect of Pseudomonas sp. RU47 Independent from Plant Species and Soil Type at the Field Scale.

PubMed

Schreiter, Susanne; Babin, Doreen; Smalla, Kornelia; Grosch, Rita

2018-01-01

Biocontrol inoculants often show inconsistency in their efficacy at field scale and the reason for this remains often unclear. A high rhizosphere competence of inoculant strains is assumed to be a key factor for successful biocontrol effects as the biocontrol strain has to compete with the indigenous microbial community in the rhizosphere. It is known that many factors, among them plant species and soil type shape the rhizosphere microbial community composition. However, microbial community composition in the rhizosphere can also be influenced by the presence of a pathogen. We hypothesized that plant species, soil type, and a pathogen affect the rhizosphere competence of a biocontrol strain and its biocontrol effect against a soil-borne pathogen. To test the hypothesis, we used an experimental plot system with three soil types (diluvial sand, alluvial loam, loess loam) kept under similar agricultural management at the same field site for 12 years. We investigate the rhizosphere competence of Pseudomonas sp. RU47 in two plant species (potato and lettuce) and its biocontrol effect against Rhizoctonia diseases. The colonization density of a rifampicin resistant mutant of RU47 in the rhizosphere of both crops was evaluated by plate counts. Bacterial community compositions were analyzed by denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments amplified from total community DNA. The inoculant RU47 was able to colonize the rhizosphere of both model crops in a sufficient density and to reduce disease severity of black scurf on potato and bottom rot on lettuce in all three soils. DGGE indicated that RU47 affected the bacterial community composition stronger in the rhizosphere of lettuce than in the potato rhizosphere. In contrast, the effect of the pathogen Rhizoctonia solani on the bacterial community was much stronger in the rhizosphere of potato than in the lettuce rhizosphere. A significant effect of RU47 on the Pseudomonas -specific gac

Rhizosphere Competence and Biocontrol Effect of Pseudomonas sp. RU47 Independent from Plant Species and Soil Type at the Field Scale

PubMed Central

Schreiter, Susanne; Babin, Doreen; Smalla, Kornelia; Grosch, Rita

2018-01-01

Biocontrol inoculants often show inconsistency in their efficacy at field scale and the reason for this remains often unclear. A high rhizosphere competence of inoculant strains is assumed to be a key factor for successful biocontrol effects as the biocontrol strain has to compete with the indigenous microbial community in the rhizosphere. It is known that many factors, among them plant species and soil type shape the rhizosphere microbial community composition. However, microbial community composition in the rhizosphere can also be influenced by the presence of a pathogen. We hypothesized that plant species, soil type, and a pathogen affect the rhizosphere competence of a biocontrol strain and its biocontrol effect against a soil-borne pathogen. To test the hypothesis, we used an experimental plot system with three soil types (diluvial sand, alluvial loam, loess loam) kept under similar agricultural management at the same field site for 12 years. We investigate the rhizosphere competence of Pseudomonas sp. RU47 in two plant species (potato and lettuce) and its biocontrol effect against Rhizoctonia diseases. The colonization density of a rifampicin resistant mutant of RU47 in the rhizosphere of both crops was evaluated by plate counts. Bacterial community compositions were analyzed by denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments amplified from total community DNA. The inoculant RU47 was able to colonize the rhizosphere of both model crops in a sufficient density and to reduce disease severity of black scurf on potato and bottom rot on lettuce in all three soils. DGGE indicated that RU47 affected the bacterial community composition stronger in the rhizosphere of lettuce than in the potato rhizosphere. In contrast, the effect of the pathogen Rhizoctonia solani on the bacterial community was much stronger in the rhizosphere of potato than in the lettuce rhizosphere. A significant effect of RU47 on the Pseudomonas-specific gacA fingerprints

Heat shock improves stress tolerance and biocontrol performance of Rhodotorula mucilaginosa

USDA-ARS?s Scientific Manuscript database

Biological control of postharvest diseases, utilizing wild species and strains of antagonistic yeasts, is a research topic and eco-friendly management approach that has received considerable attention. A few yeast-based biocontrol products are available in the market. Ecological fitness, stress to...

Fungal Endocarditis

PubMed Central

Yuan, Shi-Min

2016-01-01

Fungal endocarditis is a rare and fatal condition. The Candida and Aspergillus species are the two most common etiologic fungi found responsible for fungal endocarditis. Fever and changing heart murmur are the most common clinical manifestations. Some patients may have a fever of unknown origin as the onset symptom. The diagnosis of fungal endocarditis is challenging, and diagnosis of prosthetic valve fungal endocarditis is extremely difficult. The optimum antifungal therapy still remains debatable. Treating Candida endocarditis can be difficult because the Candida species can form biofilms on native and prosthetic heart valves. Combined treatment appears superior to monotherapy. Combination of antifungal therapy and surgical debridement might bring about better prognosis. PMID:27737409

The genome sequence of the biocontrol fungus Metarhizium anisopliae and comparative genomics of Metarhizium species.

PubMed

Pattemore, Julie A; Hane, James K; Williams, Angela H; Wilson, Bree A L; Stodart, Ben J; Ash, Gavin J

2014-08-07

Metarhizium anisopliae is an important fungal biocontrol agent of insect pests of agricultural crops. Genomics can aid the successful commercialization of biopesticides by identification of key genes differentiating closely related species, selection of virulent microbial isolates which are amenable to industrial scale production and formulation and through the reduction of phenotypic variability. The genome of Metarhizium isolate ARSEF23 was recently published as a model for M. anisopliae, however phylogenetic analysis has since re-classified this isolate as M. robertsii. We present a new annotated genome sequence of M. anisopliae (isolate Ma69) and whole genome comparison to M. robertsii (ARSEF23) and M. acridum (CQMa 102). Whole genome analysis of M. anisopliae indicates significant macrosynteny with M. robertsii but with some large genomic inversions. In comparison to M. acridum, the genome of M. anisopliae shares lower sequence homology. While alignments overall are co-linear, the genome of M. acridum is not contiguous enough to conclusively observe macrosynteny. Mating type gene analysis revealed both MAT1-1 and MAT1-2 genes present in M. anisopliae suggesting putative homothallism, despite having no known teleomorph, in contrast with the putatively heterothallic M. acridum isolate CQMa 102 (MAT1-2) and M. robertsii isolate ARSEF23 (altered MAT1-1). Repetitive DNA and RIP analysis revealed M. acridum to have twice the repetitive content of the other two species and M. anisopliae to be five times more RIP affected than M. robertsii. We also present an initial bioinformatic survey of candidate pathogenicity genes in M. anisopliae. The annotated genome of M. anisopliae is an important resource for the identification of virulence genes specific to M. anisopliae and development of species- and strain- specific assays. New insight into the possibility of homothallism and RIP affectedness has important implications for the development of M. anisopliae as a

Biocontrol activity of a cold-adapted yeast from Tibet against gray mold in cherry tomato and its action mechanism.

PubMed

Hu, Hao; Wisniewski, Michael E; Abdelfattah, Ahmed; Zheng, Xiaodong

2017-07-01

Cold-adapted biocontrol yeast was selected from four yeast isolates from Tibet against gray mold of cherry tomato in cold storage. The strain numbered LB2 showed the best biocontrol activity and identified as Cryptococcus laurentii. Competition for nutrient, space, and induced fruit resistance was also its antagonistic mechanism. Compared with C. laurentii from sea-level place, the reason why LB2 had a better biocontrol activity was studied. More trehalose and proline in cell of LB2 made it exhibit a better cellular activity at low temperature, such as higher population dynamics in the wounds of cherry tomato and more biocontrol-related enzyme secretion, chitinase and β-glucanase. The better oxidative stress tolerance was another characteristic of LB2. Maybe because of the ideal culture condition, there was no obvious difference between these two yeasts in the growth in vitro test at low temperature. Although the same phenomenon existed in the low pH stress test, LB2 still had higher cell concentration under this stress. Comparative transcriptomics method was also applied to analyze the cell activity of LB2 and C. laurentii at different temperatures. The results showed that more active response in the intracellular structure and intracellular metabolic process to cold temperature made LB2 had a better activity. The present study indicated a possibility to select cold-adapted biocontrol yeast from Tibet and also showed its primary action mechanism.

Genome Sequence, Assembly and Characterization of Two Metschnikowia fructicola Strains Used as Biocontrol Agents of Postharvest Diseases

PubMed Central

Piombo, Edoardo; Sela, Noa; Wisniewski, Michael; Hoffmann, Maria; Gullino, Maria L.; Allard, Marc W.; Levin, Elena; Spadaro, Davide; Droby, Samir

2018-01-01

The yeast Metschnikowia fructicola was reported as an efficient biological control agent of postharvest diseases of fruits and vegetables, and it is the bases of the commercial formulated product “Shemer.” Several mechanisms of action by which M. fructicola inhibits postharvest pathogens were suggested including iron-binding compounds, induction of defense signaling genes, production of fungal cell wall degrading enzymes and relatively high amounts of superoxide anions. We assembled the whole genome sequence of two strains of M. fructicola using PacBio and Illumina shotgun sequencing technologies. Using the PacBio, a high-quality draft genome consisting of 93 contigs, with an estimated genome size of approximately 26 Mb, was obtained. Comparative analysis of M. fructicola proteins with the other three available closely related genomes revealed a shared core of homologous proteins coded by 5,776 genes. Comparing the genomes of the two M. fructicola strains using a SNP calling approach resulted in the identification of 564,302 homologous SNPs with 2,004 predicted high impact mutations. The size of the genome is exceptionally high when compared with those of available closely related organisms, and the high rate of homology among M. fructicola genes points toward a recent whole-genome duplication event as the cause of this large genome. Based on the assembled genome, sequences were annotated with a gene description and gene ontology (GO term) and clustered in functional groups. Analysis of CAZymes family genes revealed 1,145 putative genes, and transcriptomic analysis of CAZyme expression levels in M. fructicola during its interaction with either grapefruit peel tissue or Penicillium digitatum revealed a high level of CAZyme gene expression when the yeast was placed in wounded fruit tissue. PMID:29666611

Escherichia coli pneumonia in combination with fungal sinusitis and meningitis in a tsunami survivor after the Great East Japan Earthquake.

PubMed

Igusa, Ryotaro; Narumi, Sodai; Murakami, Koji; Kitawaki, Yuko; Tamii, Toru; Kato, Masahiro; Sato, Mineshige; Tsuboi, Masahiro; Ota, Kozo

2012-07-01

Individuals who survive near drowning often suffer from complicated infections, including multi-organ and polymicrobial events. This pattern may be especially pronounced among patients exposed to infectious agents during catastrophic events like that of the Great East Japan Earthquake and the associated tsunami disaster. We report here on a patient who presented with Escherichia coli (E. coli) pneumonia in combination with fungal sinusitis and meningitis. A 73-year-old woman survived the tsunami that engulfed the Sanriku coast. By the time of hospital admission, the patient exhibited high fever, severe cough, and sputum production. Chest X-ray and CT scan showed consolidation in the left upper lobe. Administration of an antibacterial agent improved this pneumonia. However, the patient's consciousness was increasingly impaired. Brain CT showed the low-density lesions and partial high-density spot in the sinus, which suggests the fungal infection. MRI showed the inflammation in the sinus spread into the central nerve system. The examination of the cerebrospinal fluid showed the low glucose level, high mononuclear cell count, and highβ-D glucan level, the findings of which supported the diagnosis of fungal meningitis. Although the patient improved temporarily in response to combination treatment with anti-fungal agents, no further improvement was seen. In conclusion, this patient, who suffered from infections of pneumonia, sinusitis, and meningitis, presented a quite rare clinical progress. We propose that fungal infection should be taken into consideration in individuals who suffered near drowning, a profile expected to be frequent among tsunami survivors.

Biodeterioration agents: Bacterial and fungal diversity dwelling in or on the pre-historic rock-paints of Kabra-pahad, India.

PubMed

Biswas, Jayant; Sharma, Kavita; Harris, K K; Rajput, Yogita

2013-09-01

In the last few decades, losses of our cultural heritage due to biodeteriorationare beinghighly recognized. From museum objects to rock monuments, the microbial biodeterioration agents are found to be the most destructive. Possibilities for proper preservative measure(s) are always more when it is only a monument, statue, museum article, or pre-historic art in any small subterranean cave. Nevertheless, preservation/protection of the footprints occupying a big area, lying scattered in a very negligible manner requires safeguard against several deterioration factors; right from various physical, chemical and biological agents which are indeed interrelated to each other. In the present study, some microbial communities possibly responsible for deteriorating the rocks of Kabra-pahad, where the most famous pre-historic rock paints of India prevail have been identified. The diversity of fungi and bacteria present in the stone crust of the infected areas has been studied by employing standard laboratory methods. The cultivated cultures confirmed total fifteen fungal species, among which Aspergillus group were the most dominant. Among bacteria, total 80 numbers of colonies were observed that dominated by two major groups; Micrococcus.spp and Staphylococcus spp. The pre-historic footprint in the form of rock paints in Kabra-pahad of district Raigarh, Chhattisgarh, India is lying in a very deteriorated manner. In the present study, we have tried to identify few major deteriorating factors that are responsible for such degradation of our existing pre-historic footprints.

Leaf Treatments with a Protein-Based Resistance Inducer Partially Modify Phyllosphere Microbial Communities of Grapevine

PubMed Central

Cappelletti, Martina; Perazzolli, Michele; Antonielli, Livio; Nesler, Andrea; Torboli, Esmeralda; Bianchedi, Pier L.; Pindo, Massimo; Puopolo, Gerardo; Pertot, Ilaria

2016-01-01

Protein derivatives and carbohydrates can stimulate plant growth, increase stress tolerance, and activate plant defense mechanisms. However, these molecules can also act as a nutritional substrate for microbial communities living on the plant phyllosphere and possibly affect their biocontrol activity against pathogens. We investigated the mechanisms of action of a protein derivative (nutrient broth, NB) against grapevine downy mildew, specifically focusing on the effects of foliar treatments on plant defense stimulation and on the composition and biocontrol features of the phyllosphere microbial populations. NB reduced downy mildew symptoms and induced the expression of defense-related genes in greenhouse- and in vitro-grown plants, indicating the activation of grapevine resistance mechanisms. Furthermore, NB increased the number of culturable phyllosphere bacteria and altered the composition of bacterial and fungal populations on leaves of greenhouse-grown plants. Although, NB-induced changes on microbial populations were affected by the structure of indigenous communities originally residing on grapevine leaves, degrees of disease reduction and defense gene modulation were consistent among the experiments. Thus, modifications in the structure of phyllosphere populations caused by NB application could partially contribute to downy mildew control by competition for space or other biocontrol strategies. Particularly, changes in the abundance of phyllosphere microorganisms may provide a contribution to resistance induction, partially affecting the hormone-mediated signaling pathways involved. Modifying phyllosphere populations by increasing natural biocontrol agents with the application of selected nutritional factors can open new opportunities in terms of sustainable plant protection strategies. PMID:27486468

Synthesis and assembly of fungal melanin

PubMed Central

Casadevall, Arturo

2015-01-01

Melanin is a unique pigment with myriad functions that is found in all biological kingdoms. It is multifunctional, providing defense against environmental stresses such as ultraviolet (UV) light, oxidizing agents and ionizing radiation. Melanin contributes to the ability of fungi to survive in harsh environments. In addition, it plays a role in fungal pathogenesis. Melanin is an amorphous polymer that is produced by one of two synthetic pathways. Fungi may synthesize melanin from endogenous substrate via a 1,8-dihydroxynaphthalene (DHN) intermediate. Alternatively, some fungi produce melanin from l-3,4-dihydroxyphenylalanine (l-dopa). The detailed chemical structure of melanin is not known. However, microscopic studies show that it has an overall granular structure. In fungi, melanin granules are localized to the cell wall where they are likely cross-linked to polysaccharides. Recent studies suggest the fungal melanin may be synthesized in internal vesicles akin to mammalian melanosomes and transported to the cell wall. Potential applications of melanin take advantage of melanin's radioprotective properties and propensity to bind to a variety of substances. PMID:22173481

Biological control agents elevate hantavirus by subsidizing deer mouse populations.

PubMed

Pearson, Dean E; Callaway, Ragan M

2006-04-01

Biological control of exotic invasive plants using exotic insects is practiced under the assumption that biological control agents are safe if they do not directly attack non-target species. We tested this assumption by evaluating the potential for two host-specific biological control agents (Urophora spp.), widely established in North America for spotted knapweed (Centaurea maculosa) control, to indirectly elevate Sin Nombre hantavirus by providing food subsidies to populations of deer mice (Peromyscus maniculatus), the primary reservoir for the virus. We show that seropositive deer mice (mice testing positive for hantavirus) were over three times more abundant in the presence of the biocontrol food subsidy. Elevating densities of seropositive mice may increase risk of hantavirus infection in humans and significantly alter hantavirus ecology. Host specificity alone does not ensure safe biological control. To minimize indirect risks to non-target species, biological control agents must suppress pest populations enough to reduce their own numbers.

Pathway to Deployment of Gene Drive Mosquitoes as a Potential Biocontrol Tool for Elimination of Malaria in Sub-Saharan Africa: Recommendations of a Scientific Working Group†.

PubMed

James, Stephanie; Collins, Frank H; Welkhoff, Philip A; Emerson, Claudia; Godfray, H Charles J; Gottlieb, Michael; Greenwood, Brian; Lindsay, Steve W; Mbogo, Charles M; Okumu, Fredros O; Quemada, Hector; Savadogo, Moussa; Singh, Jerome A; Tountas, Karen H; Touré, Yeya T

2018-06-01

Gene drive technology offers the promise for a high-impact, cost-effective, and durable method to control malaria transmission that would make a significant contribution to elimination. Gene drive systems, such as those based on clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated protein, have the potential to spread beneficial traits through interbreeding populations of malaria mosquitoes. However, the characteristics of this technology have raised concerns that necessitate careful consideration of the product development pathway. A multidisciplinary working group considered the implications of low-threshold gene drive systems on the development pathway described in the World Health Organization Guidance Framework for testing genetically modified (GM) mosquitoes , focusing on reduction of malaria transmission by Anopheles gambiae s.l. mosquitoes in Africa as a case study. The group developed recommendations for the safe and ethical testing of gene drive mosquitoes, drawing on prior experience with other vector control tools, GM organisms, and biocontrol agents. These recommendations are organized according to a testing plan that seeks to maximize safety by incrementally increasing the degree of human and environmental exposure to the investigational product. As with biocontrol agents, emphasis is placed on safety evaluation at the end of physically confined laboratory testing as a major decision point for whether to enter field testing. Progression through the testing pathway is based on fulfillment of safety and efficacy criteria, and is subject to regulatory and ethical approvals, as well as social acceptance. The working group identified several resources that were considered important to support responsible field testing of gene drive mosquitoes.

Pathway to Deployment of Gene Drive Mosquitoes as a Potential Biocontrol Tool for Elimination of Malaria in Sub-Saharan Africa: Recommendations of a Scientific Working Group†

PubMed Central

James, Stephanie; Collins, Frank H.; Welkhoff, Philip A.; Emerson, Claudia; Godfray, H. Charles J.; Gottlieb, Michael; Greenwood, Brian; Lindsay, Steve W.; Mbogo, Charles M.; Okumu, Fredros O.; Quemada, Hector; Savadogo, Moussa; Singh, Jerome A.; Tountas, Karen H.; Touré, Yeya T.

2018-01-01

Abstract. Gene drive technology offers the promise for a high-impact, cost-effective, and durable method to control malaria transmission that would make a significant contribution to elimination. Gene drive systems, such as those based on clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated protein, have the potential to spread beneficial traits through interbreeding populations of malaria mosquitoes. However, the characteristics of this technology have raised concerns that necessitate careful consideration of the product development pathway. A multidisciplinary working group considered the implications of low-threshold gene drive systems on the development pathway described in the World Health Organization Guidance Framework for testing genetically modified (GM) mosquitoes, focusing on reduction of malaria transmission by Anopheles gambiae s.l. mosquitoes in Africa as a case study. The group developed recommendations for the safe and ethical testing of gene drive mosquitoes, drawing on prior experience with other vector control tools, GM organisms, and biocontrol agents. These recommendations are organized according to a testing plan that seeks to maximize safety by incrementally increasing the degree of human and environmental exposure to the investigational product. As with biocontrol agents, emphasis is placed on safety evaluation at the end of physically confined laboratory testing as a major decision point for whether to enter field testing. Progression through the testing pathway is based on fulfillment of safety and efficacy criteria, and is subject to regulatory and ethical approvals, as well as social acceptance. The working group identified several resources that were considered important to support responsible field testing of gene drive mosquitoes. PMID:29882508

Emerging fungal infections among children: A review on its clinical manifestations, diagnosis, and prevention

PubMed Central