Effects of the foliar-applied protein "Harpin(Ea)" (messenger) on tomatoes infected with Phytophthora infestans.

PubMed

Fontanilla, M; Montes, M; De Prado, R

2005-01-01

The active ingredient in Messenger, is Harpin(Ea), a naturally occurring protein derived from Erwinia amylovora, a causal agent of fire blight. When Messenger is applied to a plant, the protein Harpin(Ea) binds foliar receptors to it. The receptors recognize the presence of Harpin(Ea), sending a signal that a pathogen is present, actually "tricking" the plant into thinking that it is under attack. This binding process triggers a cascade of responses affecting a global change of gene expressions, stimulating several distinct biochemical pathways within the plant responsible for growth and disease and insect resistance. The objective of this work is to characterize the development of an induced resistance against Phytophthora infestans. No effective treatment is currently available against this pathogenic agent, which causes the loss of complete harvests of different crops. Tomato plants with and without Messenger applications were inoculated with Phytophthora infestans in the same way. In addition, some plants with and without Messenger applications were not inoculated. Inoculated plants were symptomatologically checked for local and systemic symptoms. Evaluations of the number of tomatoes produced, with or without damage, and their growth, were also carried out. Based on the data obtained from the assays, significant changes were observed in the parameters measured due to Messenger treatment. The severe damage of this disease was reduced in the plants which received Messenger applications. These results open up new pathways in the control of diseases like Phytophthora infestans, in which effective means to combat them still do not exist, or these means are harmful to the environment.

[Application and prospect of fungi elicitors in fermentation industry].

PubMed

Gu, Shaobin; Gong, Hui; Yang, Bin; Bu, Meiling

2013-11-01

Fungal elicitors are a group of chemicals that can stimulate the secondary metabolite production in plants and microbial cells. After being recognized, it could enhance the expression of related genes through the signal-transduction pathway; regulate the activity of the enzyme involved in the biosynthesis of secondary metabolites. In recent years, the inducible mechanism of fungal elicitors has been studied deeply worldwide. Meanwhile, it has acquired wide concern in the area of biological industry, especially in the fermentation industry. This paper addresses the application and prospect of fungal elicitors in the secondary metabolites of plant and microbial cells.

Effects of fungal elicitors on seed germination and tissue culture of Cymbidium goeringii

NASA Astrophysics Data System (ADS)

Gong, Mingfu; Guan, Qinlan; Lin, Tianxing; Lan, Juming; Liu, Si

2018-04-01

The endophytic fungi were isolated from the roots of Cymbidium goeringii and Cymbidium faberi and were made into liquid fungal elicitors used to co-fungus germination of seeds of C. goeringii and C. faberi. The results showed that the germination rate of the seeds of C. goeringii was increased 15% to 30% by inoculating the mixed fungal elicitors of C. goeringii and was no significant change by inoculating the mixed fungal elicitors of C. faberi. Mixed fungal elicitor promoted the acclimation of tissue culture seedlings. Mixed fungal elicitor prepared mycorrhizal inoculant made new seedlings easier to survive when transplanted.

Hpa1 harpin needs nitroxyl terminus to promote vegetative growth and leaf photosynthesis in Arabidopsis.

PubMed

Li, Xiaojie; Han, Liping; Zhao, Yanying; You, Zhenzhen; Dong, Hansong; Zhang, Chunling

2014-03-01

Hpa1 is a harpin protein produced by Xanthomonas oryzae, an important bacterial pathogen of rice, and has the growth-promoting activity in plants. To understand the molecular basis for the function of Hpa1, we generated an inactive variant protein, Hpa1 delta NT, by deleting the nitroxyl-terminal region of the Hpa1 sequence and compared Hpa1 delta NT with the full-length protein in terms of the effects on vegetative growth and related physiological responses in Arabidopsis. When Hpa1 was applied to plants, it acted to enhance the vegetative growth but did not affect the floral development. Enhanced plant growth was accompanied by induced expression of growth-promoting genes in plant leaves. The growth-promoting activity of Hpa1 was further correlated with a physiological consequence shown as promoted leaf photosynthesis as a result of facilitated CO2 conduction through leaf stomata and mesophyll cells. On the contrary, plant growth, growth-promoting gene expression, and the physiological consequence changed little in response to the Hpa1 delta NT treatment. These analyses suggest that Hpa1 requires the nitroxyl-terminus to facilitate CO2 transport inside leaf cells and promote leaf photosynthesis and vegetative growth of the plant.

Novel beta-1,3-, 1,6-oligoglucan elicitor from Alternaria alternata 102 for defense responses in tobacco.

PubMed

Shinya, Tomonori; Ménard, Rozenn; Kozone, Ikuko; Matsuoka, Hideaki; Shibuya, Naoto; Kauffmann, Serge; Matsuoka, Ken; Saito, Mikako

2006-06-01

A novel elicitor that induces chitinases in tobacco BY-2 cells was isolated from Alternaria alternata 102. Six other fungi, including A. alternata IFO 6587, could not induce, or weakly induce chitinase activity. The purified elicitor was soluble in 75% methanol and showed the chitinase-inducing activity when applied at concentrations of as low as 25 ng x mL(-1). Structural determination by methylation analysis, reducing-end analysis, MALDI-TOF/MS, and NMR spectroscopy indicated that the elicitor was a mixture of beta-1,3-, 1,6-oligoglucans mostly with a degree of polymerization of between 8 and 17. Periodate oxidation of the elicitor suggested that the 1,6-linked and nonreducing terminal residues are essential for the elicitor activity. Further analysis of the elicitor responses in BY-2 cells indicated that the activity of this beta-1,3-, 1,6-glucan elicitor was about 1000 times more potent than that of laminarin, which is a known elicitor of defense responses in tobacco. Analyzing the expression of defense-related genes indicated that a phenylalanine ammonia-lyase gene and a coumaroyl-CoA O-methyltransferase gene were transiently expressed by this beta-1,3-, 1,6-glucan elicitor. The elicitor induced a weak oxidative burst but did not induce cell death in the BY-2 cells. In the tissue of tobacco plants, this beta-1,3-, 1,6-glucan elicitor induced the expression of basic PR-3 genes, the phenylpropanoid pathway genes, and the sesquiterpenoid pathway genes. In comparison with laminarin and laminarin sulfate, which are reported to be potent elicitors of defense responses in tobacco, the expression pattern of genes induced by the purified beta-1,3-, 1,6-glucan elicitor was more similar to that induced by laminarin than to that induced by laminarin sulfate.

Thigmomorphogenesis: the relationship of mechanical perturbation to elicitor-like activity and ethylene production

NASA Technical Reports Server (NTRS)

Takahashi, H.; Jaffe, M. J.

1984-01-01

An extracellular solution obtained from bean (Phaseolus vulgaris L. cv. Resistant Cherokee Wax) stems induced phytoalexin-like substance and ethylene production in a soybean [Glycine max (L.) Merr. cv. Wayne] cotyledon bioassay. The elicitor-like activity for phytoalexin formation and ethylene production was increased by mechanical perturbation of bean stems. Moreover, the application of extracted or known elicitors to bean plants mimicked the effect of mechanical perturbation (i.e., inhibition of stem elongation and enhancement of radial growth). The effects of extract when applied exogenously, on elicitor-like activity in the bioassay as well as stem thickening were decreased by aminoethoxyvinylglycine, an inhibitor of ethylene biosynthesis. These results suggest that elicitor-like substances which are formed in response to mechanical perturbation contribute to the thigmomorphogenesis.

Bacterial avirulence genes.

PubMed

Leach, J E; White, F F

1996-01-01

Although more than 30 bacterial avirulence genes have been cloned and characterized, the function of the gene products in the elictitation of resistance is unknown in all cases but one. The product of avrD from Pseudomonas syringae pv. glycinea likely functions indirectly to elicit resistance in soybean, that is, evidence suggests the gene product is an enzyme involved in elicitor production. In most if not all cases, bacterial avirulence gene function is dependent on interactions with the hypersensitive response and pathogenicity (hrp) genes. Many hrp genes are similar to genes involved in delivery of pathogenicity factors in mammalian bacterial pathogens. Thus, analogies between mammalian and plant pathogens may provide needed clues to elucidate how virulence gene products control induction of resistance.

Responses of soybean genotypes to pathogen infection after the application of elicitors

USDA-ARS?s Scientific Manuscript database

Soybean diseases and pests can affect soybean production. One emerging pest management method is to treat plants with chemical elicitors at nontoxic levels to induce host resistance. The objective of this research was to determine if elicitors, benzothiadiazole (BTH), chitosan (CHT), phenylalanine (...

Involvement of bacterial TonB-dependent signaling in the generation of an oligogalacturonide damage-associated molecular pattern from plant cell walls exposed to Xanthomonas campestris pv. campestris pectate lyases

PubMed Central

2012-01-01

Background Efficient perception of attacking pathogens is essential for plants. Plant defense is evoked by molecules termed elicitors. Endogenous elicitors or damage-associated molecular patterns (DAMPs) originate from plant materials upon injury or pathogen activity. While there are comparably well-characterized examples for DAMPs, often oligogalacturonides (OGAs), generated by the activity of fungal pathogens, endogenous elicitors evoked by bacterial pathogens have been rarely described. In particular, the signal perception and transduction processes involved in DAMP generation are poorly characterized. Results A mutant strain of the phytopathogenic bacterium Xanthomonas campestris pv. campestris deficient in exbD2, which encodes a component of its unusual elaborate TonB system, had impaired pectate lyase activity and caused no visible symptoms for defense on the non-host plant pepper (Capsicum annuum). A co-incubation of X. campestris pv. campestris with isolated cell wall material from C. annuum led to the release of compounds which induced an oxidative burst in cell suspension cultures of the non-host plant. Lipopolysaccharides and proteins were ruled out as elicitors by polymyxin B and heat treatment, respectively. After hydrolysis with trifluoroacetic acid and subsequent HPAE chromatography, the elicitor preparation contained galacturonic acid, the monosaccharide constituent of pectate. OGAs were isolated from this crude elicitor preparation by HPAEC and tested for their biological activity. While small OGAs were unable to induce an oxidative burst, the elicitor activity in cell suspension cultures of the non-host plants tobacco and pepper increased with the degree of polymerization (DP). Maximal elicitor activity was observed for DPs exceeding 8. In contrast to the X. campestris pv. campestris wild type B100, the exbD2 mutant was unable to generate elicitor activity from plant cell wall material or from pectin. Conclusions To our knowledge, this is the

HrpW of Erwinia amylovora, a New Harpin That Contains a Domain Homologous to Pectate Lyases of a Distinct Class

PubMed Central

Kim, Jihyun F.; Beer, Steven V.

1998-01-01

Harpins, such as HrpN of Erwinia amylovora, are extracellular glycine-rich proteins that elicit the hypersensitive reaction (HR). We identified hrpW of E. amylovora, which encodes a protein similar to known harpins in that it is acidic, rich in glycine and serine, and lacks cysteine. A putative HrpL-dependent promoter was identified upstream of hrpW, and Western blot analysis of hrpL mutants indicated that the production of HrpW is regulated by hrpL. HrpW is secreted via the Hrp (type III) pathway based on analysis of wild-type strains and hrp secretion mutants. When infiltrated into plants, HrpW induced rapid tissue collapse, which required active plant metabolism. The HR-eliciting activity was heat stable and protease sensitive. Thus, we concluded that HrpW is a new harpin. HrpW of E. amylovora consists of two domains connected by a Pro and Ser-rich sequence. A fragment containing the N-terminal domain was sufficient to elicit the HR. Although no pectate lyase activity was detected, the C-terminal region of HrpW is homologous to pectate lyases of a unique class, suggesting that HrpW may be targeted to the plant cell wall. Southern analysis indicated that hrpW is conserved among several Erwinia species, and hrpW, provided in trans, enhanced the HR-inducing ability of a hrpN mutant. However, HrpW did not increase the virulence of a hrpN mutant in host tissue, and hrpW mutants retained the wild-type ability to elicit the HR in nonhosts and to cause disease in hosts. PMID:9748455

Combined enzymatic and metabolic analysis of grapevine cell responses to elicitors.

PubMed

Krzyzaniak, Yuko; Negrel, Jonathan; Lemaitre-Guillier, Christelle; Clément, Gilles; Mouille, Grégory; Klinguer, Agnès; Trouvelot, Sophie; Héloir, Marie-Claire; Adrian, Marielle

2018-02-01

Elicitors trigger plant defense responses, including phytoalexin production and cell-wall reinforcement. Primary metabolism plays an important role in these responses as it fuels the associated energetic costs and provides precursors for the synthesis of the numerous secondary metabolites involved in defenses against pathogens. In this context, we aimed to determine whether oligosaccharidic elicitors differing in their capacity to activate defense-associated secondary metabolism in grapevine would differently impact primary metabolism. To answer this question, cell suspensions were treated with two elicitors: an oligogalacturonide, and the β-glucan laminarin. Enzymatic activity assays together with targeted (HPLC) and global (GC-MS) analyses of metabolites were next performed to compare their impact on plant primary or secondary metabolism. The results showed that the oligogalacturonide, which induced the highest level of the phytoalexin resveratrol and the highest activity of stilbene synthase, also induced the highest activity of shikimate hydroxycinnamoyltransferase, a key enzyme involved in the synthesis of lignin. The oligogalacturonide-induced defenses had a significant impact on primary metabolism 24 h following elicitor treatment, with a reduced abundance of pyruvate and 2-oxoglutarate, together with an increase of a set of metabolites including carbohydrates and amino acids. Interestingly, an accumulation of galacturonate and gentiobiose was observed in the oligogalacturonide- and laminarin-treated cells, respectively, suggesting that both elicitors are rapidly hydrolyzed in grapevine cell suspension cultures. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Elicitor-Induced Defense Responses in Solanum lycopersicum against Ralstonia solanacearum

PubMed Central

Kar, Itishree; Mukherjee, Arup K.; Acharya, Priyambada

2013-01-01

We investigated on important parameters of induced resistance in hydroponic tomato (Solanum lycopersicum) against Ralstonia solanacearum using the elicitors chitosan (CHT), salicylic acid (SA), and jasmonic acid (JA). The increase in total phenolic content of roots by the elicitors was significantly higher than control. Most pronounced increase in lignin synthesis was triggered by SA followed by CHT. At 24 h post-elicitation (hpe), the activity of phenylalanine ammonia lyase was 4.5 times higher than control elicited by CHT. The peroxidase activity was about 86 nkat/mg protein at 24 hpe in case of SA and 78 nkat/mg protein in case of CHT. The activity of polyphenol oxidase increased several folds by the elicitors. Cinnamyl alcohol dehydrogenase activity increased to the maximum at 48 hpe under the influence of CHT. The results indicate that the elicitors SA and CHT induced effective defense responses in tomato plants against R. solanacearum. This was evident from reduced vascular browning and wilting symptoms of tomato plants treated with SA and CHT and challenged subsequently with R. solanacearum. This reduced disease incidence in tomato by SA and CHT may be a result of cell wall strengthening through deposition of lignin and the coincident induction of defense enzymes. PMID:24187521

Abiotic elicitors mediated elicitation of innate immunity in tomato: an ex vivo comparison.

PubMed

Chakraborty, Nilanjan; Ghosh, Sudeepa; Chandra, Swarnendu; Sengupta, Sarban; Acharya, Krishnendu

2016-07-01

Improvement of the host resistance by using hazard free chemical elicitors is emerging as an alternative approach in the field of plant disease management. In our present work, we have screened the efficacy and possible mechanism of abiogenic elicitors like Dipotassium hydrogen orthophosphate ( K 2 HPO 4 ), Oxalic acid (OA), Isonicotinic acid (INA), Salicylic acid (SA), Acetylsalicylate (AS), Arachidonic acid (AA) and Calcium chloride (CaCl 2 ) to stimulate innate immune responses in Lycopersicum esculentum Mill. Excised tomato leaves, treated with elicitors at three different concentrations, were found to stimulate defense and antioxidative enzymes, total phenol and flavonoid content after 24 h of incubation. CaCl 2 (0.5 %) followed by INA (2.5 mM) were found most effective in activation of all such defense molecules in tomato leaves. Furthermore, nitric oxide (NO), a key gaseous mediator in plant defense signaling, was also measured after subsequent elicitor application. Higher doses of elicitors showed an elevated level of reactive oxygen species (ROS) generation, enhanced lipid peroxidation rate and proline content, which indicates the extent of abiotic stress generation on the leaves. However, ROS production, lipid peroxidation rate and proline concentration remain significantly reduced as a result of CaCl 2 (0.5 %) and INA (2.5 mM) application. A sharp increase of total chlorophyll content was also recorded due to treatment of CaCl 2 (0.5 %). These results demonstrate the effects of different abiogenic elicitors to regulate the production of defense molecules. Results also suggest that among all such chemicals, CaCl 2 (0.5 %) and INA (2.5 mM) can be used as a potential elicitor in organic farming of tomato.

Plasma membrane order and fluidity are diversely triggered by elicitors of plant defence

PubMed Central

Sandor, Roman; Der, Christophe; Grosjean, Kevin; Anca, Iulia; Noirot, Elodie; Leborgne-Castel, Nathalie; Lochman, Jan; Simon-Plas, Françoise; Gerbeau-Pissot, Patricia

2016-01-01

Although plants are exposed to a great number of pathogens, they usually defend themselves by triggering mechanisms able to limit disease development. Alongside signalling events common to most such incompatible interactions, modifications of plasma membrane (PM) physical properties could be new players in the cell transduction cascade. Different pairs of elicitors (cryptogein, oligogalacturonides, and flagellin) and plant cells (tobacco and Arabidopsis) were used to address the issue of possible modifications of plant PM biophysical properties induced by elicitors and their links to other events of the defence signalling cascade. We observed an increase of PM order whatever the elicitor/plant cell pair used, provided that a signalling cascade was induced. Such membrane modification is dependent on the NADPH oxidase-mediated reactive oxygen species production. Moreover, cryptogein, which is the sole elicitor able to trap sterols, is also the only one able to trigger an increase in PM fluidity. The use of cryptogein variants with altered sterol-binding properties confirms the strong correlation between sterol removal from the PM and PM fluidity enhancement. These results propose PM dynamics as a player in early signalling processes triggered by elicitors of plant defence. PMID:27604805

The regulatory mechanism of fungal elicitor-induced secondary metabolite biosynthesis in medical plants.

PubMed

Zhai, Xin; Jia, Min; Chen, Ling; Zheng, Cheng-Jian; Rahman, Khalid; Han, Ting; Qin, Lu-Ping

2017-03-01

A wide range of external stress stimuli trigger plant cells to undergo complex network of reactions that ultimately lead to the synthesis and accumulation of secondary metabolites. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Throughout evolution, endophytic fungi, an important constituent in the environment of medicinal plants, have known to form long-term stable and mutually beneficial symbiosis with medicinal plants. The endophytic fungal elicitor can rapidly and specifically induce the expression of specific genes in medicinal plants which can result in the activation of a series of specific secondary metabolic pathways resulting in the significant accumulation of active ingredients. Here we summarize the progress made on the mechanisms of fungal elicitor including elicitor signal recognition, signal transduction, gene expression and activation of the key enzymes and its application. This review provides guidance on studies which may be conducted to promote the efficient synthesis and accumulation of active ingredients by the endogenous fungal elicitor in medicinal plant cells, and provides new ideas and methods of studying the regulation of secondary metabolism in medicinal plants.

Metabolic Fingerprint of PS3-Induced Resistance of Grapevine Leaves against Plasmopara viticola Revealed Differences in Elicitor-Triggered Defenses

PubMed Central

Adrian, Marielle; Lucio, Marianna; Roullier-Gall, Chloé; Héloir, Marie-Claire; Trouvelot, Sophie; Daire, Xavier; Kanawati, Basem; Lemaître-Guillier, Christelle; Poinssot, Benoît; Gougeon, Régis; Schmitt-Kopplin, Philippe

2017-01-01

Induction of plant resistance against pathogens by defense elicitors constitutes an attractive strategy to reduce the use of fungicides in crop protection. However, all elicitors do not systematically confer protection against pathogens. Elicitor-induced resistance (IR) thus merits to be further characterized in order to understand what makes an elicitor efficient. In this study, the oligosaccharidic defense elicitors H13 and PS3, respectively, ineffective and effective to trigger resistance of grapevine leaves against downy mildew, were used to compare their effect on the global leaf metabolism. Ultra high resolution mass spectrometry (FT-ICR-MS) analysis allowed us to obtain and compare the specific metabolic fingerprint induced by each elicitor and to characterize the associated metabolic pathways. Moreover, erythritol phosphate was identified as a putative marker of elicitor-IR. PMID:28261225

Elicitors and defense gene induction in plants with altered lignin compositions.

PubMed

Gallego-Giraldo, Lina; Posé, Sara; Pattathil, Sivakumar; Peralta, Angelo Gabriel; Hahn, Michael G; Ayre, Brian G; Sunuwar, Janak; Hernandez, Jonathan; Patel, Monika; Shah, Jyoti; Rao, Xiaolan; Knox, J Paul; Dixon, Richard A

2018-06-27

A reduction in the lignin content in transgenic plants induces the ectopic expression of defense genes, but the importance of altered lignin composition in such phenomena remains unclear. Two Arabidopsis lines with similar lignin contents, but strikingly different lignin compositions, exhibited different quantitative and qualitative transcriptional responses. Plants with lignin composed primarily of guaiacyl units overexpressed genes responsive to oomycete and bacterial pathogen attack, whereas plants with lignin composed primarily of syringyl units expressed a far greater number of defense genes, including some associated with cis-jasmone-mediated responses to aphids; these plants exhibited altered responsiveness to bacterial and aphid inoculation. Several of the defense genes were differentially induced by water-soluble extracts from cell walls of plants of the two lines. Glycome profiling, fractionation and enzymatic digestion studies indicated that the different lignin compositions led to differential extractability of a range of heterogeneous oligosaccharide epitopes, with elicitor activity originating from different cell wall polymers. Alteration of lignin composition affects interactions with plant cell wall matrix polysaccharides to alter the sequestration of multiple latent defense signal molecules with an impact on biotic stress responses. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Modulation of plant defense responses to herbivores by simultaneous recognition of different herbivore-associated elicitors in rice

PubMed Central

Shinya, Tomonori; Hojo, Yuko; Desaki, Yoshitake; Christeller, John T.; Okada, Kazunori; Shibuya, Naoto; Galis, Ivan

2016-01-01

Induced plant defense responses against insect herbivores are triggered by wounding and/or perception of herbivore elicitors from their oral secretions (OS) and/or saliva. In this study, we analyzed OS isolated from two rice chewing herbivores, Mythimna loreyi and Parnara guttata. Both types of crude OS had substantial elicitor activity in rice cell system that allowed rapid detection of early and late defense responses, i.e. accumulation of reactive oxygen species (ROS) and defense secondary metabolites, respectively. While the OS from M. loreyi contained large amounts of previously reported insect elicitors, fatty acid-amino acid conjugates (FACs), the elicitor-active P. guttata’s OS contained no detectable FACs. Subsequently, elicitor activity associated with the high molecular mass fraction in OS of both herbivores was identified, and shown to promote ROS and metabolite accumulations in rice cells. Notably, the application of N-linolenoyl-Gln (FAC) alone had only negligible elicitor activity in rice cells; however, the activity of isolated elicitor fraction was substantially promoted by this FAC. Our results reveal that plants integrate various independent signals associated with their insect attackers to modulate their defense responses and reach maximal fitness in nature. PMID:27581373

Plasma membrane order and fluidity are diversely triggered by elicitors of plant defence.

PubMed

Sandor, Roman; Der, Christophe; Grosjean, Kevin; Anca, Iulia; Noirot, Elodie; Leborgne-Castel, Nathalie; Lochman, Jan; Simon-Plas, Françoise; Gerbeau-Pissot, Patricia

2016-09-01

Although plants are exposed to a great number of pathogens, they usually defend themselves by triggering mechanisms able to limit disease development. Alongside signalling events common to most such incompatible interactions, modifications of plasma membrane (PM) physical properties could be new players in the cell transduction cascade. Different pairs of elicitors (cryptogein, oligogalacturonides, and flagellin) and plant cells (tobacco and Arabidopsis) were used to address the issue of possible modifications of plant PM biophysical properties induced by elicitors and their links to other events of the defence signalling cascade. We observed an increase of PM order whatever the elicitor/plant cell pair used, provided that a signalling cascade was induced. Such membrane modification is dependent on the NADPH oxidase-mediated reactive oxygen species production. Moreover, cryptogein, which is the sole elicitor able to trap sterols, is also the only one able to trigger an increase in PM fluidity. The use of cryptogein variants with altered sterol-binding properties confirms the strong correlation between sterol removal from the PM and PM fluidity enhancement. These results propose PM dynamics as a player in early signalling processes triggered by elicitors of plant defence. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

A Catharanthus roseus BPF-1 homologue interacts with an elicitor-responsive region of the secondary metabolite biosynthetic gene Str and is induced by elicitor via a JA-independent signal transduction pathway.

PubMed

van der Fits, L; Zhang, H; Menke, F L; Deneka, M; Memelink, J

2000-11-01

Plants respond to pathogen attack by induction of various defence responses, including the biosynthesis of protective secondary metabolites. In Catharanthus roseus, the elicitor-induced expression of the terpenoid indole alkaloid biosynthetic gene Strictosidine synthase (Str) is mediated via the plant stress hormonejasmonate. In the promoters of several defence-related genes, cis-acting elements have been identified that are important for transcriptional regulation upon stress signals. Here we show that an upstream region in the Str promoter confers responsiveness to partially purified yeast elicitor and jasmonate. Yeast one-hybrid screening with this element as a bait identified a MYB-like protein, which shows high homology to parsley box P-binding factor-1 (PcBPF-1). In vitro analyses showed that the Str promoter fragment contained a novel binding site for BPF-1-like proteins with higher binding affinity than the previously described box P. CrBPF-1 mRNA accumulated rapidly in elicitor-treated C. roseus suspension cells, whereas no induction was observed with jasmonate. Inhibitor studies indicated that CrBPF-1 plays a role in an elicitor-responsive but jasmonate-independent signal transduction pathway, acting downstream of protein phosphorylation and calcium influx.

A Novel WRKY transcription factor is required for induction of PR-1a gene expression by salicylic acid and bacterial elicitors.

PubMed

van Verk, Marcel C; Pappaioannou, Dimitri; Neeleman, Lyda; Bol, John F; Linthorst, Huub J M

2008-04-01

PR-1a is a salicylic acid-inducible defense gene of tobacco (Nicotiana tabacum). One-hybrid screens identified a novel tobacco WRKY transcription factor (NtWRKY12) with specific binding sites in the PR-1a promoter at positions -564 (box WK(1)) and -859 (box WK(2)). NtWRKY12 belongs to the class of transcription factors in which the WRKY sequence is followed by a GKK rather than a GQK sequence. The binding sequence of NtWRKY12 (WK box TTTTCCAC) deviated significantly from the consensus sequence (W box TTGAC[C/T]) shown to be recognized by WRKY factors with the GQK sequence. Mutation of the GKK sequence in NtWRKY12 into GQK or GEK abolished binding to the WK box. The WK(1) box is in close proximity to binding sites in the PR-1a promoter for transcription factors TGA1a (as-1 box) and Myb1 (MBSII box). Expression studies with PR-1a promoterbeta-glucuronidase (GUS) genes in stably and transiently transformed tobacco indicated that NtWRKY12 and TGA1a act synergistically in PR-1a expression induced by salicylic acid and bacterial elicitors. Cotransfection of Arabidopsis thaliana protoplasts with 35SNtWRKY12 and PR-1aGUS promoter fusions showed that overexpression of NtWRKY12 resulted in a strong increase in GUS expression, which required functional WK boxes in the PR-1a promoter.

Plant Defense Response to Fungal Pathogens (Activation of Host-Plasma Membrane H+-ATPase by Elicitor-Induced Enzyme Dephosphorylation).

PubMed Central

Vera-Estrella, R.; Barkla, B. J.; Higgins, V. J.; Blumwald, E.

1994-01-01

Elicitor preparations containing the avr5 gene products from race 4 of Cladosporium fulvum and tomato (Lycopersicon esculentum L.) cells near isogenic for the resistance gene Cf5 were used to investigate events following the treatment of host plasma membranes with elicitor. A 4-fold increase in H+-ATPase activity, coincident with the acidification of the extracellular medium, was detected immediately after elicitor treatment. The elicitor-induced stimulation of the plasma membrane H+-ATPase was inhibited by okadaic acid but not by staurosporine, suggesting that protein dephosphorylation was required for increased H+-ATPase activity. This observation was confirmed by [gamma]-32P labeling and immunodetection of the plasma membrane H+-ATPase. Effects of guanidine nucleotide analogs and mastoparan on the ATPase activity suggested the role of GTP-binding proteins in mediating the putative elicitor-receptor binding, resulting in activation of a phosphatase(s), which in turn stimulates the plasma membrane H+-ATPase by dephosphorylation. PMID:12232073

The application of biotic elicitor on Artemisia annua L. to increase artemisinin content

NASA Astrophysics Data System (ADS)

Darwati, I.; Manohara, D.; Rohimatun; Nurhayati, H.

2018-01-01

Artemisinin-based Combination Therapy (ACT) has been recommended by WHO as an alternative to treat malaria overcoming drug resistance. The secondary metabolic products in plants, including artemisinin, can be increased by utilizing biotic elicitor from fungi. The research was conducted in Gunung Putri Research Installation, Cipanas, West Java from 2010 to 2011. Phytophthora sp. from eggplant and Colletotrichum sp. from Artemisia annua were applied as biotic elicitor. The types of biotic elicitor applied to the plants were 1) the medium of potato dextrose broth were inoculated with fungi and harvested after 10 days (filtrate), 2) powdery mycelium of both fungi. There were 16 treatments: control negative, control positive (uninoculated medium) 1%, 2%, 3% (v/v)], Phytophthora sp. filtrate [1, 2% and 3% (v/v)], Colletotrichum sp. filtrate [1, 2% and 3% (v/v)], Phytophthora sp. mycelium [1%, 2% and 3% (w/v)], Colletotrichum sp mycelium [1%, 2% and 3% (w/v)]. The elicitor application increased plant production by 26.21% and artemisinin yield by 72% compared to control. Furthermore, the artemisinin production of the plants treated with medium inoculated with 2% filtrate of Phytophthora sp (FP2) (25.19 kg/ha) and 1% powdery mycelium of Colletotrichum sp (MC1) (26.42 kg/ha) were higher than control (K) (11.17 kg/ha).

Crystal Structure Analysis and the Identification of Distinctive Functional Regions of the Protein Elicitor Mohrip2.

PubMed

Liu, Mengjie; Duan, Liangwei; Wang, Meifang; Zeng, Hongmei; Liu, Xinqi; Qiu, Dewen

2016-01-01

The protein elicitor MoHrip2, which was extracted from Magnaporthe oryzae as an exocrine protein, triggers the tobacco immune system and enhances blast resistance in rice. However, the detailed mechanisms by which MoHrip2 acts as an elicitor remain unclear. Here, we investigated the structure of MoHrip2 to elucidate its functions based on molecular structure. The three-dimensional structure of MoHrip2 was obtained. Overall, the crystal structure formed a β-barrel structure and showed high similarity to the pathogenesis-related (PR) thaumatin superfamily protein thaumatin-like xylanase inhibitor (TL-XI). To investigate the functional regions responsible for MoHrip2 elicitor activities, the full length and eight truncated proteins were expressed in Escherichia coli and were evaluated for elicitor activity in tobacco. Biological function analysis showed that MoHrip2 triggered the defense system against Botrytis cinerea in tobacco. Moreover, only MoHrip2M14 and other fragments containing the 14 amino acids residues in the middle region of the protein showed the elicitor activity of inducing a hypersensitive response and resistance related pathways, which were similar to that of full-length MoHrip2. These results revealed that the central 14 amino acid residues were essential for anti-pathogenic activity.

Phytohormone-based activity mapping of insect herbivore-produced elicitors

USDA-ARS?s Scientific Manuscript database

In response to insect attack many plants exhibit dynamic biochemical changes resulting in the induced production of direct and indirect defenses. Elicitors present in herbivore oral secretions are believed to positively regulate many inducible plant defenses; however, little is known about the speci...

Elicitor and nitrogen applications to Garnacha, Graciano and Tempranillo vines: effect on grape amino acid composition.

PubMed

Gutiérrez-Gamboa, Gastón; Portu, Javier; López, Rosa; Santamaría, Pilar; Garde-Cerdán, Teresa

2018-04-01

Elicitors and nitrogen foliar applications to vineyards could regulate grape nitrogen composition, which has an important effect on grape and wine quality. Thus the aim of this research was to study the effect of foliar elicitor treatments, methyl jasmonate (MeJ) and yeast extract (YE), and foliar nitrogen applications, urea (Ur) and phenylalanine (Phe), to Garnacha, Graciano and Tempranillo vines on grape amino acid composition. The results showed that elicitor and nitrogen foliar applications to Garnacha and Tempranillo grapevines decreased the must amino acid concentration. However, Phe application to these two grapevines increased the must Phe content. The treatments applied to Graciano grapevines barely effected the grape amino acid content. According to the percentage of variance attributable, the variety had a higher impact on the must amino acid composition than the treatments and their interaction, except in certain amino acids such as Phe. The influence of elicitor and nitrogen foliar applications to grapevines on grape amino acid concentration was strongly conditioned by the variety. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Plant growth enhancement and associated physiological responses are coregulated by ethylene and gibberellin in response to harpin protein Hpa1.

PubMed

Li, Xiaojie; Han, Bing; Xu, Manyu; Han, Liping; Zhao, Yanying; Liu, Zhilan; Dong, Hansong; Zhang, Chunling

2014-04-01

The harpin protein Hpa1 produced by the bacterial blight pathogen of rice induces several growth-promoting responses in plants, activating the ethylene signaling pathway, increasing photosynthesis rates and EXPANSIN (EXP) gene expression levels, and thereby enhancing the vegetative growth. This study was attempted to analyze any mechanistic connections among the above and the role of gibberellin in these responses. Hpa1-induced growth enhancement was evaluated in Arabidopsis, tomato, and rice. And growth-promoting responses were determined mainly as an increase of chlorophyll a/b ratio, which indicates a potential elevation of photosynthesis rates, and enhancements of photosynthesis and EXP expression in the three plant species. In Arabidopsis, Hpa1-induced growth-promoting responses were partially compromised by a defect in ethylene perception or gibberellin biosynthesis. In tomato and rice, compromises of Hpa1-induced growth-promoting responses were caused by a pharmacological treatment with an ethylene perception inhibitor or a gibberellin biosynthesis inhibitor. In the three plant species, moreover, Hpa1-induced growth-promoting responses were significantly impaired, but not totally eliminated, by abolishing ethylene perception or gibberellin synthesis. However, simultaneous nullifications in both ethylene perception and gibberellin biosynthesis almost canceled the full effects of Hpa1 on plant growth, photosynthesis, and EXP2 expression. Theses results suggest that ethylene and gibberellin coregulate Hpa1-induced plant growth enhancement and associated physiological and molecular responses.

Complementary action of jasmonic acid on salicylic acid in mediating fungal elicitor-induced flavonol glycoside accumulation of Ginkgo biloba cells.

PubMed

Xu, Maojun; Dong, Jufang; Wang, Huizhong; Huang, Luqi

2009-08-01

The antagonistic action between jasmonic acid (JA) and salicylic acid (SA) in plant defence responses has been well documented. However, their relationship in secondary metabolite production is largely unknown. Here, we report that PB90, a protein elicitor from Phytophthora boehmeriae, triggers JA generation, SA accumulation and flavonol glycoside production of Ginkgo biloba cells. JA inhibitors suppress not only PB90-triggered JA generation, but also the elicitor-induced flavonol glycoside production. However, the elicitor can still enhance flavonol glycoside production even though the JA generation is totally inhibited. Over-expression of SA hydrolase gene NahG not only abolishes SA accumulation, but also suppresses the elicitor-induced flavonol glycoside production when JA signalling is inhibited. Interestingly, expression of NahG does not inhibit the elicitor-induced flavonol glycoside accumulation in the absence of JA inhibitors. Moreover, JA levels are significantly enhanced when SA accumulation is impaired in the transgenic cells. Together, the data suggest that both JA and SA are involved in PB90-induced flavonol glycoside production. Furthermore, we demonstrate that JA signalling might be enhanced to substitute for SA to mediate the elicitor-induced flavonol glycoside accumulation when SA signalling is impaired, which reveals an unusual complementary relationship between JA and SA in mediating plant secondary metabolite production.

Grapevine cell early activation of specific responses to DIMEB, a resveratrol elicitor

PubMed Central

Zamboni, Anita; Gatto, Pamela; Cestaro, Alessandro; Pilati, Stefania; Viola, Roberto; Mattivi, Fulvio; Moser, Claudio; Velasco, Riccardo

2009-01-01

Background In response to pathogen attack, grapevine synthesizes phytoalexins belonging to the family of stilbenes. Grapevine cell cultures represent a good model system for studying the basic mechanisms of plant response to biotic and abiotic elicitors. Among these, modified β-cyclodextrins seem to act as true elicitors inducing strong production of the stilbene resveratrol. Results The transcriptome changes of Vitis riparia × Vitis berlandieri grapevine cells in response to the modified β-cyclodextrin, DIMEB, were analyzed 2 and 6 h after treatment using a suppression subtractive hybridization experiment and a microarray analysis respectively. At both time points, we identified a specific set of induced genes belonging to the general phenylpropanoid metabolism, including stilbenes and hydroxycinnamates, and to defence proteins such as PR proteins and chitinases. At 6 h we also observed a down-regulation of the genes involved in cell division and cell-wall loosening. Conclusions We report the first large-scale study of the molecular effects of DIMEB, a resveratrol inducer, on grapevine cell cultures. This molecule seems to mimic a defence elicitor which enhances the physical barriers of the cell, stops cell division and induces phytoalexin synthesis. PMID:19660119

Linear β-1,3 Glucans Are Elicitors of Defense Responses in Tobacco

PubMed Central

Klarzynski, Olivier; Plesse, Bertrand; Joubert, Jean-Marie; Yvin, Jean-Claude; Kopp, Marguerite; Kloareg, Bernard; Fritig, Bernard

2000-01-01

Laminarin, a linear β-1,3 glucan (mean degree of polymerization of 33) was extracted and purified from the brown alga Laminaria digitata. Its elicitor activity on tobacco (Nicotiana tabacum) was compared to that of oligogalacturonides with a mean degree of polymerization of 10. The two oligosaccharides were perceived by suspension-cultured cells as distinct chemical stimuli but triggered a similar and broad spectrum of defense responses. A dose of 200 μg mL−1 laminarin or oligogalacturonides induced within a few minutes a 1.9-pH-units alkalinization of the extracellular medium and a transient release of H2O2. After a few hours, a strong stimulation of Phe ammonia-lyase, caffeic acid O-methyltransferase, and lipoxygenase activities occurred, as well as accumulation of salicylic acid. Neither of the two oligosaccharides induced tissue damage or cell death nor did they induce accumulation of the typical tobacco phytoalexin capsidiol, in contrast with the effects of the proteinaceous elicitor β-megaspermin. Structure activity studies with laminarin, laminarin oligomers, high molecular weight β-1,3–1,6 glucans from fungal cell walls, and the β-1,6–1,3 heptaglucan showed that the elicitor effects observed in tobacco with β-glucans are specific to linear β-1,3 linkages, with laminaripentaose being the smallest elicitor-active structure. In accordance with its strong stimulating effect on defense responses in tobacco cells, infiltration of 200 μg mL−1 laminarin in tobacco leaves triggered accumulation within 48 h of the four families of antimicrobial pathogenesis-related proteins investigated. Challenge of the laminarin-infiltrated leaves 5 d after treatment with the soft rot pathogen Erwinia carotovora subsp. carotovora resulted in a strong reduction of the infection when compared with water-treated leaves. PMID:11080280

Host-pathogen interactions. XXIX. Oligogalacturonides released from sodium polypectate by endopolygalacturonic acid lyase are elicitors of phytoalexins in soybean. [Glycine max L

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

Davis, K.R.; Darvill, A.G.; Albersheim, P.

1986-02-01

Recent studies have demonstrated that an apparently homogeneous preparation of an ..cap alpha..-1,4-D-endopolygalacturonic acid lyase (EC 4.2,2.2) isolated from the phytopathogenic bacterium Erwinia carotovora induced phytoalexin accumulation in cotyledons of soybean (Glycine max (L.) Merr. cv Wayne) and that this pectin-degrading enzyme released heat-stable elicitors of phytoalexins from soybean cell walls, citrus pectin, and sodium polypectate. The present paper reports the purification, by anion-exchange chromatography on QAE-Sephadex columns followed by gel-permeation chromatography on a Bio-Gel P-6 column, of the two fractions with highest specific elicitor activity present in a crude elicitor-preparation obtained by lyase treatment of sodium polypectate. Structural analysismore » of the fraction with highest specific elicitor activity indicated that the major, if not only, component was a decasaccharide of ..cap alpha..-1,4-D-galactosyluronic acid that contained the expected product of lyase cleavage, 4-deoxy-..beta..-L-5-threo-hexopyranos-4-enyluronic acid (4,5-unsaturated galactosyluronic acid), at the nonreducing terminus. This modified decagalacturonide fraction exhibited half-maximum and maximum elicitor activity at 1 microgram/cotyledon (6 micromolar) and 5 micrograms/cotyledon (32 micromolar) galactosyluronic acid equivalents, respectively. Reducing 90 to 95% of the carboxyl groups of the galactosyluronic acid residues abolished the elicitor activity of the decagalacturonide fraction. The second most elicitor-active fraction contained mostly undeca-..cap alpha..-1,4-D-galactosyluronic acid that contained 4,5-unsaturated galactosyluronic acid at the nonreducing termini. This fraction exhibited half-maximum and maximum elicitor activity at approximately 3 micrograms/cotyledon (17 micromolar) and 6 micrograms/cotyledon (34 micromolar) galactosyluronic acid equivalents, respectively.« less

Tropospheric ozone as a fungal elicitor.

PubMed

Zuccarini, Paolo

2009-03-01

Tropospheric ozone has been proven to trigger biochemical plant responses that are similar to the ones induced by an attack of fungal pathogens,i.e. it resembles fungal elicitors.This suggests that ozone can represent a valid tool for the study of stress responses and induction of resistance to pathogens. This review provides an overview of the implications of such a phenomenon for basic and applied research. After an introduction about the environmental implications of tropospheric ozone and plant responses to biotic stresses, the biochemistry of ozone stress is analysed, pointing out its similarities with plant responses to pathogens and its possible applications.

A 20 bp cis-acting element is both necessary and sufficient to mediate elicitor response of a maize PRms gene.

PubMed

Raventós, D; Jensen, A B; Rask, M B; Casacuberta, J M; Mundy, J; San Segundo, B

1995-01-01

Transient gene expression assays in barley aleurone protoplasts were used to identify a cis-regulatory element involved in the elicitor-responsive expression of the maize PRms gene. Analysis of transcriptional fusions between PRms 5' upstream sequences and a chloramphenicol acetyltransferase reporter gene, as well as chimeric promoters containing PRms promoter fragments or repeated oligonucleotides fused to a minimal promoter, delineated a 20 bp sequence which functioned as an elicitor-response element (ERE). This sequence contains a motif (-246 AATTGACC) similar to sequences found in promoters of other pathogen-responsive genes. The analysis also indicated that an enhancing sequence(s) between -397 and -296 is required for full PRms activation by elicitors. The protein kinase inhibitor staurosporine was found to completely block the transcriptional activation induced by elicitors. These data indicate that protein phosphorylation is involved in the signal transduction pathway leading to PRms expression.

Differential Induction of Lipoxygenase Isoforms in Wheat upon Treatment with Rust Fungus Elicitor, Chitin Oligosaccharides, Chitosan, and Methyl Jasmonate.

PubMed Central

Bohland, C.; Balkenhohl, T.; Loers, G.; Feussner, I.; Grambow, H. J.

1997-01-01

A glycopeptide elicitor prepared from germ tubes of the rust fungus Puccinia graminis Pers. f. sp. tritici Erikss. & Henn (Pgt), as well as chitin oligosaccharides, chitosan, and methyl jasmonate (MJ) stimulated lipoxygenase (LOX) activity (E.C. 1.13.11.12) in wheat (Triticum aestivum) leaves. Immunoblot analysis using anti-LOX antibodies revealed the induction of 92- and 103-kD LOX species after Pgt elicitor treatment. In contrast, MJ treatment led to a significant increase of a 100-kD LOX species, which was also detected at lower levels in control plants. The effects of chitin oligomers and chitosan resembled those caused by MJ. In conjunction with other observations the results suggest that separate reaction cascades exist, and that jasmonates may not be involved in Pgt elicitor action. LOX-92 appears to be mainly responsible for the increase in LOX activity after Pgt elicitor treatment because its appearance on western blots coincided with high LOX activity in distinct anion-exchange chromatography fractions. It is most active at pH 5.5 to 6.0, and product formation from linoleic and [alpha]-linolenic acid is clearly in favor of the 9-LOOHs. It is interesting that a 92-kD LOX species, which seems to correspond to the Pgt elicitor-induced LOX species, was also detected in rust-inoculated leaves. PMID:12223735

Genetic transformation of cotton with a harpin-encoding gene hpaXoo confers an enhanced defense response against different pathogens through a priming mechanism

PubMed Central

2010-01-01

Background The soil-borne fungal pathogen Verticillium dahliae Kleb causes Verticillium wilt in a wide range of crops including cotton (Gossypium hirsutum). To date, most upland cotton varieties are susceptible to V. dahliae and the breeding for cotton varieties with the resistance to Verticillium wilt has not been successful. Results Hpa1Xoo is a harpin protein from Xanthomonas oryzae pv. oryzae which induces the hypersensitive cell death in plants. When hpa1Xoo was transformed into the susceptible cotton line Z35 through Agrobacterium-mediated transformation, the transgenic cotton line (T-34) with an improved resistance to Verticillium dahliae was obtained. Cells of the transgenic T-34, when mixed with the conidia suspension of V. dahliae, had a higher tolerance to V. dahliae compared to cells of untransformed Z35. Cells of T-34 were more viable 12 h after mixing with V. dahliae conidia suspension. Immunocytological analysis showed that Hpa1Xoo, expressed in T-34, accumulated as clustered particles along the cell walls of T-34. In response to the infection caused by V. dahliae, the microscopic cell death and the generation of reactive oxygen intermediates were observed in leaves of T-34 and these responses were absent in leaves of Z35 inoculated with V. dahliae. Quantitative RT-PCR analysis indicated that five defense-related genes, ghAOX1, hin1, npr1, ghdhg-OMT, and hsr203J, were up-regulated in T-34 inoculated with V. dahliae. The up-regulations of these defense-relate genes were not observed or in a less extent in leaves of Z-35 after the inoculation. Conclusions Hpa1Xoo accumulates along the cell walls of the transgenic T-34, where it triggers the generation of H2O2 as an endogenous elicitor. T-34 is thus in a primed state, ready to protect the host from the pathogen. The results of this study suggest that the transformation of cotton with hpa1Xoo could be an effective approach for the development of cotton varieties with the improved resistance against soil

Plant immunity induced by COS-OGA elicitor is a cumulative process that involves salicylic acid.

PubMed

van Aubel, Géraldine; Cambier, Pierre; Dieu, Marc; Van Cutsem, Pierre

2016-06-01

Plant innate immunity offers considerable opportunities for plant protection but beside flagellin and chitin, not many molecules and their receptors have been extensively characterized and very few have successfully reached the field. COS-OGA, an elicitor that combines cationic chitosan oligomers (COS) with anionic pectin oligomers (OGA), efficiently protected tomato (Solanum lycopersicum) grown in greenhouse against powdery mildew (Leveillula taurica). Leaf proteomic analysis of plants sprayed with COS-OGA showed accumulation of Pathogenesis-Related proteins (PR), especially subtilisin-like proteases. qRT-PCR confirmed upregulation of PR-proteins and salicylic acid (SA)-related genes while expression of jasmonic acid/ethylene-associated genes was not modified. SA concentration and class III peroxidase activity were increased in leaves and appeared to be a cumulative process dependent on the number of sprayings with the elicitor. These results suggest a systemic acquired resistance (SAR) mechanism of action of the COS-OGA elicitor and highlight the importance of repeated applications to ensure efficient protection against disease. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Nitric Oxide Synthase-Mediated Phytoalexin Accumulation in Soybean Cotyledons in Response to the Diaporthe phaseolorum f. sp. meridionalis Elicitor1

PubMed Central

Modolo, Luzia Valentina; Cunha, Fernando Queiroz; Braga, Márcia Regina; Salgado, Ione

2002-01-01

Phytoalexin biosynthesis is part of the defense mechanism of soybean (Glycine max) plants against attack by the fungus Diaporthe phaseolorum f. sp. meridionalis (Dpm), the causal agent of stem canker disease. The treatment of soybean cotyledons with Dpm elicitor or with sodium nitroprusside (SNP), a nitric oxide (NO) donor, resulted in a high accumulation of phytoalexins. This response did not occur when SNP was replaced by ferricyanide, a structural analog of SNP devoid of the NO moiety. Phytoalexin accumulation induced by the fungal elicitor, but not by SNP, was prevented when cotyledons were pretreated with NO synthase (NOS) inhibitors. The Dpm elicitor also induced NOS activity in soybean tissues proximal to the site of inoculation. The induced NOS activity was Ca2+- and NADPH-dependent and was sensitive to the NOS inhibitors NG-nitro-l-arginine methyl ester, aminoguanidine, and l-N6-(iminoethyl) lysine. NOS activity was not observed in SNP-elicited tissues. An antibody to brain NOS labeled a 166-kD protein in elicited and nonelicited cotyledons. Isoflavones (daidzein and genistein), pterocarpans (glyceollins), and flavones (apigenin and luteolin) were identified after exposure to the elicitor or SNP, although the accumulation of glyceollins and apigenin was limited in SNP-elicited compared with fungal-elicited cotyledons. NOS activity preceded the accumulation of these flavonoids in tissues treated with the Dpm elicitor. The accumulation of these metabolites was faster in SNP-elicited than in fungal-elicited cotyledons. We conclude that the response of soybean cotyledons to Dpm elicitor involves NO formation via a constitutive NOS-like enzyme that triggers the biosynthesis of antimicrobial flavonoids. PMID:12427995

Avenanthramide biosynthesis in oat cultivars treated with systemic acquired resistance elicitors

USDA-ARS?s Scientific Manuscript database

The synthetic systemic acquired resistance elicitor benzothiadiazole (BTH) has been shown to elicit avenanthramide biosynthesis in the oat cultivar ‘Belle’. This report investigates the response of multiple oat cultivars to BTH as well as 2,6- dichloroisonicotinic acid (INA) at different growth stag...

Elicitors and co-factors in food-induced anaphylaxis in adults

PubMed Central

2013-01-01

Food-induced anaphylaxis (FIA) in adults is often insufficiently diagnosed. One reason is related to the presence of co-factors like exercise, alcohol, additives and non-steroidal anti-inflammatory drugs. The objective of this analysis was to retrospectively investigate the role of co-factors in patients with FIA. 93 adult patients with suspected FIA underwent double-blind, placebo-controlled food challenges with suspected allergens and co-factors. The elicitors of anaphylaxis were identified in 44/93 patients. 27 patients reacted to food allergens upon challenge, 15 patients reacted only when a co-factor was co-exposed with the allergen. The most common identified allergens were celery (n = 7), soy, wheat (n = 4 each) and lupine (n = 3). Among the co-factors food additives (n = 8) and physical exercise (n = 6) were most frequent. In 10 patients more than one co-factor and/or more than one food allergen was necessary to elicit a positive reaction. The implementation of co-factors into the challenge protocol increases the identification rate of elicitors in adult food anaphylactic patients. PMID:24262093

Dataset of the Botrytis cinerea phosphoproteome induced by different plant-based elicitors.

PubMed

Liñeiro, Eva; Chiva, Cristina; Cantoral, Jesús M; Sabido, Eduard; Fernández-Acero, Francisco Javier

2016-06-01

Phosphorylation is one of the main post-translational modification (PTM) involved in signaling network in the ascomycete Botrytis cinerea , one of the most relevant phytopathogenic fungus. The data presented in this article provided a differential mass spectrometry-based analysis of the phosphoproteome of B. cinerea under two different phenotypical conditions induced by the use of two different elicitors: glucose and deproteinized Tomate Cell Walls (TCW). A total 1138 and 733 phosphoproteins were identified for glucose and TCW culture conditions respectively. Raw data are deposited at the ProteomeXchange Consortium via the PRIDE partner repository with the data set identifier (PRIDE: http://www.ebi.ac.uk/pride/archive/projects/PXD003099). Further interpretation and discussion of these data are provided in our research article entitled "Phosphoproteome analysis of B.cinerea in response to different plant-based elicitors" (Liñeiro et al., 2016) [1].

Enhanced synthesis of andrographolide by Aspergillus niger and Penicillium expansum elicitors in cell suspension culture of Andrographis paniculata (Burm. f.) Nees.

PubMed

Vakil, Moinuddin M A; Mendhulkar, Vijay D

2013-12-01

Andrographis paniculata (Burm. f.) Nees is an important medicinal plant which has enormous applications in pharmaceutical industries. Cell suspension culture of Andrographis paniculata (Burm. f.) Nees. was treated with Aspergillus niger and Penicillium expansum elicitors to enhance the synthesis of andrographolide, the bioactive constituent of A. paniculata. The elicitation treatment with fungal elicitors (A. niger and P. expansum) was observed to be most suitable for eliciting andrographolide production in the culture. The quantification of andrographolide was done using High Performance Liquid Chromatography (HPLC) technique. A. niger extract (1.5 ml with10 days treatment duration) revealed 6.94 fold increase in andrographolide content (132 μg) which was higher than the control (19 μg). P. expansum elicitor (0.6% with 8 days treatment duration) could reveal 6.23 fold enhancement in andrographolide content (81.0 μg) over control (13 μg). The results obtained reveal that the longer treatment duration is most favorable for the elicitation of andrographolide using both the fungal elicitors.

Analysis and effects of cytosolic free calcium increases in response to elicitors in Nicotiana plumbaginifolia cells.

PubMed

Lecourieux, David; Mazars, Christian; Pauly, Nicolas; Ranjeva, Raoul; Pugin, Alain

2002-10-01

Cell suspensions obtained from Nicotiana plumbaginifolia plants stably expressing the apoaequorin gene were used to analyze changes in cytosolic free calcium concentrations ([Ca(2+)](cyt)) in response to elicitors of plant defenses, particularly cryptogein and oligogalacturonides. The calcium signatures differ in lag time, peak time, intensity, and duration. The intensities of both signatures depend on elicitor concentration and extracellular calcium concentration. Cryptogein signature is characterized by a long-sustained [Ca(2+)](cyt) increase that should be responsible for sustained mitogen-activated protein kinase activation, microtubule depolymerization, defense gene activation, and cell death. The [Ca(2+)](cyt) increase in elicitor-treated cells first results from a calcium influx, which in turns leads to calcium release from internal stores and additional Ca(2+) influx. H(2)O(2) resulting from the calcium-dependent activation of the NADPH oxidase also participates in [Ca(2+)](cyt) increase and may activate calcium channels from the plasma membrane. Competition assays with different elicitins demonstrate that [Ca(2+)](cyt) increase is mediated by cryptogein-receptor interaction.

Analysis and Effects of Cytosolic Free Calcium Increases in Response to Elicitors in Nicotiana plumbaginifolia Cells

PubMed Central

Lecourieux, David; Mazars, Christian; Pauly, Nicolas; Ranjeva, Raoul; Pugin, Alain

2002-01-01

Cell suspensions obtained from Nicotiana plumbaginifolia plants stably expressing the apoaequorin gene were used to analyze changes in cytosolic free calcium concentrations ([Ca2+]cyt) in response to elicitors of plant defenses, particularly cryptogein and oligogalacturonides. The calcium signatures differ in lag time, peak time, intensity, and duration. The intensities of both signatures depend on elicitor concentration and extracellular calcium concentration. Cryptogein signature is characterized by a long-sustained [Ca2+]cyt increase that should be responsible for sustained mitogen-activated protein kinase activation, microtubule depolymerization, defense gene activation, and cell death. The [Ca2+]cyt increase in elicitor-treated cells first results from a calcium influx, which in turns leads to calcium release from internal stores and additional Ca2+ influx. H2O2 resulting from the calcium-dependent activation of the NADPH oxidase also participates in [Ca2+]cyt increase and may activate calcium channels from the plasma membrane. Competition assays with different elicitins demonstrate that [Ca2+]cyt increase is mediated by cryptogein–receptor interaction. PMID:12368509

Cutin monomers and surface wax constituents elicit H2O2 in conditioned cucumber hypocotyl segments and enhance the activity of other H2O2 elicitors

PubMed

Fauth; Schweizer; Buchala; Markstadter; Riederer; Kato; Kauss

1998-08-01

Hypocotyls from etiolated cucumber (Cucumis sativus L.) seedlings were gently abraded at their epidermal surface and cut segments were conditioned to develop competence for H2O2 elicitation. Alkaline hydrolysates of cutin from cucumber, tomato, and apple elicited H2O2 in such conditioned segments. The most active constituent of cucumber cutin was identified as dodecan-1-ol, a novel cutin monomer capable of forming hydrophobic terminal chains. Additionally, the cutin hydrolysates enhanced the activity of a fungal H2O2 elicitor, similar to cucumber surface wax, which contained newly identified alkan-1,3-diols. The specificity of elicitor and enhancement activity was further elaborated using some pure model compounds. Certain saturated hydroxy fatty acids were potent H2O2 elicitors as well as enhancers. Some unsaturated epoxy and hydroxy fatty acids were also excellent H2O2 elicitors but inhibited the fungal elicitor activity. Short-chain alkanols exhibited good elicitor and enhancer activity, whereas longer-chain alkan-1-ols were barely active. The enhancement effect was also observed for H2O2 elicitation by ergosterol and chitosan. The physiological significance of these observations might be that once the cuticle is degraded by fungal cutinase, the cutin monomers may act as H2O2 elicitors. Corrosion of cutin may also bring surface wax constituents in contact with protoplasts and enhance elicitation.

Over-expression of the Pseudomonas syringae harpin-encoding gene hrpZm confers enhanced tolerance to Phytophthora root and stem rot in transgenic soybean.

PubMed

Du, Qian; Yang, Xiangdong; Zhang, Jinhua; Zhong, Xiaofang; Kim, Kyung Seok; Yang, Jing; Xing, Guojie; Li, Xiaoyu; Jiang, Zhaoyuan; Li, Qiyun; Dong, Yingshan; Pan, Hongyu

2018-06-01

Phytophthora root and stem rot (PRR) caused by Phytophthora sojae is one of the most devastating diseases reducing soybean (Glycine max) production all over the world. Harpin proteins in many plant pathogenic bacteria were confirmed to enhance disease and insect resistance in crop plants. Here, a harpin protein-encoding gene hrpZpsta from the P. syringae pv. tabaci strain Psta218 was codon-optimized (renamed hrpZm) and introduced into soybean cultivars Williams 82 and Shennong 9 by Agrobacterium-mediated transformation. Three independent transgenic lines over-expressing hrpZm were obtained and exhibited stable and enhanced tolerance to P. sojae infection in T 2 -T 4 generations compared to the non-transformed (NT) and empty vector (EV)-transformed plants. Quantitative real-time PCR (qRT-PCR) analysis revealed that the expression of salicylic acid-dependent genes PR1, PR12, and PAL, jasmonic acid-dependent gene PPO, and hypersensitive response (HR)-related genes GmNPR1 and RAR was significantly up-regulated after P. sojae inoculation. Moreover, the activities of defense-related enzymes such as phenylalanine ammonia lyase (PAL), polyphenoloxidase (PPO), peroxidase, and superoxide dismutase also increased significantly in the transgenic lines compared to the NT and EV-transformed plants after inoculation. Our results suggest that over-expression of the hrpZm gene significantly enhances PRR tolerance in soybean by eliciting resistance responses mediated by multiple defense signaling pathways, thus providing an alternative approach for development of soybean varieties with improved tolerance against the soil-borne pathogen PRR.

Polygalacturonase from Rhizopus stolonifer, an Elicitor of Casbene Synthetase Activity in Castor Bean (Ricinus communis L.) Seedlings 1

PubMed Central

Lee, Sung-Chul; West, Charles A.

1981-01-01

Apparently homogeneous polygalacturonase-elicitor purified from the filtrates of Rhizopus stolonifer cultures stimulates germinating castor bean seedlings to produce greatly increased levels of casbene synthetase activity. The purification procedure involved gel-filtration chromatography on Sephadex G-25 and G-75 columns followed by cation-exchange chromatography on a Sephadex CM C-50 column. Homogeneity of the purified preparation was indicated by the results of cationic polyacrylamide disc gel electrophoresis and isoelectric focusing (pI = 8.0). The identity of the casbene elicitor activity and polygalacturonase were indicated by the coincidence of the two activities at all stages of purification, the coincidence of both activities with the single protein-staining band detected on a cationic polyacrylamide disc gel and an isoelectric focusing gel, and the identical behavior of both activities on an agarose gel affinity column. The purified polygalacturonase-elicitor is a glycoprotein with approximately 20% carbohydrate content and an estimated molecular weight of 32,000 by polyacrylamide disc gel electrophoresis. PMID:16661728

Effects of elicitors of host plant defenses on pear psylla (Cacopsylla pyricola: Psyllidae)

USDA-ARS?s Scientific Manuscript database

Pear psylla, Cacopsylla pyricola (Foerster) (Hemiptera: Psyllidae), is a key pest of cultivated pear (Pyrus communis L.) in North America and Europe. We examined the effects of foliar applications of three commercially available chemical elicitors of host-plant defenses, Actigard, Employ, and ODC, ...

Emotion elicitor or emotion messenger? Subliminal priming reveals two faces of facial expressions.

PubMed

Ruys, Kirsten I; Stapel, Diederik A

2008-06-01

Facial emotional expressions can serve both as emotional stimuli and as communicative signals. The research reported here was conducted to illustrate how responses to both roles of facial emotional expressions unfold over time. As an emotion elicitor, a facial emotional expression (e.g., a disgusted face) activates a response that is similar to responses to other emotional stimuli of the same valence (e.g., a dirty, nonflushed toilet). As an emotion messenger, the same facial expression (e.g., a disgusted face) serves as a communicative signal by also activating the knowledge that the sender is experiencing a specific emotion (e.g., the sender feels disgusted). By varying the duration of exposure to disgusted, fearful, angry, and neutral faces in two subliminal-priming studies, we demonstrated that responses to faces as emotion elicitors occur prior to responses to faces as emotion messengers, and that both types of responses may unfold unconsciously.

The hepta-beta-glucoside elicitor-binding proteins from legumes represent a putative receptor family.

PubMed

Mithöfer, A; Fliegmann, J; Neuhaus-Url, G; Schwarz, H; Ebel, J

2000-08-01

The ability of legumes to recognize and respond to beta-glucan elicitors by synthesizing phytoalexins is consistent with the existence of a membrane-bound beta-glucan-binding site. Related proteins of approximately 75 kDa and the corresponding mRNAs were detected in various species of legumes which respond to beta-glucans. The cDNAs for the beta-glucan-binding proteins of bean and soybean were cloned. The deduced 75-kDa proteins are predominantly hydrophilic and constitute a unique class of glucan-binding proteins with no currently recognizable functional domains. Heterologous expression of the soybean beta-glucan-binding protein in tomato cells resulted in the generation of a high-affinity binding site for the elicitor-active hepta-beta-glucoside conjugate (Kd = 4.5 nM). Ligand competition experiments with the recombinant binding sites demonstrated similar ligand specificities when compared with soybean. In both soybean and transgenic tomato, membrane-bound, active forms of the glucan-binding proteins coexist with immunologically detectable, soluble but inactive forms of the proteins. Reconstitution of a soluble protein fraction into lipid vesicles regained beta-glucoside-binding activity but with lower affinity (Kd = 130 nM). We conclude that the beta-glucan elicitor receptors of legumes are composed of the 75 kDa glucan-binding proteins as the critical components for ligand-recognition, and of an as yet unknown membrane anchor constituting the plasma membrane-associated receptor complex.

Plant oligosaccharides - outsiders among elicitors?

PubMed

Larskaya, I A; Gorshkova, T A

2015-07-01

This review substantiates the need to study the plant oligoglycome. The available information on oligosaccharins - physiologically active fragments of plant cell wall polysaccharides - is summarized. The diversity of such compounds in chemical composition, origin, and proved biological activity is highlighted. At the same time, plant oligosaccharides can be considered as outsiders among elicitors of various natures in research intensity of recent decades. This review discusses the reasons for such attitude towards these regulators, which are largely connected with difficulties in isolation and identification. Together with that, approaches are suggested whose potentials can be used to study oligosaccharins. The topics of oligosaccharide metabolism in plants, including the ways of formation, transport, and inactivation are presented, together with data on biological activity and interaction with plant hormones. The current viewpoints on the mode of oligosaccharin action - perception, signal transduction, and possible "targets" - are considered. The potential uses of such compounds in medicine, food industry, agriculture, and biotechnology are discussed.

A novel elicitor protein from Phytophthora parasitica induces plant basal immunity and systemic acquired resistance.

PubMed

Chang, Yi-Hsuan; Yan, Hao-Zhi; Liou, Ruey-Fen

2015-02-01

The interaction between Phytophthora pathogens and host plants involves the exchange of complex molecular signals from both sides. Recent studies of Phytophthora have led to the identification of various apoplastic elicitors known to trigger plant immunity. Here, we provide evidence that the protein encoded by OPEL of Phytophthora parasitica is a novel elicitor. Homologues of OPEL were identified only in oomycetes, but not in fungi and other organisms. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) revealed that OPEL is expressed throughout the development of P. parasitica and is especially highly induced after plant infection. Infiltration of OPEL recombinant protein from Escherichia coli into leaves of Nicotiana tabacum (cv. Samsun NN) resulted in cell death, callose deposition, the production of reactive oxygen species and induced expression of pathogen-associated molecular pattern (PAMP)-triggered immunity markers and salicylic acid-responsive defence genes. Moreover, the infiltration conferred systemic resistance against a broad spectrum of pathogens, including Tobacco mosaic virus, the bacteria wilt pathogen Ralstonia solanacearum and P. parasitica. In addition to the signal peptide, OPEL contains three conserved domains: a thaumatin-like domain, a glycine-rich protein domain and a glycosyl hydrolase (GH) domain. Intriguingly, mutation of a putative laminarinase active site motif in the predicted GH domain abolished its elicitor activity, which suggests enzymatic activity of OPEL in triggering the defence response. © 2014 BSPP AND JOHN WILEY & SONS LTD.

Isolation, characterization, and expression analyses of plant elicitor peptides (pep) genes in maize

USDA-ARS?s Scientific Manuscript database

PROPEP1, PROPEP 2, and PROPEP3 genes appear to have roles in a feedback loop that amplifies defense signaling pathways initiated by pathogens. We present evidence to support the role of peptides derived from PROPEP genes as endogenous elicitors that are generated in response to pathogens. The preval...

Elicitors as alternative strategy to pesticides in grapevine? Current knowledge on their mode of action from controlled conditions to vineyard.

PubMed

Delaunois, Bertrand; Farace, Giovanni; Jeandet, Philippe; Clément, Christophe; Baillieul, Fabienne; Dorey, Stéphan; Cordelier, Sylvain

2014-04-01

Development and optimisation of alternative strategies to reduce the use of classic chemical inputs for protection against diseases in vineyard is becoming a necessity. Among these strategies, one of the most promising consists in the stimulation and/or potentiation of the grapevine defence responses by the means of elicitors. Elicitors are highly diverse molecules both in nature and origins. This review aims at providing an overview of the current knowledge on these molecules and will highlight their potential efficacy from the laboratory in controlled conditions to vineyards. Recent findings and concepts (especially on plant innate immunity) and the new terminology (microbe-associated molecular patterns, effectors, etc.) are also discussed in this context. Other objectives of this review are to highlight the difficulty of transferring elicitors use and results from the controlled conditions to the vineyard, to determine their practical and effective use in viticulture and to propose ideas for improving their efficacy in non-controlled conditions.

A novel protein elicitor (SsCut) from Sclerotinia sclerotiorum induces multiple defense responses in plants.

PubMed

Zhang, Huajian; Wu, Qun; Cao, Shun; Zhao, Tongyao; Chen, Ling; Zhuang, Peitong; Zhou, Xiuhong; Gao, Zhimou

2014-11-01

In this study, we report the cloning of the SsCut gene encoding cutinase from Sclerotinia sclerotiorum. We isolated a 609-bp cDNA encoding a polypeptide of 202 amino acids with a molecular weight of 20.4 kDa. Heterologous expression of SsCut in Escherichia coli (His-SsCut) caused the formation of lesions in tobacco that closely resembled hypersensitive response lesions. Mutational analysis identified the C-terminal-half peptide and the same amino acids indispensable for both enzyme and elicitor activity. His-SsCut was caused cell death in Arabidopsis, soybean (Glycine max), oilseed rape (Brassica napus), rice (Oryza sativa), maize (Zea mays), and wheat (Triticum aestivum), indicating that both dicot and monocot species are responsive to the elicitor. Furthermore, the elicitation of tobacco was effective in the induction of the activities of hydrogen peroxide, phenylalanine ammonia-lyase, peroxides, and polyphenol oxidase. His-SsCut-treated plants exhibited enhanced resistance as indicated by a significant reduction in the number and size of S. sclerotiorum, Phytophthora sojae, and P. nicotianae lesions on leaves relative to controls. Real-time PCR results indicated that the expression of defense-related genes and genes involved in signal transduction were induced by His-SsCut. Our results demonstrate that SsCut is an elicitor that triggers defense responses in plants and will help to clarify its relationship to downstream signaling pathways that induce defense responses.

Inducible De Novo Biosynthesis of Isoflavonoids in Soybean Leaves by Spodoptera litura Derived Elicitors: Tracer Techniques Aided by High Resolution LCMS.

PubMed

Nakata, Ryu; Kimura, Yuki; Aoki, Kenta; Yoshinaga, Naoko; Teraishi, Masayoshi; Okumoto, Yutaka; Huffaker, Alisa; Schmelz, Eric A; Mori, Naoki

2016-12-01

Isoflavonoids are a characteristic family of natural products in legumes known to mediate a range of plant-biotic interactions. For example, in soybean (Glycine max: Fabaceae) multiple isoflavones are induced and accumulate in leaves following attack by Spodoptera litura (Lepidoptera: Noctuidae) larvae. To quantitatively examine patterns of activated de novo biosynthesis, soybean (Var. Enrei) leaves were treated with a combination of plant defense elicitors present in S. litura gut content extracts and L-α-[ 13 C 9 , 15 N]phenylalanine as a traceable isoflavonoid precursor. Combined treatments promoted significant increases in 13 C-labeled isoflavone aglycones (daidzein, formononetin, and genistein), 13 C-labeled isoflavone 7-O-glucosides (daidzin, ononin, and genistin), and 13 C-labeled isoflavone 7-O-(6″-O-malonyl-β-glucosides) (malonyldaidzin, malonylononin, and malonylgenistin). In contrast levels of 13 C-labeled flavones and flavonol (4',7-dihydroxyflavone, kaempferol, and apigenin) were not significantly altered. Curiously, application of fatty acid-amino acid conjugate (FAC) elicitors present in S. litura gut contents, namely N-linolenoyl-L-glutamine and N-linoleoyl-L-glutamine, both promoted the induced accumulation of isoflavone 7-O-glucosides and isoflavone 7-O-(6″-O-malonyl-β-glucosides), but not isoflavone aglycones in the leaves. These results demonstrate that at least two separate reactions are involved in elicitor-induced soybean leaf responses to the S. litura gut contents: one is the de novo biosynthesis of isoflavone conjugates induced by FACs, and the other is the hydrolysis of the isoflavone conjugates to yield isoflavone aglycones. Gut content extracts alone displayed no hydrolytic activity. The quantitative analysis of isoflavone de novo biosynthesis, with respect to both aglycones and conjugates, affords a useful bioassay system for the discovery of additional plant defense elicitor(s) in S. litura gut contents that specifically

Evaluation of Grenache, Graciano and Tempranillo grape stilbene content after field applications of elicitors and nitrogen compounds.

PubMed

Portu, Javier; López, Rosa; Ewald, Philipp; Santamaría, Pilar; Winterhalter, Peter; Garde-Cerdán, Teresa

2018-03-01

Stilbenes have a significant biological activity and are one of the most important non-flavonoid contributors to grape and wine health-related properties. The accumulation of this class of compounds could be favored by viticultural practices such as the application of biostimulants. However, stilbene concentration also depends on several factors, including, for example, grape variety. Therefore, the aim of this work was to study the influence of foliar treatments carried out with elicitors (methyl jasmonate (MeJ) and a commercial foliar spray (YD)) and nitrogen compounds (phenylalanine and urea) on the grape stilbene composition of three varieties: Grenache, Graciano and Tempranillo. An ultra-high-pressure liquid chromatographic methodology was validated for stilbene determination. Results showed that, despite the huge influence of the grape variety, YD significantly improved stilbene composition in Grenache and Graciano, while MeJ increased the stilbene content in Graciano and Tempranillo. As for the nitrogen treatments, phenylalanine significantly increased the stilbene concentration in Graciano, while urea treatment increased it in Tempranillo. However, the application of elicitors had a greater effect than the nitrogen compounds. Overall, the foliar application of the elicitors could be a suitable practice for increasing the amount of stilbenes in grape and, therefore, its nutraceutical properties. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Two rice GRAS family genes responsive to N -acetylchitooligosaccharide elicitor are induced by phytoactive gibberellins: evidence for cross-talk between elicitor and gibberellin signaling in rice cells.

PubMed

Day, R Bradley; Tanabe, Shigeru; Koshioka, Masaji; Mitsui, Toshiaki; Itoh, Hironori; Ueguchi-Tanaka, Miyako; Matsuoka, Makoto; Kaku, Hanae; Shibuya, Naoto; Minami, Eiichi

2004-01-01

In this study, we present data showing that two members of the GRAS family of genes from rice, CIGR1 and CIGR2 (chitin-inducible gibberellin-responsive), inducible by the potent elicitor N -acetylchitooligosaccharide (GN), are rapidly induced by exogenous gibberellins. The pattern of mRNA accumulation was dependent on the dose and biological activity of the gibberellins, suggesting that the induction of the genes by gibberellin is mediated by a biological receptor capable of specific recognition and signal transduction upon perception of the phytoactive compounds. Further pharmacological analysis revealed that the CIGR1 and CIGR2 mRNA accumulation by treatment with gibberellin is dependent upon protein phosphorylation/dephosphorylation events. In rice calli derived from slender rice 1, a constitutive gibberellin-responsive mutant, or d1, a mutant deficient in the alpha -subunit of the heterotrimeric G-protein, CIGR1 and CIGR2 were induced by a GN elicitor, yet not by gibberellin. Neither gibberellin nor GN showed related activities in defense or development, respectively. These results strongly suggested that the signal transduction cascade from gibberellin is independent of that from GN, and further implied that CIGR1 and CIGR2 have dual, distinct roles in defense and development.

Key steps in type III secretion system (T3SS) towards translocon assembly with potential sensor at plant plasma membrane.

PubMed

Ji, Hongtao; Dong, Hansong

2015-09-01

Many plant- and animal-pathogenic Gram-negative bacteria employ the type III secretion system (T3SS) to translocate effector proteins from bacterial cells into the cytosol of eukaryotic host cells. The effector translocation occurs through an integral component of T3SS, the channel-like translocon, assembled by hydrophilic and hydrophobic proteinaceous translocators in a two-step process. In the first, hydrophilic translocators localize to the tip of a proteinaceous needle in animal pathogens, or a proteinaceous pilus in plant pathogens, and associate with hydrophobic translocators, which insert into host plasma membranes in the second step. However, the pilus needs to penetrate plant cell walls in advance. All hydrophilic translocators so far identified in plant pathogens are characteristic of harpins: T3SS accessory proteins containing a unitary hydrophilic domain or an additional enzymatic domain. Two-domain harpins carrying a pectate lyase domain potentially target plant cell walls and facilitate the penetration of the pectin-rich middle lamella by the bacterial pilus. One-domain harpins target plant plasma membranes and may play a crucial role in translocon assembly, which may also involve contrapuntal associations of hydrophobic translocators. In all cases, sensory components in the target plasma membrane are indispensable for the membrane recognition of translocators and the functionality of the translocon. The conjectural sensors point to membrane lipids and proteins, and a phosphatidic acid and an aquaporin are able to interact with selected harpin-type translocators. Interactions between translocators and their sensors at the target plasma membrane are assumed to be critical for translocon assembly. © 2014 BSPP AND JOHN WILEY & SONS LTD.

Influence of growth regulators and elicitors on cell growth and α-tocopherol and pigment productions in cell cultures of Carthamus tinctorius L.

PubMed

Chavan, Smita P; Lokhande, Vinayak H; Nitnaware, Kirti M; Nikam, Tukaram D

2011-03-01

The present study examined the effects of plant growth hormones, incubation period, biotic (Trametes versicolor, Mucor sp., Penicillium notatum, Rhizopus stolonifer, and Fusarium oxysporum) and abiotic (NaCl, MgSO(4), FeSO(4), ZnSO(4), and FeCl(3)) elicitors on cell growth and α-tocopherol and pigment (red and yellow) productions in Carthamus tinctorius cell cultures. The cell growth and α-tocopherol and pigment contents improved significantly on Murashige and Skoog (MS) liquid medium containing 50.0 μM α-naphthalene acetic acid (NAA) and 2.5 μM 6-Benzyladenine (BA) at 28 days of incubation period. Incorporation of T. versicolor (50 mg l(-1)) significantly enhanced the production of α-tocopherol (12.7-fold) and red pigment (4.24-fold). Similarly, supplementation of 30 mg l(-1) T. versicolor (7.54-fold) and 70 mg l(-1) Mucor sp. (7.40-fold) significantly increased the production of yellow pigment. Among abiotic elicitors, NaCl (50-70 mg l(-1)) and MgSO(4) (10-30 mg l(-1)) significantly improved production of α-tocopherol (1.24-fold) and red pigment (20-fold), whereas yellow pigment content increased considerably by all the abiotic elicitor treatments. Taken together, the present study reports improved productions of α-tocopherol and the pigment as a stress response of safflower cell cultures exposed to these elicitors.

Light and Fungal Elicitor Induce 3-Deoxy-d-arabino-Heptulosonate 7-Phosphate Synthase mRNA in Suspension Cultured Cells of Parsley (Petroselinum crispum L.) 1

PubMed Central

Henstrand, John M.; McCue, Kent F.; Brink, Kent; Handa, Avtar K.; Herrmann, Klaus M.; Conn, Eric E.

1992-01-01

Light and fungal elicitor induce mRNA encoding 3-deoxy-d-arabino-heptulosonate 7-phosphate (DAHP) synthase in suspension cultured cells of parsley (Petroselinum crispum L.). The kinetics and dose response of mRNA accumulation were similar for DAHP synthase and phenylalanine ammonia-lyase (PAL). Six micrograms of elicitor from Phytophthora megasperma f. glycinia gave a detectable induction within 1 hour. Induction of DAHP synthase and PAL mRNAs by light was transient, reaching maximal levels at 4 hours and returning to pretreatment levels after 24 hours. Our data suggest that either light or fungal elicitor transcriptionally activate DAHP synthase. A coordinate regulation for key enzymes in the synthesis of primary and secondary metabolites is indicated. ImagesFigure 1 PMID:16668708

Effect of elicitors on the production of gossypol and methylated gossypol in cotton hairy roots

USDA-ARS?s Scientific Manuscript database

The effect of two-chemical elicitors, salicylic acid and methyl jasmonate, on the production of gossypol, 6-methoxy gossypol, and 6,6'-dimethoxy gossypol in Gossypium barbadense hairy roots was examined. Methyl jasmonate, but not salicylic acid, was found to increase the production of gossypol and ...

A paralog of the proteinaceous elicitor sm1 affects colonization of maize roots by Trichoderma virens

USDA-ARS?s Scientific Manuscript database

The biocontrol agent, Trichoderma virens, has the ability to protect plants from pathogens by eliciting plant defense responses, involvement in mycoparasitism, or secreting antagonistic secondary metabolites. SM1, an elicitor of induced systemic resistance (ISR), was found to have three paralogs wi...

Release of elicitors from rice blast spores under the action of reactive oxygen species

USDA-ARS?s Scientific Manuscript database

The effects of reactive oxygen species (ROS) on secretion of hypothesized elicitors from spores of rice blast causal fungus Magnaporthe grisea were studied. For spore exposure to exogenous ROS, they were germinated for 5 h in 50 µM H2O2 followed by addition of catalase E.C. 1.11.1.6 (to decompose pe...

The plant cytoskeleton controls regulatory volume increase.

PubMed

Liu, Qiong; Qiao, Fei; Ismail, Ahmed; Chang, Xiaoli; Nick, Peter

2013-09-01

The ability to adjust cell volume is required for the adaptation to osmotic stress. Plant protoplasts can swell within seconds in response to hypoosmotic shock suggesting that membrane material is released from internal stores. Since the stability of plant membranes depends on submembraneous actin, we asked, whether this regulatory volume control depends on the cytoskeleton. As system we used two cell lines from grapevine which differ in their osmotic tolerance and observed that the cytoskeleton responded differently in these two cell lines. To quantify the ability for regulatory volume control, we used hydraulic conductivity (Lp) as readout and demonstrated a role of the cytoskeleton in protoplast swelling. Chelation of calcium, inhibition of calcium channels, or manipulation of membrane fluidity, did not significantly alter Lp, whereas direct manipulation of the cytoskeleton via specific chemical reagents, or indirectly, through the bacterial elicitor Harpin or activation of phospholipase D, was effective. By optochemical engineering of actin using a caged form of the phytohormone auxin we can break the symmetry of actin organisation resulting in a localised deformation of cell shape indicative of a locally increased Lp. We interpret our findings in terms of a model, where the submembraneous cytoskeleton controls the release of intracellular membrane stores during regulatory volume change. Copyright © 2013 Elsevier B.V. All rights reserved.

Host plant species determines symbiotic bacterial community mediating suppression of plant defenses.

PubMed

Chung, Seung Ho; Scully, Erin D; Peiffer, Michelle; Geib, Scott M; Rosa, Cristina; Hoover, Kelli; Felton, Gary W

2017-01-03

Herbivore associated bacteria are vital mediators of plant and insect interactions. Host plants play an important role in shaping the gut bacterial community of insects. Colorado potato beetles (CPB; Leptinotarsa decemlineata) use several Solanum plants as hosts in their natural environment. We previously showed that symbiotic gut bacteria from CPB larvae suppressed jasmonate (JA)-induced defenses in tomato. However, little is known about how changes in the bacterial community may be involved in the manipulation of induced defenses in wild and cultivated Solanum plants of CPB. Here, we examined suppression of JA-mediated defense in wild and cultivated hosts of CPB by chemical elicitors and their symbiotic bacteria. Furthermore, we investigated associations between the gut bacterial community and suppression of plant defenses using 16 S rRNA amplicon sequencing. Symbiotic bacteria decreased plant defenses in all Solanum hosts and there were different gut bacterial communities in CPB fed on different host plants. When larvae were reared on different hosts, defense suppression differed among host plants. These results demonstrate that host plants influence herbivore gut bacterial communities and consequently affect the herbivore's ability to manipulate JA-mediated plant defenses. Thus, the presence of symbiotic bacteria that suppress plant defenses might help CPB adapt to host plants.

Host plant species determines symbiotic bacterial community mediating suppression of plant defenses

PubMed Central

Chung, Seung Ho; Scully, Erin D.; Peiffer, Michelle; Geib, Scott M.; Rosa, Cristina; Hoover, Kelli; Felton, Gary W.

2017-01-01

Herbivore associated bacteria are vital mediators of plant and insect interactions. Host plants play an important role in shaping the gut bacterial community of insects. Colorado potato beetles (CPB; Leptinotarsa decemlineata) use several Solanum plants as hosts in their natural environment. We previously showed that symbiotic gut bacteria from CPB larvae suppressed jasmonate (JA)-induced defenses in tomato. However, little is known about how changes in the bacterial community may be involved in the manipulation of induced defenses in wild and cultivated Solanum plants of CPB. Here, we examined suppression of JA-mediated defense in wild and cultivated hosts of CPB by chemical elicitors and their symbiotic bacteria. Furthermore, we investigated associations between the gut bacterial community and suppression of plant defenses using 16 S rRNA amplicon sequencing. Symbiotic bacteria decreased plant defenses in all Solanum hosts and there were different gut bacterial communities in CPB fed on different host plants. When larvae were reared on different hosts, defense suppression differed among host plants. These results demonstrate that host plants influence herbivore gut bacterial communities and consequently affect the herbivore’s ability to manipulate JA-mediated plant defenses. Thus, the presence of symbiotic bacteria that suppress plant defenses might help CPB adapt to host plants. PMID:28045052

Increased universality of Lepidopteran elicitor compounds across insects: Identification of fatty acid amino acid conjugates (FACs)

USDA-ARS?s Scientific Manuscript database

Fatty acid amino acid conjugates (FACs) are known elicitors of induced release of volatile compounds in plants that, in turn, attract foraging parasitoids. Since the discovery of volicitin [N-(17-hydroxylinolenoyl)-L-glutamine] in the regurgitant of larval Spodoptera exigua1, a series of related FAC...

Bacterial Outer Membrane Vesicles Induce Plant Immune Responses.

PubMed

Bahar, Ofir; Mordukhovich, Gideon; Luu, Dee Dee; Schwessinger, Benjamin; Daudi, Arsalan; Jehle, Anna Kristina; Felix, Georg; Ronald, Pamela C

2016-05-01

Gram-negative bacteria continuously pinch off portions of their outer membrane, releasing membrane vesicles. These outer membrane vesicles (OMVs) are involved in multiple processes including cell-to-cell communication, biofilm formation, stress tolerance, horizontal gene transfer, and virulence. OMVs are also known modulators of the mammalian immune response. Despite the well-documented role of OMVs in mammalian-bacterial communication, their interaction with plants is not well studied. To examine whether OMVs of plant pathogens modulate the plant immune response, we purified OMVs from four different plant pathogens and used them to treat Arabidopsis thaliana. OMVs rapidly induced a reactive oxygen species burst, medium alkalinization, and defense gene expression in A. thaliana leaf discs, cell cultures, and seedlings, respectively. Western blot analysis revealed that EF-Tu is present in OMVs and that it serves as an elicitor of the plant immune response in this form. Our results further show that the immune coreceptors BAK1 and SOBIR1 mediate OMV perception and response. Taken together, our results demonstrate that plants can detect and respond to OMV-associated molecules by activation of their immune system, revealing a new facet of plant-bacterial interactions.

[Callose accumulation during treatment of tomato (Lycopersicon esculentum L.) cells with biotic elicitors].

PubMed

Emel'ianov, V I; Kravchuk, Zh N; Poliakovskiĭ, S A; Dmitriev, A P

2008-01-01

Time-course of induced accumulation of callose in tomato cells has been studied. Localization of callose in L. esculenthum cells was investigated by fluorescent microscopy technique, and the optimal time for its determination was found. Callose accumulation in tomato cells treated with different biotic elicitors was determined. Nonlinear dependence between callose accumulation and concentration of chitin oligomers (with 3-5 N-acetylglucosamine fragments) was established. Increasing of callose accumulation in tomato cells was proportional to the increase of concentration ofchitin dimer and chitosan in the culture medium.

Cloning of soybean genes induced during hypersensitive cell death caused by syringolide elicitor.

PubMed

Hagihara, Takuya; Hashi, Masaru; Takeuchi, Yoji; Yamaoka, Naoto

2004-02-01

Syringolide elicitors produced by bacteria expressing Pseudomonas syringae pv. glycinea avirulence gene D (avrD) induce hypersensitive cell death (HCD) only in soybean (Glycine max [L.] Merr.) plants carrying the Rpg4 disease resistance gene. Employing a differential display method, we isolated 13 gene fragments induced in cultured cells of a soybean cultivar Harosoy (Rpg4) treated with syringolides. Several genes for isolated fragments were induced by syringolides in an rpg4 cultivar Acme as well as in Harosoy; however, the genes for seven fragments designated as SIH (for syringolide-induced/ HCD associated) were induced exclusively or strongly in Harosoy. cDNA clones for SIH genes were obtained from a cDNA library of Harosoy treated with syringolide. Several sequences are homologous to proteins associated with plant defense responses. The SIH genes did not respond to a non-specific beta-glucan elicitor, which induces phytoalexin accumulation but not HCD, suggesting that the induction of the SIH genes is specific for the syringolide-Harosoy interaction. HCD and the induction of SIH genes by syringolides were independent of H(2)O(2). On the other hand, Ca(2+) was required for HCD and the induction of some SIH genes. These results suggest that the induction of SIH genes by syringolides could be activated through the syringolide-specific signaling pathway and the SIH gene products may play an important role(s) in the processes of HCD induced by syringolides.

Effects of elicitors on the production of resveratrol and viniferins in cell cultures of Vitis vinifera L. cv Italia.

PubMed

Santamaria, Anna Rita; Mulinacci, Nadia; Valletta, Alessio; Innocenti, Marzia; Pasqua, Gabriella

2011-09-14

Methyl jasmonate, jasmonic acid and chitosan were tested as elicitors on cell suspension cultures obtained from Vitis vinifera cv Italia to investigate their effect on stilbene production. Stilbene accumulation in the callus, grown under nonelicited conditions, was also investigated. Calli and cell suspensions were obtained in a B5 culture medium supplemented with 0.2 mg L(-1) NAA and 1 mg L(-1) KIN. Stilbene determination was achieved by HPLC/DAD/MS. Whereas callus biosynthesized only piceid, cell suspensions elicited with jasmonates produced several stilbenes, mainly viniferins. In suspended cells, methyl jasmonate and jasmonic acid were the most effective in stimulating stilbene biosynthesis, whereas chitosan was less effective; in fact, the amount of stilbenes obtained with this elicitor was not significantly different from that obtained for the control cells. The maximum production of total stilbenes was at day 20 of culture with 0.970 and 1.023 mg g(-1) DW for MeJA and JA, respectively.

Enhanced disease resistance and drought tolerance in transgenic rice plants overexpressing protein elicitors from Magnaporthe oryzae.

PubMed

Wang, Zhenzhen; Han, Qiang; Zi, Qian; Lv, Shun; Qiu, Dewen; Zeng, Hongmei

2017-01-01

Exogenous application of the protein elicitors MoHrip1 and MoHrip2, which were isolated from the pathogenic fungus Magnaporthe oryzae (M. oryzae), was previously shown to induce a hypersensitive response in tobacco and to enhance resistance to rice blast. In this work, we successfully transformed rice with the mohrip1 and mohrip2 genes separately. The MoHrip1 and MoHrip2 transgenic rice plants displayed higher resistance to rice blast and stronger tolerance to drought stress than wild-type (WT) rice and the vector-control pCXUN rice. The expression of salicylic acid (SA)- and abscisic acid (ABA)-related genes was also increased, suggesting that these two elicitors may trigger SA signaling to protect the rice from damage during pathogen infection and regulate the ABA content to increase drought tolerance in transgenic rice. Trypan blue staining indicated that expressing MoHrip1 and MoHrip2 in rice plants inhibited hyphal growth of the rice blast fungus. Relative water content (RWC), water usage efficiency (WUE) and water loss rate (WLR) were measured to confirm the high capacity for water retention in transgenic rice. The MoHrip1 and MoHrip2 transgenic rice also exhibited enhanced agronomic traits such as increased plant height and tiller number.

Effect of elicitors and precursors on azadirachtin production in hairy root culture of Azadirachta indica.

PubMed

Srivastava, Smita; Srivastava, A K

2014-02-01

The present study involved strategies for enhancement in in vitro azadirachtin (commercially used biopesticide) production by hairy root cultivation of Azadirachta indica. Improvement in the azadirachtin production via triggering its biosynthetic pathway in plant cells was carried out by the exogenous addition of precursors and elicitors in the growth medium. Among the different abiotic stress inducers (Ag(+), Hg(+2), Co(+2), Cu(+2)) and signal molecules (methyl jasmonate and salicylic acid) tested, salicylic acid at 15 mg l(-1) of concentration was found to enhance the azadirachtin yield in the hairy roots to the maximum (up to 4.95 mg g(-1)). Similarly, among the different biotic elicitors tested (filter-sterilized fungal culture filtrates of Phoma herbarium, Alternaria alternata, Myrothecium sp., Fusarium solani, Curvularia lunata, and Sclerotium rolfsii; yeast extract; and yeast extract carbohydrate fraction), addition of filter-sterilized fungal culture filtrate of C. lunata (1 % v/v) resulted in maximum azadirachtin yield enhancement in hairy root biomass (up to 7.1 mg g(-1)) with respect to the control (3.3 mg g(-1)). Among all the biosynthetic precursors studied (sodium acetate, cholesterol, squalene, isopentynyl pyrophosphate, mavalonic acid lactone, and geranyl pyrophosphate), the overall azadirachtin production (70.42 mg l(-1) in 25 days) was found to be the highest with cholesterol (50 mg l(-1)) addition as an indirect precursor in the medium.

Metabolomics reveals biotic and abiotic elicitor effects on the soft coral Sarcophyton ehrenbergi terpenoid content.

PubMed

Farag, Mohamed A; Al-Mahdy, Dalia A; Meyer, Achim; Westphal, Hildegard; Wessjohann, Ludger A

2017-04-05

The effects of six biotic and abiotic elicitors, i.e. MeJA (methyl jasmonate), SA (salicylic acid), ZnCl 2 , glutathione and β-glucan BG (fungal elicitor), and wounding, on the secondary metabolite accumulation in the soft coral Sarcophyton ehrenbergi were assessed. Upon elicitation, metabolites were extracted and analysed by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Except for MeJA, no differences in photosynthetic efficiency were observed after treatments, suggesting the absence of a remarkable stress on primary production. Chemometric analyses of UPLC-MS data showed clear segregation of SA and ZnCl 2 elicited samples at 24 and 48 h post elicitation. Levels of acetylated diterpene and sterol viz., sarcophytonolide I and cholesteryl acetate, was increased in ZnCl 2 and SA groups, respectively, suggesting an activation of specific acetyl transferases. Post elicitation, sarcophytonolide I level increased 132 and 17-folds at 48 h in 0.1 mM SA and 1 mM ZnCl 2 groups, respectively. Interestingly, decrease in sarcophine, a major diterpene was observed only in response to ZnCl 2 , whereas no change was observed in sesquiterpene content following treatments. To the best of our knowledge, this study provides the first documentation for elicitation effects on a soft corals secondary metabolome and suggests that SA could be applied to increase diterpenoid levels in corals.

Chalcone isomerase cDNA cloning and mRNA induction by fungal elicitor, wounding and infection

PubMed Central

Mehdy, Mona C.; Lamb, Christopher J.

1987-01-01

The environmentally regulated synthesis of phenylpropanoid natural products was studied by examining the expression of the gene encoding chalcone isomerase (CHI). This enzyme catalyzes a step common to the synthesis of flavonoid pigments and isoflavonoid phytoalexins. A λgt11 library was constructed using mRNA from cell cultures of bean (Phaseolus vulgaris L.) treated with fungal elicitor. Two positive clones were obtained by screening 105 recombinants with an antiserum to purified bean CHI. The identity of the cloned sequences was confirmed by hybrid-select translation and the production of antigenic polypeptides from transcripts synthesized in vitro. Addition of elicitor to cell cultures resulted in the rapid accumulation of CHI mRNA, with maximum levels achieved 3–4 h after elicitation. CHI mRNA also accumulated during the natural infection of hypocotyls with the fungal pathogen Colletotrichum lindemuthianum, and in mechanically wounded hypocotyls. The kinetics of accumulation of CHI mRNA in response to these environmental signals were strikingly similar to those of mRNAs encoding two other phenylpropanoid pathway enzymes, phenylalanine ammonialyase and chalcone synthase. In contrast to the multi-gene families encoding these two enzymes, chalcone isomerase is encoded by a single gene which is regulated by several environmental stimuli. ImagesFig. 2.Fig. 3.Fig. 4.Fig. 5.Fig. 6.Fig. 9. PMID:16453768

Integration of Bioinformatics and Synthetic Promoters Leads to the Discovery of Novel Elicitor-Responsive cis-Regulatory Sequences in Arabidopsis1[C][W][OA

PubMed Central

Koschmann, Jeannette; Machens, Fabian; Becker, Marlies; Niemeyer, Julia; Schulze, Jutta; Bülow, Lorenz; Stahl, Dietmar J.; Hehl, Reinhard

2012-01-01

A combination of bioinformatic tools, high-throughput gene expression profiles, and the use of synthetic promoters is a powerful approach to discover and evaluate novel cis-sequences in response to specific stimuli. With Arabidopsis (Arabidopsis thaliana) microarray data annotated to the PathoPlant database, 732 different queries with a focus on fungal and oomycete pathogens were performed, leading to 510 up-regulated gene groups. Using the binding site estimation suite of tools, BEST, 407 conserved sequence motifs were identified in promoter regions of these coregulated gene sets. Motif similarities were determined with STAMP, classifying the 407 sequence motifs into 37 families. A comparative analysis of these 37 families with the AthaMap, PLACE, and AGRIS databases revealed similarities to known cis-elements but also led to the discovery of cis-sequences not yet implicated in pathogen response. Using a parsley (Petroselinum crispum) protoplast system and a modified reporter gene vector with an internal transformation control, 25 elicitor-responsive cis-sequences from 10 different motif families were identified. Many of the elicitor-responsive cis-sequences also drive reporter gene expression in an Agrobacterium tumefaciens infection assay in Nicotiana benthamiana. This work significantly increases the number of known elicitor-responsive cis-sequences and demonstrates the successful integration of a diverse set of bioinformatic resources combined with synthetic promoter analysis for data mining and functional screening in plant-pathogen interaction. PMID:22744985

Diversity‐Oriented Synthesis of Natural‐Product‐like Libraries Containing a 3‐Methylbenzofuran Moiety for the Discovery of New Chemical Elicitors

PubMed Central

He, Xingrui; Chen, Xia; Lin, Songbo; Mo, Xiaochang; Zhou, Pengyong; Zhang, Zhihao; Lu, Yaoyao; Yang, Yu; Gu, Haining

2016-01-01

Abstract Natural products are a major source of biological molecules. The 3‐methylfuran scaffold is found in a variety of plant secondary metabolite chemical elicitors that confer host‐plant resistance against insect pests. Herein, the diversity‐oriented synthesis of a natural‐product‐like library is reported, in which the 3‐methylfuran core is fused in an angular attachment to six common natural product scaffolds—coumarin, chalcone, flavone, flavonol, isoflavone and isoquinolinone. The structural diversity of this library is assessed computationally using cheminformatic analysis. Phenotypic high‐throughput screening of β‐glucuronidase activity uncovers several hits. Further in vivo screening confirms that these hits can induce resistance in rice to nymphs of the brown planthopper Nilaparvata lugens. This work validates the combination of diversity‐oriented synthesis and high‐throughput screening of β‐glucuronidase activity as a strategy for discovering new chemical elicitors. PMID:28168155

Effects of Polysaccharide Elicitors from Endophytic Fusarium oxysporum Fat9 on the Growth, Flavonoid Accumulation and Antioxidant Property of Fagopyrum tataricum Sprout Cultures.

PubMed

Zhong, Lingyun; Niu, Bei; Tang, Lin; Chen, Fang; Zhao, Gang; Zhao, Jianglin

2016-11-25

The purpose of this study was to evaluate the effects of four different fungal polysaccharides, named water-extracted mycelia polysaccharide (WPS), sodium hydroxide-extracted mycelia polysaccharide (SPS), hydrochloric-extracted mycelia polysaccharide (APS), and exo-polysaccharide (EPS) obtained from the endophytic Fusarium oxysporum Fat9 on the sprout growth, flavonoid accumulation, and antioxidant capacity of tartary buckwheat. Without visible changes in the appearance of the sprouts, the exogenous polysaccharide elicitors strongly stimulated sprout growth and flavonoid production, and the stimulation effect was closely related with the polysaccharide (PS) species and its treatment dosage. With application of 200 mg/L of EPS, 200 mg/L of APS, 150 mg/L of WPS, or 100 mg/L of SPS, the total rutin and quercetin yields of buckwheat sprouts were significantly increased to 41.70 mg/(100 sprouts), 41.52 mg/(100 sprouts), 35.88 mg/(100 sprouts), and 32.95 mg/(100 sprouts), respectively. This was about 1.11 to 1.40-fold compared to the control culture of 31.40 mg/(100 sprouts). Moreover, the antioxidant capacity of tartary buckwheat sprouts was also enhanced after treatment with the four PS elicitors. Furthermore, the present study revealed the polysaccharide elicitation that caused the accumulation of functional flavonoid by stimulating the phenylpropanoid pathway. The application of beneficial fungal polysaccharide elicitors may be an effective approach to improve the nutritional and functional characteristics of tartary buckwheat sprouts.

PIOX, a new pathogen-induced oxygenase with homology to animal cyclooxygenase.

PubMed

Sanz, A; Moreno, J I; Castresana, C

1998-09-01

Changes in gene expression induced in tobacco leaves by the harpin HrpN protein elicitor were examined, and a new cDNA, piox (for pathogen-induced oxygenase), with homology to genes encoding cyclooxygenase or prostaglandin endoperoxide synthase (PGHS), was identified. In addition to the amino acid identity determined, the protein encoded by piox is predicted to have a structural core similar to that of ovine PGHS-1. Moreover, studies of protein functionality demonstrate that the PIOX recombinant protein possesses at least one of the two enzymatic activities of PGHSs, that of catalyzing the oxygenation of polyunsaturated fatty acids. piox transcripts accumulated after protein elicitor treatment or inoculation with bacteria. Expression of piox was induced in tissues responding to inoculation with both incompatible and compatible bacteria, but RNA and protein accumulation differed for both types of interactions. We show that expression of piox is rapidly induced in response to various cellular signals mediating plant responses to pathogen infection and that activation of piox expression is most likely related to the oxidative burst that takes place during the cell death processes examined. Cyclooxygenase catalyzes the first committed step in the formation of prostaglandins and thromboxanes, which are lipid-derived signal molecules that mediate many cellular processes, including the immune response in vertebrates. The finding of tobacco PIOX suggests that more similarities than hitherto expected will be found between the lipid-based responses for plant and animal systems.

The interplay between light, plant growth regulators and elicitors on growth and secondary metabolism in cell cultures of Fagonia indica.

PubMed

Khan, Tariq; Abbasi, Bilal Haider; Khan, Mubarak Ali

2018-06-09

Manipulation in the light regimes combined with the effects of plant growth regulators (PGRs) and elicitors through plant cell culture technology is a promising strategy for enhancing the yield of medicinally important secondary metabolites. In this study, the effects of interplay between PGRs, elicitors and light regimes on cell cultures of F. indica have been investigated. The results showed that callus cultures resulted in maximum biomass formation (13.2 g/L) when incubated on solid MS (Murashige and Skoog) medium containing 1.0 mg/L BA under continuous light for 4 weeks. Among the other PGRs, compared with the auxins such as 2,4-D, and IBA, TDZ resulted in higher biomass accumulation (12.1 g/L). Elicitors (Me-J and PAA) resulted in a lower growth response, when compared with cytokinins and a higher response than auxins under all the light regimes on solid MS media. However, in liquid media, no significant increase in biomass was observed in response to the combined effects of PGRs and photoperiod regimes. Further, the highest phenolic content (TPC = 6.8 mg) and flavonoid content (TFC = 5.2 mg) were detected in the dark-grown cell cultures raised in vitro at 0.5 mg/L Me-J. The highest antioxidant activity (88%) was recorded in the dark-grown cell cultures harvested from LOG phase of the growth cycle supplemented with 0.5 mg/L Me-J. Furthermore, BA resulted in considerable flavonoids production (TFC = 4.7 mg) in the cell cultures grown under continuous light. However, overall dark treatment and elicitation with Me-J resulted in the optimal metabolic response in terms of secondary metabolites accumulation in cell suspension cultures of F. indica. Copyright © 2018 Elsevier B.V. All rights reserved.

Changes in EEG alpha power to different disgust elicitors: the specificity of mutilations.

PubMed

Sarlo, Michela; Buodo, Giulia; Poli, Silvia; Palomba, Daniela

2005-07-15

It is unclear in the literature whether the various disgust elicitors are differentially processed by the brain and/or able to elicit distinct psychophysiological response patterns. On the other hand, disgusting stimuli depicting mutilations have been proved to elicit a distinct autonomic response pattern and to demand greater attentional resources, as compared with other unpleasant visual stimuli. In this EEG study, 34 participants viewed 4 film-clips depicting surgery, cockroach invasion, human attack and neutral landscape during EEG recording, and then rated the clips for valence, arousal and the basic emotions. Independent of location, the highest cortical activation was found during the viewing of the surgery scene. Moreover, the above activation was prominent over the right posterior regions.

The Elicitor Protein AsES Induces a Systemic Acquired Resistance Response Accompanied by Systemic Microbursts and Micro-Hypersensitive Responses in Fragaria ananassa.

PubMed

Hael-Conrad, Verónica; Perato, Silvia Marisa; Arias, Marta Eugenia; Martínez-Zamora, Martín Gustavo; Di Peto, Pía de Los Ángeles; Martos, Gustavo Gabriel; Castagnaro, Atilio Pedro; Díaz-Ricci, Juan Carlos; Chalfoun, Nadia Regina

2018-01-01

The elicitor AsES (Acremonium strictum elicitor subtilisin) is a 34-kDa subtilisin-like protein secreted by the opportunistic fungus Acremonium strictum. AsES activates innate immunity and confers resistance against anthracnose and gray mold diseases in strawberry plants (Fragaria × ananassa Duch.) and the last disease also in Arabidopsis. In the present work, we show that, upon AsES recognition, a cascade of defense responses is activated, including: calcium influx, biphasic oxidative burst (O 2 ⋅- and H 2 O 2 ), hypersensitive cell-death response (HR), accumulation of autofluorescent compounds, cell-wall reinforcement with callose and lignin deposition, salicylic acid accumulation, and expression of defense-related genes, such as FaPR1, FaPG1, FaMYB30, FaRBOH-D, FaRBOH-F, FaCHI23, and FaFLS. All these responses occurred following a spatial and temporal program, first induced in infiltrated leaflets (local acquired resistance), spreading out to untreated lateral leaflets, and later, to distal leaves (systemic acquired resistance). After AsES treatment, macro-HR and macro-oxidative bursts were localized in infiltrated leaflets, while micro-HRs and microbursts occurred later in untreated leaves, being confined to a single cell or a cluster of a few epidermal cells that differentiated from the surrounding ones. The differentiated cells initiated a time-dependent series of physiological and anatomical changes, evolving to idioblasts accumulating H 2 O 2 and autofluorescent compounds that blast, delivering its content into surrounding cells. This kind of systemic cell-death process in plants is described for the first time in response to a single elicitor. All data presented in this study suggest that AsES has the potential to activate a wide spectrum of biochemical and molecular defense responses in F. ananassa that may explain the induced protection toward pathogens of opposite lifestyle, like hemibiotrophic and necrotrophic fungi.

Grapevine fatty acid hydroperoxide lyase generates actin-disrupting volatiles and promotes defence-related cell death

PubMed Central

Wang, Hao; Claudel, Patricia; Riemann, Michael; Hause, Bettina; Hugueney, Philippe; Nick, Peter

2018-01-01

Abstract Fatty acid hydroperoxides can generate short-chained volatile aldehydes that may participate in plant defence. A grapevine hydroperoxide lyase (VvHPL1) clustering to the CYP74B class was functionally characterized with respect to a role in defence. In grapevine leaves, transcripts of this gene accumulated rapidly to high abundance in response to wounding. Cellular functions of VvHPL1 were investigated upon heterologous expression in tobacco BY-2 cells. A C-terminal green fluorescent protein (GFP) fusion of VvHPL1 was located in plastids. The overexpression lines were found to respond to salinity stress or the bacterial elicitor harpin by increasing cell death. This signal-dependent mortality response was mitigated either by addition of exogenous jasmonic acid or by treatment with diphenyleneiodonium (DPI), an inhibitor of NADPH oxidases. By feeding different substrates to recombinantly expressed enzyme, VvHPL1 could also be functionally classified as true 13-HPL. The cognate products generated by this 13-HPL were cis-3-hexenal and trans-2-hexenal. Using a GFP-tagged actin marker line, one of these isomeric products, cis-3-hexenal, was found specifically to elicit a rapid disintegration of actin filaments. This response was not only observed in the heterologous system (tobacco BY-2), but also in a grapevine cell strain expressing this marker, as well as in leaf discs from an actin marker grape used as a homologous system. These results are discussed in the context of a role for VvHPL1 in a lipoxygenase-dependent signalling pathway triggering cell death-related defence that bifurcates from jasmonate-dependent basal immunity. PMID:29659985

A complex protein derivative acts as biogenic elicitor of grapevine resistance against powdery mildew under field conditions.

PubMed

Nesler, Andrea; Perazzolli, Michele; Puopolo, Gerardo; Giovannini, Oscar; Elad, Yigal; Pertot, Ilaria

2015-01-01

Powdery mildew caused by Erysiphe necator is one of the most important grapevine diseases in several viticulture areas, and high fungicide input is required to control it. However, numerous synthetic chemical pesticides are under scrutiny due to concerns about their impact on human health and the environment. Biopesticides, such as biogenic elicitors, are a promising alternative to chemical fungicides. Although several studies have reported on effective elicitors against grapevine diseases, their efficacy under field conditions has not been investigated extensively or has occurred at rather limited levels. Our goal was to examine the efficacy of a protein-based composition, namely nutrient broth (NB), against powdery mildew under field conditions and to characterize its mechanism of action. Weekly treatments with NB was highly effective in controlling powdery mildew on grapevine across seasons with different disease pressures. The level of disease control achieved with NB was comparable to standard fungicide treatments both on leaves and bunches across three different years. NB has no direct toxic effect on the germination of E. necator conidia, and it activates plant resistance with both systemic and translaminar effect in experiments with artificial inoculation under controlled conditions. NB induced the expression of defense-related genes in grapevine, demonstrating stimulation of plant defense mechanisms, prior to and in the early stages of pathogen infection. NB is a natural derivative from meat and yeast, substances that tend not to raise concerns about toxicological and ecotoxicological properties. NB represents a valid control tool for integrated plant protection programs against powdery mildew, to reduce the use of synthetic pesticides on grapevine.

A complex protein derivative acts as biogenic elicitor of grapevine resistance against powdery mildew under field conditions

PubMed Central

Nesler, Andrea; Perazzolli, Michele; Puopolo, Gerardo; Giovannini, Oscar; Elad, Yigal; Pertot, Ilaria

2015-01-01

Powdery mildew caused by Erysiphe necator is one of the most important grapevine diseases in several viticulture areas, and high fungicide input is required to control it. However, numerous synthetic chemical pesticides are under scrutiny due to concerns about their impact on human health and the environment. Biopesticides, such as biogenic elicitors, are a promising alternative to chemical fungicides. Although several studies have reported on effective elicitors against grapevine diseases, their efficacy under field conditions has not been investigated extensively or has occurred at rather limited levels. Our goal was to examine the efficacy of a protein-based composition, namely nutrient broth (NB), against powdery mildew under field conditions and to characterize its mechanism of action. Weekly treatments with NB was highly effective in controlling powdery mildew on grapevine across seasons with different disease pressures. The level of disease control achieved with NB was comparable to standard fungicide treatments both on leaves and bunches across three different years. NB has no direct toxic effect on the germination of E. necator conidia, and it activates plant resistance with both systemic and translaminar effect in experiments with artificial inoculation under controlled conditions. NB induced the expression of defense-related genes in grapevine, demonstrating stimulation of plant defense mechanisms, prior to and in the early stages of pathogen infection. NB is a natural derivative from meat and yeast, substances that tend not to raise concerns about toxicological and ecotoxicological properties. NB represents a valid control tool for integrated plant protection programs against powdery mildew, to reduce the use of synthetic pesticides on grapevine. PMID:26442029

Elicitor-Based Biostimulant PSP1 Protects Soybean Against Late Season Diseases in Field Trials

PubMed Central

Chalfoun, Nadia R.; Durman, Sandra B.; González-Montaner, Jorge; Reznikov, Sebastián; De Lisi, Vicente; González, Victoria; Moretti, Enrique R.; Devani, Mario R.; Ploper, L. Daniel; Castagnaro, Atilio P.; Welin, Björn

2018-01-01

Currently, fungicide application in soybean production accounts for an important amount of global pesticide use, and it is therefore most desirable to find new healthier and more environmental friendly alternatives for the phytosanitary management in this crop. In this study, we present convincing evidence for effective induction of disease protection by the agricultural biostimulant PSP1, a formulation based on the plant-defense eliciting activity of the fungal protease AsES (Acremonium strictum elicitor subtilisin), in multiple field trials in Argentina. PSP1 was shown to combine well with commercial spray adjuvants, an insecticide, a herbicide and fungicides used in Argentinian soybean production without losing any defense-inducing activity, indicating an easy and efficient adaptability to conventional soybean production and disease management in the region. Results from multiple soybean field trials conducted with different elite genotypes at several locations during two consecutive growing seasons, showed that PSP1 is able to induce an enhanced pathogen defense which effectively reduced late season disease (LSD) development in field-grown soybean. This defense response seems to be broad-range as disease development was clearly reduced for at least three different fungi causing LSDs in soybean (Septoria glycines, Cercospora kikuchii and Cercospora sojina). It was noteworthy that application of PSP1 in soybean alone gave a similar protection against fungal diseases as compared to the commercial fungicides included in the field trials and that PSP1 applied together with a fungicide at reproductive stages enhanced disease protection and significantly increased grain yields. PSP1 is the first example of an elicitor-based strategy in order to efficiently control multiple fungal diseases under field conditions in the soybean crop. These results show the feasibility of using induced resistance products as complements or even full-good replacements to currently used

Plant defense induced in in vitro propagated banana (Musa paradisiaca) plantlets by Fusarium derived elicitors.

PubMed

Patel, Miral; Kothari, I L; Mohan, J S S

2004-07-01

Perception of microbial signal molecules is part of the strategy evolved by plants to survive attacks by potential pathogens. To gain a more complete understanding of the early signaling events involved in these responses, we used fungal components of Fusarium under in vitro condition and checked the rise in signal molecule, salicylic acid (SA), and marker enzymes in defense reactions against the pathogen. SA level increased by 21 folds in elicitor treated plantlets as compared to that of control plantlets and there was marked increase in phenylalanine ammonia-lyase(PAL), peroxidase(POX), polyphenol oxidase(PPO) along with higher total phenolic content. Present results indicated that use of fungal components had successfully induced systemic resistance in in vitro cultured banana plantlets.

Preparation, Characterization, and In Vitro Testing of Nanoclay Antimicrobial Activities and Elicitor Capacity.

PubMed

Merino, Danila; Mansilla, Andrea Y; Casalongué, Claudia A; Alvarez, Vera A

2018-03-28

Clay-based nanocomposites (nanoclays) are interesting systems to hold a wide type of active substances with a wide field of industrial applications. Bentonite-chitosan nanoclay was obtained via cationic exchange of natural bentonite (Bent) with an aqueous solution of chitosan (CS). Their physicochemical and morphological properties were discussed under the light of Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. Bent-CS characterization indicated that CS was intercalated in 10% (w/w). This polycationic polymer was oriented mostly in a monolayer arrangement, interacting by electrostatic forces between Bent sheets. The antimicrobial action of Bent-CS nanoclay was assayed onto phytopathogens, the bacterium model Pseudomonas syringe pv. tomato DC3000 ( Psy) and the necrotrophic fungus Fusarium solani f. sp. eumartii ( F. eumartii). In addition to demonstrating cell death on both microorganisms, Bent-CS exerted elicitor property on tomato plantlets. The biological actions of this natural nanomaterial might make it proper to be used in crops.

Elicitor induction of a microsomal 5-O-(4-coumaroyl)shikimate 3'-hydroxylase in parsley cell suspension cultures.

PubMed

Heller, W; Kühnl, T

1985-09-01

Microsomal preparations from parsley cell suspension cultures challenged with an elicitor from Phytophthora megasperma f.sp. glycinea (Pmg) catalyze the formation of trans-5-O-caffeoylshikimate from trans-5-O-(4-coumaroyl)shikimate. Neither the cis isomer nor free 4-coumarate, 4-coumaroyl-CoA, or 5-O-(4-coumaroyl)quinate are substrates for this enzyme. The reaction is strictly dependent on NADPH as a reducing cofactor and on molecular oxygen. NADH, ascorbic acid, and 6,7-dimethyl-5,6,7,8-tetrahydropterine cannot substitute for NADPH. However, NADH enhances enzyme activity observed in the presence of NADPH. Cytochrome c and carbon monoxide inhibit the hydroxylation reaction, suggesting a cytochrome P-450-dependent mixed-function monooxygenase.

High affinity binding of a fungal oligopeptide elicitor to parsley plasma membranes triggers multiple defense responses.

PubMed

Nürnberger, T; Nennstiel, D; Jabs, T; Sacks, W R; Hahlbrock, K; Scheel, D

1994-08-12

An oligopeptide of 13 amino acids (Pep-13) identified within a 42 kDa glycoprotein elicitor from P. mega-sperma was shown to be necessary and sufficient to stimulate a complex defense response in parsley cells comprising H+/Ca2+ influxes, K+/Cl- effluxes, an oxidative burst, defense-related gene activation, and phytoalexin formation. Binding of radiolabeled Pep-13 to parsley microsomes and protoplasts was specific, reversible, and saturable. Identical structural features of Pep-13 were found to be responsible for specific binding and initiation of all plant responses analyzed. The high affinity binding site recognizing the peptide ligand (KD = 2.4 nM) may therefore represent a novel class of receptors in plants, and the rapidly induced ion fluxes may constitute elements of the signal transduction cascade triggering pathogen defense in plants.

A consortium of rhizobacterial strains and biochemical growth elicitors improve cold and drought stress tolerance in rice (Oryza sativa L.).

PubMed

Kakar, K U; Ren, X-L; Nawaz, Z; Cui, Z-Q; Li, B; Xie, G-L; Hassan, M A; Ali, E; Sun, G-C

2016-05-01

In the present study, a consortium of two rhizobacteria Bacillus amyloliquefaciens Bk7 and Brevibacillus laterosporus B4, termed 'BB', biochemical elicitors salicylic acid and β-aminobutyric acid (SB) and their mixture (BBSB) were investigated for cold and drought stress tolerance in rice plants. After withholding water for 16 days, rice plants treated with BBSB showed 100% survival, improved seedling height (35.4 cm), shoot number (6.12), and showed minimum symptoms of chlorosis (19%), wilting (4%), necrosis (6%) and rolling of leaves. Similarly, BB inoculation enhanced plant growth and reduced overall symptoms in rice seedlings subjected to 0 ± 5 °C for 24 h. Our results imply several mechanisms underlying BB- and BBSB-elicited stress tolerance. In contrast to the control, both treatments significantly decreased leaf monodehydroascorbate (MDA) content and electrolyte leakage, and increased leaf proline and cholorophyll content. Moreover, activities of antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT) increased 3.0- and 3.6-fold, respectively. Moreover, expression of OsMYB3R-2, OsDIL, OsDREB1A and OsCDPK13 genes was significantly up-regulated, suggesting that these genes play important roles in abiotic stress tolerance of rice. In addition, bacterial strains Bk7 and B4 were able to produce high amounts of IAA and siderophores, and colonise the plant roots, while only strain Bk7 exhibited the capability to form biofilms and solubilise inorganic phosphate. This study indicates that the BB and BBSB bio-formulations can be used to confer induced systematic tolerance and improve the health of rice plants subject to chilling and drought stress. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

A Proteinaceous Elicitor Sm1 from the Beneficial Fungus Trichoderma virens Is Required for Induced Systemic Resistance in Maize1[W

PubMed Central

Djonović, Slavica; Vargas, Walter A.; Kolomiets, Michael V.; Horndeski, Michelle; Wiest, Aric; Kenerley, Charles M.

2007-01-01

We have previously shown that the beneficial filamentous fungus Trichoderma virens secretes the highly effective hydrophobin-like elicitor Sm1 that induces systemic disease resistance in the dicot cotton (Gossypium hirsutum). In this study we tested whether colonization of roots by T. virens can induce systemic protection against a foliar pathogen in the monocot maize (Zea mays), and we further demonstrated the importance of Sm1 during maize-fungal interactions using a functional genomics approach. Maize seedlings were inoculated with T. virens Gv29-8 wild type and transformants in which SM1 was disrupted or constitutively overexpressed in a hydroponic system or in soil-grown maize seedlings challenged with the pathogen Colletotrichum graminicola. We show that similar to dicot plants, colonization of maize roots by T. virens induces systemic protection of the leaves inoculated with C. graminicola. This protection was associated with notable induction of jasmonic acid- and green leaf volatile-biosynthetic genes. Neither deletion nor overexpression of SM1 affected normal growth or development of T. virens, conidial germination, production of gliotoxin, hyphal coiling, hydrophobicity, or the ability to colonize maize roots. Plant bioassays showed that maize grown with SM1-deletion strains exhibited the same levels of systemic protection as non-Trichoderma-treated plants. Moreover, deletion and overexpression of SM1 resulted in significantly reduced and enhanced levels of disease protection, respectively, compared to the wild type. These data together indicate that T. virens is able to effectively activate systemic disease protection in maize and that the functional Sm1 elicitor is required for this activity. PMID:17885089

The signal peptide-like segment of hpaXm is required for its association to the cell wall in transgenic tobacco plants

PubMed Central

Li, Le; Miao, Weiguo; Liu, Wenbo; Zhang, Shujian

2017-01-01

Harpins, encoded by hrp (hypersensitive response and pathogenicity) genes of Gram-negative plant pathogens, are elicitors of hypersensitive response (HR). HpaXm is a novel harpin-like protein described from cotton leaf blight bacteria, Xanthomonas citri subsp. malvacearum—a synonym of X. campestris pv. malvacearum (Smith 1901–1978). A putative signal peptide (1-MNSLNTQIGANSSFL-15) of hpaXm was predicted in the nitroxyl-terminal (N-terminal)by SignalP (SignalP 3.0 server). Here, we explored the function of the N-terminal leader peptide like segment of hpaXm using transgenic tobacco (Nicotiana tabacum cv. Xanthi nc.). Transgenic tobacco lines expressing the full-length hpaXm and the signal peptide-like segment-deleted mutant hpaXmΔLP were developed using transformation mediated by Agrobacterium tumefaciens. The target genes were confirmed integrated into the tobacco genomes and expressed normally. Using immune colloidal-gold detection technique, hpaXm protein was found to be transferred to the cytoplasm, the cell membrane, and organelles such as chloroplasts, mitochondria, and nucleus, as well as the cell wall. However, the deletion mutant hpaXmΔLP expressed in transgenic tobacco was found unable to cross the membrane to reach the cell wall. Additionally, soluble proteins extracted from plants transformed with hpaXm and hpaXmΔLP were bio-active. Defensive micro-HR induced by the transgene expression of hpaXm and hpaXmΔLP were observed on transgenic tobacco leaves. Disease resistance bioassays to tobacco mosaic virus (TMV) showed that tobacco plants transformed with hpaXm and with hpaXmΔLP exhibited enhanced resistance to TMV. In summary, the N-terminal signal peptide-like segment (1–45 bp) in hpaXm sequence is not necessary for transgene expression, bioactivity of hpaXm and resistance to TMV in transgenic tobacco, but is required for the protein to be translocated to the cell wall. PMID:28141855

Real-time electrochemical detection of extracellular nitric oxide in tobacco cells exposed to cryptogein, an elicitor of defence responses

PubMed Central

Besson-Bard, Angélique; Griveau, Sophie; Bedioui, Fethi; Wendehenne, David

2008-01-01

It was previously reported that cryptogein, an elicitor of defence responses, induces an intracellular production of nitric oxide (NO) in tobacco. Here, the possibility was explored that cryptogein might also trigger an increase of NO extracellular content through two distinct approaches, an indirect method using the NO probe 4,5-diaminofluorescein (DAF-2) and an electrochemical method involving a chemically modified microelectrode probing free NO in biological media. While the chemical nature of DAF-2-reactive compound(s) is still uncertain, the electrochemical modified microelectrodes provide real-time evidence that cryptogein induces an increase of extracellular NO. Direct measurement of free extracellular NO might offer important new insights into its role in plants challenged by biotic stresses. PMID:18653691

Accumulation of hydroxyproline-rich glycoprotein mRNAs in response to fungal elicitor and infection.

PubMed

Showalter, A M; Bell, J N; Cramer, C L; Bailey, J A; Varner, J E; Lamb, C J

1985-10-01

Hydroxyproline-rich glycoproteins (HRGPs) are important structural components of plant cell walls and also accumulate in response to infection as an apparent defense mechanism. Accumulation of HRGP mRNA in biologically stressed bean (Phaseolus vulgaris L.) cells was monitored by blot hybridization with (32)P-labeled tomato genomic HRGP sequences. Elicitor treatment of suspension-cultured cells caused a marked increase in hybridizable HRGP mRNA. The response was less rapid but more prolonged than that observed for mRNAs encoding enzymes of phytoalexin biosynthesis. HRGP mRNA also accumulated during race:cultivar-specific interactions between bean hypocotyls and the partially biotrophic fungus Colletotrichum lindemuthianum, the causal agent of anthracnose. In an incompatible interaction (host resistant) there was an early increase in HRGP mRNA correlated with expression of hypersensitive resistance; whereas, in a compatible interaction (host susceptible), marked accumulation of HRGP mRNA occurred as a delayed response at the onset of lesion formation. In both interactions, mRNA accumulation was observed in uninfected cells distant from the site of fungal inoculation, indicating intercellular transmission of an elicitation signal.

Effect of elicitors on the evolution of grape phenolic compounds during the ripening period.

PubMed

Gómez-Plaza, Encarna; Bautista-Ortín, Ana B; Ruiz-García, Yolanda; Fernández-Fernández, José I; Gil-Muñoz, Rocío

2017-02-01

The effect of the application of benzothiadiazole (BTH) and methyl jasmonate (MeJ) at veraison on the phenolic composition of grapes from three varieties (Monastrell, Syrah and Merlot) was studied during the ripening period, using HPLC techniques to measure flavonols, anthocyanins and tannins. The effects of the treatments differed in the three varieties, and the maximum concentration of phenolic compounds was not always reached at the end of the ripening period but some days before harvest. At the end of ripening both treated Syrah grapes only differed from control grapes in the flavonol concentration, whereas MeJ-treated Merlot grapes presented higher anthocyanin and skin tannin contents than the control and BTH-treated grapes. Only the anthocyanin content was significantly higher in treated Monastrell grapes at the moment of harvest. The results indicate that the moment of elicitor treatment should be more studied since differences between treated and control grapes were, in general greater several days before harvest in all three varieties. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Dissecting the Transcriptional Response to Elicitors in Vitis vinifera Cells

PubMed Central

Belchí-Navarro, Sarai; Bru, Roque; Martínez-Zapater, José M.; Lijavetzky, Diego; Pedreño, María A.

2014-01-01

The high effectiveness of cyclic oligosaccharides like cyclodextrins in the production of trans-resveratrol in Vitis vinifera cell cultures is enhanced in the presence of methyl jasmonate. In order to dissect the basis of the interactions among the elicitation responses triggered by these two compounds, a transcriptional analysis of grapevine cell cultures treated with cyclodextrins and methyl jasmonate separately or in combination was carried out. The results showed that the activation of genes encoding enzymes from phenylpropanoid and stilbene biosynthesis induced by cyclodextrins alone was partially enhanced in the presence of methyl jasmonate, which correlated with their effects on trans-resveratrol production. In addition, protein translation and cell cycle regulation were more highly repressed in cells treated with cyclodextrins than in those treated with methyl jasmonate, and this response was enhanced in the combined treatment. Ethylene signalling was activated by all treatments, while jasmonate signalling and salicylic acid conjugation were activated only in the presence of methyl jasmonate and cyclodextrins, respectively. Moreover, the combined treatment resulted in a crosstalk between the signalling cascades activated by cyclodextrins and methyl jasmonate, which, in turn, provoked the activation of additional regulatory pathways involving the up-regulation of MYB15, NAC and WRKY transcription factors, protein kinases and calcium signal transducers. All these results suggest that both elicitors cause an activation of the secondary metabolism in detriment of basic cell processes like the primary metabolism or cell division. Crosstalk between cyclodextrins and methyl jasmonate-induced signalling provokes an intensification of these responses resulting in a greater trans-resveratrol production. PMID:25314001

40 CFR 180.1204 - Harpin protein; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... food commodities to enhance plant growth, quality and yield, to improve overall plant health, and to... bacterial plant pathogens not known to be mammalian pathogens. (c) Elicits the hypersensitive response (HR...

40 CFR 180.1204 - Harpin protein; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2014 CFR

2014-07-01

... food commodities to enhance plant growth, quality and yield, to improve overall plant health, and to... bacterial plant pathogens not known to be mammalian pathogens. (c) Elicits the hypersensitive response (HR...

40 CFR 180.1204 - Harpin protein; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... food commodities to enhance plant growth, quality and yield, to improve overall plant health, and to... bacterial plant pathogens not known to be mammalian pathogens. (c) Elicits the hypersensitive response (HR...

40 CFR 180.1204 - Harpin protein; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2012 CFR

2012-07-01

... food commodities to enhance plant growth, quality and yield, to improve overall plant health, and to... bacterial plant pathogens not known to be mammalian pathogens. (c) Elicits the hypersensitive response (HR...

40 CFR 180.1204 - Harpin protein; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2013 CFR

2013-07-01

... food commodities to enhance plant growth, quality and yield, to improve overall plant health, and to... bacterial plant pathogens not known to be mammalian pathogens. (c) Elicits the hypersensitive response (HR...

Preharvest Application of Methyl Jasmonate as an Elicitor Improves the Yield and Phenolic Content of Artichoke.

PubMed

Martínez-Esplá, Alejandra; Valero, Daniel; Martínez-Romero, Domingo; Castillo, Salvador; Giménez, María José; García-Pastor, Maria Emma; Serrano, María; Zapata, Pedro Javier

2017-10-25

The effects of methyl jasmonate (MeJa) treatment as an elicitor of artichoke plants [Cynara cardunculus var. scolymus (L.) Fiori] on the yield and quality attributes of artichokes, especially those related to individual phenolic content and antioxidant activity, at two harvest dates and along storage were analyzed in this research. Plants treated gave a higher yield of artichokes in comparison to control plants, with 0.55 kg more per plant. MeJa treatment also increased artichoke quality and phenolic content in the edible fraction at harvest and during storage at 2 °C for 28 days as a result of the accumulation of hydroxycinnamic acids and luteolin derivatives. In addition, antioxidant activity was enhanced by MeJa treatment and correlated with the total phenolic content. Results suggest that MeJa foliar application could be a simple and practical tool to improve the yield and phytochemical content on artichokes, with elicitation being a cheap and environmentally friendly procedure to improve the health-beneficial effects of artichoke consumption.

Improved health-relevant functionality in dark germinated Mucuna pruriens sprouts by elicitation with peptide and phytochemical elicitors.

PubMed

Randhir, Reena; Kwon, Young-In; Shetty, Kalidas

2009-10-01

The health-relevant functionality of Mucuna pruriens was improved by priming the seeds with elicitors of the pentose phosphate pathway (PPP) such as fish protein hydrolysates (FPHs), lactoferrin (LF) and oregano extract (OE) followed by dark germination. FPH elicited the highest phenolic content of 19 mg/g FW on day 1, which was 38% higher than control sprouts. OE enhanced Parkinson's disease-relevant L-DOPA content by 33% on day 1 compared to control sprouts. Anti-diabetes-relevant alpha-amylase inhibition percent (AIP) and alpha-glucosidase inhibition percent (GIP) were high in the cotyledons and decreased following elicitation and sprouting. For potential anti-diabetic applications, low AIP and high GIP with moderate L-DOPA content on day 4 of dark germination could be optimal. Improved L-DOPA concentrations in a soluble phenolic and antioxidant-rich M. pruriens background on day 1 sprouts have potential for Parkinson's disease management.

The HERBIVORE ELICITOR-REGULATED1 Gene Enhances Abscisic Acid Levels and Defenses against Herbivores in Nicotiana attenuata Plants1[C][W][OPEN

PubMed Central

Dinh, Son Truong; Baldwin, Ian T.; Galis, Ivan

2013-01-01

Nicotiana attenuata plants can distinguish the damage caused by herbivore feeding from other types of damage by perceiving herbivore-associated elicitors, such as the fatty acid-amino acid conjugates (FACs) in oral secretions (OS) of Manduca sexta larvae, which are introduced into wounds during feeding. However, the transduction of FAC signals into downstream plant defense responses is still not well established. We identified a novel FAC-regulated protein in N. attenuata (NaHER1; for herbivore elicitor regulated) and show that it is an indispensable part of the OS signal transduction pathway. N. attenuata plants silenced in the expression of NaHER1 by RNA interference (irHER1) were unable to amplify their defenses beyond basal, wound-induced levels in response to OS elicitation. M. sexta larvae performed 2-fold better when reared on irHER1 plants, which released less volatile organic compounds (indirect defense) and had strongly reduced levels of several direct defense metabolites, including trypsin proteinase inhibitors, 17-hydroxygeranyllinallool diterpene glycosides, and caffeoylputrescine, after real and/or simulated herbivore attack. In parallel to impaired jasmonate signaling and metabolism, irHER1 plants were more drought sensitive and showed reduced levels of abscisic acid (ABA) in the leaves, suggesting that silencing of NaHER1 interfered with ABA metabolism. Because treatment of irHER1 plants with ABA results in both the accumulation of significantly more ABA catabolites and the complete restoration of normal wild-type levels of OS-induced defense metabolites, we conclude that NaHER1 acts as a natural suppressor of ABA catabolism after herbivore attack, which, in turn, activates the full defense profile and resistance against herbivores. PMID:23784463

Enhanced bacoside production in shoot cultures of Bacopa monnieri under the influence of abiotic elicitors.

PubMed

Sharma, Munish; Ahuja, Ashok; Gupta, Rajinder; Mallubhotla, Sharada

2015-01-01

The effect of different abiotic elicitors [jasmonic acid, copper sulphate (CuSO4) and salicyclic acid] at varying concentrations on the stimulation of biomass and bacoside production in in vitro Bacopa monnieri shoot culture was studied. A systematic study conducted over a period of 35 days indicated that the maximum bacoside production (6.74 mg g(-1) dry weight (DW)) was obtained after a lag of 7 days and thereafter, the content decreased gradually to again increase at 28 days (5.91 mg g(-1) DW). Therefore, elicitation experiments were carried out over a period of 3, 6 and 9 days. The shoot cultures treated with 45 mg L(-1) of CuSO4 exhibited the highest bacoside content of 8.73 mg g(-1) DW (∼1.42-fold higher) than in control cultures (6.14 mg g(-1) DW). This study indicates the effectiveness of abiotic elicitation on bacoside production in in vitro shoot cultures of this medicinally important herb known for its memory-enhancing properties.

Vacuolar and cytoskeletal dynamics during elicitor-induced programmed cell death in tobacco BY-2 cells.

PubMed

Higaki, Takumi; Kadota, Yasuhiro; Goh, Tatsuaki; Hayashi, Teruyuki; Kutsuna, Natsumaro; Sano, Toshio; Hasezawa, Seiichiro; Kuchitsu, Kazuyuki

2008-09-01

Responses of plant cells to environmental stresses often involve morphological changes, differentiation and redistribution of various organelles and cytoskeletal network. Tobacco BY-2 cells provide excellent model system for in vivo imaging of these intracellular events. Treatment of the cell cycle-synchronized BY-2 cells with a proteinaceous oomycete elicitor, cryptogein, induces highly synchronous programmed cell death (PCD) and provide a model system to characterize vacuolar and cytoskeletal dynamics during the PCD. Sequential observation revealed dynamic reorganization of the vacuole and actin microfilaments during the execution of the PCD. We further characterized the effects cryptogein on mitotic microtubule organization in cell cycle-synchronized cells. Cryptogein treatment at S phase inhibited formation of the preprophase band, a cortical microtubule band that predicts the cell division site. Cortical microtubules kept their random orientation till their disruption that gradually occurred during the execution of the PCD twelve hours after the cryptogein treatment. Possible molecular mechanisms and physiological roles of the dynamic behavior of the organelles and cytoskeletal network in the pathogenic signal-induced PCD are discussed.

Molecular Steps in the Immune Signaling Pathway Evoked by Plant Elicitor Peptides: Ca2+-Dependent Protein Kinases, Nitric Oxide, and Reactive Oxygen Species Are Downstream from the Early Ca2+ Signal1[OPEN

PubMed Central

Ma, Yi; Zhao, Yichen; Walker, Robin K.; Berkowitz, Gerald A.

2013-01-01

Endogenous plant elicitor peptides (Peps) can act to facilitate immune signaling and pathogen defense responses. Binding of these peptides to the Arabidopsis (Arabidopsis thaliana) plasma membrane-localized Pep receptors (PEPRs) leads to cytosolic Ca2+ elevation, an early event in a signaling cascade that activates immune responses. This immune response includes the amplification of signaling evoked by direct perception of pathogen-associated molecular patterns by plant cells under assault. Work included in this report further characterizes the Pep immune response and identifies new molecular steps in the signal transduction cascade. The PEPR coreceptor BRASSINOSTEROID-INSENSITIVE1 Associated Kinase1 contributes to generation of the Pep-activated Ca2+ signal and leads to increased defense gene expression and resistance to a virulent bacterial pathogen. Ca2+-dependent protein kinases (CPKs) decode the Ca2+ signal, also facilitating defense gene expression and enhanced resistance to the pathogen. Nitric oxide and reduced nicotinamide adenine dinucleotide phosphate oxidase-dependent reactive oxygen species generation (due to the function of Respiratory Burst Oxidase Homolog proteins D and F) are also involved downstream from the Ca2+ signal in the Pep immune defense signal transduction cascade, as is the case with BRASSINOSTEROID-INSENSITIVE1 Associated Kinase1 and CPK5, CPK6, and CPK11. These steps of the pathogen defense response are required for maximal Pep immune activation that limits growth of a virulent bacterial pathogen in the plant. We find a synergism between function of the PEPR and Flagellin Sensing2 receptors in terms of both nitric oxide and reactive oxygen species generation. Presented results are also consistent with the involvement of the secondary messenger cyclic GMP and a cyclic GMP-activated Ca2+-conducting channel in the Pep immune signaling pathway. PMID:24019427

Elicitor-induced transcription factors for metabolic reprogramming of secondary metabolism in Medicago truncatula

PubMed Central

Naoumkina, Marina A; He, XianZhi; Dixon, Richard A

2008-01-01

Background Exposure of Medicago truncatula cell suspension cultures to pathogen or wound signals leads to accumulation of various classes of flavonoid and/or triterpene defense molecules, orchestrated via a complex signalling network in which transcription factors (TFs) are essential components. Results In this study, we analyzed TFs responding to yeast elicitor (YE) or methyl jasmonate (MJ). From 502 differentially expressed TFs, WRKY and AP2/EREBP gene families were over-represented among YE-induced genes whereas Basic Helix-Loop-Helix (bHLH) family members were more over-represented among the MJ-induced genes. Jasmonate ZIM-domain (JAZ) transcriptional regulators were highly induced by MJ treatment. To investigate potential involvement of WRKY TFs in signalling, we expressed four Medicago WRKY genes in tobacco. Levels of soluble and wall bound phenolic compounds and lignin were increased in all cases. WRKY W109669 also induced tobacco endo-1,3-β-glucanase (NtPR2) and enhanced the systemic defense response to tobacco mosaic virus in transgenic tobacco plants. Conclusion These results confirm that Medicago WRKY TFs have broad roles in orchestrating metabolic responses to biotic stress, and that they also represent potentially valuable reagents for engineering metabolic changes that impact pathogen resistance. PMID:19102779

Effects on grape amino acid concentration through foliar application of three different elicitors.

PubMed

Gutiérrez-Gamboa, G; Portu, J; Santamaría, P; López, R; Garde-Cerdán, T

2017-09-01

Elicitors play an important role in the defense against pathogens as an alternative to chemical pesticides by increasing secondary metabolites. Their effect on grape amino acid has been little investigated. Thus, the aim of this research was to study the influence of methyl jasmonate (MeJ), chitosan (CHT), and a yeast extract (YE) on grape amino acid composition, through foliar applications to grapevines. The must amino acid concentration was analyzed by HPLC. The results showed that CHT and YE treatments decreased the must concentration of several amino acids, affecting total amino acid content (from 2364 to 1961, and 1818mg/L, respectively). However, MeJ treatment had a slight effect on grape amino acid content, increasing the concentration of Met (from 8.95 to 12.13mg/L) and Phe (from 7.96 to 9.29mg/L). It seems to be that, the resistance induction through CHT and YE treatments results in physiological costs to grapevines associated with a decrease on grape amino acid concentration. Consequently, MeJ applications, as a viticultural practice, could be a better tool than CHT and YE treatments, because did not affect grape amino acid concentration. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transgenic expression of a functional fragment of harpin protein Hpa1 in wheat induces the phloem-based defence against English grain aphid

PubMed Central

Fu, Maoqiang; Xu, Manyu; Zhang, Chunling

2014-01-01

The harpin protein Hpa1 has multiple beneficial effects in plants, promoting plant growth and development, increasing crop yield, and inducing resistance to pathogens and insect pests. For these effects, the 10–40 residue fragment (Hpa110–42) isolated from the Hpa1 sequence is 1.3- to 7.5-fold more effective than the full-length protein. Here it is reported that the expression of Hpa110–42 under the direction of an insect-induced promoter induces the phloem-based defence to English grain aphid, a dominant species of wheat aphids. The expression of Hpa110–42 was found to compromise the colonization preference of aphids on the plant and further inhibit aphid reproduction in leaf colonies. In Hpa110–42-expressing wheat lines, moreover, aphid feeding from the phloem was repressed in correlation with the phloem-based defence. This defensive mechanism was shown as enhanced expression of wheat genes encoding phloem lectin proteins (PP2-A1 and PP2-A2) and β-1,3-glucan synthase-like enzymes (GSL2, GSL10, and GSL12). Both PP2-A and β-1,3-glucan formed high molecular mass polymers to block phloem sieve plate pores and therefore impede aphid feeding from the phloem. However, the phloem-based defence was impaired by treating plants with ethylene signalling inhibitors, suggesting the requirement for the ethylene signalling pathway. In addition, if Hpa110–42-expressing plants were subjected to attack by a small number of aphids, they newly acquired agriculturally beneficial characters, such as enhanced vegetative growth and increased tiller numbers and grain output values. These results suggest that the defensive and developmental roles of Hpa110–42 can be integrated into the germplasm of this agriculturally significant crop. PMID:24676030

Early events in plant hypersensitive response leaves revealed by IR thermography

NASA Astrophysics Data System (ADS)

Boccara, Martine; Boue, Christine; De Paepe, Rosine; Boccara, Albert C.

2001-10-01

Infrared thermography is used to reveal the establishment of Erwinia amylovora harpin-induced hypersensitive response (HR) in Nicotiana sylvestris leaves. We observed a decrease in temperature (1-2 degree(s)C) in the harpin infiltrated zone, correlated with an increase in stomatal opening, strongly suggesting that the temperature decrease is due to higher transpiration rate. IRT experiments were conducted in a laboratory environment and could be widely applied for genotype screening and monitoring drug effects.

Transgenic expression of a functional fragment of harpin protein Hpa1 in wheat induces the phloem-based defence against English grain aphid.

PubMed

Fu, Maoqiang; Xu, Manyu; Zhou, Ting; Wang, Defu; Tian, Shan; Han, Liping; Dong, Hansong; Zhang, Chunling

2014-04-01

The harpin protein Hpa1 has multiple beneficial effects in plants, promoting plant growth and development, increasing crop yield, and inducing resistance to pathogens and insect pests. For these effects, the 10-40 residue fragment (Hpa1₁₀₋₄₂) isolated from the Hpa1 sequence is 1.3- to 7.5-fold more effective than the full-length protein. Here it is reported that the expression of Hpa1₁₀₋₄₂ under the direction of an insect-induced promoter induces the phloem-based defence to English grain aphid, a dominant species of wheat aphids. The expression of Hpa1₁₀₋₄₂ was found to compromise the colonization preference of aphids on the plant and further inhibit aphid reproduction in leaf colonies. In Hpa1₁₀₋₄₂-expressing wheat lines, moreover, aphid feeding from the phloem was repressed in correlation with the phloem-based defence. This defensive mechanism was shown as enhanced expression of wheat genes encoding phloem lectin proteins (PP2-A1 and PP2-A2) and β-1,3-glucan synthase-like enzymes (GSL2, GSL10, and GSL12). Both PP2-A and β-1,3-glucan formed high molecular mass polymers to block phloem sieve plate pores and therefore impede aphid feeding from the phloem. However, the phloem-based defence was impaired by treating plants with ethylene signalling inhibitors, suggesting the requirement for the ethylene signalling pathway. In addition, if Hpa1₁₀₋₄₂-expressing plants were subjected to attack by a small number of aphids, they newly acquired agriculturally beneficial characters, such as enhanced vegetative growth and increased tiller numbers and grain output values. These results suggest that the defensive and developmental roles of Hpa1₁₀₋₄₂ can be integrated into the germplasm of this agriculturally significant crop.

Plant elicitor peptides are conserved signals regulating direct and indirect antiherbivore defense

PubMed Central

Huffaker, Alisa; Pearce, Gregory; Veyrat, Nathalie; Erb, Matthias; Turlings, Ted C. J.; Sartor, Ryan; Shen, Zhouxin; Briggs, Steven P.; Vaughan, Martha M.; Alborn, Hans T.; Teal, Peter E. A.; Schmelz, Eric A.

2013-01-01

Insect-induced defenses occur in nearly all plants and are regulated by conserved signaling pathways. As the first described plant peptide signal, systemin regulates antiherbivore defenses in the Solanaceae, but in other plant families, peptides with analogous activity have remained elusive. In the current study, we demonstrate that a member of the maize (Zea mays) plant elicitor peptide (Pep) family, ZmPep3, regulates responses against herbivores. Consistent with being a signal, expression of the ZmPROPEP3 precursor gene is rapidly induced by Spodoptera exigua oral secretions. At concentrations starting at 5 pmol per leaf, ZmPep3 stimulates production of jasmonic acid, ethylene, and increased expression of genes encoding proteins associated with herbivory defense. These include proteinase inhibitors and biosynthetic enzymes for production of volatile terpenes and benzoxazinoids. In accordance with gene expression data, plants treated with ZmPep3 emit volatiles similar to those from plants subjected to herbivory. ZmPep3-treated plants also exhibit induced accumulation of the benzoxazinoid phytoalexin 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside. Direct and indirect defenses induced by ZmPep3 contribute to resistance against S. exigua through significant reduction of larval growth and attraction of Cotesia marginiventris parasitoids. ZmPep3 activity is specific to Poaceous species; however, peptides derived from PROPEP orthologs identified in Solanaceous and Fabaceous plants also induce herbivory-associated volatiles in their respective species. These studies demonstrate that Peps are conserved signals across diverse plant families regulating antiherbivore defenses and are likely to be the missing functional homologs of systemin outside of the Solanaceae. PMID:23509266

Abscisic acid negatively regulates elicitor-induced synthesis of capsidiol in wild tobacco.

PubMed

Mialoundama, Alexis Samba; Heintz, Dimitri; Debayle, Delphine; Rahier, Alain; Camara, Bilal; Bouvier, Florence

2009-07-01

In the Solanaceae, biotic and abiotic elicitors induce de novo synthesis of sesquiterpenoid stress metabolites known as phytoalexins. Because plant hormones play critical roles in the induction of defense-responsive genes, we have explored the effect of abscisic acid (ABA) on the synthesis of capsidiol, the major wild tobacco (Nicotiana plumbaginifolia) sesquiterpenoid phytoalexin, using wild-type plants versus nonallelic mutants Npaba2 and Npaba1 that are deficient in ABA synthesis. Npaba2 and Npaba1 mutants exhibited a 2-fold higher synthesis of capsidiol than wild-type plants when elicited with either cellulase or arachidonic acid or when infected by Botrytis cinerea. The same trend was observed for the expression of the capsidiol biosynthetic genes 5-epi-aristolochene synthase and 5-epi-aristolochene hydroxylase. Treatment of wild-type plants with fluridone, an inhibitor of the upstream ABA pathway, recapitulated the behavior of Npaba2 and Npaba1 mutants, while the application of exogenous ABA reversed the enhanced synthesis of capsidiol in Npaba2 and Npaba1 mutants. Concomitant with the production of capsidiol, we observed the induction of ABA 8'-hydroxylase in elicited plants. In wild-type plants, the induction of ABA 8'-hydroxylase coincided with a decrease in ABA content and with the accumulation of ABA catabolic products such as phaseic acid and dihydrophaseic acid, suggesting a negative regulation exerted by ABA on capsidiol synthesis. Collectively, our data indicate that ABA is not required per se for the induction of capsidiol synthesis but is essentially implicated in a stress-response checkpoint to fine-tune the amplification of capsidiol synthesis in challenged plants.

The coat protein of Alternanthera mosaic virus is the elicitor of a temperature-sensitive systemic necrosis in Nicotiana benthamiana, and interacts with a host boron transporter protein

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

Lim, Hyoun-Sub, E-mail: hyounlim@cnu.ac.kr; Nam, Jiryun, E-mail: jilyoon@naver.com; Seo, Eun-Young, E-mail: sey22@cnu.ac.kr

Different isolates of Alternanthera mosaic virus (AltMV; Potexvirus), including four infectious clones derived from AltMV-SP, induce distinct systemic symptoms in Nicotiana benthamiana. Virus accumulation was enhanced at 15 °C compared to 25 °C; severe clone AltMV 3-7 induced systemic necrosis (SN) and plant death at 15 °C. No interaction with potexvirus resistance gene Rx was detected, although SN was ablated by silencing of SGT1, as for other cases of potexvirus-induced necrosis. Substitution of AltMV 3-7 coat protein (CP{sub SP}) with that from AltMV-Po (CP{sub Po}) eliminated SN at 15 °C, and ameliorated symptoms in Alternanthera dentata and soybean. Substitution ofmore » only two residues from CP{sub Po} [either MN(13,14)ID or LA(76,77)IS] efficiently ablated SN in N. benthamiana. CP{sub SP} but not CP{sub Po} interacted with Arabidopsis boron transporter protein AtBOR1 by yeast two-hybrid assay; N. benthamiana homolog NbBOR1 interacted more strongly with CP{sub SP} than CP{sub Po} in bimolecular fluorescence complementation, and may affect recognition of CP as an elicitor of SN. - Highlights: • Alternanthera mosaic virus CP is an elicitor of systemic necrosis in N. benthamiana. • Virus-induced systemic necrosis is enhanced at 15 °C compared to 25 °C. • Induction of systemic necrosis is dependent on as few as two CP amino acid residues. • These residues are at subunit interfaces within the same turn of the virion helix. • Inducer/non-inducer CPs interact differentially with a boron transporter protein.« less

The Phytoalexin Resveratrol Regulates the Initiation of Hypersensitive Cell Death in Vitis Cell

PubMed Central

Chang, Xiaoli; Heene, Ernst; Qiao, Fei; Nick, Peter

2011-01-01

Resveratrol is a major phytoalexin produced by plants in response to various stresses and promotes disease resistance. The resistance of North American grapevine Vitis rupestris is correlated with a hypersensitive reaction (HR), while susceptible European Vitis vinifera cv. ‘Pinot Noir’ does not exhibit HR, but expresses basal defence. We have shown previously that in cell lines derived from the two Vitis species, the bacterial effector Harpin induced a rapid and sensitive accumulation of stilbene synthase (StSy) transcripts, followed by massive cell death in V. rupestris. In the present work, we analysed the function of the phytoalexin resveratrol, the product of StSy. We found that cv. ‘Pinot Noir’ accumulated low resveratrol and its glycoside trans-piceid, whereas V. rupestris produced massive trans-resveratrol and the toxic oxidative δ-viniferin, indicating that the preferred metabolitism of resveratrol plays role in Vitis resistance. Cellular responses to resveratrol included rapid alkalinisation, accumulation of pathogenesis-related protein 5 (PR5) transcripts, oxidative burst, actin bundling, and cell death. Microtubule disruption and induction of StSy were triggered by Harpin, but not by resveratrol. Whereas most responses proceeded with different amplitude for the two cell lines, the accumulation of resveratrol, and the competence for resveratrol-induced oxidative burst differed in quality. The data lead to a model, where resveratrol, in addition to its classical role as antimicrobial phytoalexin, represents an important regulator for initiation of HR-related cell death. PMID:22053190

Jasmonate-Dependent Induction of Indole Glucosinolates in Arabidopsis by Culture Filtrates of the Nonspecific Pathogen Erwinia carotovora1

PubMed Central

Brader, Günter; Tas, Éva; Palva, E. Tapio

2001-01-01

Elicitors from the plant pathogen Erwinia carotovora trigger coordinate induction of the tryptophan (Trp) biosynthesis pathway and Trp oxidizing genes in Arabidopsis. To elucidate the biological role of such pathogen-induced activation we characterized the production of secondary defense metabolites such as camalexin and indole glucosinolates derived from precursors of this pathway. Elicitor induction was followed by a specific increase in 3-indolylmethylglucosinolate (IGS) content, but only a barely detectable accumulation of the indole-derived phytoalexin camalexin. The response is mediated by jasmonic acid as shown by lack of IGS induction in the jasmonate-insensitive mutant coi1-1. In accordance with this, methyl jasmonate was able to trigger IGS accumulation in Arabidopsis. In contrast, ethylene and salicylic acid seem to play a minor role in the response. They did not trigger alterations in IGS levels, and methyl jasmonate- or elicitor-induced IGS accumulation in NahG and ethylene-insensitive ein2-1 mutant plants was similar as in the wild type. The breakdown products of IGS and other glucosinolates were able to inhibit growth of E. carotovora. The results suggest that IGS is of importance in the defense against bacterial pathogens. PMID:11402212

Herbivore- and Elicitor- Induced Resistance in Groundnut to Asian armyworm, Spodoptera litura (Fab.) (Lepidoptera: Noctuidae)

PubMed Central

War, Abdul Rashid; Paulraj, Michael Gabriel; War, Mohd Yousf; Ignacimuthu, Savarimuthu

2011-01-01

Induced defense was studied in three groundnut genotypes ICGV 86699 (resistant), NCAc 343 (resistant) and TMV 2 (susceptible) in response to Spodoptera litura infestation and jasmonic acid (JA) application. The activity of the oxidative enzymes [peroxidase (POD) and polyphenol oxidase (PPO)] and the amounts other host plant defense components [total phenols, hydrogen peroxide (H2O2), malondialdehyde (MDA), and protein content] were recorded at 24, 48, 72 and 96 h in JA pretreated (one day before) plants and infested with S. litura, and JA application and simultaneous infestation with S. litura to understand the defense response of groundnut genotypes against S. litura damage. Data on plant damage, larval survival and larval weights were also recorded. There was a rapid increase in the activities of POD and PPO and in the quantities of total phenols, H2O2, MDA and protein content in the JA pretreated + S. litura infested plants. All the three genotypes showed quick response to JA application and S. litura infestation by increasing the defensive compounds. Among all the genotypes, higher induction was recorded in ICGV 86699 in most of the parameters. Reduced plant damage, low larval survival and larval weights were observed in JA pretreated plants. It suggests that pretreatment with elicitors, such as JA could provide more opportunity for plant defense against herbivores. PMID:22042128

The cytoskeleton is disrupted by the bacterial effector HrpZ, but not by the bacterial PAMP flg22, in tobacco BY-2 cells.

PubMed

Guan, Xin; Buchholz, Günther; Nick, Peter

2013-04-01

Plant innate immunity is composed of two layers. Basal immunity is triggered by pathogen-associated molecular patterns (PAMPs) such as the flagellin-peptide flg22 and is termed PAMP-triggered immunity (PTI). In addition, effector-triggered immunity (ETI) linked with programmed cell death and cytoskeletal reorganization can be induced by pathogen-derived factors, such as the Harpin proteins originating from phytopathogenic bacteria. To get insight into the link between cytoskeleton and PTI or ETI, this study followed the responses of actin filaments and microtubules to flg22 and HrpZ in vivo by spinning-disc confocal microscopy in GFP-tagged marker lines of tobacco BY-2. At a concentration that clearly impairs mitosis, flg22 can induce only subtle cytoskeletal responses. In contrast, HrpZ causes a rapid and massive bundling of actin microfilaments (completed in ~20 min, i.e. almost simultaneously with extracellular alkalinization), which is followed by progressive disintegration of actin cables and cytoplasmic microtubules, a loss of cytoplasmic structure, and vacuolar disintegration. Cytoskeletal disruption is proposed as an early event that discriminates HrpZ-triggered ETI-like defence from flg22-triggered PTI.

The cytoskeleton is disrupted by the bacterial effector HrpZ, but not by the bacterial PAMP flg22, in tobacco BY-2 cells

PubMed Central

Guan, Xin; Buchholz, Günther; Nick, Peter

2013-01-01

Plant innate immunity is composed of two layers. Basal immunity is triggered by pathogen-associated molecular patterns (PAMPs) such as the flagellin-peptide flg22 and is termed PAMP-triggered immunity (PTI). In addition, effector-triggered immunity (ETI) linked with programmed cell death and cytoskeletal reorganization can be induced by pathogen-derived factors, such as the Harpin proteins originating from phytopathogenic bacteria. To get insight into the link between cytoskeleton and PTI or ETI, this study followed the responses of actin filaments and microtubules to flg22 and HrpZ in vivo by spinning-disc confocal microscopy in GFP-tagged marker lines of tobacco BY-2. At a concentration that clearly impairs mitosis, flg22 can induce only subtle cytoskeletal responses. In contrast, HrpZ causes a rapid and massive bundling of actin microfilaments (completed in ~20min, i.e. almost simultaneously with extracellular alkalinization), which is followed by progressive disintegration of actin cables and cytoplasmic microtubules, a loss of cytoplasmic structure, and vacuolar disintegration. Cytoskeletal disruption is proposed as an early event that discriminates HrpZ-triggered ETI-like defence from flg22-triggered PTI. PMID:23408828

Impact of biochar application to soil on the root-associated bacterial community structure of fully developed greenhouse pepper plants.

PubMed

Kolton, Max; Meller Harel, Yael; Pasternak, Zohar; Graber, Ellen R; Elad, Yigal; Cytryn, Eddie

2011-07-01

Adding biochar to soil has environmental and agricultural potential due to its long-term carbon sequestration capacity and its ability to improve crop productivity. Recent studies have demonstrated that soil-applied biochar promotes the systemic resistance of plants to several prominent foliar pathogens. One potential mechanism for this phenomenon is root-associated microbial elicitors whose presence is somehow augmented in the biochar-amended soils. The objective of this study was to assess the effect of biochar amendment on the root-associated bacterial community composition of mature sweet pepper (Capsicum annuum L.) plants. Molecular fingerprinting (denaturing gradient gel electrophoresis and terminal restriction fragment length polymorphism) of 16S rRNA gene fragments showed a clear differentiation between the root-associated bacterial community structures of biochar-amended and control plants. The pyrosequencing of 16S rRNA amplicons from the rhizoplane of both treatments generated a total of 20,142 sequences, 92 to 95% of which were affiliated with the Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes phyla. The relative abundance of members of the Bacteroidetes phylum increased from 12 to 30% as a result of biochar amendment, while that of the Proteobacteria decreased from 71 to 47%. The Bacteroidetes-affiliated Flavobacterium was the strongest biochar-induced genus. The relative abundance of this group increased from 4.2% of total root-associated operational taxonomic units (OTUs) in control samples to 19.6% in biochar-amended samples. Additional biochar-induced genera included chitin and cellulose degraders (Chitinophaga and Cellvibrio, respectively) and aromatic compound degraders (Hydrogenophaga and Dechloromonas). We hypothesize that these biochar-augmented genera may be at least partially responsible for the beneficial effect of biochar amendment on plant growth and viability.

Defense Priming and Jasmonates: A Role for Free Fatty Acids in Insect Elicitor-Induced Long Distance Signaling

PubMed Central

Li, Ting; Cofer, Tristan; Engelberth, Marie; Engelberth, Jurgen

2016-01-01

Green leaf volatiles (GLV) prime plants against insect herbivore attack resulting in stronger and faster signaling by jasmonic acid (JA). In maize this response is specifically linked to insect elicitor (IE)-induced signaling processes, which cause JA accumulation not only around the damage site, but also in distant tissues, presumably through the activation of electrical signals. Here, we present additional data further characterizing these distal signaling events in maize. Also, we describe how exposure to GLV increases free fatty acid (fFA) levels in maize seedlings, but also in other plants, and how increased fFA levels affect IE-induced JA accumulation. Increased fFA, in particular α-linolenic acid (LnA), caused a significant increase in JA accumulation after IE treatment, while JA induced by mechanical wounding (MW) alone was not affected. We also identified treatments that significantly decreased certain fFA level including simulated wind and rain. In such treated plants, IE-induced JA accumulation was significantly reduced when compared to un-moved control plants, while MW-induced JA accumulation was not significantly affected. Since only IE-induced JA accumulation was altered by changes in the fFA composition, we conclude that changing levels of fFA affect primarily IE-induced signaling processes rather than serving as a substrate for JA. PMID:27135225

The prospect of applying chemical elicitors and plant strengtheners to enhance the biological control of crop pests

PubMed Central

Sobhy, Islam S.; Erb, Matthias; Lou, Yonggen; Turlings, Ted C. J.

2014-01-01

An imminent food crisis reinforces the need for novel strategies to increase crop yields worldwide. Effective control of pest insects should be part of such strategies, preferentially with reduced negative impact on the environment and optimal protection and utilization of existing biodiversity. Enhancing the presence and efficacy of native biological control agents could be one such strategy. Plant strengthener is a generic term for several commercially available compounds or mixtures of compounds that can be applied to cultivated plants in order to ‘boost their vigour, resilience and performance’. Studies into the consequences of boosting plant resistance against pests and diseases on plant volatiles have found a surprising and dramatic increase in the plants' attractiveness to parasitic wasps. Here, we summarize the results from these studies and present new results from assays that illustrate the great potential of two commercially available resistance elicitors. We argue that plant strengtheners may currently be the best option to enhance the attractiveness of cultivated plants to biological control agents. Other options, such as the genetic manipulation of the release of specific volatiles may offer future solutions, but in most systems, we still miss fundamental knowledge on which key attractants should be targeted for this approach. PMID:24535390

The plant host pathogen interface: cell wall and membrane dynamics of pathogen-induced responses.

PubMed

Day, Brad; Graham, Terry

2007-10-01

Perception of pathogens by their hosts is the outcome of a highly coordinated and sophisticated surveillance network, tightly regulated by both host and pathogen elicitors, effectors, and signaling processes. In this article, we focus on two relatively well-studied host-pathogens systems, one involving a bacterial-plant interaction (Pseudomonas syringae-Arabidopsis) and the other involving an oomycete-plant interaction (Phytophthora sojae-soybean). We discuss the status of current research related to events occurring at the host-pathogen interface in these two systems, and how these events influence the organization and activation of resistance responses in the respective hosts. This recent research has revealed that in addition to the previously identified resistance machinery (R-proteins, molecular chaperones, etc.), the dynamics of the cell wall, membrane trafficking, and the actin cytoskeleton are intimately associated with the activation of resistance in plants. Specifically, in Arabidopsis, a possible connection between the actin machinery and R-protein- mediated induction of disease resistance is described. In the case of the P. sojae-soybean interaction, we describe the fact that a classical basal resistance elicitor, the cell wall glucan elicitor from the pathogen, can directly activate host hypersensitive cell death, which is apparently modulated in a race-specific manner by the presence of R genes in the host.

Abscisic Acid Negatively Regulates Elicitor-Induced Synthesis of Capsidiol in Wild Tobacco1[W

PubMed Central

Mialoundama, Alexis Samba; Heintz, Dimitri; Debayle, Delphine; Rahier, Alain; Camara, Bilal; Bouvier, Florence

2009-01-01

In the Solanaceae, biotic and abiotic elicitors induce de novo synthesis of sesquiterpenoid stress metabolites known as phytoalexins. Because plant hormones play critical roles in the induction of defense-responsive genes, we have explored the effect of abscisic acid (ABA) on the synthesis of capsidiol, the major wild tobacco (Nicotiana plumbaginifolia) sesquiterpenoid phytoalexin, using wild-type plants versus nonallelic mutants Npaba2 and Npaba1 that are deficient in ABA synthesis. Npaba2 and Npaba1 mutants exhibited a 2-fold higher synthesis of capsidiol than wild-type plants when elicited with either cellulase or arachidonic acid or when infected by Botrytis cinerea. The same trend was observed for the expression of the capsidiol biosynthetic genes 5-epi-aristolochene synthase and 5-epi-aristolochene hydroxylase. Treatment of wild-type plants with fluridone, an inhibitor of the upstream ABA pathway, recapitulated the behavior of Npaba2 and Npaba1 mutants, while the application of exogenous ABA reversed the enhanced synthesis of capsidiol in Npaba2 and Npaba1 mutants. Concomitant with the production of capsidiol, we observed the induction of ABA 8′-hydroxylase in elicited plants. In wild-type plants, the induction of ABA 8′-hydroxylase coincided with a decrease in ABA content and with the accumulation of ABA catabolic products such as phaseic acid and dihydrophaseic acid, suggesting a negative regulation exerted by ABA on capsidiol synthesis. Collectively, our data indicate that ABA is not required per se for the induction of capsidiol synthesis but is essentially implicated in a stress-response checkpoint to fine-tune the amplification of capsidiol synthesis in challenged plants. PMID:19420326

A novel exopolysaccharide elicitor from endophytic fungus Gilmaniella sp. AL12 on volatile oils accumulation in Atractylodes lancea

NASA Astrophysics Data System (ADS)

Chen, Fei; Ren, Cheng-Gang; Zhou, Tong; Wei, Yu-Jia; Dai, Chuan-Chao

2016-10-01

Endophytes and plants can establish specific long-term symbiosis through the accumulation of secondary metabolites. Previous studies have shown that the endophytic fungus Gilmaniella sp. AL12 can stimulate Atractylodes lancea to produce volatile oils. The purpose of this report is to investigate key factors involved in the stimulation of A. lancea by AL12 and reveal the mechanism. We identified the active component from AL12 as an extracellular mannan with a polymerization degree of 26-42. Differential membrane proteomics of A. lancea was performed by 2D electrophoresis. The results showed that there were significant differences in the expression of 83 proteins. Based on these results, we conclude that AL12 secreted mannan contributes to the antagonistic balance seen in interactions between AL12 and A. lancea. One portion of the mannan was degraded to mannose for hexokinase activation, promoting photosynthesis and energy metabolism, with a potential metabolic fluxes flowing towards terpenoid biosynthesis. The other portion of the mannan directly enhanced autoimmunity of A. lancea through G protein-mediated signal transduction and the mannan-binding lectin pathway. Volatile oil accumulation was ultimately promoted in subsequent defense reactions. This study provides a new perspective on the regulation of secondary metabolites by endophytic fungal elicitors in medicinal plants.

A novel exopolysaccharide elicitor from endophytic fungus Gilmaniella sp. AL12 on volatile oils accumulation in Atractylodes lancea.

PubMed

Chen, Fei; Ren, Cheng-Gang; Zhou, Tong; Wei, Yu-Jia; Dai, Chuan-Chao

2016-10-05

Endophytes and plants can establish specific long-term symbiosis through the accumulation of secondary metabolites. Previous studies have shown that the endophytic fungus Gilmaniella sp. AL12 can stimulate Atractylodes lancea to produce volatile oils. The purpose of this report is to investigate key factors involved in the stimulation of A. lancea by AL12 and reveal the mechanism. We identified the active component from AL12 as an extracellular mannan with a polymerization degree of 26-42. Differential membrane proteomics of A. lancea was performed by 2D electrophoresis. The results showed that there were significant differences in the expression of 83 proteins. Based on these results, we conclude that AL12 secreted mannan contributes to the antagonistic balance seen in interactions between AL12 and A. lancea. One portion of the mannan was degraded to mannose for hexokinase activation, promoting photosynthesis and energy metabolism, with a potential metabolic fluxes flowing towards terpenoid biosynthesis. The other portion of the mannan directly enhanced autoimmunity of A. lancea through G protein-mediated signal transduction and the mannan-binding lectin pathway. Volatile oil accumulation was ultimately promoted in subsequent defense reactions. This study provides a new perspective on the regulation of secondary metabolites by endophytic fungal elicitors in medicinal plants.

Bacterial prostatitis.

PubMed

Gill, Bradley C; Shoskes, Daniel A

2016-02-01

The review provides the infectious disease community with a urologic perspective on bacterial prostatitis. Specifically, the article briefly reviews the categorization of prostatitis by type and provides a distillation of new findings published on bacterial prostatitis over the past year. It also highlights key points from the established literature. Cross-sectional prostate imaging is becoming more common and may lead to more incidental diagnoses of acute bacterial prostatitis. As drug resistance remains problematic in this condition, the reemergence of older antibiotics such as fosfomycin, has proven beneficial. With regard to chronic bacterial prostatitis, no clear clinical risk factors emerged in a large epidemiological study. However, bacterial biofilm formation has been associated with more severe cases. Surgery has a limited role in bacterial prostatitis and should be reserved for draining of a prostatic abscess or the removal of infected prostatic stones. Prostatitis remains a common and bothersome clinical condition. Antibiotic therapy remains the basis of treatment for both acute and chronic bacterial prostatitis. Further research into improving prostatitis treatment is indicated.

Bacterial Sialidase

NASA Technical Reports Server (NTRS)

2004-01-01

Data shows that elevated sialidase in bacterial vaginosis patients correlates to premature births in women. Bacterial sialidase also plays a significant role in the unusual colonization of Pseudomonas aeruginosa in cystic fibrosis patients. Crystals of Salmonella sialidase have been reproduced and are used for studying the inhibitor-enzyme complexes. These inhibitors may also be used to inhibit a trans-sialidase of Trypanosome cruzi, a very similar enzyme to bacterial sialidase, therefore preventing T. cruzi infection, the causitive agent of Chagas' disease. The Center for Macromolecular Crystallography suggests that inhibitors of bacterial sialidases can be used as prophylactic drugs to prevent bacterial infections in these critical cases.

Host-pathogen interactions in plants. Plants, when exposed to oligosaccharides of fungal origin, defend themselves by accumulating antibiotics

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

Albersheim, P.; Valent, B.S.

1978-01-01

The ability to synthesize phytoalexins is a mechanism by which plants are able to stop the growth of microorganisms which have not become pathogenic on the phytoalexin-producing plant. Although not sufficient for its complete resistence to pathogens, an ability to synthesize phytoalexins is likely to be one essential criterion for a plant to be resistant to pathogens. Plants recognize the presence of many nonpathogenic fungi by recognizing a structural component of the mycelial walls of the fungi. Other microorganisms do not have structural glucans in their walls. There is, likely, some other components of bacteria, for instance, which act asmore » elicitors in plants since it is known that they do elicit phytoalexin production in plants. The authors are attempting to identify a bacterial elicitor. It is known that the soybean pathogen Phytophthora magasperma is an oligosaccharide composed only of glucose. This is of general biological interest since it shows that oligosaccharides can act as regulatory molecules.« less

[Bacterial meningitis].

PubMed

Brouwer, M C; van de Beek, D

2012-05-01

Bacterial meningitis is a severe disease which affects 35.000 Europeans each year and has a mortality rate of about 20%. During the past 25 years the epidemiology of bacterial meningitis has changed significantly due to the implementation of vaccination against Haemophilus influenzae, Neisseria meningtidis group C and Streptococcus pneumoniae. Due to these vaccines, meningitis is now predominantly a disease occurring in adults, caused especially by Streptococcus pneumoniae, while it was formerly a child disease which was largely caused by Haemophilus influenzae. Bacterial meningitis is often difficult to recognize since the classical presentation with neck stiffness, reduced awareness and fever occurs in less than half of the patients. The only way to diagnose or exclude bacterial meningitis is by performing low-threshold cerebrospinal fluid examination with a suspicion of bacterial meningitis. The treatment consists of the prescription of antibiotics and dexamethasone.

A stilbene synthase allele from a Chinese wild grapevine confers resistance to powdery mildew by recruiting salicylic acid signalling for efficient defence.

PubMed

Jiao, Yuntong; Xu, Weirong; Duan, Dong; Wang, Yuejin; Nick, Peter

2016-10-01

Stilbenes are central phytoalexins in Vitis, and induction of the key enzyme stilbene synthase (STS) is pivotal for disease resistance. Here, we address the potential for breeding resistance using an STS allele isolated from Chinese wild grapevine Vitis pseudoreticulata (VpSTS) by comparison with its homologue from Vitis vinifera cv. 'Carigane' (VvSTS). Although the coding regions of both alleles are very similar (>99% identity on the amino acid level), the promoter regions are significantly different. By expression in Arabidopsis as a heterologous system, we show that the allele from the wild Chinese grapevine can confer accumulation of stilbenes and resistance against the powdery mildew Golovinomyces cichoracearum, whereas the allele from the vinifera cultivar cannot. To dissect the upstream signalling driving the activation of this promoter, we used a dual-luciferase reporter system in a grapevine cell culture. We show elevated responsiveness of the promoter from the wild grape to salicylic acid (SA) and to the pathogen-associated molecular pattern (PAMP) flg22, equal induction of both alleles by jasmonic acid (JA), and a lack of response to the cell death-inducing elicitor Harpin. This elevated SA response of the VpSTS promoter depends on calcium influx, oxidative burst by RboH, mitogen-activated protein kinase (MAPK) signalling, and JA synthesis. We integrate the data in the context of a model where the resistance of V. pseudoreticulata is linked to a more efficient recruitment of SA signalling for phytoalexin synthesis. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Presidential Green Chemistry Challenge: 2001 Small Business Award

EPA Pesticide Factsheets

Presidential Green Chemistry Challenge 2001 award winner, EDEN Bioscience, discovered and commercialized harpins: nontoxic, naturally occurring, biodegradable proteins that activate a plant's defense and growth mechanisms.

Bacterial meningitis.

PubMed

Heckenberg, Sebastiaan G B; Brouwer, Matthijs C; van de Beek, Diederik

2014-01-01

Bacterial meningitis is a neurologic emergency. Vaccination against common pathogens has decreased the burden of disease. Early diagnosis and rapid initiation of empiric antimicrobial and adjunctive therapy are vital. Therapy should be initiated as soon as blood cultures have been obtained, preceding any imaging studies. Clinical signs suggestive of bacterial meningitis include fever, headache, meningismus, and an altered level of consciousness but signs may be scarce in children, in the elderly, and in meningococcal disease. Host genetic factors are major determinants of susceptibility to meningococcal and pneumococcal disease. Dexamethasone therapy has been implemented as adjunctive treatment of adults with pneumococcal meningitis. Adequate and prompt treatment of bacterial meningitis is critical to outcome. In this chapter we review the epidemiology, pathophysiology, and management of bacterial meningitis. © 2014 Elsevier B.V. All rights reserved.

Revelation and cloning of valinomycin synthetase genes in Streptomyces lavendulae ACR-DA1 and their expression analysis under different fermentation and elicitation conditions.

PubMed

Sharma, Richa; Jamwal, Vijaylakshmi; Singh, Varun P; Wazir, Priya; Awasthi, Praveen; Singh, Deepika; Vishwakarma, Ram A; Gandhi, Sumit G; Chaubey, Asha

2017-07-10

Streptomyces species are amongst the most exploited microorganisms due to their ability to produce a plethora of secondary metabolites with bioactive potential, including several well known drugs. They are endowed with immense unexplored potential and substantial efforts are required for their isolation as well as characterization for their bioactive potential. Unexplored niches and extreme environments are host to diverse microbial species. In this study, we report Streptomyces lavendulae ACR-DA1, isolated from extreme cold deserts of the North Western Himalayas, which produces a macrolactone antibiotic, valinomycin. Valinomycin is a K + ionophoric non-ribosomal cyclodepsipeptide with a broad range of bioactivities including antibacterial, antifungal, antiviral and cytotoxic/anticancer activities. Production of valinomycin by the strain S. lavendulae ACR-DA1 was studied under different fermentation conditions like fermentation medium, temperature and addition of biosynthetic precursors. Synthetic medium at 10°C in the presence of precursors i.e. valine and pyruvate showed enhanced valinomycin production. In order to assess the impact of various elicitors, expression of the two genes viz. vlm1 and vlm2 that encode components of heterodimeric valinomycin synthetase, was analyzed using RT-PCR and correlated with quantity of valinomycin using LC-MS/MS. Annelid, bacterial and yeast elicitors increased valinomycin production whereas addition of fungal and plant elicitors down regulated the biosynthetic genes and reduced valinomycin production. This study is also the first report of valinomycin biosynthesis by Streptomyces lavendulae. Copyright © 2017 Elsevier B.V. All rights reserved.

Structural differences in the bacterial flagellar motor among bacterial species.

PubMed

Terashima, Hiroyuki; Kawamoto, Akihiro; Morimoto, Yusuke V; Imada, Katsumi; Minamino, Tohru

2017-01-01

The bacterial flagellum is a supramolecular motility machine consisting of the basal body as a rotary motor, the hook as a universal joint, and the filament as a helical propeller. Intact structures of the bacterial flagella have been observed for different bacterial species by electron cryotomography and subtomogram averaging. The core structures of the basal body consisting of the C ring, the MS ring, the rod and the protein export apparatus, and their organization are well conserved, but novel and divergent structures have also been visualized to surround the conserved structure of the basal body. This suggests that the flagellar motors have adapted to function in various environments where bacteria live and survive. In this review, we will summarize our current findings on the divergent structures of the bacterial flagellar motor.

Bacterial mycophagy: definition and diagnosis of a unique bacterial-fungal interaction.

PubMed

Leveau, Johan H J; Preston, Gail M

2008-01-01

This review analyses the phenomenon of bacterial mycophagy, which we define as a set of phenotypic behaviours that enable bacteria to obtain nutrients from living fungi and thus allow the conversion of fungal into bacterial biomass. We recognize three types of bacterial strategies to derive nutrition from fungi: necrotrophy, extracellular biotrophy and endocellular biotrophy. Each is characterized by a set of uniquely sequential and differently overlapping interactions with the fungal target. We offer a detailed analysis of the nature of these interactions, as well as a comprehensive overview of methodologies for assessing and quantifying their individual contributions to the mycophagy phenotype. Furthermore, we discuss future prospects for the study and exploitation of bacterial mycophagy, including the need for appropriate tools to detect bacterial mycophagy in situ in order to be able to understand, predict and possibly manipulate the way in which mycophagous bacteria affect fungal activity, turnover, and community structure in soils and other ecosystems.

Cellular damage in bacterial meningitis: an interplay of bacterial and host driven toxicity.

PubMed

Weber, Joerg R; Tuomanen, Elaine I

2007-03-01

Bacterial meningitis is still an important infectious disease causing death and disability. Invasive bacterial infections of the CNS generate some of the most powerful inflammatory responses known in medicine. Although the components of bacterial cell surfaces are now chemically defined in exquisite detail and the interaction with several receptor pathways has been discovered, it is only very recently that studies combining these advanced biochemical and cell biological tools have been done. Additional to the immunological response direct bacterial toxicity has been identified as an important contributor to neuronal damage. A detailed understanding of the complex interaction of bacterial toxicity and host response may generate opportunities for innovative and specific neuroprotective therapies.

Bacterial surface adaptation

NASA Astrophysics Data System (ADS)

Utada, Andrew

2014-03-01

Biofilms are structured multi-cellular communities that are fundamental to the biology and ecology of bacteria. Parasitic bacterial biofilms can cause lethal infections and biofouling, but commensal bacterial biofilms, such as those found in the gut, can break down otherwise indigestible plant polysaccharides and allow us to enjoy vegetables. The first step in biofilm formation, adaptation to life on a surface, requires a working knowledge of low Reynolds number fluid physics, and the coordination of biochemical signaling, polysaccharide production, and molecular motility motors. These crucial early stages of biofilm formation are at present poorly understood. By adapting methods from soft matter physics, we dissect bacterial social behavior at the single cell level for several prototypical bacterial species, including Pseudomonas aeruginosa and Vibrio cholerae.

C-reactive Protein Versus Neutrophil/lymphocyte Ratio in Differentiating Bacterial and Non-bacterial Pneumonia in Children.

PubMed

Gauchan, E; Adhikari, S

2016-09-01

Pneumonia is a leading cause of childhood mortality in a low resource country. Simple laboratory markers can help differentiate between bacterial and non-bacterial pneumonias for appropriate management. In children aged one to 60 months with features of lower respiratory infection, C-reactive protein (CRP) and neutrophil-lymphocyte ratio (NLR) were used to differentiate between bacterial and non-bacterial pneumonias. The cutoff values for detecting bacterial pneumonias were evaluated by statistical tools. Bacterial pneumonia was diagnosed in 285 (43.6%) children out of 654 studied. At a cut-off value of 36 mg/L CRP was predictive of bacterial pneumonias with sensitivity and specificity of 61.8% and 91.3% respectively while the sensitivity and specificity for predicting bacterial pneumonia using NLR was 45.6% and 64% respectively with 1.28 used as a cut-off. Our study shows that CRP is superior to NLR in differentiating bacterial from non-bacterial pneumonias in children.

Acetic acid acts as an elicitor exerting a chitosan-like effect on xanthone biosynthesis in Hypericum perforatum L. root cultures.

PubMed

Valletta, Alessio; De Angelis, Giulia; Badiali, Camilla; Brasili, Elisa; Miccheli, Alfredo; Di Cocco, Maria Enrica; Pasqua, Gabriella

2016-05-01

Acetic acid acts as a signal molecule, strongly enhancing xanthone biosynthesis in Hypericum perforatum root cultures. This activity is specific, as demonstrated by the comparison with other short-chain monocarboxylic acids. We have recently demonstrated that Hypericum perforatum root cultures constitutively produce xanthones at higher levels than the root of the plant and that they respond to chitosan (CHIT) elicitation with a noteworthy increase in xanthone production. In the present study, CHIT was administered to H. perforatum root cultures using three different elicitation protocols, and the increase in xanthone production was evaluated. The best results (550 % xanthone increase) were obtained by subjecting the roots to a single elicitation with 200 mg l(-1) CHIT and maintaining the elicitor in the culture medium for 7 days. To discriminate the effect of CHIT from that of the solvent, control experiments were performed by administering AcOH alone at the same concentration used for CHIT solubilization. Unexpectedly, AcOH caused an increase in xanthone production comparable to that observed in response to CHIT. Feeding experiments with (13)C-labeled AcOH demonstrated that this compound was not incorporated into the xanthone skeleton. Other short-chain monocarboxylic acids (i.e., propionic and butyric acid) have little or no effect on the production of xanthones. These results indicate that AcOH acts as a specific signal molecule, able to greatly enhance xanthone biosynthesis in H. perforatum root cultures.

Quantitative proteomics reveals a dynamic association of proteins to detergent-resistant membranes upon elicitor signaling in tobacco.

PubMed

Stanislas, Thomas; Bouyssie, David; Rossignol, Michel; Vesa, Simona; Fromentin, Jérôme; Morel, Johanne; Pichereaux, Carole; Monsarrat, Bernard; Simon-Plas, Françoise

2009-09-01

A large body of evidence from the past decade supports the existence, in membrane from animal and yeast cells, of functional microdomains playing important roles in protein sorting, signal transduction, or infection by pathogens. In plants, as previously observed for animal microdomains, detergent-resistant fractions, enriched in sphingolipids and sterols, were isolated from plasma membrane. A characterization of their proteic content revealed their enrichment in proteins involved in signaling and response to biotic and abiotic stress and cell trafficking suggesting that these domains were likely to be involved in such physiological processes. In the present study, we used (14)N/(15)N metabolic labeling to compare, using a global quantitative proteomics approach, the content of tobacco detergent-resistant membranes extracted from cells treated or not with cryptogein, an elicitor of defense reaction. To analyze the data, we developed a software allowing an automatic quantification of the proteins identified. The results obtained indicate that, although the association to detergent-resistant membranes of most proteins remained unchanged upon cryptogein treatment, five proteins had their relative abundance modified. Four proteins related to cell trafficking (four dynamins) were less abundant in the detergent-resistant membrane fraction after cryptogein treatment, whereas one signaling protein (a 14-3-3 protein) was enriched. This analysis indicates that plant microdomains could, like their animal counterpart, play a role in the early signaling process underlying the setup of defense reaction. Furthermore proteins identified as differentially associated to tobacco detergent-resistant membranes after cryptogein challenge are involved in signaling and vesicular trafficking as already observed in similar studies performed in animal cells upon biological stimuli. This suggests that the ways by which the dynamic association of proteins to microdomains could participate in

Quantitative Proteomics Reveals a Dynamic Association of Proteins to Detergent-resistant Membranes upon Elicitor Signaling in Tobacco*

PubMed Central

Stanislas, Thomas; Bouyssie, David; Rossignol, Michel; Vesa, Simona; Fromentin, Jérôme; Morel, Johanne; Pichereaux, Carole; Monsarrat, Bernard; Simon-Plas, Françoise

2009-01-01

A large body of evidence from the past decade supports the existence, in membrane from animal and yeast cells, of functional microdomains playing important roles in protein sorting, signal transduction, or infection by pathogens. In plants, as previously observed for animal microdomains, detergent-resistant fractions, enriched in sphingolipids and sterols, were isolated from plasma membrane. A characterization of their proteic content revealed their enrichment in proteins involved in signaling and response to biotic and abiotic stress and cell trafficking suggesting that these domains were likely to be involved in such physiological processes. In the present study, we used 14N/15N metabolic labeling to compare, using a global quantitative proteomics approach, the content of tobacco detergent-resistant membranes extracted from cells treated or not with cryptogein, an elicitor of defense reaction. To analyze the data, we developed a software allowing an automatic quantification of the proteins identified. The results obtained indicate that, although the association to detergent-resistant membranes of most proteins remained unchanged upon cryptogein treatment, five proteins had their relative abundance modified. Four proteins related to cell trafficking (four dynamins) were less abundant in the detergent-resistant membrane fraction after cryptogein treatment, whereas one signaling protein (a 14-3-3 protein) was enriched. This analysis indicates that plant microdomains could, like their animal counterpart, play a role in the early signaling process underlying the setup of defense reaction. Furthermore proteins identified as differentially associated to tobacco detergent-resistant membranes after cryptogein challenge are involved in signaling and vesicular trafficking as already observed in similar studies performed in animal cells upon biological stimuli. This suggests that the ways by which the dynamic association of proteins to microdomains could participate in the

Bacterial Prostatitis: Bacterial Virulence, Clinical Outcomes, and New Directions.

PubMed

Krieger, John N; Thumbikat, Praveen

2016-02-01

Four prostatitis syndromes are recognized clinically: acute bacterial prostatitis, chronic bacterial prostatitis, chronic prostatitis/chronic pelvic pain syndrome, and asymptomatic prostatitis. Because Escherichia coli represents the most common cause of bacterial prostatitis, we investigated the importance of bacterial virulence factors and antimicrobial resistance in E. coli strains causing prostatitis and the potential association of these characteristics with clinical outcomes. A structured literature review revealed that we have limited understanding of the virulence-associated characteristics of E. coli causing acute prostatitis. Therefore, we completed a comprehensive microbiological and molecular investigation of a unique strain collection isolated from healthy young men. We also considered new data from an animal model system suggesting certain E. coli might prove important in the etiology of chronic prostatitis/chronic pelvic pain syndrome. Our human data suggest that E. coli needs multiple pathogenicity-associated traits to overcome anatomic and immune responses in healthy young men without urological risk factors. The phylogenetic background and accumulation of an exceptional repertoire of extraintestinal pathogenic virulence-associated genes indicate that these E. coli strains belong to a highly virulent subset of uropathogenic variants. In contrast, antibiotic resistance confers little added advantage to E. coli strains in these healthy outpatients. Our animal model data also suggest that certain pathogenic E. coli may be important in the etiology of chronic prostatitis/chronic pelvic pain syndrome through mechanisms that are dependent on the host genetic background and the virulence of the bacterial strain.

[Current treatment of bacterial vaginosis].

PubMed

Borisov, I

1999-01-01

Therapeutic options for the treatment of accurately diagnosed bacterial vaginosis are reviewed on the basis of current concepts for treatment of bacterial vaginosis. The importance for screening for bacterial vaginosis is pointed out especially before intrauterine procedures and in pregnant women at risk for premature deliveries. Treatment regimens for pregnant women are discussed as well. Emphasis is given to treatment modalities for recurrent bacterial vaginosis.

Bacterial Cell Mechanics.

PubMed

Auer, George K; Weibel, Douglas B

2017-07-25

Cellular mechanical properties play an integral role in bacterial survival and adaptation. Historically, the bacterial cell wall and, in particular, the layer of polymeric material called the peptidoglycan were the elements to which cell mechanics could be primarily attributed. Disrupting the biochemical machinery that assembles the peptidoglycan (e.g., using the β-lactam family of antibiotics) alters the structure of this material, leads to mechanical defects, and results in cell lysis. Decades after the discovery of peptidoglycan-synthesizing enzymes, the mechanisms that underlie their positioning and regulation are still not entirely understood. In addition, recent evidence suggests a diverse group of other biochemical elements influence bacterial cell mechanics, may be regulated by new cellular mechanisms, and may be triggered in different environmental contexts to enable cell adaptation and survival. This review summarizes the contributions that different biomolecular components of the cell wall (e.g., lipopolysaccharides, wall and lipoteichoic acids, lipid bilayers, peptidoglycan, and proteins) make to Gram-negative and Gram-positive bacterial cell mechanics. We discuss the contribution of individual proteins and macromolecular complexes in cell mechanics and the tools that make it possible to quantitatively decipher the biochemical machinery that contributes to bacterial cell mechanics. Advances in this area may provide insight into new biology and influence the development of antibacterial chemotherapies.

In vitro bacterial isolate susceptibility to empirically selected antimicrobials in 111 dogs with bacterial pneumonia.

PubMed

Proulx, Alexandre; Hume, Daniel Z; Drobatz, Kenneth J; Reineke, Erica L

2014-01-01

To determine the proportion of airway bacterial isolates resistant to both empirically selected and recently administered antimicrobials, and to assess the impact of inappropriate initial empiric antimicrobials selection on length of hospital stay and survival to discharge in dogs with bacterial pneumonia. Retrospective study. University veterinary teaching hospital. One hundred and eleven dogs with a clinical diagnosis of bacterial pneumonia that had aerobic bacterial culture and susceptibility testing performed from a tracheal wash sample. None. Overall, 26% (29/111) of the dogs had at least 1 bacterial isolate that was resistant to empirically selected antimicrobials. In dogs with a history of antimicrobial administration within the preceding 4 weeks, a high incidence (57.4%, 31/54) of in vitro bacterial resistance to those antimicrobials was found: 64.7% (11/17) in the community-acquired pneumonia group, 55.2% (16/29) in the aspiration pneumonia group, and 50.0% (4/8) in the other causes of bacterial pneumonia group. No statistically significant association was found between bacterial isolate resistance to empirically selected antimicrobials and length of hospital stay or mortality. The high proportion of in vitro airway bacterial resistance to empiric antimicrobials would suggest that airway sampling for bacterial culture and susceptibility testing may be helpful in guiding antimicrobial therapy and recently administered antimicrobials should be avoided when empirically selecting antimicrobials. Although no relationship was found between inappropriate initial empiric antimicrobial selection and length of hospital stay or mortality, future prospective studies using standardized airway-sampling techniques, treatment modalities, and stratification of disease severity based on objective values, such as arterial blood gas analysis in all dogs with pneumonia, would be needed to determine if a clinical effect of in vitro bacterial resistance to empirically

Facial bacterial infections: folliculitis.

PubMed

Laureano, Ana Cristina; Schwartz, Robert A; Cohen, Philip J

2014-01-01

Facial bacterial infections are most commonly caused by infections of the hair follicles. Wherever pilosebaceous units are found folliculitis can occur, with the most frequent bacterial culprit being Staphylococcus aureus. We review different origins of facial folliculitis, distinguishing bacterial forms from other infectious and non-infectious mimickers. We distinguish folliculitis from pseudofolliculitis and perifolliculitis. Clinical features, etiology, pathology, and management options are also discussed. Copyright © 2014. Published by Elsevier Inc.

Treatment of bacterial meningitis: an update.

PubMed

Shin, Seon Hee; Kim, Kwang Sik

2012-10-01

The introduction of protein conjugate vaccines for Haemophilus influenzae type b (Hib), Streptococcus pneumoniae (S. pneumoniae) and Neisseria meningitidis (N. menigitidis) has changed the epidemiology of bacterial meningitis. Bacterial meningitis continues to be an important cause of mortality and morbidity, and our incomplete knowledge of its pathogenesis and emergence of antimicrobial resistant bacteria contribute to such mortality and morbidity. An early empiric antibiotic treatment is critical for the management of patients with bacterial meningitis. This article gives an overview on optimal treatment strategies of bacterial meningitis, along with considerations of new insights on epidemiology, clinical and laboratory findings supportive of bacterial meningitis, chemoprophylaxis, selection of initial antimicrobial agents for suspected bacterial meningitis, antimicrobial resistance and utility of new antibiotics, status on anti-inflammatory agents and adjunctive therapy, and pathogenesis of bacterial meningitis. Prompt treatment of bacterial meningitis with an appropriate antibiotic is essential. Optimal antimicrobial treatment of bacterial meningitis requires bactericidal agents able to penetrate the blood-brain barrier (BBB), with efficacy in cerebrospinal fluid (CSF). Several new antibiotics have been introduced for the treatment of meningitis caused by resistant bacteria, but their use in human studies has been limited. More complete understanding of the microbial and host interactions that are involved in the pathogenesis of bacterial meningitis and associated neurologic sequelae is likely to help in developing new strategies for the prevention and therapy of bacterial meningitis.

Small bowel bacterial overgrowth

MedlinePlus

Overgrowth - intestinal bacteria; Bacterial overgrowth - intestine; Small intestinal bacterial overgrowth; SIBO ... intestine does not have a high number of bacteria. Excess bacteria in the small intestine may use ...

Exploring bacterial infections: theoretical and experimental studies of the bacterial population dynamics and antibiotic treatment

NASA Astrophysics Data System (ADS)

Shao, Xinxian

Bacterial infections are very common in human society. Thus extensive research has been conducted to reveal the molecular mechanisms of the pathogenesis and to evaluate the antibiotics' efficacy against bacteria. Little is known, however, about the population dynamics of bacterial populations and their interactions with the host's immune system. In this dissertation, a stochatic model is developed featuring stochastic phenotypic switching of bacterial individuals to explain the single-variant bottleneck discovered in multi strain bacterial infections. I explored early events in a bacterial infection establishment using classical experiments of Moxon and Murphy on neonatal rats. I showed that the minimal model and its simple variants do not work. I proposed modifications to the model that could explain the data quantitatively. The bacterial infections are also commonly established in physical structures, as biofilms or 3-d colonies. In contrast, most research on antibiotic treatment of bacterial infections has been conducted in well-mixed liquid cultures. I explored the efficacy of antibiotics to treat such bacterial colonies, a broadly applicable method is designed and evaluated where discrete bacterial colonies on 2-d surfaces were exposed to antibiotics. I discuss possible explanations and hypotheses for the experimental results. To verify these hypotheses, we investigated the dynamics of bacterial population as 3-d colonies. We showed that a minimal mathematical model of bacterial colony growth in 3-d was able to account for the experimentally observed presence of a diffusion-limited regime. The model further revealed highly loose packing of the cells in 3-d colonies and smaller cell sizes in colonies than plancktonic cells in corresponding liquid culture. Further experimental tests of the model predictions have revealed that the ratio of the cell size in liquid culture to that in colony cultures was consistent with the model prediction, that the dead cells

Production of plant growth modulating volatiles is widespread among rhizosphere bacteria and strongly depends on culture conditions.

PubMed

Blom, D; Fabbri, C; Connor, E C; Schiestl, F P; Klauser, D R; Boller, T; Eberl, L; Weisskopf, L

2011-11-01

Recent studies have suggested that bacterial volatiles play an important role in bacterial-plant interactions. However, few reports of bacterial species that produce plant growth modulating volatiles have been published, raising the question whether this is just an anecdotal phenomenon. To address this question, we performed a large screen of strains originating from the soil for volatile-mediated effects on Arabidopsis thaliana. All of the 42 strains tested showed significant volatile-mediated plant growth modulation, with effects ranging from plant death to a sixfold increase in plant biomass. The effects of bacterial volatiles were highly dependent on the cultivation medium and the inoculum quantity. GC-MS analysis of the tested strains revealed over 130 bacterial volatile compounds. Indole, 1-hexanol and pentadecane were selected for further studies because they appeared to promote plant growth. None of these compounds triggered a typical defence response, using production of ethylene and of reactive oxygen species (ROS) as read-outs. However, when plants were challenged with the flg-22 epitope of bacterial flagellin, a prototypical elicitor of defence responses, additional exposure to the volatiles reduced the flg-22-induced production of ethylene and ROS in a dose-dependent manner, suggesting that bacterial volatiles may act as effectors to inhibit the plant's defence response. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

Enhanced production of L-DOPA in cell cultures of Mucuna pruriens L. and Mucuna prurita H.

PubMed

Raghavendra, S; Kumar, V; Ramesh, C K; Khan, M H Moinuddin

2012-01-01

A comparative study on the production of 3,4-dihydroxyphenylalanine (L-DOPA) was carried out in cell cultures of two Mucuna species by elicitor treatment and precursor feeding. The influence of elicitors and the precursor molecule on L-DOPA production, polyphenol oxidase (PPO) and tyrosinase activities was also studied. Callus cultures were initiated in Mucuna pruriens L. and Mucuna prurita H. on MS medium supplemented with BAP and IAA at different concentrations. Suspension cultures were established in MS liquid medium supplemented with BAP, IAA, the elicitors methyl jasmonate, chitin and pectin or the precursor L-tyrosine at different concentrations for L-DOPA production. Compared to the controls, several-fold increases in L-DOPA concentration were observed in elicitor-treated and precursor-fed suspension cultures of both plant species. L-DOPA concentrations were comparatively higher in precursor-fed cultures than those receiving elicitor treatments. A parallel increase in tyrosinase and PPO levels was also observed. Loss of cell viability was observed at high concentrations of elicitor-treated cultures, whereas L-tyrosine did not cause any cell death. Compared to elicitor treatments, precursor feeding resulted in higher concentrations of L-DOPA production and tyrosinase activity. The efficacy of L-DOPA production was found to be higher for suspension cultures of M. pruriens compared to M. prurita in all treatments.

Bacterial pneumonia as an influenza complication.

PubMed

Martin-Loeches, Ignacio; van Someren Gréve, Frank; Schultz, Marcus J

2017-04-01

The pathogenesis and impact of coinfection, in particular bacterial coinfection, in influenza are incompletely understood. This review summarizes results from studies on bacterial coinfection in the recent pandemic influenza outbreak. Systemic immune mechanisms play a key role in the development of coinfection based on the complexity of the interaction of the host and the viral and bacterial pathogens. Several studies were performed to determine the point prevalence of bacterial coinfection in influenza. Coinfection in influenza is frequent in critically ill patients with Streptococcus pneumoniae being the most frequent bacterial pathogen and higher rates of potentially resistant pathogens over the years. Bacterial pneumonia is certainly an influenza complication. The recent epidemiology findings have helped to partially resolve the contribution of different pathogens. Immunosuppression is a risk factor for bacterial coinfection in influenza, and the epidemiology of coinfection has changed over the years during the last influenza pandemic, and these recent findings should be taken into account during present outbreaks.

Zoonotic bacterial meningitis in human adults.

PubMed

van Samkar, Anusha; Brouwer, Matthijs C; van der Ende, Arie; van de Beek, Diederik

2016-09-13

To describe the epidemiology, etiology, clinical characteristics, treatment, outcome, and prevention of zoonotic bacterial meningitis in human adults. We identified 16 zoonotic bacteria causing meningitis in adults. Zoonotic bacterial meningitis is uncommon compared to bacterial meningitis caused by human pathogens, and the incidence has a strong regional distribution. Zoonotic bacterial meningitis is mainly associated with animal contact, consumption of animal products, and an immunocompromised state of the patient. In a high proportion of zoonotic bacterial meningitis cases, CSF analysis showed only a mildly elevated leukocyte count. The recommended antibiotic therapy differs per pathogen, and the overall mortality is low. Zoonotic bacterial meningitis is uncommon but is associated with specific complications. The suspicion should be raised in patients with bacterial meningitis who have recreational or professional contact with animals and in patients living in regions endemic for specific zoonotic pathogens. An immunocompromised state is associated with a worse prognosis. Identification of risk factors and underlying disease is necessary to improve treatment. © 2016 American Academy of Neurology.

Community-acquired bacterial meningitis.

PubMed

Costerus, Joost M; Brouwer, Matthijs C; Bijlsma, Merijn W; van de Beek, Diederik

2017-02-01

Bacterial meningitis is a medical emergency and is associated with a high disease burden. We reviewed recent progress in the management of patients with community-acquired bacterial meningitis. The worldwide burden of disease of bacterial meningitis remains high, despite the decreasing incidence following introduction of routine vaccination campaigns. Delay in diagnosis and treatment remain major concerns in the management of acute bacterial meningitis. European Society of Clinical Microbiology and Infectious Diseases guidelines strive for a door-to-antibiotic-time less than 1 h. Polymerase chain reaction (PCR) has emerged as an important diagnostic tool to identify the causative organism. Point-of-care tests using fast multiplex PCR have been developed, but additional value has not been proven. Although anecdotal observations advocate pressure-based management, a randomized controlled trial will need to be performed first to determine efficacy and safety of such an aggressive treatment approach. Adjunctive dexamethasone remains the only adjunctive therapy with proven efficacy. The incidence of bacterial meningitis has been decreasing after the implementation of effective vaccines. Treatment should be administered as soon as possible and time to treatment should not exceed 1 h.

[Spontaneous bacterial peritonitis].

PubMed

Velkey, Bálint; Vitális, Eszter; Vitális, Zsuzsanna

2017-01-01

Spontaneous bacterial peritonitis occurs most commonly in cirrhotic patients with ascites. Pathogens get into the circulation by intestinal translocation and colonize in peritoneal fluid. Diagnosis of spontaneous bacterial peritonitis is based on elevated polymorphonuclear leukocyte count in the ascites (>0,25 G/L). Ascites culture is often negative but aids to get information about antibiotic sensitivity in positive cases. Treatment in stable patient can be intravenous then orally administrated ciprofloxacin or amoxicillin/clavulanic acid, while in severe cases intravenous III. generation cephalosporin. Nosocomial spontaneous bacterial peritonitis often caused by Gram-positive bacteria and multi-resistant pathogens can also be expected thus carbapenem should be the choice of the empiric treatment. Antibiotic prophylaxis should be considered. Norfloxacin is used most commonly, but changes are expected due to increase in quinolone resistance. As a primary prophylaxis, a short-term antibiotic treatment is recommended after gastrointestinal bleeding for 5 days, while long-term prophylaxis is for patients with low ascites protein, and advanced disease (400 mg/day). Secondary prophylaxis is recommended for all patients recovered from spontaneous bacterial peritonitis. Due to increasing antibiotic use of antibiotics prophylaxis is debated to some degree. Orv. Hetil., 2017, 158(2), 50-57.

The coat protein of Alternanthera mosaic virus is the elicitor of a temperature-sensitive systemic necrosis in Nicotiana benthamiana, and interacts with a host boron transporter protein.

PubMed

Lim, Hyoun-Sub; Nam, Jiryun; Seo, Eun-Young; Nam, Moon; Vaira, Anna Maria; Bae, Hanhong; Jang, Chan-Yong; Lee, Cheol Ho; Kim, Hong Gi; Roh, Mark; Hammond, John

2014-03-01

Different isolates of Alternanthera mosaic virus (AltMV; Potexvirus), including four infectious clones derived from AltMV-SP, induce distinct systemic symptoms in Nicotiana benthamiana. Virus accumulation was enhanced at 15 °C compared to 25 °C; severe clone AltMV 3-7 induced systemic necrosis (SN) and plant death at 15 °C. No interaction with potexvirus resistance gene Rx was detected, although SN was ablated by silencing of SGT1, as for other cases of potexvirus-induced necrosis. Substitution of AltMV 3-7 coat protein (CPSP) with that from AltMV-Po (CP(Po)) eliminated SN at 15 °C, and ameliorated symptoms in Alternanthera dentata and soybean. Substitution of only two residues from CP(Po) [either MN(13,14)ID or LA(76,77)IS] efficiently ablated SN in N. benthamiana. CPSP but not CP(Po) interacted with Arabidopsis boron transporter protein AtBOR1 by yeast two-hybrid assay; N. benthamiana homolog NbBOR1 interacted more strongly with CPSP than CP(Po) in bimolecular fluorescence complementation, and may affect recognition of CP as an elicitor of SN. Published by Elsevier Inc.

Diagnosis of bacterial vaginosis by wet mount identification of bacterial morphotypes in vaginal fluid.

PubMed

Schmidt, H; Hansen, J G

2000-03-01

In order to develop a more practical way of diagnosing bacterial vaginosis (BV), we evaluated a scoring system, weighting small bacterial morphotypes versus lactobacillary morphotypes in wet mounts, assessed criteria for BV and normalcy from this scoring, and then evaluated their reproducibility and accuracy. We examined 754 women for pH, homogeneous vaginal discharge, amine odour, clue cells and the composite clinical diagnosis. We also examined wet mounts for small bacterial morphotypes and lactobacillary morphotypes, and weighted their quantitative presence as a bacterial morphotype score. The term 'small bacterial morphotypes' denotes a group of small bacillary forms comprising coccobacilli, tiny rods, and mobile curved rods. The different characteristics of BV were all gradually associated with increased bacterial morphotype scoring. We deemed a score of 0-1 as normal, 2-4 as intermediate phase, grade I, 5-6 as intermediate phase, grade II, and 7-8 indicative of BV. Reproducibility of the interpretation was high, both for the new grading system (weighted Kappa 0.90 in women perceiving and 0.81 in women not perceiving abnormal vaginal discharge) and for the new criterion for BV (non-weighted Kappa 0.91 and 0.84 in the 2 groups of women). The new criterion also proved highly concurrent with the composite clinical diagnosis (Kappa 0.91 and 0.81 in the 2 groups). In conclusion, the wet mount bacterial morphotype scoring is valid for grading of the disorder of the vaginal microbial ecosystem, and the new criterion for BV a more practical option than existing diagnostic methods.

Insight into the effects of different cropping systems on soil bacterial community and tobacco bacterial wilt rate.

PubMed

Niu, Jiaojiao; Chao, Jin; Xiao, Yunhua; Chen, Wu; Zhang, Chao; Liu, Xueduan; Rang, Zhongwen; Yin, Huaqun; Dai, Linjian

2017-01-01

Rotation is an effective strategy to control crop disease and improve plant health. However, the effects of crop rotation on soil bacterial community composition and structure, and crop health remain unclear. In this study, using 16S rRNA gene sequencing, we explored the soil bacterial communities under four different cropping systems, continuous tobacco cropping (control group), tobacco-maize rotation, tobacco-lily rotation, and tobacco-turnip rotation. Results of detrended correspondence analysis and dissimilarity tests showed that soil bacterial community composition and structure changed significantly among the four groups, such that Acidobacteria and Actinobacteria were more abundant in the maize rotation group (16.6 and 11.5%, respectively) than in the control (8.5 and 7.1%, respectively). Compared with the control group (57.78%), maize and lily were effective rotation crops in controlling tobacco bacterial wilt (about 23.54 and 48.67%). On the other hand, tobacco bacterial wilt rate was increased in the turnip rotation (59.62%) relative to the control. Further study revealed that the abundances of several bacterial populations were directly correlated with tobacco bacterial wilt. For example, Acidobacteria and Actinobacteria were significantly negatively correlated to the tobacco bacterial wilt rate, so they may be probiotic bacteria. Canonical correspondence analysis showed that soil pH and calcium content were key factors in determining soil bacterial communities. In conclusion, our study revealed the composition and structure of bacterial communities under four different cropping systems and may unveil molecular mechanisms for the interactions between soil microorganisms and crop health. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Membrane-bound guaiacol peroxidases from maize (Zea mays L.) roots are regulated by methyl jasmonate, salicylic acid, and pathogen elicitors

PubMed Central

Mika, Angela; Boenisch, Marike Johanne; Hopff, David; Lüthje, Sabine

2010-01-01

Plant peroxidases are involved in numerous cellular processes in plant development and stress responses. Four plasma membrane-bound peroxidases have been identified and characterized in maize (Zea mays L.) roots. In the present study, maize seedlings were treated with different stresses and signal compounds, and a functional analysis of these membrane-bound class III peroxidases (pmPOX1, pmPOX2a, pmPOX2b, and pmPOX3) was carried out. Total guaiacol peroxidase activities from soluble and microsomal fractions of maize roots were compared and showed weak changes. By contrast, total plasma membrane and washed plasma membrane peroxidase activities, representing peripheral and integral membrane proteins, revealed strong changes after all of the stresses applied. A proteomic approach using 2D-PAGE analysis showed that pmPOX3 was the most abundant class III peroxidase at plasma membranes of control plants, followed by pmPOX2a >pmPOX2b >pmPOX1. The molecular mass (63 kDa) and the isoelectric point (9.5) of the pmPOX2a monomer were identified for the first time. The protein levels of all four enzymes changed in response to multiple stresses. While pmPOX2b was the only membrane peroxidase down-regulated by wounding, all four enzymes were differentially but strongly stimulated by methyl jasmonate, salicylic acid, and elicitors (Fusarium graminearum and Fusarium culmorum extracts, and chitosan) indicating their function in pathogen defence. Oxidative stress applied as H2O2 treatment up-regulated pmPOX2b >pmPOX2a, while pmPOX3 was down-regulated. Treatment with the phosphatase inhibitor chantharidin resulted in distinct responses. PMID:20032108

Growth of Bacterial Colonies

NASA Astrophysics Data System (ADS)

Warren, Mya; Hwa, Terence

2013-03-01

On hard agar gel, there is insufficient surface hydration for bacteria to swim or swarm. Instead, growth occurs in colonies of close-packed cells, which expand purely due to repulsive interactions: individual bacteria push each other out of the way through the force of their growth. In this way, bacterial colonies represent a new type of ``active'' granular matter. In this study, we investigate the physical, biochemical, and genetic elements that determine the static and dynamic aspects of this mode of bacterial growth for E. coli. We characterize the process of colony expansion empirically, and use discrete and continuum models to examine the extent to which our observations can be explained by the growth characteristics of non-communicating cells, coupled together by physical forces, nutrients, and waste products. Our results challenge the commonly accepted modes of bacterial colony growth and provide insight into sources of growth limitation in crowded bacterial communities.

Periodic growth of bacterial colonies

NASA Astrophysics Data System (ADS)

Yamazaki, Yoshihiro; Ikeda, Takemasa; Shimada, Hirotoshi; Hiramatsu, Fumiko; Kobayashi, Naoki; Wakita, Jun-ichi; Itoh, Hiroto; Kurosu, Sayuri; Nakatsuchi, Michio; Matsuyama, Tohey; Matsushita, Mitsugu

2005-06-01

The formation of concentric ring colonies by bacterial species Bacillus subtilis and Proteus mirabilis has been investigated experimentally, focusing our attention on the dependence of local cell density upon the bacterial motility. It has been confirmed that these concentric ring colonies reflect the periodic change of the bacterial motility between motile cell state and immotile cell state. We conclude that this periodic change is macroscopically determined neither by biological factors (i.e., biological clock) nor by chemical factors (chemotaxis as inhibitor). And our experimental results strongly suggest that the essential factor for the change of the bacterial motility during concentric ring formation is the local cell density.

Nanoparticle Approaches against Bacterial Infections

PubMed Central

Gao, Weiwei; Thamphiwatana, Soracha; Angsantikul, Pavimol; Zhang, Liangfang

2014-01-01

Despite the wide success of antibiotics, the treatment of bacterial infection still faces significant challenges, particularly the emergence of antibiotic resistance. As a result, nanoparticle drug delivery platforms including liposomes, polymeric nanoparticles, dendrimers, and various inorganic nanoparticles have been increasingly exploited to enhance the therapeutic effectiveness of existing antibiotics. This review focuses on areas where nanoparticle approaches hold significant potential to advance the treatment of bacterial infection. These areas include targeted antibiotic delivery, environmentally responsive antibiotic delivery, combinatorial antibiotic delivery, nanoparticle-enabled antibacterial vaccination, and nanoparticle-based bacterial detection. In each area we highlight the innovative antimicrobial nanoparticle platforms and review their progress made against bacterial infections. PMID:25044325

Bacterial symbionts and natural products.

PubMed

Crawford, Jason M; Clardy, Jon

2011-07-21

The study of bacterial symbionts of eukaryotic hosts has become a powerful discovery engine for chemistry. This highlight looks at four case studies that exemplify the range of chemistry and biology involved in these symbioses: a bacterial symbiont of a fungus and a marine invertebrate that produce compounds with significant anticancer activity, and bacterial symbionts of insects and nematodes that produce compounds that regulate multilateral symbioses.

Postviral Complications: Bacterial Pneumonia.

PubMed

Prasso, Jason E; Deng, Jane C

2017-03-01

Secondary bacterial pneumonia after viral respiratory infection remains a significant source of morbidity and mortality. Susceptibility is mediated by a variety of viral and bacterial factors, and complex interactions with the host immune system. Prevention and treatment strategies are limited to influenza vaccination and antibiotics/antivirals respectively. Novel approaches to identifying the individuals with influenza who are at increased risk for secondary bacterial pneumonias are urgently needed. Given the threat of further pandemics and the heightened prevalence of these viruses, more research into the immunologic mechanisms of this disease is warranted with the hope of discovering new potential therapies. Published by Elsevier Inc.

Community-acquired bacterial meningitis.

PubMed

van de Beek, Diederik; Brouwer, Matthijs; Hasbun, Rodrigo; Koedel, Uwe; Whitney, Cynthia G; Wijdicks, Eelco

2016-11-03

Meningitis is an inflammation of the meninges and subarachnoid space that can also involve the brain cortex and parenchyma. It can be acquired spontaneously in the community - community-acquired bacterial meningitis - or in the hospital as a complication of invasive procedures or head trauma (nosocomial bacterial meningitis). Despite advances in treatment and vaccinations, community-acquired bacterial meningitis remains one of the most important infectious diseases worldwide. Streptococcus pneumoniae and Neisseria meningitidis are the most common causative bacteria and are associated with high mortality and morbidity; vaccines targeting these organisms, which have designs similar to the successful vaccine that targets Haemophilus influenzae type b meningitis, are now being used in many routine vaccination programmes. Experimental and genetic association studies have increased our knowledge about the pathogenesis of bacterial meningitis. Early antibiotic treatment improves the outcome, but the growing emergence of drug resistance as well as shifts in the distribution of serotypes and groups are fuelling further development of new vaccines and treatment strategies. Corticosteroids were found to be beneficial in high-income countries depending on the bacterial species. Further improvements in the outcome are likely to come from dampening the host inflammatory response and implementing preventive measures, especially the development of new vaccines.

Messing with Bacterial Quorum Sensing

PubMed Central

González, Juan E.; Keshavan, Neela D.

2006-01-01

Quorum sensing is widely recognized as an efficient mechanism to regulate expression of specific genes responsible for communal behavior in bacteria. Several bacterial phenotypes essential for the successful establishment of symbiotic, pathogenic, or commensal relationships with eukaryotic hosts, including motility, exopolysaccharide production, biofilm formation, and toxin production, are often regulated by quorum sensing. Interestingly, eukaryotes produce quorum-sensing-interfering (QSI) compounds that have a positive or negative influence on the bacterial signaling network. This eukaryotic interference could result in further fine-tuning of bacterial quorum sensing. Furthermore, recent work involving the synthesis of structural homologs to the various quorum-sensing signal molecules has resulted in the development of additional QSI compounds that could be used to control pathogenic bacteria. The creation of transgenic plants that express bacterial quorum-sensing genes is yet another strategy to interfere with bacterial behavior. Further investigation on the manipulation of quorum-sensing systems could provide us with powerful tools against harmful bacteria. PMID:17158701

Bacterial 'immunity' against bacteriophages.

PubMed

Abedon, Stephen T

2012-01-01

Vertebrate animals possess multiple anti-pathogen defenses. Individual mechanisms usually are differentiated into those that are immunologically adaptive vs. more "primitive" anti-pathogen phenomena described as innate responses. Here I frame defenses used by bacteria against bacteriophages as analogous to these animal immune functions. Included are numerous anti-phage defenses in addition to the adaptive immunity associated with CRISPR/cas systems. As these other anti-pathogen mechanisms are non-adaptive they can be described as making up an innate bacterial immunity. This exercise was undertaken in light of the recent excitement over the discovery that CRISPR/cas systems can serve, as noted, as a form of bacterial adaptive immunity. The broader goal, however, is to gain novel insight into bacterial defenses against phages by fitting these mechanisms into considerations of how multicellular organisms also defend themselves against pathogens. This commentary can be viewed in addition as a bid toward integrating these numerous bacterial anti-phage defenses into a more unified immunology.

Bacterial meningitis - principles of antimicrobial treatment.

PubMed

Jawień, Miroslaw; Garlicki, Aleksander M

2013-01-01

Bacterial meningitis is associated with significant morbidity and mortality despite the availability of effective antimicrobial therapy. The management approach to patients with suspected or proven bacterial meningitis includes emergent cerebrospinal fluid analysis and initiation of appropriate antimicrobial and adjunctive therapies. The choice of empirical antimicrobial therapy is based on the patient's age and underlying disease status; once the infecting pathogen is isolated, antimicrobial therapy can be modified for optimal treatment. Successful treatment of bacterial meningitis requires the knowledge on epidemiology including prevalence of antimicrobial resistant pathogens, pathogenesis of meningitis, pharmacokinetics and pharmacodynamics of antimicrobial agents. The emergence of antibiotic-resistant bacterial strains in recent years has necessitated the development of new strategies for empiric antimicrobial therapy for bacterial meningitis.

Sequence-Specific Affinity Chromatography of Bacterial Small Regulatory RNA-Binding Proteins from Bacterial Cells.

PubMed

Gans, Jonathan; Osborne, Jonathan; Cheng, Juliet; Djapgne, Louise; Oglesby-Sherrouse, Amanda G

2018-01-01

Bacterial small RNA molecules (sRNAs) are increasingly recognized as central regulators of bacterial stress responses and pathogenesis. In many cases, RNA-binding proteins are critical for the stability and function of sRNAs. Previous studies have adopted strategies to genetically tag an sRNA of interest, allowing isolation of RNA-protein complexes from cells. Here we present a sequence-specific affinity purification protocol that requires no prior genetic manipulation of bacterial cells, allowing isolation of RNA-binding proteins bound to native RNA molecules.

A necrosis-inducing elicitor domain encoded by both symptomatic and asymptomatic Plantago asiatica mosaic virus isolates, whose expression is modulated by virus replication.

PubMed

Komatsu, Ken; Hashimoto, Masayoshi; Maejima, Kensaku; Shiraishi, Takuya; Neriya, Yutaro; Miura, Chihiro; Minato, Nami; Okano, Yukari; Sugawara, Kyoko; Yamaji, Yasuyuki; Namba, Shigetou

2011-04-01

Systemic necrosis is the most destructive symptom induced by plant pathogens. We previously identified amino acid 1154, in the polymerase domain (POL) of RNA-dependent RNA polymerase (RdRp) of Plantago asiatica mosaic virus (PlAMV), which affects PlAMV-induced systemic necrosis in Nicotiana benthamiana. By point-mutation analysis, we show that amino acid 1,154 alone is not sufficient for induction of necrotic symptoms. However, PlAMV replicons that can express only RdRp, derived from a necrosis-inducing PlAMV isolate, retain their ability to induce necrosis, and transient expression of PlAMV-encoded proteins indicated that the necrosis-eliciting activity resides in RdRp. Moreover, inducible-overexpression analysis demonstrated that the necrosis was induced in an RdRp dose-dependent manner. In addition, during PlAMV infection, necrotic symptoms are associated with high levels of RdRp accumulation. Surprisingly, necrosis-eliciting activity resides in the helicase domain (HEL), not in the amino acid 1,154-containing POL, of RdRp, and this activity was observed even in HELs of PlAMV isolates of which infection does not cause necrosis. Moreover, HEL-induced necrosis had characteristics similar to those induced by PlAMV infection. Overall, our data suggest that necrotic symptoms induced by PlAMV infection depend on the accumulation of a non-isolate specific elicitor HEL (even from nonnecrosis isolates), whose expression is indirectly regulated by amino acid 1,154 that controls replication.

Harpin-induced expression and transgenic overexpression of the phloem protein gene AtPP2-A1 in Arabidopsis repress phloem feeding of the green peach aphid Myzus persicae

PubMed Central

2011-01-01

Background Treatment of plants with HrpNEa, a protein of harpin group produced by Gram-negative plant pathogenic bacteria, induces plant resistance to insect herbivores, including the green peach aphid Myzus persicae, a generalist phloem-feeding insect. Under attacks by phloem-feeding insects, plants defend themselves using the phloem-based defense mechanism, which is supposed to involve the phloem protein 2 (PP2), one of the most abundant proteins in the phloem sap. The purpose of this study was to obtain genetic evidence for the function of the Arabidopsis thaliana (Arabidopsis) PP2-encoding gene AtPP2-A1 in resistance to M. persicae when the plant was treated with HrpNEa and after the plant was transformed with AtPP2-A1. Results The electrical penetration graph technique was used to visualize the phloem-feeding activities of apterous agamic M. persicae females on leaves of Arabidopsis plants treated with HrpNEa and an inactive protein control, respectively. A repression of phloem feeding was induced by HrpNEa in wild-type (WT) Arabidopsis but not in atpp2-a1/E/142, the plant mutant that had a defect in the AtPP2-A1 gene, the most HrpNEa-responsive of 30 AtPP2 genes. In WT rather than atpp2-a1/E/142, the deterrent effect of HrpNEa treatment on the phloem-feeding activity accompanied an enhancement of AtPP2-A1 expression. In PP2OETAt (AtPP2-A1-overexpression transgenic Arabidopsis thaliana) plants, abundant amounts of the AtPP2-A1 gene transcript were detected in different organs, including leaves, stems, calyces, and petals. All these organs had a deterrent effect on the phloem-feeding activity compared with the same organs of the transgenic control plant. When a large-scale aphid population was monitored for 24 hours, there was a significant decrease in the number of aphids that colonized leaves of HrpNEa-treated WT and PP2OETAt plants, respectively, compared with control plants. Conclusions The repression in phloem-feeding activities of M. persicae as a result

Harpin-induced expression and transgenic overexpression of the phloem protein gene AtPP2-A1 in Arabidopsis repress phloem feeding of the green peach aphid Myzus persicae.

PubMed

Zhang, Chunling; Shi, Haojie; Chen, Lei; Wang, Xiaomeng; Lü, Beibei; Zhang, Shuping; Liang, Yuan; Liu, Ruoxue; Qian, Jun; Sun, Weiwei; You, Zhenzhen; Dong, Hansong

2011-01-13

Treatment of plants with HrpNEa, a protein of harpin group produced by Gram-negative plant pathogenic bacteria, induces plant resistance to insect herbivores, including the green peach aphid Myzus persicae, a generalist phloem-feeding insect. Under attacks by phloem-feeding insects, plants defend themselves using the phloem-based defense mechanism, which is supposed to involve the phloem protein 2 (PP2), one of the most abundant proteins in the phloem sap. The purpose of this study was to obtain genetic evidence for the function of the Arabidopsis thaliana (Arabidopsis) PP2-encoding gene AtPP2-A1 in resistance to M. persicae when the plant was treated with HrpNEa and after the plant was transformed with AtPP2-A1. The electrical penetration graph technique was used to visualize the phloem-feeding activities of apterous agamic M. persicae females on leaves of Arabidopsis plants treated with HrpNEa and an inactive protein control, respectively. A repression of phloem feeding was induced by HrpNEa in wild-type (WT) Arabidopsis but not in atpp2-a1/E/142, the plant mutant that had a defect in the AtPP2-A1 gene, the most HrpNEa-responsive of 30 AtPP2 genes. In WT rather than atpp2-a1/E/142, the deterrent effect of HrpNEa treatment on the phloem-feeding activity accompanied an enhancement of AtPP2-A1 expression. In PP2OETAt (AtPP2-A1-overexpression transgenic Arabidopsis thaliana) plants, abundant amounts of the AtPP2-A1 gene transcript were detected in different organs, including leaves, stems, calyces, and petals. All these organs had a deterrent effect on the phloem-feeding activity compared with the same organs of the transgenic control plant. When a large-scale aphid population was monitored for 24 hours, there was a significant decrease in the number of aphids that colonized leaves of HrpNEa-treated WT and PP2OETAt plants, respectively, compared with control plants. The repression in phloem-feeding activities of M. persicae as a result of AtPP2-A1 overexpression, and

Bacterial detection: from microscope to smartphone.

PubMed

Gopinath, Subash C B; Tang, Thean-Hock; Chen, Yeng; Citartan, Marimuthu; Lakshmipriya, Thangavel

2014-10-15

The ubiquitous nature of bacteria enables them to survive in a wide variety of environments. Hence, the rise of various pathogenic species that are harmful to human health raises the need for the development of accurate sensing systems. Sensing systems are necessary for diagnosis and epidemiological control of pathogenic organism, especially in the food-borne pathogen and sanitary water treatment facility' bacterial populations. Bacterial sensing for the purpose of diagnosis can function in three ways: bacterial morphological visualization, specific detection of bacterial component and whole cell detection. This paper provides an overview of the currently available bacterial detection systems that ranges from microscopic observation to state-of-the-art smartphone-based detection. Copyright © 2014 Elsevier B.V. All rights reserved.

Spatial distribution of marine airborne bacterial communities

PubMed Central

Seifried, Jasmin S; Wichels, Antje; Gerdts, Gunnar

2015-01-01

The spatial distribution of bacterial populations in marine bioaerosol samples was investigated during a cruise from the North Sea to the Baltic Sea via Skagerrak and Kattegat. The analysis of the sampled bacterial communities with a pyrosequencing approach revealed that the most abundant phyla were represented by the Proteobacteria (49.3%), Bacteroidetes (22.9%), Actinobacteria (16.3%), and Firmicutes (8.3%). Cyanobacteria were assigned to 1.5% of all bacterial reads. A core of 37 bacterial OTUs made up more than 75% of all bacterial sequences. The most abundant OTU was Sphingomonas sp. which comprised 17% of all bacterial sequences. The most abundant bacterial genera were attributed to distinctly different areas of origin, suggesting highly heterogeneous sources for bioaerosols of marine and coastal environments. Furthermore, the bacterial community was clearly affected by two environmental parameters – temperature as a function of wind direction and the sampling location itself. However, a comparison of the wind directions during the sampling and calculated backward trajectories underlined the need for more detailed information on environmental parameters for bioaerosol investigations. The current findings support the assumption of a bacterial core community in the atmosphere. They may be emitted from strong aerosolizing sources, probably being mixed and dispersed over long distances. PMID:25800495

Bacterial membrane proteomics.

PubMed

Poetsch, Ansgar; Wolters, Dirk

2008-10-01

About one quarter to one third of all bacterial genes encode proteins of the inner or outer bacterial membrane. These proteins perform essential physiological functions, such as the import or export of metabolites, the homeostasis of metal ions, the extrusion of toxic substances or antibiotics, and the generation or conversion of energy. The last years have witnessed completion of a plethora of whole-genome sequences of bacteria important for biotechnology or medicine, which is the foundation for proteome and other functional genome analyses. In this review, we discuss the challenges in membrane proteome analysis, starting from sample preparation and leading to MS-data analysis and quantification. The current state of available proteomics technologies as well as their advantages and disadvantages will be described with a focus on shotgun proteomics. Then, we will briefly introduce the most abundant proteins and protein families present in bacterial membranes before bacterial membrane proteomics studies of the last years will be presented. It will be shown how these works enlarged our knowledge about the physiological adaptations that take place in bacteria during fine chemical production, bioremediation, protein overexpression, and during infections. Furthermore, several examples from literature demonstrate the suitability of membrane proteomics for the identification of antigens and different pathogenic strains, as well as the elucidation of membrane protein structure and function.

Molecular diagnosis of bacterial vaginosis: Does adjustment for total bacterial load or human cellular content improve diagnostic performance?

PubMed

Plummer, E L; Garland, S M; Bradshaw, C S; Law, M G; Vodstrcil, L A; Hocking, J S; Fairley, C K; Tabrizi, S N

2017-02-01

We investigated the utility of quantitative PCR assays for diagnosis of bacterial vaginosis and found that while the best model utilized bacterial copy number adjusted for total bacterial load (sensitivity=98%, specificity=93%, AUC=0.95[95%CI=0.93,0.97]), adjusting for total bacterial or human cell load did not consistently increase the diagnostic performance of the assays. Copyright © 2017 Elsevier B.V. All rights reserved.

Arsenic uptake in bacterial calcite

NASA Astrophysics Data System (ADS)

Catelani, Tiziano; Perito, Brunella; Bellucci, Francesco; Lee, Sang Soo; Fenter, Paul; Newville, Matthew; Rimondi, Valentina; Pratesi, Giovanni; Costagliola, Pilario

2018-02-01

Bio-mediated processes for arsenic (As) uptake in calcite were investigated by means of X-ray Diffraction (XRD) and X-ray Absorption Spectroscopy (XAS) coupled with X-ray Fluorescence measurements. The environmental bacterial strain Bacillus licheniformis BD5, sampled at the Bullicame Hot Springs (Viterbo, Central Italy), was used to synthesize calcite from As-enriched growth media. Both liquid and solid cultures were applied to simulate planktonic and biofilm community environments, respectively. Bacterial calcite samples cultured in liquid media had an As enrichment factor (Kd) 50 times higher than that from solid media. The XRD analysis revealed an elongation of the crystal lattice along the c axis (by 0.03 Å) for biogenic calcite, which likely resulted from the substitution of larger arsenate for carbonate in the crystal. The XAS data also showed a clear difference in the oxidation state of sorbed As between bacterial and abiotic calcite. Abiotic chemical processes yielded predominantly As(V) uptake whereas bacterial precipitation processes led to the uptake of both As(III) and As(V). The presence of As(III) in bacterial calcite is proposed to result from subsequent reduction of arsenate to arsenite by bacterial activities. To the best of our knowledge, this is the first experimental observation of the incorporation of As(III) in the calcite crystal lattice, revealing a critical role of biochemical processes for the As cycling in nature.

Methyl jasmonate and yeast elicitor induce differential transcriptional and metabolic re-programming in cell suspension cultures of the model legume Medicago truncatula.

PubMed

Suzuki, Hideyuki; Reddy, M S Srinivasa; Naoumkina, Marina; Aziz, Naveed; May, Gregory D; Huhman, David V; Sumner, Lloyd W; Blount, Jack W; Mendes, Pedro; Dixon, Richard A

2005-03-01

Exposure of cell suspension cultures of Medicago truncatula Gaerth. to methyl jasmonate (MeJA) resulted in up to 50-fold induction of transcripts encoding the key triterpene biosynthetic enzyme beta-amyrin synthase (betaAS; EC 5.4.99.-). Transcripts reached maximum levels at 24 h post-elicitation with 0.5 mM MeJA. The entry point enzymes into the phenylpropanoid and flavonoid pathways, L: -phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) and chalcone synthase (CHS; EC 2.3.1.74), respectively, were not induced by MeJA. In contrast, exposure of cells to yeast elicitor (YE) resulted in up to 45- and 14-fold induction of PAL and CHS transcripts, respectively, at only 2 h post-elicitation. betaAS transcripts were weakly induced at 12 h after exposure to YE. Over 30 different triterpene saponins were identified in the cultures, many of which were strongly induced by MeJA, but not by YE. In contrast, cinnamic acids, benzoic acids and isoflavone-derived compounds accumulated following exposure of cultures to YE, but few changes in phenylpropanoid levels were observed in response to MeJA. DNA microarray analysis confirmed the strong differential transcriptional re-programming of the cell cultures for multiple genes in the phenylpropanoid and triterpene pathways in response to MeJA and YE, and indicated different responses of individual members of gene families. This work establishes Medicago cell cultures as an excellent model for future genomics approaches to understand the regulation of legume secondary metabolism.

Bacterial interactions in dental biofilm development.

PubMed

Hojo, K; Nagaoka, S; Ohshima, T; Maeda, N

2009-11-01

Recent analyses with ribosomal RNA-based technologies have revealed the diversity of bacterial populations within dental biofilms, and have highlighted their important contributions to oral health and disease. Dental biofilms are exceedingly complex and multispecies ecosystems, where oral bacteria interact cooperatively or competitively with other members. Bacterial interactions that influence dental biofilm communities include various different mechanisms. During the early stage of biofilm formation, it is known that planktonic bacterial cells directly attach to surfaces of the oral cavity or indirectly bind to other bacterial cells that have already colonized. Adherence through co-aggregation may be critical for the temporary retention of bacteria on dental surfaces, and may facilitate eventual bacterial colonization. It is likely that metabolic communication, genetic exchange, production of inhibitory factors (e.g., bacteriocins, hydrogen peroxide, etc.), and quorum-sensing are pivotal regulatory factors that determine the bacterial composition and/or metabolism. Since each bacterium can easily access a neighboring bacterial cell and its metabolites, genetic exchanges and metabolic communication may occur frequently in dental biofilms. Quorum-sensing is defined as gene regulation in response to cell density, which influences various functions, e.g., virulence and bacteriocin production. In this review, we discuss these important interactions among oral bacteria within the dental biofilm communities.

Host-Pathogen interactions. 25. Endopolygalacturonic acid lyase from Erwinia carotovora elicits phytoalexin accumulation by releasing plant cell wall fragments

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

Davis, K.R.; Lyon, G.D.; Darvill, A.G.

1984-01-01

Heat-labile elicitors of phytoalexin accumulation in soybeans (Glycine max L. Merr. cv Wayne) were detected in culture filtrates of Erwinia carotovora grown on a defined medium containing citrus pectin as the sole carbon source. The heat-labile elicitors were highly purified by cation-exchange chromatography on a CM-Sephadex (C-50) column, followed by agarose-affinity chromatography on a Bio-Gel A-0.5m gel filtration column. The heat-labile elicitor activity co-purified with two ..cap alpha..-1,4-endopolygalacturonic acid lyases (EC 4 x 2 x 2 x 2). Endopolygalacturonic acid lyase activity appeared to be necessary for elicitor activity because heat-inactivated enzyme preparations did not elicit phytoalexins. The purified endopolygalacturonicmore » acid lyases elicited pterocarpan phytoalexins at microbial-inhibitory concentrations in the soybean-cotyledon bioassay when applied at a concentration of 55 nanograms per milliliter (1 x 10/sup -9/ molar). One of these lyases released heat-stable elicitors from soybean cell walls, citrus pectin, and sodium polypectate. The heat-stable elicitor-active material solubilized from soybean cell walls by the lyase was composed of at least 90% (w/v) uronosyl residues. These results demonstrate that endopolygalacturonic acid lyase elicits phytoalexin accumulation by releasing fragments from pectic polysaccharides in plant cell walls.« less

Endophytic Bacteria Isolated from Panax ginseng Improves Ginsenoside Accumulation in Adventitious Ginseng Root Culture.

PubMed

Song, Xiaolin; Wu, Hao; Yin, Zhenhao; Lian, Meilan; Yin, Chengri

2017-05-23

Ginsenoside is the most important secondary metabolite of ginseng. Natural sources of wild ginseng have been overexploited. Although root culture could reduce the length of the growth cycle of ginseng, the number of ginsenosides is fewer and their contents are lower in adventitious roots of ginseng than that in ginseng cultivated in the field. In this study, we investigated the effects of endophytic bacterial elicitors on biomass and ginsenoside production in adventitious roots cultures of Panax ginseng . Endophyte LB 5-3 as an elicitor could increase biomass and ginsenoside accumulation in ginseng adventitious root culture. After 6 days elicitation with a 10.0 mL of strain LB 5-3, the content of total ginsenoside was 2.026 mg g -1 which was four times more than that in unchallenged roots. The combination of methyl jasmonate and strain LB 5-3 had a negative effect on ginseng adventitious root growth and ginsenoside production. The genomic DNA of strain LB 5-3 was sequenced, and was found to be most closely related to Bacillus altitudinis (KX230132.1). The challenged ginseng adventitious root extracts exerted inhibitory effect against the HepG2 cells, which IC 50 value was 0.94 mg mL -1 .

Volatiles in Inter-Specific Bacterial Interactions

PubMed Central

Tyc, Olaf; Zweers, Hans; de Boer, Wietse; Garbeva, Paolina

2015-01-01

The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures of well-described bacterial genera. In this study we aimed to understand how inter-specific bacterial interactions affect the composition, production and activity of volatiles. Four phylogenetically different bacterial species namely: Chryseobacterium, Dyella, Janthinobacterium, and Tsukamurella were selected. Earlier results had shown that pairwise combinations of these bacteria induced antimicrobial activity in agar media whereas this was not the case for monocultures. In the current study, we examined if these observations were also reflected by the production of antimicrobial volatiles. Thus, the identity and antimicrobial activity of volatiles produced by the bacteria were determined in monoculture as well in pairwise combinations. Antimicrobial activity of the volatiles was assessed against fungal, oomycetal, and bacterial model organisms. Our results revealed that inter-specific bacterial interactions affected volatiles blend composition. Fungi and oomycetes showed high sensitivity to bacterial volatiles whereas the effect of volatiles on bacteria varied between no effects, growth inhibition to growth promotion depending on the volatile blend composition. In total 35 volatile compounds were detected most of which were sulfur-containing compounds. Two commonly produced sulfur-containing volatile compounds (dimethyl disulfide and dimethyl trisulfide) were tested for their effect on three target bacteria. Here, we display the importance of inter-specific interactions on bacterial volatiles production and their antimicrobial activities. PMID:26733959

Pro-inflammatory cytokines can act as intracellular modulators of commensal bacterial virulence

PubMed Central

Mahdavi, Jafar; Royer, Pierre-Joseph; Sjölinder, Hong S.; Azimi, Sheyda; Self, Tim; Stoof, Jeroen; Wheldon, Lee M.; Brännström, Kristoffer; Wilson, Raymond; Moreton, Joanna; Moir, James W. B.; Sihlbom, Carina; Borén, Thomas; Jonsson, Ann-Beth; Soultanas, Panos; Ala'Aldeen, Dlawer A. A.

2013-01-01

Interactions between commensal pathogens and hosts are critical for disease development but the underlying mechanisms for switching between the commensal and virulent states are unknown. We show that the human pathogen Neisseria meningitidis, the leading cause of pyogenic meningitis, can modulate gene expression via uptake of host pro-inflammatory cytokines leading to increased virulence. This uptake is mediated by type IV pili (Tfp) and reliant on the PilT ATPase activity. Two Tfp subunits, PilE and PilQ, are identified as the ligands for TNF-α and IL-8 in a glycan-dependent manner, and their deletion results in decreased virulence and increased survival in a mouse model. We propose a novel mechanism by which pathogens use the twitching motility mode of the Tfp machinery for sensing and importing host elicitors, aligning with the inflamed environment and switching to the virulent state. PMID:24107297

Elucidating Duramycin's Bacterial Selectivity and Mode of Action on the Bacterial Cell Envelope.

PubMed

Hasim, Sahar; Allison, David P; Mendez, Berlin; Farmer, Abigail T; Pelletier, Dale A; Retterer, Scott T; Campagna, Shawn R; Reynolds, Todd B; Doktycz, Mitchel J

2018-01-01

The use of naturally occurring antimicrobial peptides provides a promising route to selectively target pathogenic agents and to shape microbiome structure. Lantibiotics, such as duramycin, are one class of bacterially produced peptidic natural products that can selectively inhibit the growth of other bacteria. However, despite longstanding characterization efforts, the microbial selectivity and mode of action of duramycin are still obscure. We describe here a suite of biological, chemical, and physical characterizations that shed new light on the selective and mechanistic aspects of duramycin activity. Bacterial screening assays have been performed using duramycin and Populus -derived bacterial isolates to determine species selectivity. Lipidomic profiles of selected resistant and sensitive strains show that the sensitivity of Gram-positive bacteria depends on the presence of phosphatidylethanolamine (PE) in the cell membrane. Further the surface and interface morphology were studied by high resolution atomic force microscopy and showed a progression of cellular changes in the cell envelope after treatment with duramycin for the susceptible bacterial strains. Together, these molecular and cellular level analyses provide insight into duramycin's mode of action and a better understanding of its selectivity.

Vulvovaginal symptoms in women with bacterial vaginosis.

PubMed

Klebanoff, Mark A; Schwebke, Jane R; Zhang, Jun; Nansel, Tonja R; Yu, Kai-Fun; Andrews, William W

2004-08-01

A substantial, but highly variable, percentage of women with bacterial vaginosis are said to be asymptomatic. The purpose of this study was to estimate the prevalence of symptoms among women with bacterial vaginosis compared with women without bacterial vaginosis by direct, explicit, and detailed questioning of these women. Women presenting for a routine health care visit at 12 health department clinics in Birmingham, Alabama, were recruited to participate in a longitudinal study of vaginal flora. At the first visit, they underwent a pelvic examination, lower genital tract microbiological evaluation, and an interview that included detailed questions regarding lower genital tract symptoms. The prevalence of symptoms among women with and without bacterial vaginosis (Gram stain score 7 or higher) was compared. Among 2,888 women without gonorrhea, Chlamydia, or trichomonas, 75% of women with and 82% of women without bacterial vaginosis never noted any vaginal odor in the past 6 months (P <.001). The corresponding values were 63% and 65% for never noting vaginal "wetness" (P =.02); 58% and 57% for vaginal discharge (P =.65); 91% and 86% for irritation (P =.004); 88% and 85% for itching (P =.64); and 96% and 94% for dysuria (P =.002), respectively. Cumulatively, 58% of women with bacterial vaginosis noted odor, discharge, and/or wetness in the past 6 months compared with 57% of women without bacterial vaginosis (P =.70). The 2 classic symptoms of bacterial vaginosis discharge and odor are each reported by a minority of women with bacterial vaginosis and are only slightly more prevalent than among women without bacterial vaginosis.

Viral-bacterial associations in acute apical abscesses.

PubMed

Ferreira, Dennis C; Rôças, Isabela N; Paiva, Simone S M; Carmo, Flávia L; Cavalcante, Fernanda S; Rosado, Alexandre S; Santos, Kátia R N; Siqueira, José F

2011-08-01

Viral-bacterial and bacterial synergism have been suggested to contribute to the pathogenesis of several human diseases. This study sought to investigate the possible associations between 9 candidate endodontic bacterial pathogens and 9 human viruses in samples from acute apical abscesses. DNA extracts from purulent exudate aspirates of 33 cases of acute apical abscess were surveyed for the presence of 9 selected bacterial species using a 16S ribosomal RNA gene-based nested polymerase chain reaction (PCR) approach. Single or nested PCR assays were used for detection of the human papillomavirus (HPV) and herpesviruses types 1 to 8. Two-thirds of the abscess samples were positive for at least one of the target viruses. Specifically, the most frequently detected viruses were HHV-8 (54.5%); HPV (9%); and varicella zoster virus (VZV), Epstein-Barr virus (EBV), and HHV-6 (6%). Bacterial DNA was present in all cases and the most prevalent bacterial species were Treponema denticola (70%), Tannerella forsythia (67%), Porphyromonas endodontalis (67%), Dialister invisus (61%), and Dialister pneumosintes (57.5%). HHV-8 was positively associated with 7 of the target bacterial species and HPV with 4, but all these associations were weak. Several bacterial pairs showed a moderate positive association. Viral coinfection was found in 6 abscess cases, but no significant viral association could be determined. Findings demonstrated that bacterial and viral DNA occurred concomitantly in two-thirds of the samples from endodontic abscesses. Although this may suggest a role for viruses in the etiology of apical abscesses, the possibility also exists that the presence of viruses in abscess samples is merely a consequence of the bacterially induced disease process. Further studies are necessary to clarify the role of these viral-bacterial interactions, if any, in the pathogenesis of acute apical abscesses. Copyright © 2011 Mosby, Inc. All rights reserved.

An evaluation of bacterial contamination of barriers used in periapical tissue regeneration: Part 1--Bacterial adherence.

PubMed

Sharma, Priya; Mickel, André K; Chogle, Sami; Sharma, Prem Nath; Han, Yiping W; Jones, Jefferson J

2008-02-01

To compare the adherence of Prevotella melaninogenica and Enterococcus faecalis to 3 guided tissue regeneration membranes: Atrisorb, Lambone, and OsseoQuest. It was hypothesized that OsseoQuest would show increased bacterial adherence compared to Lambone and Atrisorb. The barriers were suspended in trypticase soy broth containing an inoculum of either P melaninogenica or E faecalis. The samples were incubated under appropriate conditions for 6, 24, and 48 hours. Following incubation, each membrane was mixed in fresh media in a vortex machine to dislodge adherent bacteria. The vortexed media was quantitatively assessed using serial dilutions for viable cell count. E faecalis exhibited higher adherence compared to P melaninogenica with time. Of the membranes tested, Lambone displayed the least bacterial adherence. An analysis of the results indicated that bacterial adherence was time-dependent for all membranes. Membrane structure, chemical configuration, hydrophobicity, and bacterial cell surface structure were suggested as factors contributing to variance in bacterial adherence.

Arsenic uptake in bacterial calcite

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

Catelani, Tiziano; Perito, Brunella; Bellucci, Francesco

Bio-mediated processes for arsenic (As) uptake in calcite were investigated by means of X-ray Diffraction (XRD) and Xray Absorption Spectroscopy (XAS) coupled with X-ray Fluorescence measurements. The environmental bacterial strain Bacillus licheniformis BD5, sampled at the Bullicame Hot Springs (Viterbo, Central Italy), was used to synthesize calcite from As-enriched growth media. Both liquid and solid cultures were applied to simulate planktonic and biofilm community environments, respectively. Bacterial calcite samples cultured in liquid media had an As enrichment factor (Kd) 50 times higher than that from solid media. The XRD analysis revealed an elongation of the crystal lattice along the cmore » axis (by 0.03Å) for biogenic calcite, which likely resulted from the substitution of larger arsenate for carbonate in the crystal. The XAS data also showed a clear difference in the oxidation state of sorbed As between bacterial and abiotic calcite. Abiotic chemical processes yielded predominantly As(V) uptake whereas bacterial precipitation processes led to the uptake of both As(III) and As(V). The presence of As(III) in bacterial calcite is proposed to result from subsequent reduction of arsenate to arsenite by bacterial activities. To the best of our knowledge, this is the first experimental observation of the incorporation of As(III) in the calcite crystal lattice, revealing a critical role of biochemical processes for the As cycling in nature.« less

Gamma-irradiated bacterial preparation having anti-tumor activity

DOEpatents

Vass, Arpad A.; Tyndall, Richard L.; Terzaghi-Howe, Peggy

1999-01-01

A bacterial preparation from Pseudomonas species isolated #15 ATCC 55638 that has been exposed to gamma radiation exhibits cytotoxicity that is specific for neoplastic carcinoma cells. A method for obtaining a bacterial preparation having antitumor activity consists of suspending a bacterial isolate in media and exposing the suspension to gamma radiation. A bacterial preparation of an aged culture of an amoeba-associated bacteria exhibits anti-reverse transcriptase activity. A method for obtaining a bacterial preparation having anti-reverse transcriptase activity from an amoeba-associated bacterial isolate grown to stationary phase is disclosed.

Bacteriophages and Bacterial Plant Diseases

PubMed Central

Buttimer, Colin; McAuliffe, Olivia; Ross, R. P.; Hill, Colin; O’Mahony, Jim; Coffey, Aidan

2017-01-01

Losses in crop yields due to disease need to be reduced in order to meet increasing global food demands associated with growth in the human population. There is a well-recognized need to develop new environmentally friendly control strategies to combat bacterial crop disease. Current control measures involving the use of traditional chemicals or antibiotics are losing their efficacy due to the natural development of bacterial resistance to these agents. In addition, there is an increasing awareness that their use is environmentally unfriendly. Bacteriophages, the viruses of bacteria, have received increased research interest in recent years as a realistic environmentally friendly means of controlling bacterial diseases. Their use presents a viable control measure for a number of destructive bacterial crop diseases, with some phage-based products already becoming available on the market. Phage biocontrol possesses advantages over chemical controls in that tailor-made phage cocktails can be adapted to target specific disease-causing bacteria. Unlike chemical control measures, phage mixtures can be easily adapted for bacterial resistance which may develop over time. In this review, we will examine the progress and challenges for phage-based disease biocontrol in food crops. PMID:28163700

Bacterial symbionts and natural products

PubMed Central

Crawford, Jason M.; Clardy, Jon

2011-01-01

The study of bacterial symbionts of eukaryotic hosts has become a powerful discovery engine for chemistry. This highlight looks at four case studies that exemplify the range of chemistry and biology involved in these symbioses: a bacterial symbiont of a fungus and a marine invertebrate that produce compounds with significant anticancer activity, and bacterial symbionts of insects and nematodes that produce compounds that regulate multilateral symbioses. In the last ten years, a series of shocking revelations – the molecular equivalents of a reality TV show’s uncovering the true parents of a well known individual or a deeply hidden family secret – altered the study of genetically encoded small molecules, natural products for short. These revelations all involved natural products produced by bacterial symbionts, and while details differed, two main plot lines emerged: parentage, in which the real producers of well known natural products with medical potential were not the organisms from which they were originally discovered, and hidden relationships, in which bacterially produced small molecules turned out to be the unsuspected regulators of complex interactions. For chemists, these studies led to new molecules, new biosynthetic pathways, and an understanding of the biological functions these molecules fulfill. PMID:21594283

Evolution of bacterial virulence.

PubMed

Diard, Médéric; Hardt, Wolf-Dietrich

2017-09-01

Bacterial virulence is highly dynamic and context-dependent. For this reason, it is challenging to predict how molecular changes affect the growth of a pathogen in a host and its spread in host population. Two schools of thought have taken quite different directions to decipher the underlying principles of bacterial virulence. While molecular infection biology is focusing on the basic mechanisms of the pathogen-host interaction, evolution biology takes virulence as one of several parameters affecting pathogen spread in a host population. We review both approaches and discuss how they can complement each other in order to obtain a comprehensive understanding of bacterial virulence, its emergence, maintenance and evolution. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Endocarditis in adults with bacterial meningitis.

PubMed

Lucas, Marjolein J; Brouwer, Matthijs C; van der Ende, Arie; van de Beek, Diederik

2013-05-21

Endocarditis may precede or complicate bacterial meningitis, but the incidence and impact of endocarditis in bacterial meningitis are unknown. We assessed the incidence and clinical characteristics of patients with meningitis and endocarditis from a nationwide cohort study of adults with community-acquired bacterial meningitis in the Netherlands from 2006 to 2012. Endocarditis was identified in 24 of 1025 episodes (2%) of bacterial meningitis. Cultures yielded Streptococcus pneumoniae in 13 patients, Staphylococcus aureus in 8 patients, and Streptococcus agalactiae, Streptococcus pyogenes, and Streptococcus salivarius in 1 patient each. Clues leading to the diagnosis of endocarditis were cardiac murmurs, persistent or recurrent fever, a history of heart valve disease, and S aureus as the causative pathogen of bacterial meningitis. Treatment consisted of prolonged antibiotic therapy in all patients and surgical valve replacement in 10 patients (42%). Two patients were treated with oral anticoagulants, and both developed life-threatening intracerebral hemorrhage. Systemic (70%) and neurological (54%) complications occurred frequently, leading to a high proportion of patients with unfavorable outcome (63%). Seven of 24 patients (29%) with meningitis and endocarditis died. Endocarditis is an uncommon coexisting condition in bacterial meningitis but is associated with a high rate of unfavorable outcome.

Phenotypic Signatures Arising from Unbalanced Bacterial Growth

PubMed Central

Tan, Cheemeng; Smith, Robert Phillip; Tsai, Ming-Chi; Schwartz, Russell; You, Lingchong

2014-01-01

Fluctuations in the growth rate of a bacterial culture during unbalanced growth are generally considered undesirable in quantitative studies of bacterial physiology. Under well-controlled experimental conditions, however, these fluctuations are not random but instead reflect the interplay between intra-cellular networks underlying bacterial growth and the growth environment. Therefore, these fluctuations could be considered quantitative phenotypes of the bacteria under a specific growth condition. Here, we present a method to identify “phenotypic signatures” by time-frequency analysis of unbalanced growth curves measured with high temporal resolution. The signatures are then applied to differentiate amongst different bacterial strains or the same strain under different growth conditions, and to identify the essential architecture of the gene network underlying the observed growth dynamics. Our method has implications for both basic understanding of bacterial physiology and for the classification of bacterial strains. PMID:25101949

Phenotypic signatures arising from unbalanced bacterial growth.

PubMed

Tan, Cheemeng; Smith, Robert Phillip; Tsai, Ming-Chi; Schwartz, Russell; You, Lingchong

2014-08-01

Fluctuations in the growth rate of a bacterial culture during unbalanced growth are generally considered undesirable in quantitative studies of bacterial physiology. Under well-controlled experimental conditions, however, these fluctuations are not random but instead reflect the interplay between intra-cellular networks underlying bacterial growth and the growth environment. Therefore, these fluctuations could be considered quantitative phenotypes of the bacteria under a specific growth condition. Here, we present a method to identify "phenotypic signatures" by time-frequency analysis of unbalanced growth curves measured with high temporal resolution. The signatures are then applied to differentiate amongst different bacterial strains or the same strain under different growth conditions, and to identify the essential architecture of the gene network underlying the observed growth dynamics. Our method has implications for both basic understanding of bacterial physiology and for the classification of bacterial strains.

Modeling Intraocular Bacterial Infections

PubMed Central

Astley, Roger A.; Coburn, Phillip S.; Parkunan, Salai Madhumathi; Callegan, Michelle C.

2016-01-01

Bacterial endophthalmitis is an infection and inflammation of the posterior segment of the eye which can result in significant loss of visual acuity. Even with prompt antibiotic, anti-inflammatory and surgical intervention, vision and even the eye itself may be lost. For the past century, experimental animal models have been used to examine various aspects of the pathogenesis and pathophysiology of bacterial endophthalmitis, to further the development of anti-inflammatory treatment strategies, and to evaluate the pharmacokinetics and efficacies of antibiotics. Experimental models allow independent control of many parameters of infection and facilitate systematic examination of infection outcomes. While no single animal model perfectly reproduces the human pathology of bacterial endophthalmitis, investigators have successfully used these models to understand the infectious process and the host response, and have provided new information regarding therapeutic options for the treatment of bacterial endophthalmitis. This review highlights experimental animal models of endophthalmitis and correlates this information with the clinical setting. The goal is to identify knowledge gaps that may be addressed in future experimental and clinical studies focused on improvements in the therapeutic preservation of vision during and after this disease. PMID:27154427

[The composition of the gastrointestinal bacterial flora of mouse embryos and the placenta tissue bacterial flora].

PubMed

Lei, D; Lin, Y; Jiang, X; Lan, L; Zhang, W; Wang, B X

2017-03-02

Objective: To explore the composition of the gastrointestinal bacterial flora of mouse embryos and the placenta tissue bacterial flora. Method: Twenty-four specimens were collected from pregnant Kunming mouse including 8 mice of early embryonic (12-13 days) gastrointestinal tissues, 8 cases of late embryonic (19-20 days)gastrointestinal tissues, 8 of late pregnancy placental tissues.The 24 samples were extracted by DNeasy Blood & Tissue kit for high-throughput DNA sequencing. Result: The level of Proteobacteria, Bacteroidetes, Actino-bacteria and Firmicutes were predominantin all specimens.The relative content of predominant bacterial phyla in each group: Proteobacteria (95.00%, 88.14%, 87.26%), Bacteroidetes(1.71%, 2.15%, 2.63%), Actino-Bacteria(1.16%, 4.10%, 3.38%), Firmicutes(0.75%, 2.62%, 2.01%). At the level of family, there were nine predominant bacterial families in which Enterobacteriaeae , Shewanel laceae and Moraxellaceae were dominant.The relative content of dominant bacterial family in eachgroup: Enterobacteriaeae (46.99%, 44.34%, 41.08%), Shewanellaceae (21.99%, 21.10%, 19.05%), Moraxellaceae (9.18%, 7.09%, 5.64%). From the species of flora, the flora from fetal gastrointestinal in early pregnancy and late pregnancy (65.44% and 62.73%) were the same as that from placenta tissue in the late pregnancy.From the abundance of bacteria, at the level of family, the same content of bacteria in three groups accounted for 78.16%, 72.53% and 65.78% respectively. Conclusion: It was proved that the gastrointestinal bacterial flora of mouse embryos and the placenta tissue bacterial flora were colonized. At the same time the bacteria are classified.

Rhizophagus irregularis as an elicitor of rosmarinic acid and antioxidant production by transformed roots of Ocimum basilicum in an in vitro co-culture system.

PubMed

Srivastava, Shivani; Conlan, Xavier A; Cahill, David M; Adholeya, Alok

2016-11-01

Arbuscular mycorrhiza is a symbiotic association formed between plant roots and soil borne fungi that alter and at times improve the production of secondary metabolites. Detailed information is available on mycorrhizal development and its influence on plants grown under various edapho-climatic conditions, however, very little is known about their influence on transformed roots that are rich reserves of secondary metabolites. This raises the question of how mycorrhizal colonization progresses in transformed roots grown in vitro and whether the mycorrhizal fungus presence influences the production of secondary metabolites. To fully understand mycorrhizal ontogenesis and its effect on root morphology, root biomass, total phenolics, rosmarinic acid, caffeic acid and antioxidant production under in vitro conditions, a co-culture was developed between three Agrobacterium rhizogenes-derived, elite-transformed root lines of Ocimum basilicum and Rhizophagus irregularis. We found that mycorrhizal ontogenesis in transformed roots was similar to mycorrhizal roots obtained from an in planta system. Mycorrhizal establishment was also found to be transformed root line-specific. Colonization of transformed roots increased the concentration of rosmarinic acid, caffeic acid and antioxidant production while no effect was observed on root morphological traits and biomass. Enhancement of total phenolics and rosmarinic acid in the three mycorrhizal transformed root lines was found to be transformed root line-specific and age dependent. We reveal the potential of R. irregularis as a biotic elicitor in vitro and propose its incorporation into commercial in vitro secondary metabolite production via transformed roots.

Gamma-irradiated bacterial preparation having anti-tumor activity

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

Vass, A.A.; Tyndall, R.L.; Terzaghi-Howe, P.

1999-11-16

This application describes a bacterial preparation from Pseudomonas species isolated {number{underscore}sign}15 ATCC 55638 that has been exposed to gamma radiation exhibits cytotoxicity that is specific for neoplastic carcinoma cells. A method for obtaining a bacterial preparation having antitumor activity consists of suspending a bacterial isolate in media and exposing the suspension to gamma radiation. A bacterial preparation of an aged culture of an amoeba-associated bacteria exhibits anti-reverse transcriptase activity. A method for obtaining a bacterial preparation having anti-reverse transcriptase activity from an amoeba-associated bacterial isolate grown to stationary phase is disclosed.

Plant growth-promoting bacterial endophytes.

PubMed

Santoyo, Gustavo; Moreno-Hagelsieb, Gabriel; Orozco-Mosqueda, Ma del Carmen; Glick, Bernard R

2016-02-01

Bacterial endophytes ubiquitously colonize the internal tissues of plants, being found in nearly every plant worldwide. Some endophytes are able to promote the growth of plants. For those strains the mechanisms of plant growth-promotion known to be employed by bacterial endophytes are similar to the mechanisms used by rhizospheric bacteria, e.g., the acquisition of resources needed for plant growth and modulation of plant growth and development. Similar to rhizospheric plant growth-promoting bacteria, endophytic plant growth-promoting bacteria can act to facilitate plant growth in agriculture, horticulture and silviculture as well as in strategies for environmental cleanup (i.e., phytoremediation). Genome comparisons between bacterial endophytes and the genomes of rhizospheric plant growth-promoting bacteria are starting to unveil potential genetic factors involved in an endophytic lifestyle, which should facilitate a better understanding of the functioning of bacterial endophytes. Copyright © 2015 Elsevier GmbH. All rights reserved.

Pseudomonas fluorescens N21.4 metabolites enhance secondary metabolism isoflavones in soybean (Glycine max) calli cultures.

PubMed

Algar, Elena; Gutierrez-Mañero, Francisco Javier; Bonilla, Alfonso; Lucas, Jose Antonio; Radzki, Wojtek; Ramos-Solano, Beatriz

2012-11-07

Phytopharmaceuticals are plant secondary metabolites that are strongly inducible and especially sensitive to biotic changes. Plant cell cultures are a good alternative to obtain secondary metabolites, in case effective stimulation can be achieved. In this study, metabolic elicitors from two rhizobacteria able to enhance isoflavone content in soybean seedlings were tested on three different soybean calli cell lines. Results show that metabolic elicitors from Chryseobacterium balustinum Aur9 were not effective. However, there are at least two different metabolic elicitors from Pseudomonas fluorescens N21.4, one under 10 kDa and another over 10 kDa, that trigger isoflavone metabolism in the three cell lines with different isoflavone content. Elicitors from N21.4 achieved total isoflavone increases up to 29.7% (0.205 mg/g), 64.5% (0.487 mg/g), and 23.4% (0.726 mg/g) in the low-, intermediate-, and high-yield lines, respectively. Therefore, these elicitors have a great potential to enhance isoflavone production in cell cultures for development of functional ingredients.

[Bacterial vaginosis].

PubMed

Romero Herrero, Daniel; Andreu Domingo, Antonia

2016-07-01

Bacterial vaginosis (BV) is the main cause of vaginal dysbacteriosis in the women during the reproductive age. It is an entity in which many studies have focused for years and which is still open for discussion topics. This is due to the diversity of microorganisms that cause it and therefore, its difficult treatment. Bacterial vaginosis is probably the result of vaginal colonization by complex bacterial communities, many of them non-cultivable and with interdependent metabolism where anaerobic populations most likely play an important role in its pathogenesis. The main symptoms are an increase of vaginal discharge and the unpleasant smell of it. It can lead to serious consequences for women, such as an increased risk of contracting sexually transmitted infections including human immunodeficiency virus and upper genital tract and pregnancy complications. Gram stain is the gold standard for microbiological diagnosis of BV, but can also be diagnosed using the Amsel clinical criteria. It should not be considered a sexually transmitted disease but it is highly related to sex. Recurrence is the main problem of medical treatment. Apart from BV, there are other dysbacteriosis less characterized like aerobic vaginitis of which further studies are coming slowly but are achieving more attention and consensus among specialists. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

Advances in Bacterial Methionine Aminopeptidase Inhibition

PubMed Central

Helgren, Travis R.; Wangtrakuldee, Phumvadee; Staker, Bart L.; Hagen, Timothy J.

2016-01-01

Methionine aminopeptidases (MetAPs) are metalloenzymes that cleave the N-terminal methionine from newly synthesized peptides and proteins. These MetAP enzymes are present in bacteria, and knockout experiments have shown that MetAP activity is essential for cell life, suggesting that MetAPs are good antibacterial drug targets. MetAP enzymes are also present in the human host and selectivity is essential. There have been significant structural biology efforts and over 65 protein crystal structures of bacterial MetAPs are deposited into the PDB. This review highlights the available crystallographic data for bacterial MetAPs. Structural comparison of bacterial MetAPs with human MetAPs highlights differences that can lead to selectivity. In addition, this review includes the chemical diversity of molecules that bind and inhibit the bacterial MetAP enzymes. Analysis of the structural biology and chemical space of known bacterial MetAP inhibitors leads to a greater understanding of this antibacterial target and the likely development of potential antibacterial agents. PMID:26268344

[Bacterial translocation: gap in the shield].

PubMed

Rosero, Olivér; Kovács, Tibor; Onody, Péter; Harsányi, László; Szijártó, Attila

2014-02-23

The gastrointestinal tract is not only regarded as a system where nutrient absorption takes place, but also as a vital barrier against intraluminal pathogens entering the circulation and the maintenance of immune homeostasis. Bacterial translocation is defined as the penetration of viable bacteria or bacterial compounds from the gastrointestinal tract to extraintestinal sites. This disorder has been described in several clinical conditions. The main promoting factors for bacterial translocation have been proposed to be changes in the intestinal microflora, mucosal barrier failure and defects in host immunity. The presence of bacterial translocation has been associated with higher complications and mortality rates; therefore it should be taken into account in the therapeutic strategies of patients with predisposing factors.

Host Biomarkers for Distinguishing Bacterial from Non-Bacterial Causes of Acute Febrile Illness: A Comprehensive Review

PubMed Central

Kapasi, Anokhi J.; Dittrich, Sabine; González, Iveth J.; Rodwell, Timothy C.

2016-01-01

Background In resource limited settings acute febrile illnesses are often treated empirically due to a lack of reliable, rapid point-of-care diagnostics. This contributes to the indiscriminate use of antimicrobial drugs and poor treatment outcomes. The aim of this comprehensive review was to summarize the diagnostic performance of host biomarkers capable of differentiating bacterial from non-bacterial infections to guide the use of antibiotics. Methods Online databases of published literature were searched from January 2010 through April 2015. English language studies that evaluated the performance of one or more host biomarker in differentiating bacterial from non-bacterial infection in patients were included. Key information extracted included author information, study methods, population, pathogens, clinical information, and biomarker performance data. Study quality was assessed using a combination of validated criteria from the QUADAS and Lijmer checklists. Biomarkers were categorized as hematologic factors, inflammatory molecules, cytokines, cell surface or metabolic markers, other host biomarkers, host transcripts, clinical biometrics, and combinations of markers. Findings Of the 193 citations identified, 59 studies that evaluated over 112 host biomarkers were selected. Most studies involved patient populations from high-income countries, while 19% involved populations from low- and middle-income countries. The most frequently evaluated host biomarkers were C-reactive protein (61%), white blood cell count (44%) and procalcitonin (34%). Study quality scores ranged from 23.1% to 92.3%. There were 9 high performance host biomarkers or combinations, with sensitivity and specificity of ≥85% or either sensitivity or specificity was reported to be 100%. Five host biomarkers were considered weak markers as they lacked statistically significant performance in discriminating between bacterial and non-bacterial infections. Discussion This manuscript provides a summary

The intrinsic resistome of bacterial pathogens

PubMed Central

Olivares, Jorge; Bernardini, Alejandra; Garcia-Leon, Guillermo; Corona, Fernando; B. Sanchez, Maria; Martinez, Jose L.

2013-01-01

Intrinsically resistant bacteria have emerged as a relevant health problem in the last years. Those bacterial species, several of them with an environmental origin, present naturally low-level susceptibility to several drugs. It has been proposed that intrinsic resistance is mainly the consequence of the impermeability of cellular envelopes, the activity of multidrug efflux pumps or the lack of appropriate targets for a given family of drugs. However, recently published articles indicate that the characteristic phenotype of susceptibility to antibiotics of a given bacterial species depends on the concerted activity of several elements, what has been named as intrinsic resistome. These determinants comprise not just classical resistance genes. Other elements, several of them involved in basic bacterial metabolic processes, are of relevance for the intrinsic resistance of bacterial pathogens. In the present review we analyze recent publications on the intrinsic resistomes of Escherichia coli and Pseudomonas aeruginosa. We present as well information on the role that global regulators of bacterial metabolism, as Crc from P. aeruginosa, may have on modulating bacterial susceptibility to antibiotics. Finally, we discuss the possibility of searching inhibitors of the intrinsic resistome in the aim of improving the activity of drugs currently in use for clinical practice. PMID:23641241

The intrinsic resistome of bacterial pathogens.

PubMed

Olivares, Jorge; Bernardini, Alejandra; Garcia-Leon, Guillermo; Corona, Fernando; B Sanchez, Maria; Martinez, Jose L

2013-01-01

Intrinsically resistant bacteria have emerged as a relevant health problem in the last years. Those bacterial species, several of them with an environmental origin, present naturally low-level susceptibility to several drugs. It has been proposed that intrinsic resistance is mainly the consequence of the impermeability of cellular envelopes, the activity of multidrug efflux pumps or the lack of appropriate targets for a given family of drugs. However, recently published articles indicate that the characteristic phenotype of susceptibility to antibiotics of a given bacterial species depends on the concerted activity of several elements, what has been named as intrinsic resistome. These determinants comprise not just classical resistance genes. Other elements, several of them involved in basic bacterial metabolic processes, are of relevance for the intrinsic resistance of bacterial pathogens. In the present review we analyze recent publications on the intrinsic resistomes of Escherichia coli and Pseudomonas aeruginosa. We present as well information on the role that global regulators of bacterial metabolism, as Crc from P. aeruginosa, may have on modulating bacterial susceptibility to antibiotics. Finally, we discuss the possibility of searching inhibitors of the intrinsic resistome in the aim of improving the activity of drugs currently in use for clinical practice.

Statistical analysis of the Bacterial Carbohydrate Structure Data Base (BCSDB): Characteristics and diversity of bacterial carbohydrates in comparison with mammalian glycans

PubMed Central

Herget, Stephan; Toukach, Philip V; Ranzinger, René; Hull, William E; Knirel, Yuriy A; von der Lieth, Claus-Wilhelm

2008-01-01

Background There are considerable differences between bacterial and mammalian glycans. In contrast to most eukaryotic carbohydrates, bacterial glycans are often composed of repeating units with diverse functions ranging from structural reinforcement to adhesion, colonization and camouflage. Since bacterial glycans are typically displayed at the cell surface, they can interact with the environment and, therefore, have significant biomedical importance. Results The sequence characteristics of glycans (monosaccharide composition, modifications, and linkage patterns) for the higher bacterial taxonomic classes have been examined and compared with the data for mammals, with both similarities and unique features becoming evident. Compared to mammalian glycans, the bacterial glycans deposited in the current databases have a more than ten-fold greater diversity at the monosaccharide level, and the disaccharide pattern space is approximately nine times larger. Specific bacterial subclasses exhibit characteristic glycans which can be distinguished on the basis of distinctive structural features or sequence properties. Conclusion For the first time a systematic database analysis of the bacterial glycome has been performed. This study summarizes the current knowledge of bacterial glycan architecture and diversity and reveals putative targets for the rational design and development of therapeutic intervention strategies by comparing bacterial and mammalian glycans. PMID:18694500

The quest for bacterial allergens.

PubMed

Nordengrün, Maria; Michalik, Stephan; Völker, Uwe; Bröker, Barbara M; Gómez-Gascón, Lidia

2018-04-26

Allergies are complex diseases featuring local tissue inflammation, which is characterized by an exaggerated type 2 immune response to environmental compounds known as allergens. Pollens, environmental fungi, and house dust mites are examples of common allergens. Bacteria have a dual role in allergy. Usually, they are associated with protection, however, certain bacterial species promote the development and exacerbation of allergic inflammation. Notably, IgE antibodies specific for bacterial antigens are found in the sera of allergic individuals. This implies that some bacterial factors are allergens, eliciting a specific type 2 immune response. However, to date, only a few of these are molecularly defined. This review summarizes the current knowledge about known bacterial allergens, and it provides an overview of the available techniques for the discovery of new allergens as well as for measuring the immune responses directed against them. Copyright © 2018 The Authors. Published by Elsevier GmbH.. All rights reserved.

Characterisation of the gill mucosal bacterial communities of four butterflyfish species: a reservoir of bacterial diversity in coral reef ecosystems.

PubMed

Reverter, Miriam; Sasal, Pierre; Tapissier-Bontemps, N; Lecchini, D; Suzuki, M

2017-06-01

While recent studies have suggested that fish mucus microbiota play an important role in homeostasis and prevention of infections, very few studies have investigated the bacterial communities of gill mucus. We characterised the gill mucus bacterial communities of four butterflyfish species and although the bacterial diversity of gill mucus varied significantly between species, Shannon diversities were high (H = 3.7-5.7) in all species. Microbiota composition differed between butterflyfishes, with Chaetodon lunulatus and C. ornatissimus having the most similar bacterial communities, which differed significantly from C. vagabundus and C. reticulatus. The core bacterial community of all species consisted of mainly Proteobacteria followed by Actinobacteria and Firmicutes. Chaetodonlunulatus and C. ornatissimus bacterial communities were mostly dominated by Gammaproteobacteria with Vibrio as the most abundant genus. Chaetodonvagabundus and C. reticulatus presented similar abundances of Gammaproteobacteria and Alphaproteobacteria, which were well represented by Acinetobacter and Paracoccus, respectively. In conclusion, our results indicate that different fish species present specific bacterial assemblages. Finally, as mucus layers are nutrient hotspots for heterotrophic bacteria living in oligotrophic environments, such as coral reef waters, the high bacterial diversity found in butterflyfish gill mucus might indicate external fish mucus surfaces act as a reservoir of coral reef bacterial diversity. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Mechanical Homogenization Increases Bacterial Homogeneity in Sputum

PubMed Central

Stokell, Joshua R.; Khan, Ammad

2014-01-01

Sputum obtained from patients with cystic fibrosis (CF) is highly viscous and often heterogeneous in bacterial distribution. Adding dithiothreitol (DTT) is the standard method for liquefaction prior to processing sputum for molecular detection assays. To determine if DTT treatment homogenizes the bacterial distribution within sputum, we measured the difference in mean total bacterial abundance and abundance of Burkholderia multivorans between aliquots of DTT-treated sputum samples with and without a mechanical homogenization (MH) step using a high-speed dispersing element. Additionally, we measured the effect of MH on bacterial abundance. We found a significant difference between the mean bacterial abundances in aliquots that were subjected to only DTT treatment and those of the aliquots which included an MH step (all bacteria, P = 0.04; B. multivorans, P = 0.05). There was no significant effect of MH on bacterial abundance in sputum. Although our results are from a single CF patient, they indicate that mechanical homogenization increases the homogeneity of bacteria in sputum. PMID:24759710

Temperate bacterial viruses as double-edged swords in bacterial warfare.

PubMed

Gama, João Alves; Reis, Ana Maria; Domingues, Iolanda; Mendes-Soares, Helena; Matos, Ana Margarida; Dionisio, Francisco

2013-01-01

It has been argued that bacterial cells may use their temperate viruses as biological weapons. For instance, a few bacterial cells among a population of lysogenic cells could release the virus and kill susceptible non-lysogenic competitors, while their clone mates would be immune. Because viruses replicate inside their victims upon infection, this process would amplify their number in the arena. Sometimes, however, temperate viruses spare recipient cells from death by establishing themselves in a dormant state inside cells. This phenomenon is called lysogenization and, for some viruses such as the λ virus, the probability of lysogenization increases with the multiplicity of infection. Therefore, the amplification of viruses leads to conflicting predictions about the efficacy of temperate viruses as biological weapons: amplification can increase the relative advantage of clone mates of lysogens but also the likelihood of saving susceptible cells from death, because the probability of lysogenization is higher. To test the usefulness of viruses as biological weapons, we performed competition experiments between lysogenic Escherichia coli cells carrying the λ virus and susceptible λ-free E. coli cells, either in a structured or unstructured habitat. In structured and sometimes in unstructured habitats, the λ virus qualitatively behaved as a "replicating toxin". However, such toxic effect of λ viruses ceased after a few days of competition. This was due to the fact that many of initially susceptible cells became lysogenic. Massive lysogenization of susceptible cells occurred precisely under the conditions where the amplification of the virus was substantial. From then on, these cells and their descendants became immune to the λ virus. In conclusion, if at short term bacterial cells may use temperate viruses as biological weapons, after a few days only the classical view of temperate bacterial viruses as parasitic agents prevails.

Temperate Bacterial Viruses as Double-Edged Swords in Bacterial Warfare

PubMed Central

Gama, João Alves; Reis, Ana Maria; Domingues, Iolanda; Mendes-Soares, Helena; Matos, Ana Margarida; Dionisio, Francisco

2013-01-01

It has been argued that bacterial cells may use their temperate viruses as biological weapons. For instance, a few bacterial cells among a population of lysogenic cells could release the virus and kill susceptible non-lysogenic competitors, while their clone mates would be immune. Because viruses replicate inside their victims upon infection, this process would amplify their number in the arena. Sometimes, however, temperate viruses spare recipient cells from death by establishing themselves in a dormant state inside cells. This phenomenon is called lysogenization and, for some viruses such as the λ virus, the probability of lysogenization increases with the multiplicity of infection. Therefore, the amplification of viruses leads to conflicting predictions about the efficacy of temperate viruses as biological weapons: amplification can increase the relative advantage of clone mates of lysogens but also the likelihood of saving susceptible cells from death, because the probability of lysogenization is higher. To test the usefulness of viruses as biological weapons, we performed competition experiments between lysogenic Escherichia coli cells carrying the λ virus and susceptible λ-free E. coli cells, either in a structured or unstructured habitat. In structured and sometimes in unstructured habitats, the λ virus qualitatively behaved as a “replicating toxin”. However, such toxic effect of λ viruses ceased after a few days of competition. This was due to the fact that many of initially susceptible cells became lysogenic. Massive lysogenization of susceptible cells occurred precisely under the conditions where the amplification of the virus was substantial. From then on, these cells and their descendants became immune to the λ virus. In conclusion, if at short term bacterial cells may use temperate viruses as biological weapons, after a few days only the classical view of temperate bacterial viruses as parasitic agents prevails. PMID:23536852

Steroids in bacterial meningitis: yes.

PubMed

Benninger, Felix; Steiner, Israel

2013-02-01

Bacterial meningitis is an infectious condition associated with severe morbidity and mortality, even with rapid diagnosis and appropriate antibiotic therapy. Despite decrease in the rate of bacterial meningitis brought about by vaccination programs against Haemophilus influenzae type-B and Streptococcus pneumonia, the incidence of meningitis is still unacceptably high and acute treatment remains the mainstay of therapy. The infection is accompanied by intense inflammatory response, which may carry deleterious effects upon the tissue. This led to the possibility of adjuvant corticosteroid therapy, as an anti-inflammatory agent, in bacterial meningitis. The debate focuses on the rational and evidence supporting and refuting such an approach.

Bacterial disease management: challenges, experience, innovation and future prospects: Challenges in Bacterial Molecular Plant Pathology.

PubMed

Sundin, George W; Castiblanco, Luisa F; Yuan, Xiaochen; Zeng, Quan; Yang, Ching-Hong

2016-12-01

Plant diseases caused by bacterial pathogens place major constraints on crop production and cause significant annual losses on a global scale. The attainment of consistent effective management of these diseases can be extremely difficult, and management potential is often affected by grower reliance on highly disease-susceptible cultivars because of consumer preferences, and by environmental conditions favouring pathogen development. New and emerging bacterial disease problems (e.g. zebra chip of potato) and established problems in new geographical regions (e.g. bacterial canker of kiwifruit in New Zealand) grab the headlines, but the list of bacterial disease problems with few effective management options is long. The ever-increasing global human population requires the continued stable production of a safe food supply with greater yields because of the shrinking areas of arable land. One major facet in the maintenance of the sustainability of crop production systems with predictable yields involves the identification and deployment of sustainable disease management solutions for bacterial diseases. In addition, the identification of novel management tactics has also come to the fore because of the increasing evolution of resistance to existing bactericides. A number of central research foci, involving basic research to identify critical pathogen targets for control, novel methodologies and methods of delivery, are emerging that will provide a strong basis for bacterial disease management into the future. Near-term solutions are desperately needed. Are there replacement materials for existing bactericides that can provide effective disease management under field conditions? Experience should inform the future. With prior knowledge of bactericide resistance issues evolving in pathogens, how will this affect the deployment of newer compounds and biological controls? Knowledge is critical. A comprehensive understanding of bacterial pathosystems is required to not

Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

NASA Astrophysics Data System (ADS)

Maruthupandy, Muthusamy; Anand, Muthusamy; Maduraiveeran, Govindhan; Sait Hameedha Beevi, Akbar; Jeeva Priya, Radhakrishnan

2015-12-01

The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices.

Rifaximin has minor effects on bacterial composition, inflammation, and bacterial translocation in cirrhosis: A randomized trial.

PubMed

Kimer, Nina; Pedersen, Julie S; Tavenier, Juliette; Christensen, Jeffrey E; Busk, Troels M; Hobolth, Lise; Krag, Aleksander; Al-Soud, Waleed Abu; Mortensen, Martin S; Sørensen, Søren J; Møller, Søren; Bendtsen, Flemming

2018-01-01

Decompensated cirrhosis is characterized by disturbed hemodynamics, immune dysfunction, and high risk of infections. Translocation of viable bacteria and bacterial products from the gut to the blood is considered a key driver in this process. Intestinal decontamination with rifaximin may reduce bacterial translocation (BT) and decrease inflammation. A randomized, placebo-controlled trial investigated the effects of rifaximin on inflammation and BT in decompensated cirrhosis. Fifty-four out-patients with cirrhosis and ascites were randomized, mean age 56 years (± 8.4), and model for end-stage liver disease score 12 (± 3.9). Patients received rifaximin 550-mg BD (n = 36) or placebo BD (n = 18). Blood and fecal (n = 15) sampling were conducted at baseline and after 4 weeks. Bacterial DNA in blood was determined by real-time qPCR 16S rRNA gene quantification. Bacterial composition in feces was analyzed by 16S rRNA gene sequencing. Circulating markers of inflammation, including tumor necrosis factor alpha, interleukins 6, 10, and 18, stromal cell-derived factor 1-α, transforming growth factor β-1, and high sensitivity C-reactive protein, were unaltered by rifaximin treatment. Rifaximin altered abundance of bacterial taxa in blood marginally, only a decrease in Pseudomonadales was observed. In feces, rifaximin decreased bacterial richness, but effect on particular species was not observed. Subgroup analyses on patients with severely disturbed hemodynamics (n = 34) or activated lipopolysaccharide binding protein (n = 37) revealed no effect of rifaximin. Four weeks of treatment with rifaximin had no impact on the inflammatory state and only minor effects on BT and intestinal bacterial composition in stable, decompensated cirrhosis (NCT01769040). © 2017 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

Bacterial Meningitis

MedlinePlus

... Links Vaccine Schedules Preteen & Teen Vaccines Meningococcal Disease Sepsis Bacterial Meningitis Language: English (US) Español (Spanish) Recommend ... can also be associated with another serious illness, sepsis . Sepsis is the body’s overwhelming and life-threatening ...

Bacterial communities in floral nectar.

PubMed

Fridman, Svetlana; Izhaki, Ido; Gerchman, Yoram; Halpern, Malka

2012-02-01

Floral nectar is regarded as the most important reward available to animal-pollinated plants to attract pollinators. Despite the vast amount of publications on nectar properties, the role of nectar as a natural bacterial habitat is yet unexplored. To gain a better understanding of bacterial communities inhabiting floral nectar, culture-dependent and -independent (454-pyrosequencing) methods were used. Our findings demonstrate that bacterial communities in nectar are abundant and diverse. Using culture-dependent method we showed that bacterial communities of nectar displayed significant variation among three plant species: Amygdalus communis, Citrus paradisi and Nicotiana glauca. The dominant class in the nectar bacterial communities was Gammaproteobacteria. About half of the isolates were novel species (< 97% similarities of the 16S rRNA gene with known species). Using 454-pyrosequencing we demonstrated that nectar microbial community are distinct for each of the plant species while there are no significant differences between nectar microbial communities within nectars taken from different plants of the same species. Primary selection of the nectar bacteria is unclear; it may be affected by variations in the chemical composition of the nectar in each plant. The role of the rich and diverse nectar microflora in the attraction-repulsion relationships between the plant and its nectar consumers has yet to be explored. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

Transcriptome landscape of a bacterial pathogen under plant immunity.

PubMed

Nobori, Tatsuya; Velásquez, André C; Wu, Jingni; Kvitko, Brian H; Kremer, James M; Wang, Yiming; He, Sheng Yang; Tsuda, Kenichi

2018-03-27

Plant pathogens can cause serious diseases that impact global agriculture. The plant innate immunity, when fully activated, can halt pathogen growth in plants. Despite extensive studies into the molecular and genetic bases of plant immunity against pathogens, the influence of plant immunity in global pathogen metabolism to restrict pathogen growth is poorly understood. Here, we developed RNA sequencing pipelines for analyzing bacterial transcriptomes in planta and determined high-resolution transcriptome patterns of the foliar bacterial pathogen Pseudomonas syringae in Arabidopsis thaliana with a total of 27 combinations of plant immunity mutants and bacterial strains. Bacterial transcriptomes were analyzed at 6 h post infection to capture early effects of plant immunity on bacterial processes and to avoid secondary effects caused by different bacterial population densities in planta We identified specific "immune-responsive" bacterial genes and processes, including those that are activated in susceptible plants and suppressed by plant immune activation. Expression patterns of immune-responsive bacterial genes at the early time point were tightly linked to later bacterial growth levels in different host genotypes. Moreover, we found that a bacterial iron acquisition pathway is commonly suppressed by multiple plant immune-signaling pathways. Overexpression of a P. syringae sigma factor gene involved in iron regulation and other processes partially countered bacterial growth restriction during the plant immune response triggered by AvrRpt2. Collectively, this study defines the effects of plant immunity on the transcriptome of a bacterial pathogen and sheds light on the enigmatic mechanisms of bacterial growth inhibition during the plant immune response.

Analysis of bacterial communities and bacterial pathogens in a biogas plant by the combination of ethidium monoazide, PCR and Ion Torrent sequencing.

PubMed

Luo, Gang; Angelidaki, Irini

2014-09-01

The present study investigated the changes of bacterial community composition including bacterial pathogens along a biogas plant, i.e. from the influent, to the biogas reactor and to the post-digester. The effects of post-digestion temperature and time on the changes of bacterial community composition and bacterial pathogens were also studied. Microbial analysis was made by Ion Torrent sequencing of the PCR amplicons from ethidium monoazide treated samples, and ethidium monoazide was used to cleave DNA from dead cells and exclude it from PCR amplification. Both similarity and taxonomic analysis showed that the bacterial community composition in the influent was changed after anaerobic digestion. Firmicutes were dominant in all the samples, while Proteobacteria decreased in the biogas reactor compared with the influent. Variations of bacterial community composition in the biogas reactor with time were also observed. This could be attributed to varying composition of the influent. Batch experiments showed that the methane recovery from the digested residues (obtained from biogas reactor) was mainly related with post-digestion temperature. However, post-digestion time rather than temperature had a significant effect on the changes of bacterial community composition. The changes of bacterial community composition were also reflected in the changes of relative abundance of bacterial pathogens. The richness and relative abundance of bacterial pathogens were reduced after anaerobic digestion in the biogas reactor. It was found in batch experiments that bacterial pathogens showed the highest relative abundance and richness after 30 days' post-digestion. Streptococcus bovis was found in all the samples. Our results showed that special attention should be paid to the post-digestion since the increase in relative abundance of bacterial pathogens after post-digestion might reflect regrowth of bacterial pathogens and limit biosolids disposal vectors. Copyright © 2014 Elsevier

Non-homogeneous flow profiles in sheared bacterial suspensions

NASA Astrophysics Data System (ADS)

Samanta, Devranjan; Cheng, Xiang

Bacterial suspensions under shear exhibit interesting rheological behaviors including the remarkable ``superfluidic'' state with vanishing viscosity at low shear rates. Theoretical studies have shown that such ``superfluidic'' state is linked with non-homogeneous shear flows, which are induced by coupling between nematic order of active fluids and hydrodynamics of shear flows. However, although bulk rheology of bacterial suspensions has been experimentally studied, shear profiles within bacterial suspensions have not been explored so far. Here, we experimentally investigate the flow behaviors of E. coli suspensions under planar oscillatory shear. Using confocal microscopy and PIV, we measure velocity profiles across gap between two shear plates. We find that with increasing shear rates, high-concentration bacterial suspensions exhibit an array of non-homogeneous flow behaviors like yield-stress flows and shear banding. We show that these non-homogeneous flows are due to collective motion of bacterial suspensions. The phase diagram of sheared bacterial suspensions is systematically mapped as functions of shear rates an bacterial concentrations. Our experiments provide new insights into rheology of bacterial suspensions and shed light on shear induced dynamics of active fluids. Chemical Engineering and Material Science department.

Bacterial reproductive pathogens of cats and dogs.

PubMed

Graham, Elizabeth M; Taylor, David J

2012-05-01

With the notable exception of Brucella canis, exogenous bacterial pathogens are uncommon causes of reproductive disease in cats and dogs. Most bacterial reproductive infections are endogenous, and predisposing factors for infection are important. This article reviews the etiology, pathogenesis, clinical presentation, diagnosis, treatment, and public health significance of bacterial reproductive pathogens in cats and dogs.

Role of quorum sensing in bacterial infections

PubMed Central

Castillo-Juárez, Israel; Maeda, Toshinari; Mandujano-Tinoco, Edna Ayerim; Tomás, María; Pérez-Eretza, Berenice; García-Contreras, Silvia Julieta; Wood, Thomas K; García-Contreras, Rodolfo

2015-01-01

Quorum sensing (QS) is cell communication that is widely used by bacterial pathogens to coordinate the expression of several collective traits, including the production of multiple virulence factors, biofilm formation, and swarming motility once a population threshold is reached. Several lines of evidence indicate that QS enhances virulence of bacterial pathogens in animal models as well as in human infections; however, its relative importance for bacterial pathogenesis is still incomplete. In this review, we discuss the present evidence from in vitro and in vivo experiments in animal models, as well as from clinical studies, that link QS systems with human infections. We focus on two major QS bacterial models, the opportunistic Gram negative bacteria Pseudomonas aeruginosa and the Gram positive Staphylococcus aureus, which are also two of the main agents responsible of nosocomial and wound infections. In addition, QS communication systems in other bacterial, eukaryotic pathogens, and even immune and cancer cells are also reviewed, and finally, the new approaches proposed to combat bacterial infections by the attenuation of their QS communication systems and virulence are also discussed. PMID:26244150

Bacterial Community Succession in Pine-Wood Decomposition.

PubMed

Kielak, Anna M; Scheublin, Tanja R; Mendes, Lucas W; van Veen, Johannes A; Kuramae, Eiko E

2016-01-01

Though bacteria and fungi are common inhabitants of decaying wood, little is known about the relationship between bacterial and fungal community dynamics during natural wood decay. Based on previous studies involving inoculated wood blocks, strong fungal selection on bacteria abundance and community composition was expected to occur during natural wood decay. Here, we focused on bacterial and fungal community compositions in pine wood samples collected from dead trees in different stages of decomposition. We showed that bacterial communities undergo less drastic changes than fungal communities during wood decay. Furthermore, we found that bacterial community assembly was a stochastic process at initial stage of wood decay and became more deterministic in later stages, likely due to environmental factors. Moreover, composition of bacterial communities did not respond to the changes in the major fungal species present in the wood but rather to the stage of decay reflected by the wood density. We concluded that the shifts in the bacterial communities were a result of the changes in wood properties during decomposition and largely independent of the composition of the wood-decaying fungal communities.

Bacterial Community Succession in Pine-Wood Decomposition

PubMed Central

Kielak, Anna M.; Scheublin, Tanja R.; Mendes, Lucas W.; van Veen, Johannes A.; Kuramae, Eiko E.

2016-01-01

Though bacteria and fungi are common inhabitants of decaying wood, little is known about the relationship between bacterial and fungal community dynamics during natural wood decay. Based on previous studies involving inoculated wood blocks, strong fungal selection on bacteria abundance and community composition was expected to occur during natural wood decay. Here, we focused on bacterial and fungal community compositions in pine wood samples collected from dead trees in different stages of decomposition. We showed that bacterial communities undergo less drastic changes than fungal communities during wood decay. Furthermore, we found that bacterial community assembly was a stochastic process at initial stage of wood decay and became more deterministic in later stages, likely due to environmental factors. Moreover, composition of bacterial communities did not respond to the changes in the major fungal species present in the wood but rather to the stage of decay reflected by the wood density. We concluded that the shifts in the bacterial communities were a result of the changes in wood properties during decomposition and largely independent of the composition of the wood-decaying fungal communities. PMID:26973611

Corticosteroids for Bacterial Keratitis

PubMed Central

Srinivasan, Muthiah; Mascarenhas, Jeena; Rajaraman, Revathi; Ravindran, Meenakshi; Lalitha, Prajna; Glidden, David V.; Ray, Kathryn J.; Hong, Kevin C.; Oldenburg, Catherine E.; Lee, Salena M.; Zegans, Michael E.; McLeod, Stephen D.; Lietman, Thomas M.; Acharya, Nisha R.

2013-01-01

Objective To determine whether there is a benefit in clinical outcomes with the use of topical corticosteroids as adjunctive therapy in the treatment of bacterial corneal ulcers. Methods Randomized, placebo-controlled, double-masked, multicenter clinical trial comparing prednisolone sodium phosphate, 1.0%, to placebo as adjunctive therapy for the treatment of bacterial corneal ulcers. Eligible patients had a culture-positive bacterial corneal ulcer and received topical moxifloxacin for at least 48 hours before randomization. Main Outcome Measures The primary outcome was best spectacle-corrected visual acuity (BSCVA) at 3 months from enrollment. Secondary outcomes included infiltrate/scar size, reepithelialization, and corneal perforation. Results Between September 1, 2006, and February 22, 2010, 1769 patients were screened for the trial and 500 patients were enrolled. No significant difference was observed in the 3-month BSCVA (−0.009 logarithm of the minimum angle of resolution [logMAR]; 95% CI, −0.085 to 0.068; P = .82), infiltrate/scar size (P = .40), time to reepithelialization (P = .44), or corneal perforation (P > .99). A significant effect of corticosteroids was observed in subgroups of baseline BSCVA (P = .03) and ulcer location (P = .04). At 3 months, patients with vision of counting fingers or worse at baseline had 0.17 logMAR better visual acuity with corticosteroids (95% CI, −0.31 to −0.02; P = .03) compared with placebo, and patients with ulcers that were completely central at baseline had 0.20 logMAR better visual acuity with corticosteroids (−0.37 to −0.04; P = .02). Conclusions We found no overall difference in 3-month BSCVA and no safety concerns with adjunctive corticosteroid therapy for bacterial corneal ulcers. Application to Clinical Practice Adjunctive topical corticosteroid use does not improve 3-month vision in patients with bacterial corneal ulcers. PMID:21987582

Diagnosis and treatment of bacterial prostatitis.

PubMed

Videčnik Zorman, Jerneja; Matičič, Mojca; Jeverica, Samo; Smrkolj, Tomaž

2015-01-01

Prostate inflammation is a common syndrome, especially in men under 50. It usually presents with voiding symptoms and pain in the genitourinary area, and sometimes as sexual dysfunction. Based on clinical and laboratory characteristics, prostatitis is classified as acute bacterial prostatitis, chronic bacterial prostatitis, chronic inflammatory and non-inflammatory prostatitis or chronic pelvic pain syndrome, and asymptomatic inflammatory prostatitis. Bacterial prostatitis is most often caused by infection with uropathogens, mainly Gram-negative bacilli, but Gram-positive and atypical microorganisms have also been identified as causative organisms of chronic prostatitis. According to reports by several authors, Chlamydia trachomatis and Trichomonas vaginalis are some of the most common pathogens, making chronic prostatitis a sexually transmitted disease. Diagnosis and treatment of acute and chronic bacterial prostatitis in particular can be challenging.

Bacterial endophytes enhance competition by invasive plants.

PubMed

Rout, Marnie E; Chrzanowski, Thomas H; Westlie, Tara K; DeLuca, Thomas H; Callaway, Ragan M; Holben, William E

2013-09-01

Invasive plants can alter soil microbial communities and profoundly alter ecosystem processes. In the invasive grass Sorghum halepense, these disruptions are consequences of rhizome-associated bacterial endophytes. We describe the effects of N2-fixing bacterial strains from S. halepense (Rout and Chrzanowski, 2009) on plant growth and show that bacteria interact with the plant to alter soil nutrient cycles, enabling persistence of the invasive. • We assessed fluxes in soil nutrients for ∼4 yr across a site invaded by S. halepense. We assayed the N2-fixing bacteria in vitro for phosphate solubilization, iron chelation, and production of the plant-growth hormone indole-3-acetic acid (IAA). We assessed the plant's ability to recruit bacterial partners from substrates and vertically transmit endophytes to seeds and used an antibiotic approach to inhibit bacterial activity in planta and assess microbial contributions to plant growth. • We found persistent alterations to eight biogeochemical cycles (including nitrogen, phosphorus, and iron) in soils invaded by S. halepense. In this context, three bacterial isolates solubilized phosphate, and all produced iron siderophores and IAA in vitro. In growth chamber experiments, bacteria were transmitted vertically, and molecular analysis of bacterial community fingerprints from rhizomes indicated that endophytes are also horizontally recruited. Inhibiting bacterial activity with antibiotics resulted in significant declines in plant growth rate and biomass, with pronounced rhizome reductions. • This work suggests a major role of endophytes on growth and resource allocation of an invasive plant. Indeed, bacterial isolate physiology is correlated with invader effects on biogeochemical cycles of nitrogen, phosphate, and iron.

Elucidating Duramycin’s Bacterial Selectivity and Mode of Action on the Bacterial Cell Envelope

DOE PAGES

Hasim, Sahar; Allison, David P.; Mendez, Berlin; ...

2018-02-14

The use of naturally occurring antimicrobial peptides provides a promising route to selectively target pathogenic agents and to shape microbiome structure. Lantibiotics, such as duramycin, are one class of bacterially produced peptidic natural products that can selectively inhibit the growth of other bacteria. However, despite longstanding characterization efforts, the microbial selectivity and mode of action of duramycin are still obscure. We describe here a suite of biological, chemical, and physical characterizations that shed new light on the selective and mechanistic aspects of duramycin activity. Bacterial screening assays have been performed using duramycin and Populus-derived bacterial isolates to determine species selectivity.more » Lipidomic profiles of selected resistant and sensitive strains show that the sensitivity of Gram-positive bacteria depends on the presence of phosphatidylethanolamine (PE) in the cell membrane. Further the surface and interface morphology were studied by high resolution atomic force microscopy and showed a progression of cellular changes in the cell envelope after treatment with duramycin for the susceptible bacterial strains. Together, these molecular and cellular level analyses provide insight into duramycin’s mode of action and a better understanding of its selectivity.« less

Elucidating Duramycin’s Bacterial Selectivity and Mode of Action on the Bacterial Cell Envelope

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

Hasim, Sahar; Allison, David P.; Mendez, Berlin

The use of naturally occurring antimicrobial peptides provides a promising route to selectively target pathogenic agents and to shape microbiome structure. Lantibiotics, such as duramycin, are one class of bacterially produced peptidic natural products that can selectively inhibit the growth of other bacteria. However, despite longstanding characterization efforts, the microbial selectivity and mode of action of duramycin are still obscure. We describe here a suite of biological, chemical, and physical characterizations that shed new light on the selective and mechanistic aspects of duramycin activity. Bacterial screening assays have been performed using duramycin and Populus-derived bacterial isolates to determine species selectivity.more » Lipidomic profiles of selected resistant and sensitive strains show that the sensitivity of Gram-positive bacteria depends on the presence of phosphatidylethanolamine (PE) in the cell membrane. Further the surface and interface morphology were studied by high resolution atomic force microscopy and showed a progression of cellular changes in the cell envelope after treatment with duramycin for the susceptible bacterial strains. Together, these molecular and cellular level analyses provide insight into duramycin’s mode of action and a better understanding of its selectivity.« less

Diagnosis of bacterial vaginosis by Amsel's criteria.

PubMed

Iftikhar, Razia

2003-02-01

To evaluate Amsel's criteria for the diagnosis of bacterial vaginosis in reproductive age group. Prospective study. This study was conducted in a private hospital in Jeddah, K.S.A between January, 2001 and January, 2002. Patients attending the clinic with complaint of vaginal discharge were selected and screened out for bacterial vaginosis on the basis of Amsel's criteria. Ot of 100 cases 35 (35%) cases were diagnosed as bacterial vaginosis, 25 (25%) were of Candida albicans and 15 (15%) were suffering from trichomoniasis. No pathogen was found in 25 patients. Amsel's criteria is an accurate test for the diagnosis of bacterial vaginosis.

Local mechanical stimulation induces components of the pathogen defense response in parsley

PubMed Central

Gus-Mayer, Sabine; Naton, Beatrix; Hahlbrock, Klaus; Schmelzer, Elmon

1998-01-01

Cell suspension cultures of parsley (Petroselinum crispum) have previously been used as a suitable system for studies of the nonhost resistance response to Phytophthora sojae. In this study, we replaced the penetrating fungus by local mechanical stimulation by using a needle of the same diameter as a fungal hypha, by local application of a structurally defined fungus-derived elicitor, or by a combination of the two stimuli. Similar to the fungal infection hypha, the local mechanical stimulus alone induced the translocation of cytoplasm and nucleus to the site of stimulation, the generation of intracellular reactive oxygen intermediates (ROI), and the expression of some, but not all, elicitor-responsive genes. When the elicitor was applied locally to the cell surface without mechanical stimulation, intracellular ROI also accumulated rapidly, but morphological changes were not detected. A combination of the mechanical stimulus with simultaneous application of low doses of elicitor closely simulated early reactions to fungal infection, including cytoplasmic aggregation, nuclear migration, and ROI accumulation. By contrast, cytoplasmic rearrangements were impaired at high elicitor concentrations. Neither papilla formation nor hypersensitive cell death occurred under the conditions tested. These results suggest that mechanical stimulation by the invading fungus is responsible for the observed intracellular rearrangements and may trigger some of the previously demonstrated changes in the activity of elicitor-responsive genes, whereas chemical stimulation is required for additional biochemical processes. As yet unidentified signals may be involved in papilla formation and hypersensitive cell death. PMID:9653198

Phytoalexin Induction in French Bean 1

PubMed Central

Dixon, Richard A.; Dey, Prakash M.; Lawton, Michael A.; Lamb, Christopher J.

1983-01-01

Treatment of hypocotyl sections or cell suspension cultures of dwarf French bean (Phaseolus vulgaris L.) with an abiotic elicitor (denatured ribonuclease A) resulted in increased extractable activity of the enzyme l-phenylalanine ammonia-lyase. This induction could be transmitted from treated cells through a dialysis membrane to cells which were not in direct contact with the elicitor. In hypocotyl sections, induction of isoflavonoid phytoalexin accumulation was also transmitted across a dialysis membrane, although levels of insoluble, lignin-like phenolic material remained unchanged in elicitor-treated and control sections. In bean cell suspension cultures, the induction of phenylalanine ammonia-lyase in cells separated from ribonuclease-treated cells by a dialysis membrane was also accompanied by increases in the activities of chalcone synthase and chalcone isomerase, two enzymes previously implicated in the phytoalexin defense response. Such intercellular transmission of elicitation did not occur in experiments with cells treated with a biotic elicitor preparation heat-released from the cell walls of the bean pathogen Colletotrichum lindemuthianum. The results confirm and extend previous suggestions that a low molecular weight, diffusible factor of host plant origin is involved (in French bean) in the intercellular transmission of the elicitation response to abiotic elicitors. PMID:16662813

QTLs for Resistance to Major Rice Diseases Exacerbated by Global Warming: Brown Spot, Bacterial Seedling Rot, and Bacterial Grain Rot.

PubMed

Mizobuchi, Ritsuko; Fukuoka, Shuichi; Tsushima, Seiya; Yano, Masahiro; Sato, Hiroyuki

2016-12-01

In rice (Oryza sativa L.), damage from diseases such as brown spot, caused by Bipolaris oryzae, and bacterial seedling rot and bacterial grain rot, caused by Burkholderia glumae, has increased under global warming because the optimal temperature ranges for growth of these pathogens are relatively high (around 30 °C). Therefore, the need for cultivars carrying genes for resistance to these diseases is increasing to ensure sustainable rice production. In contrast to the situation for other important rice diseases such as blast and bacterial blight, no genes for complete resistance to brown spot, bacterial seedling rot or bacterial grain rot have yet been discovered. Thus, rice breeders have to use partial resistance, which is largely influenced by environmental conditions. Recent progress in molecular genetics and improvement of evaluation methods for disease resistance have facilitated detection of quantitative trait loci (QTLs) associated with resistance. In this review, we summarize the results of worldwide screening for cultivars with resistance to brown spot, bacterial seedling rot and bacterial grain rot and we discuss the identification of QTLs conferring resistance to these diseases in order to provide useful information for rice breeding programs.

Bacterially mediated mineralization of vaterite

NASA Astrophysics Data System (ADS)

Rodriguez-Navarro, Carlos; Jimenez-Lopez, Concepcion; Rodriguez-Navarro, Alejandro; Gonzalez-Muñoz, Maria Teresa; Rodriguez-Gallego, Manuel

2007-03-01

Myxococcus xanthus, a common soil bacterium, plays an active role in the formation of spheroidal vaterite. Bacterial production of CO 2 and NH 3 and the transformation of the NH 3 to NH4+ and OH -, thus increasing solution pH and carbonate alkalinity, set the physicochemical conditions (high supersaturation) leading to vaterite precipitation in the microenvironment around cells, and directly onto the surface of bacterial cells. In the latter case, fossilization of bacteria occurs. Vaterite crystals formed by aggregation of oriented nanocrystals with c-axis normal to the bacterial cell-wall, or to the core of the spherulite when bacteria were not encapsulated. While preferred orientation of vaterite c-axis appears to be determined by electrostatic affinity (ionotropic effect) between vaterite crystal (0001) planes and the negatively charged functional groups of organic molecules on the bacterium cell-wall or on extracellular polymeric substances (EPS), analysis of the changes in the culture medium chemistry as well as high resolution transmission electron microscopy (HRTEM) observations point to polymorph selection by physicochemical (kinetic) factors (high supersaturation) and stabilization by organics, both connected with bacterial activity. The latter is in agreement with inorganic precipitation of vaterite induced by NH 3 and CO 2 addition in the protein-rich sterile culture medium. Our results as well as recent studies on vaterite precipitation in the presence of different types of bacteria suggest that bacterially mediated vaterite precipitation is not strain-specific, and could be more common than previously thought.

Peritonitis - spontaneous bacterial

MedlinePlus

Spontaneous bacterial peritonitis (SBP); Ascites - peritonitis; Cirrhosis - peritonitis ... who are on peritoneal dialysis for kidney failure. Peritonitis may have other causes . These include infection from ...

Crossroads between Bacterial and Mammalian Glycosyltransferases

PubMed Central

Brockhausen, Inka

2014-01-01

Bacterial glycosyltransferases (GT) often synthesize the same glycan linkages as mammalian GT; yet, they usually have very little sequence identity. Nevertheless, enzymatic properties, folding, substrate specificities, and catalytic mechanisms of these enzyme proteins may have significant similarity. Thus, bacterial GT can be utilized for the enzymatic synthesis of both bacterial and mammalian types of complex glycan structures. A comparison is made here between mammalian and bacterial enzymes that synthesize epitopes found in mammalian glycoproteins, and those found in the O antigens of Gram-negative bacteria. These epitopes include Thomsen–Friedenreich (TF or T) antigen, blood group O, A, and B, type 1 and 2 chains, Lewis antigens, sialylated and fucosylated structures, and polysialic acids. Many different approaches can be taken to investigate the substrate binding and catalytic mechanisms of GT, including crystal structure analyses, mutations, comparison of amino acid sequences, NMR, and mass spectrometry. Knowledge of the protein structures and functions helps to design GT for specific glycan synthesis and to develop inhibitors. The goals are to develop new strategies to reduce bacterial virulence and to synthesize vaccines and other biologically active glycan structures. PMID:25368613

Effectiveness of Polyvalent Bacterial Lysate and Autovaccines Against Upper Respiratory Tract Bacterial Colonization by Potential Pathogens: A Randomized Study

PubMed Central

Zagólski, Olaf; Stręk, Paweł; Kasprowicz, Andrzej; Białecka, Anna

2015-01-01

Background Polyvalent bacterial lysate (PBL) is an oral immunostimulating vaccine consisting of bacterial standardized lysates obtained by lysis of different strains of bacteria. Autovaccines are individually prepared based on the results of smears obtained from the patient. Both types of vaccine can be used to treat an ongoing chronic infection. This study sought to determine which method is more effective against nasal colonization by potential respiratory tract pathogens. Material/Methods We enrolled 150 patients with aerobic Gram stain culture and count results indicating bacterial colonization of the nose and/or throat by potential pathogens. The participants were randomly assigned to each of the following groups: 1. administration of PBL, 2. administration of autovaccine, and 3. no intervention (controls). Results Reduction of the bacterial count in Streptococcus pneumoniae-colonized participants was significant after the autovaccine (p<0.001) and PBL (p<0.01). Reduction of the bacterial count of other β-hemolytic streptococcal strains after treatment with the autovaccine was significant (p<0.01) and was non-significant after PBL. In Haemophilus influenzae colonization, significant reduction in the bacterial count was noted in the PBL group (p<0.01). Methicillin-resistant Staphylococcus aureus colonization did not respond to either treatment. Conclusions The autovaccine is more effective than PBL for reducing bacterial count of Streptococcus pneumoniae and β-hemolytic streptococci, while PBL was more effective against Haemophilus influenzae colonization. PMID:26434686

An evaluation of bacterial contamination of barriers used in periapical tissue regeneration: Part 2--Bacterial penetration.

PubMed

Sharma, Priya; Mickel, André K; Chogle, Sami; Sharma, Prem Nath; Han, Yiping W; Jones, Jefferson J

2008-03-01

To compare the relative penetration of Prevotella melaninogenica and Enterococcus faecalis through 3 guided tissue regeneration membranes: Atrisorb, Lambone, and OsseoQuest. It was hypothesized that OsseoQuest would show increased bacterial penetration when compared to Lambone and Atrisorb. Centrifuge tubes containing trypticase soy broth were sealed with circular sections of membranes and placed in test tubes containing culture media. The bacterial penetration was assessed by passage of bacteria from the outer tube culture media to the inner centrifuge tube media through the membrane. After incubation for 4 and 48 hours, the media from the outer and inner tubes were compared for bacterial count. P melaninogenica exhibited 91% penetration for Lambone in 2 days, while OsseoQuest displayed 87% penetration with E faecalis in the same time. Atrisorb displayed a minimal penetration with both bacteria (2%). Atrisorb displayed the least bacterial penetration, which may be attributed to membrane structure, chemical configuration, hydrophobicity, and porosity of tested membranes.

Bacterial Degradation of Aromatic Compounds

PubMed Central

Seo, Jong-Su; Keum, Young-Soo; Li, Qing X.

2009-01-01

Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatics. Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups. Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds. Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms. PMID:19440284

Assembling the bacterial segrosome.

PubMed

Hayes, Finbarr; Barillà, Daniela

2006-05-01

Genome segregation in prokaryotes is a highly ordered process that integrates with DNA replication, cytokinesis and other fundamental facets of the bacterial cell cycle. The segrosome is the nucleoprotein complex that mediates DNA segregation in bacteria, its assembly and organization is best understood for plasmid partition. The recent elucidation of structures of the ParB plasmid segregation protein bound to centromeric DNA, and of the tertiary structures of other segregation proteins, are key milestones in the path to deciphering the molecular basis of bacterial DNA segregation.

Direct detection of various pathogens by loop-mediated isothermal amplification assays on bacterial culture and bacterial colony.

PubMed

Yan, Muxia; Li, Weidong; Zhou, Zhenwen; Peng, Hongxia; Luo, Ziyan; Xu, Ling

2017-01-01

In this work, loop-mediated isothermal amplification based detection assay using bacterial culture and bacterial colony for various common pathogens direct detection had been established, evaluated and further applied. A total of five species of common pathogens and nine detection targets (tlh, tdh and trh for V. Parahaemolyticus, rfbE, stx1 and stx2 for E. coli, oprI for P. aeruginosa, invA for Salmonella and hylA for L. monocytogenes) were performed on bacterial culture and bacterial colony LAMP. To evaluate and optimize this assay, a total of 116 standard strains were included. Then, for each detected targets, 20 random selected strains were applied. Results were determined through both visual observation of the changed color by naked eye and electrophoresis, which increased the accuracy of survey. The minimum adding quantity of each primer had been confirmed, and the optimal amplification was obtained under 65 °C for 45 min with 25 μl reaction volume. The detection limit of bacterial culture LAMP and PCR assay were determined to be 10 2 and 10 4 or 10 5  CFU/reaction, respectively. No false positive amplification was observed when subjecting the bacterial -LAMP assay to 116 reference strains. This was the first report of colony-LAMP and culture-LAMP assay, which had been demonstrated to be a fast, reliable, cost-effective and simple method on detection of various common pathogens. Copyright © 2016 Elsevier Ltd. All rights reserved.

Marine mesocosm bacterial colonisation of volcanic ash

NASA Astrophysics Data System (ADS)

Witt, Verena; Cimarelli, Corrado; Ayris, Paul; Kueppers, Ulrich; Erpenbeck, Dirk; Dingwell, Donald; Woerheide, Gert

2015-04-01

Volcanic eruptions regularly eject large quantities of ash particles into the atmosphere, which can be deposited via fallout into oceanic environments. Such fallout has the potential to alter pH, light and nutrient availability at local scales. Shallow-water coral reef ecosystems - "rainforests of the sea" - are highly sensitive to disturbances, such as ocean acidification, sedimentation and eutrophication. Therefore, wind-delivered volcanic ash may lead to burial and mortality of such reefs. Coral reef ecosystem resilience may depend on pioneer bacterial colonisation of the ash layer, supporting subsequent establishment of the micro- and ultimately the macro-community. However, which bacteria are involved in pioneer colonisation remain unknown. We hypothesize that physico-chemical properties (i.e., morphology, mineralogy) of the ash may dictate bacterial colonisation. The effect of substrate properties on bacterial colonisation was tested by exposing five substrates: i) quartz sand ii) crystalline ash (Sakurajima, Japan) iii) volcanic glass iv) carbonate reef sand and v) calcite sand of similar grain size, in controlled marine coral reef aquaria under low light conditions for six months. Bacterial communities were screened every month by Automated Ribosomal Intergenic Spacer Analysis of the 16S-23S rRNA Internal Transcribed Spacer region. Multivariate statistics revealed discrete groupings of bacterial communities on substrates of volcanic origin (ash and glass) and reef origin (three sands). Analysis of Similarity supported significantly different communities associated with all substrates (p=0.0001), only quartz did not differ from both carbonate and calcite sands. The ash substrate exhibited the most diverse bacterial community with the most substrate-specific bacterial operational taxonomic units. Our findings suggest that bacterial diversity and community composition during colonisation of volcanic ash in a coral reef-like environment is controlled by the

Marine Mesocosm Bacterial Colonisation of Volcanic Ash

NASA Astrophysics Data System (ADS)

Witt, V.; Cimarelli, C.; Ayris, P. M.; Kueppers, U.; Erpenbeck, D.; Dingwell, D. B.; Woerheide, G.

2014-12-01

Explosive volcanic eruptions regularly eject large quantities of ash particles into the atmosphere, which can be deposited via fallout into oceanic environments. Such fallout has the potential to alter pH, light and nutrient availability at local or regional scales. Shallow-water coral reef ecosystems - "rainforests of the sea" - are highly sensitive to disturbances, such as ocean acidification, sedimentation and eutrophication. Therefore, ash deposition may lead to burial and mortality of such reefs. Coral reef ecosystem resilience may depend on pioneer bacterial colonisation of the ash layer, supporting subsequent establishment of the micro- and ultimately the macro-community. However, it is currently unknown which bacteria are involved in pioneer colonisation. We hypothesize that physico-chemical properties (i.e., morphology, chemistry, mineralogy) of the ash may dictate bacterial colonisation. We have tested the effect of substrate properties on bacterial diversity and abundance colonising five substrates: i) quartz sand ii) crystalline ash from the Sakurajima volcano (Japan) iii) volcanic glass iv) carbonate reef sand and v) calcite sand of similar grain size - by incubation in a controlled marine mesocosm (coral reef aquarium) under low light conditions for three months. Bacterial communities were screened every month by Automated Ribosomal Intergenic Spacer Analysis of the 16S-23S rRNA Internal Transcribed Spacer region. Multivariate statistics revealed discrete groupings of bacterial communities on substrates of volcanic origin (ash and glass) and reef origin (three sands). Analysis Of Similarity supports significantly different communities associated with all substrates (p=0.0001), only quartz did not differ from both carbonate and calcite sands. The ash substrate exhibited the most diverse bacterial community and carried the most substrate-specific bacterial operational taxonomic units. Our findings suggest that bacterial diversity and community

Copper effects on bacterial activity of estuarine silty sediments

NASA Astrophysics Data System (ADS)

Almeida, Adelaide; Cunha, Ângela; Fernandes, Sandra; Sobral, Paula; Alcântara, Fernanda

2007-07-01

Bacteria of silty estuarine sediments were spiked with copper to 200 μg Cu g -1 dry weight sediment in order to assess the impact of copper on bacterial degradation of organic matter and on bacterial biomass production. Bacterial density was determined by direct counting under epifluorescence microscopy and bacterial production by the incorporation of 3H-Leucine. Leucine turnover rate was evaluated by 14C-leucine incorporation and ectoenzymatic activities were estimated as the hydrolysis rate of model substrates for β-glucosidase and leucine-aminopeptidase. The presence of added copper in the microcosms elicited, after 21 days of incubation, generalised anoxia and a decrease in organic matter content. The non-eroded surface of the copper-spiked sediment showed, when compared to the control, a decrease in bacterial abundance and significant lower levels of bacterial production and of leucine turnover rate. Bacterial production and leucine turnover rate decreased to 1.4% and 13% of the control values, respectively. Ectoenzymatic activities were also negatively affected but by smaller factors. After erosion by the water current in laboratory flume conditions, the eroded surface of the control sediment showed a generalised decline in all bacterial activities. The erosion of the copper-spiked sediment showed, however, two types of responses with respect to bacterial activities at the exposed surface: positive responses of bacterial production and leucine turnover rate contrasting with slight negative responses of ectoenzymatic activities. The effects of experimental erosion in the suspended cells were also different in the control and in the copper-spiked sediment. Bacterial cells in the control microcosm exhibited, when compared to the non-eroded sediment cells, decreases in all activities after the 6-h suspension. The response of the average suspended copper-spiked sediment cell differed from the control by a less sharp decrease in ectoenzymatic activities and

Colon-targeted delivery of live bacterial cell biotherapeutics including microencapsulated live bacterial cells

PubMed Central

Prakash, Satya; Malgorzata Urbanska, Aleksandra

2008-01-01

There has been an ample interest in delivery of therapeutic molecules using live cells. Oral delivery has been stipulated as best way to deliver live cells to humans for therapy. Colon, in particular, is a part of gastrointestinal (GI) tract that has been proposed to be an oral targeted site. The main objective of these oral therapy procedures is to deliver live cells not only to treat diseases like colorectal cancer, inflammatory bowel disease, and other GI tract diseases like intestinal obstruction and gastritis, but also to deliver therapeutic molecules for overall therapy in various diseases such as renal failure, coronary heart disease, hypertension, and others. This review provides a comprehensive summary of recent advancement in colon targeted live bacterial cell biotherapeutics. Current status of bacterial cell therapy, principles of artificial cells and its potentials in oral delivery of live bacterial cell biotherapeutics for clinical applications as well as biotherapeutic future perspectives are also discussed in our review. PMID:19707368

Polymicrobial airway bacterial communities in adult bronchiectasis patients

PubMed Central

2014-01-01

Background Chronic airway infection contributes to the underlying pathogenesis of non-cystic fibrosis bronchiectasis (NCFBr). In contrast to other chronic airway infections, associated with COPD and CF bronchiectasis, where polymicrobial communities have been implicated in lung damage due to the vicious circle of recurrent bacterial infections and inflammation, there is sparse information on the composition of bacterial communities in NCFBr. Seventy consecutive patients were recruited from an outpatient adult NCFBr clinic. Bacterial communities in sputum samples were analysed by culture and pyrosequencing approaches. Bacterial sequences were analysed using partial least square discrimination analyses to investigate trends in community composition and identify those taxa that contribute most to community variation. Results The lower airway in NCFBr is dominated by three bacterial taxa Pasteurellaceae, Streptococcaceae and Pseudomonadaceae. Moreover, the bacterial community is much more diverse than indicated by culture and contains significant numbers of other genera including anaerobic Prevotellaceae, Veillonellaceae and Actinomycetaceae. We found particular taxa are correlated with different clinical states, 27 taxa were associated with acute exacerbations, whereas 11 taxa correlated with stable clinical states. We were unable to demonstrate a significant effect of antibiotic therapy, gender, or lung function on the diversity of the bacterial community. However, presence of clinically significant culturable taxa; particularly Pseudomonas aeruginosa and Haemophilus influenzae correlated with a significant change in the diversity of the bacterial community in the lung. Conclusions We have demonstrated that acute exacerbations, the frequency of exacerbation and episodes of clinical stability are correlated, in some patients, with a significantly different bacterial community structure, that are associated with a presence of particular taxa in the NCFBr lung. Moreover

Msp40 effector of root-knot nematode manipulates plant immunity to facilitate parasitism.

PubMed

Niu, Junhai; Liu, Pei; Liu, Qian; Chen, Changlong; Guo, Quanxin; Yin, Junmei; Yang, Guangsui; Jian, Heng

2016-01-22

Root-knot nematodes (RKNs) are obligate biotrophic parasites that invade plant roots and engage in prolonged and intimate relationships with their hosts. Nematode secretions, some of which have immunosuppressing activity, play essential roles in successful parasitism; however, their mechanisms of action remain largely unknown. Here, we show that the RKN-specific gene MiMsp40, cloned from Meloidogyne incognita, is expressed exclusively in subventral oesophageal gland cells and is strongly upregulated during early parasitic stages. Arabidopsis plants overexpressing MiMsp40 were more susceptible to nematode infection than were wild type plants. Conversely, the host-derived MiMsp40 RNAi suppressed nematode parasitism and/or reproduction. Moreover, overexpression of MiMsp40 in plants suppressed the deposition of callose and the expression of marker genes for bacterial elicitor elf18-triggered immunity. Transient expression of MiMsp40 prevented Bax-triggered defence-related programmed cell death. Co-agroinfiltration assays indicated that MiMsp40 also suppressed macroscopic cell death triggered by MAPK cascades or by the ETI cognate elicitors R3a/Avr3a. Together, these results demonstrate that MiMsp40 is a novel Meloidogyne-specific effector that is injected into plant cells by early parasitic stages of the nematode and that plays a role in suppressing PTI and/or ETI signals to facilitate RKN parasitism.

Phytoalexins of the Pyrinae: Biphenyls and dibenzofurans

PubMed Central

Chizzali, Cornelia

2012-01-01

Summary Biphenyls and dibenzofurans are the phytoalexins of the Pyrinae, a subtribe of the plant family Rosaceae. The Pyrinae correspond to the long-recognized Maloideae. Economically valuable species of the Pyrinae are apples and pears. Biphenyls and dibenzofurans are formed de novo in response to infection by bacterial and fungal pathogens. The inducible defense compounds were also produced in cell suspension cultures after treatment with biotic and abiotic elicitors. The antimicrobial activity of the phytoalexins was demonstrated. To date, 10 biphenyls and 17 dibenzofurans were isolated from 14 of the 30 Pyrinae genera. The most widely distributed compounds are the biphenyl aucuparin and the dibenzofuran γ-cotonefuran. The biosynthesis of the two classes of defense compounds is not well understood, despite the importance of the fruit crops. More recent studies have revealed simultaneous accumulation of biphenyls and dibenzofurans, suggesting sequential, rather than the previously proposed parallel, biosynthetic pathways. Elicitor-treated cell cultures of Sorbus aucuparia served as a model system for studying phytoalexin metabolism. The key enzyme that forms the carbon skeleton is biphenyl synthase. The starter substrate for this type-III polyketide synthase is benzoyl-CoA. In apples, biphenyl synthase is encoded by a gene family, members of which are differentially regulated. Metabolism of the phytoalexins may provide new tools for designing disease control strategies for fruit trees of the Pyrinae subtribe. PMID:22563359

Msp40 effector of root-knot nematode manipulates plant immunity to facilitate parasitism

PubMed Central

Niu, Junhai; Liu, Pei; Liu, Qian; Chen, Changlong; Guo, Quanxin; Yin, Junmei; Yang, Guangsui; Jian, Heng

2016-01-01

Root-knot nematodes (RKNs) are obligate biotrophic parasites that invade plant roots and engage in prolonged and intimate relationships with their hosts. Nematode secretions, some of which have immunosuppressing activity, play essential roles in successful parasitism; however, their mechanisms of action remain largely unknown. Here, we show that the RKN-specific gene MiMsp40, cloned from Meloidogyne incognita, is expressed exclusively in subventral oesophageal gland cells and is strongly upregulated during early parasitic stages. Arabidopsis plants overexpressing MiMsp40 were more susceptible to nematode infection than were wild type plants. Conversely, the host-derived MiMsp40 RNAi suppressed nematode parasitism and/or reproduction. Moreover, overexpression of MiMsp40 in plants suppressed the deposition of callose and the expression of marker genes for bacterial elicitor elf18-triggered immunity. Transient expression of MiMsp40 prevented Bax-triggered defence-related programmed cell death. Co-agroinfiltration assays indicated that MiMsp40 also suppressed macroscopic cell death triggered by MAPK cascades or by the ETI cognate elicitors R3a/Avr3a. Together, these results demonstrate that MiMsp40 is a novel Meloidogyne-specific effector that is injected into plant cells by early parasitic stages of the nematode and that plays a role in suppressing PTI and/or ETI signals to facilitate RKN parasitism. PMID:26797310

Ciprofloxacin triggered glutamate production by Corynebacterium glutamicum.

PubMed

Lubitz, Dorit; Wendisch, Volker F

2016-10-07

Corynebacterium glutamicum is a well-studied bacterium which naturally overproduces glutamate when induced by an elicitor. Glutamate production is accompanied by decreased 2-oxoglutatate dehydrogenase activity. Elicitors of glutamate production by C. glutamicum analyzed to molecular detail target the cell envelope. Ciprofloxacin, an inhibitor of bacterial DNA gyrase and topoisomerase IV, was shown to inhibit growth of C. glutamicum wild type with concomitant excretion of glutamate. Enzyme assays showed that 2-oxoglutarate dehydrogenase activity was decreased due to ciprofloxacin addition. Transcriptome analysis revealed that this inhibitor of DNA gyrase increased RNA levels of genes involved in DNA synthesis, repair and modification. Glutamate production triggered by ciprofloxacin led to glutamate titers of up to 37 ± 1 mM and a substrate specific glutamate yield of 0.13 g/g. Even in the absence of the putative glutamate exporter gene yggB, ciprofloxacin effectively triggered glutamate production. When C. glutamicum wild type was cultivated under nitrogen-limiting conditions, 2-oxoglutarate rather than glutamate was produced as consequence of exposure to ciprofloxacin. Recombinant C. glutamicum strains overproducing lysine, arginine, ornithine, and putrescine, respectively, secreted glutamate instead of the desired amino acid when exposed to ciprofloxacin. Ciprofloxacin induced DNA synthesis and repair genes, reduced 2-oxoglutarate dehydrogenase activity and elicited glutamate production by C. glutamicum. Production of 2-oxoglutarate could be triggered by ciprofloxacin under nitrogen-limiting conditions.

Insect-Induced Daidzein, Formononetin and Their Conjugates in Soybean Leaves

PubMed Central

Murakami, Shinichiro; Nakata, Ryu; Aboshi, Takako; Yoshinaga, Naoko; Teraishi, Masayoshi; Okumoto, Yutaka; Ishihara, Atsushi; Morisaka, Hironobu; Huffaker, Alisa; Schmelz, Eric A; Mori, Naoki

2014-01-01

In response to attack by bacterial pathogens, soybean (Gylcine max) leaves accumulate isoflavone aglucones, isoflavone glucosides, and glyceollins. In contrast to pathogens, the dynamics of related insect-inducible metabolites in soybean leaves remain poorly understood. In this study, we analyzed the biochemical responses of soybean leaves to Spodoptera litura (Lepidoptera: Noctuidae) herbivory and also S. litura gut contents, which contain oral secretion elicitors. Following S. litura herbivory, soybean leaves displayed an induced accumulation of the flavone and isoflavone aglycones 4’,7-dihyroxyflavone, daidzein, and formononetin, and also the isoflavone glucoside daidzin. Interestingly, foliar application of S. litura oral secretions also elicited the accumulation of isoflavone aglycones (daidzein and formononetin), isoflavone 7-O-glucosides (daidzin, ononin), and isoflavone 7-O-(6’-O-malonyl-β-glucosides) (malonyldaidzin, malonylononin). Consistent with the up-regulation of the isoflavonoid biosynthetic pathway, folair phenylalanine levels also increased following oral secretion treatment. To establish that these metabolitic changes were the result of de novo biosynthesis, we demonstrated that labeled (13C9) phenylalanine was incorporated into the isoflavone aglucones. These results are consistent with the presence of soybean defense elicitors in S. litura oral secretions. We demonstrate that isoflavone aglycones and isoflavone conjugates are induced in soybean leaves, not only by pathogens as previously demonstrated, but also by foliar insect herbivory. PMID:25000357

Molecular Cloning and Ethylene Induction of mRNA Encoding a Phytoalexin Elicitor-Releasing Factor, beta-1,3-Endoglucanase, in Soybean.

PubMed

Takeuchi, Y; Yoshikawa, M; Takeba, G; Tanaka, K; Shibata, D; Horino, O

1990-06-01

Soybean (Glycine max) beta-1,3-endoglucanase (EC 3.2. 1.39) is involved in one of the earliest plant-pathogen interactions that may lead to active disease resistance by releasing elicitor-active carbohydrates from the cell walls of fungal pathogens. Ethylene induced beta-1,3-endoglucanase activity to 2- to 3-fold higher levels in cotyledons of soybean seedlings. A specific polyclonal antiserum raised against purified soybean beta-1,3-endoglucanase was used to immunoprecipitate in vitro translation products, demonstrating that ethylene induction increased translatable beta-1,3-endoglucanase mRNA. Several cDNA clones for the endoglucanase gene were obtained by antibody screening of a lambda-gt11 expression library prepared from soybean cotyledons. Hybrid-select translation experiments indicated that the cloned cDNA encoded a 36-kilodalton precursor protein product that was specifically immunoprecipitated with beta-1,3-endoglucanase antiserum. Escherichia coli cells expressing the cloned cDNA also synthesized an immunologically positive protein. Nucleotide sequence of three independent clones revealed a single uninterrupted open reading frame of 1041 nucleotides, corresponding to a polypeptide of 347 residue long. The primary amino acid sequence of beta-1,3-endoglucanase as deduced from the nucleotide sequence was confirmed by direct amino acid sequencing of trypsin digests of the glucanase. The soybean beta-1,3-endoglucanase exhibited 53% amino acid homology to a beta-1,3-glucanase cloned from cultured tobacco cells and 48% homology to a beta-(1,3-1,4)-glucanase from barley. Utilizing the largest cloned cDNA (pEG488) as a hybridization probe, it was found that the increase in translatable beta-1,3-endoglucanase mRNA seen upon ethylene treatment of soybean seedlings was due to 50- to 100-fold increase in steady state mRNA levels, indicating that ethylene regulates gene expression of this enzyme important in disease resistance at the level of gene transcription.

Microbiology: Detection of Bacterial Pathogens and Their Occurrence.

ERIC Educational Resources Information Center

Reasoner, Donald J.

1978-01-01

Presents a literature review of bacterial pathogens that are related to water pollution, covering publications from 1976-77. This review includes: (1) bacterial pathogens in animals; and (2) detection and identification of waterborne bacterial pathogens. A list of 129 references is also presented. (HM)

Bacterial fatty acid metabolism in modern antibiotic discovery.

PubMed

Yao, Jiangwei; Rock, Charles O

2017-11-01

Bacterial fatty acid synthesis is essential for many pathogens and different from the mammalian counterpart. These features make bacterial fatty acid synthesis a desirable target for antibiotic discovery. The structural divergence of the conserved enzymes and the presence of different isozymes catalyzing the same reactions in the pathway make bacterial fatty acid synthesis a narrow spectrum target rather than the traditional broad spectrum target. Furthermore, bacterial fatty acid synthesis inhibitors are single-targeting, rather than multi-targeting like traditional monotherapeutic, broad-spectrum antibiotics. The single-targeting nature of bacterial fatty acid synthesis inhibitors makes overcoming fast-developing, target-based resistance a necessary consideration for antibiotic development. Target-based resistance can be overcome through multi-targeting inhibitors, a cocktail of single-targeting inhibitors, or by making the single targeting inhibitor sufficiently high affinity through a pathogen selective approach such that target-based mutants are still susceptible to therapeutic concentrations of drug. Many of the pathogens requiring new antibiotic treatment options encode for essential bacterial fatty acid synthesis enzymes. This review will evaluate the most promising targets in bacterial fatty acid metabolism for antibiotic therapeutics development and review the potential and challenges in advancing each of these targets to the clinic and circumventing target-based resistance. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop. Copyright © 2016 Elsevier B.V. All rights reserved.

Formation and dissolution of bacterial colonies.

PubMed

Weber, Christoph A; Lin, Yen Ting; Biais, Nicolas; Zaburdaev, Vasily

2015-09-01

Many organisms form colonies for a transient period of time to withstand environmental pressure. Bacterial biofilms are a prototypical example of such behavior. Despite significant interest across disciplines, physical mechanisms governing the formation and dissolution of bacterial colonies are still poorly understood. Starting from a kinetic description of motile and interacting cells we derive a hydrodynamic equation for their density on a surface, where most of the kinetic coefficients are estimated from experimental data for N. gonorrhoeae bacteria. We use it to describe the formation of multiple colonies with sizes consistent with experimental observations. Finally, we show how the changes in the cell-to-cell interactions lead to the dissolution of the bacterial colonies. The successful application of kinetic theory to a complex far from equilibrium system such as formation and dissolution of living bacterial colonies potentially paves the way for the physical quantification of the initial stages of biofilm formation.

Demonstrating Bacterial Flagella.

ERIC Educational Resources Information Center

Porter, John R.; And Others

1992-01-01

Describes an effective laboratory method for demonstrating bacterial flagella that utilizes the Proteus mirabilis organism and a special harvesting technique. Includes safety considerations for the laboratory exercise. (MDH)

Initial insights into bacterial succession during human decomposition.

PubMed

Hyde, Embriette R; Haarmann, Daniel P; Petrosino, Joseph F; Lynne, Aaron M; Bucheli, Sibyl R

2015-05-01

Decomposition is a dynamic ecological process dependent upon many factors such as environment, climate, and bacterial, insect, and vertebrate activity in addition to intrinsic properties inherent to individual cadavers. Although largely attributed to microbial metabolism, very little is known about the bacterial basis of human decomposition. To assess the change in bacterial community structure through time, bacterial samples were collected from several sites across two cadavers placed outdoors to decompose and analyzed through 454 pyrosequencing and analysis of variable regions 3-5 of the bacterial 16S ribosomal RNA (16S rRNA) gene. Each cadaver was characterized by a change in bacterial community structure for all sites sampled as time, and decomposition, progressed. Bacteria community structure is variable at placement and before purge for all body sites. At bloat and purge and until tissues began to dehydrate or were removed, bacteria associated with flies, such as Ignatzschineria and Wohlfahrtimonas, were common. After dehydration and skeletonization, bacteria associated with soil, such as Acinetobacter, were common at most body sites sampled. However, more cadavers sampled through multiple seasons are necessary to assess major trends in bacterial succession.

Jellyfish modulate bacterial dynamic and community structure.

PubMed

Tinta, Tinkara; Kogovšek, Tjaša; Malej, Alenka; Turk, Valentina

2012-01-01

Jellyfish blooms have increased in coastal areas around the world and the outbreaks have become longer and more frequent over the past few decades. The Mediterranean Sea is among the heavily affected regions and the common bloom-forming taxa are scyphozoans Aurelia aurita s.l., Pelagia noctiluca, and Rhizostoma pulmo. Jellyfish have few natural predators, therefore their carcasses at the termination of a bloom represent an organic-rich substrate that supports rapid bacterial growth, and may have a large impact on the surrounding environment. The focus of this study was to explore whether jellyfish substrate have an impact on bacterial community phylotype selection. We conducted in situ jellyfish-enrichment experiment with three different jellyfish species. Bacterial dynamic together with nutrients were monitored to assess decaying jellyfish-bacteria dynamics. Our results show that jellyfish biomass is characterized by protein rich organic matter, which is highly bioavailable to 'jellyfish-associated' and 'free-living' bacteria, and triggers rapid shifts in bacterial population dynamics and composition. Based on 16S rRNA clone libraries and denaturing gradient gel electrophoresis (DGGE) analysis, we observed a rapid shift in community composition from unculturable Alphaproteobacteria to culturable species of Gammaproteobacteria and Flavobacteria. The results of sequence analyses of bacterial isolates and of total bacterial community determined by culture independent genetic analysis showed the dominance of the Pseudoalteromonadaceae and the Vibrionaceae families. Elevated levels of dissolved proteins, dissolved organic and inorganic nutrient release, bacterial abundance and carbon production as well as ammonium concentrations characterized the degradation process. The biochemical composition of jellyfish species may influence changes in the amount of accumulated dissolved organic and inorganic nutrients. Our results can contribute insights into possible changes in

The burden of bacterial vaginosis: women's experience of the physical, emotional, sexual and social impact of living with recurrent bacterial vaginosis.

PubMed

Bilardi, Jade E; Walker, Sandra; Temple-Smith, Meredith; McNair, Ruth; Mooney-Somers, Julie; Bellhouse, Clare; Fairley, Christopher K; Chen, Marcus Y; Bradshaw, Catriona

2013-01-01

Bacterial vaginosis is a common vaginal infection, causing an abnormal vaginal discharge and/or odour in up to 50% of sufferers. Recurrence is common following recommended treatment. There are limited data on women's experience of bacterial vaginosis, and the impact on their self-esteem, sexual relationships and quality of life. The aim of this study was to explore the experiences and impact of recurrent bacterial vaginosis on women. A social constructionist approach was chosen as the framework for the study. Thirty five women with male and/or female partners participated in semi-structured interviews face-to-face or by telephone about their experience of recurrent bacterial vaginosis. Recurrent bacterial vaginosis impacted on women to varying degrees, with some women reporting it had little impact on their lives but most reporting it had a moderate to severe impact. The degree to which it impacted on women physically, emotionally, sexually and socially often depended on the frequency of episodes and severity of symptoms. Women commonly reported that symptoms of bacterial vaginosis made them feel embarrassed, ashamed, 'dirty' and very concerned others may detect their malodour and abnormal discharge. The biggest impact of recurrent bacterial vaginosis was on women's self-esteem and sex lives, with women regularly avoiding sexual activity, in particular oral sex, as they were too embarrassed and self-conscious of their symptoms to engage in these activities. Women often felt confused about why they were experiencing recurrent bacterial vaginosis and frustrated at their lack of control over recurrence. Women's experience of recurrent bacterial vaginosis varied broadly and significantly in this study. Some women reported little impact on their lives but most reported a moderate to severe impact, mainly on their self-esteem and sex life. Further support and acknowledgement of these impacts are required when managing women with recurrent bacterial vaginosis.

Characterization of Bacterial Cellulose by Gluconacetobacter hansenii CGMCC 3917.

PubMed

Feng, Xianchao; Ullah, Niamat; Wang, Xuejiao; Sun, Xuchun; Li, Chenyi; Bai, Yun; Chen, Lin; Li, Zhixi

2015-10-01

In this study, comprehensive characterization and drying methods on properties of bacterial cellulose were analyzed. Bacterial cellulose was prepared by Gluconacetobacter hansenii CGMCC 3917, which was mutated by high hydrostatic pressure (HHP) treatment. Bacterial cellulose is mainly comprised of cellulose Iα with high crystallinity and purity. High-water holding and absorption capacity were examined by reticulated structure. Thermogravimetric analysis showed high thermal stability. High tensile strength and Young's modulus indicated its mechanical properties. The rheological analysis showed that bacterial cellulose had good consistency and viscosity. These results indicated that bacterial cellulose is a potential food additive and also could be used for a food packaging material. The high textural stability during freeze-thaw cycles makes bacterial cellulose an effective additive for frozen food products. In addition, the properties of bacterial cellulose can be affected by drying methods. Our results suggest that the bacterial cellulose produced from HHP-mutant strain has an effective characterization, which can be used for a wide range of applications in food industry. © 2015 Institute of Food Technologists®

Assessing the Robustness of Complete Bacterial Genome Segmentations

NASA Astrophysics Data System (ADS)

Devillers, Hugo; Chiapello, Hélène; Schbath, Sophie; El Karoui, Meriem

Comparison of closely related bacterial genomes has revealed the presence of highly conserved sequences forming a "backbone" that is interrupted by numerous, less conserved, DNA fragments. Segmentation of bacterial genomes into backbone and variable regions is particularly useful to investigate bacterial genome evolution. Several software tools have been designed to compare complete bacterial chromosomes and a few online databases store pre-computed genome comparisons. However, very few statistical methods are available to evaluate the reliability of these software tools and to compare the results obtained with them. To fill this gap, we have developed two local scores to measure the robustness of bacterial genome segmentations. Our method uses a simulation procedure based on random perturbations of the compared genomes. The scores presented in this paper are simple to implement and our results show that they allow to discriminate easily between robust and non-robust bacterial genome segmentations when using aligners such as MAUVE and MGA.

Epidemiology of community-acquired bacterial meningitis.

PubMed

Brouwer, Matthijs C; van de Beek, Diederik

2018-02-01

The epidemiology of bacterial meningitis has been dynamic in the past 30 years following introduction of conjugated vaccines against Haemophilus influenzae type B, Streptococcus pneumoniae and Neisseria meningitidis. The purpose of this review is to describe recent developments in bacterial meningitis epidemiology. The incidence of bacterial meningitis in Western countries (Finland, Netherlands, and the United States) gradually declined by 3-4% per year to 0.7-0.9 per 100 000 per year in the past 10-20 years. In African countries (Burkina Faso and Malawi), incidence rates are still substantially higher at 10-40 per 100 000 persons per year. Introduction of pneumococcal conjugate vaccines have not consistently decreased overall pneumococcal meningitis incidence because of serotype replacement. Following the introduction of serogroup A and C meningococcal vaccines, the incidence of meningococcal meningitis because of these serogroups strongly decreased. Novel outbreaks in the African meningitis belt by serogroup C and increased incidence of serogroup W in the United Kingdom and the Netherlands were observed recently. Bacterial meningitis remains an important infectious disease, despite a gradual decline in incidence after large-scale vaccination campaigns. Further development of vaccines with broader coverage is important, as is continuous surveillance of bacterial meningitis cases.

The epidemiology of bacterial meningitis in Kosovo.

PubMed

Namani, Sadie A; Koci, Remzie A; Qehaja-Buçaj, Emine; Ajazaj-Berisha, Lindita; Mehmeti, Murat

2014-07-14

The purpose of this study was to present the epidemiologic features of bacterial meningitis in the developing country of Kosovo. Data were collected from active surveillance of bacterial meningitis cases treated at the University Clinical Center of Kosovo in the years 2000 (first post-war year) and 2010. Meningitis cases in 2000 compared with 2010 showed a 35.5% decline in incidence (from 4.8 to 3.1 cases per 100,000 population) and a decrease in the case fatality rate from 10% to 5%. In children, there was a lower mortality rate (5% versus 2%) and a lower incidence of neurological complications (13% versus 16%) as compared to adults (32% versus 10% and 16% versus 35%, respectively). Neisseria meningitidis was the most common pathogen of bacterial meningitis in both study periods. Bacterial meningitis was most prevalent in the pediatric population, and showed an increase in the median age, from three years in 2000 to seven years in 2010. A steady number of bacterial meningitis cases in adults throughout last decade (around 20 cases per year) was recorded. During the last decade, gradual changes have been observed in the epidemiology of bacterial meningitis that are unrelated to the introduction of new vaccines, but are partly due to the improvement of living conditions.

7 CFR 58.135 - Bacterial estimate.

Code of Federal Regulations, 2011 CFR

2011-01-01

..., GENERAL SPECIFICATIONS FOR APPROVED PLANTS AND STANDARDS FOR GRADES OF DAIRY PRODUCTS 1 General Specifications for Dairy Plants Approved for USDA Inspection and Grading Service 1 Quality Specifications for Raw Milk § 58.135 Bacterial estimate. (a) Methods of Testing. Milk shall be tested for bacterial estimate...

Nest Material Shapes Eggs Bacterial Environment.

PubMed

Ruiz-Castellano, Cristina; Tomás, Gustavo; Ruiz-Rodríguez, Magdalena; Martín-Gálvez, David; Soler, Juan José

2016-01-01

Selective pressures imposed by pathogenic microorganisms to embryos have selected in hosts for a battery of antimicrobial lines of defenses that includes physical and chemical barriers. Due to the antimicrobial properties of volatile compounds of green plants and of chemicals of feather degrading bacteria, the use of aromatic plants and feathers for nest building has been suggested as one of these barriers. However, experimental evidence suggesting such effects is scarce in the literature. During two consecutive years, we explored experimentally the effects of these nest materials on loads of different groups of bacteria (mesophilic bacteria, Enterobacteriaceae, Staphylococcus and Enterococcus) of eggshells in nests of spotless starlings (Sturnus unicolor) at the beginning and at the end of the incubation period. This was also explored in artificial nests without incubation activity. We also experimentally increased bacterial density of eggs in natural and artificial nests and explored the effects of nest lining treatments on eggshell bacterial load. Support for the hypothetical antimicrobial function of nest materials was mainly detected for the year and location with larger average values of eggshell bacterial density. The beneficial effects of feathers and plants were more easily detected in artificial nests with no incubation activity, suggesting an active role of incubation against bacterial colonization of eggshells. Pigmented and unpigmented feathers reduced eggshell bacterial load in starling nests and artificial nest boxes. Results from artificial nests allowed us to discuss and discard alternative scenarios explaining the detected association, particularly those related to the possible sexual role of feathers and aromatic plants in starling nests. All these results considered together confirm the antimicrobial functionality mainly of feathers but also of plants used as nest materials, and highlight the importance of temporally and geographically

Nest Material Shapes Eggs Bacterial Environment

PubMed Central

Ruiz-Castellano, Cristina; Tomás, Gustavo; Ruiz-Rodríguez, Magdalena; Martín-Gálvez, David; Soler, Juan José

2016-01-01

Selective pressures imposed by pathogenic microorganisms to embryos have selected in hosts for a battery of antimicrobial lines of defenses that includes physical and chemical barriers. Due to the antimicrobial properties of volatile compounds of green plants and of chemicals of feather degrading bacteria, the use of aromatic plants and feathers for nest building has been suggested as one of these barriers. However, experimental evidence suggesting such effects is scarce in the literature. During two consecutive years, we explored experimentally the effects of these nest materials on loads of different groups of bacteria (mesophilic bacteria, Enterobacteriaceae, Staphylococcus and Enterococcus) of eggshells in nests of spotless starlings (Sturnus unicolor) at the beginning and at the end of the incubation period. This was also explored in artificial nests without incubation activity. We also experimentally increased bacterial density of eggs in natural and artificial nests and explored the effects of nest lining treatments on eggshell bacterial load. Support for the hypothetical antimicrobial function of nest materials was mainly detected for the year and location with larger average values of eggshell bacterial density. The beneficial effects of feathers and plants were more easily detected in artificial nests with no incubation activity, suggesting an active role of incubation against bacterial colonization of eggshells. Pigmented and unpigmented feathers reduced eggshell bacterial load in starling nests and artificial nest boxes. Results from artificial nests allowed us to discuss and discard alternative scenarios explaining the detected association, particularly those related to the possible sexual role of feathers and aromatic plants in starling nests. All these results considered together confirm the antimicrobial functionality mainly of feathers but also of plants used as nest materials, and highlight the importance of temporally and geographically

Multiple reservoirs contribute to intraoperative bacterial transmission.

PubMed

Loftus, Randy W; Brown, Jeremiah R; Koff, Matthew D; Reddy, Sundara; Heard, Stephen O; Patel, Hetal M; Fernandez, Patrick G; Beach, Michael L; Corwin, Howard L; Jensen, Jens T; Kispert, David; Huysman, Bridget; Dodds, Thomas M; Ruoff, Kathryn L; Yeager, Mark P

2012-06-01

Intraoperative stopcock contamination is a frequent event associated with increased patient mortality. In the current study we examined the relative contributions of anesthesia provider hands, the patient, and the patient environment to stopcock contamination. Our secondary aims were to identify risk factors for stopcock contamination and to examine the prior association of stopcock contamination with 30-day postoperative infection and mortality. Additional microbiological analyses were completed to determine the prevalence of bacterial pathogens within intraoperative bacterial reservoirs. Pulsed-field gel electrophoresis was used to assess the contribution of reservoir bacterial pathogens to 30-day postoperative infections. In a multicenter study, stopcock transmission events were observed in 274 operating rooms, with the first and second cases of the day in each operating room studied in series to identify within- and between-case transmission events. Reservoir bacterial cultures were obtained and compared with stopcock set isolates to determine the origin of stopcock contamination. Between-case transmission was defined by the isolation of 1 or more bacterial isolates from the stopcock set of a subsequent case (case 2) that were identical to reservoir isolates from the preceding case (case 1). Within-case transmission was defined by the isolation of 1 or more bacterial isolates from a stopcock set that were identical to bacterial reservoirs from the same case. Bacterial pathogens within these reservoirs were identified, and their potential contribution to postoperative infections was evaluated. All patients were followed for 30 days postoperatively for the development of infection and all-cause mortality. Stopcock contamination was detected in 23% (126 out of 548) of cases with 14 between-case and 30 within-case transmission events confirmed. All 3 reservoirs contributed to between-case (64% environment, 14% patient, and 21% provider) and within-case (47

Detergent-compatible bacterial amylases.

PubMed

Niyonzima, Francois N; More, Sunil S

2014-10-01

Proteases, lipases, amylases, and cellulases are enzymes used in detergent formulation to improve the detergency. The amylases are specifically supplemented to the detergent to digest starchy stains. Most of the solid and liquid detergents that are currently manufactured contain alkaline enzymes. The advantages of using alkaline enzymes in the detergent formulation are that they aid in removing tough stains and the process is environmentally friendly since they reduce the use of toxic detergent ingredients. Amylases active at low temperature are preferred as the energy consumption gets reduced, and the whole process becomes cost-effective. Most microbial alkaline amylases are used as detergent ingredients. Various reviews report on the production, purification, characterization, and application of amylases in different industry sectors, but there is no specific review on bacterial or fungal alkaline amylases or detergent-compatible amylases. In this mini-review, an overview on the production and property studies of the detergent bacterial amylases is given, and the stability and compatibility of the alkaline bacterial amylases in the presence of the detergents and the detergent components are highlighted.

Molecular Survey of Bacterial Communities Associated with Bacterial Chondronecrosis with Osteomyelitis (BCO) in Broilers

PubMed Central

Jiang, Tieshan; Mandal, Rabindra K.; Wideman, Robert F.; Khatiwara, Anita; Pevzner, Igal; Min Kwon, Young

2015-01-01

Bacterial chondronecrosis with osteomyelitis (BCO) is recognized as an important cause of lameness in commercial broiler chickens (meat-type chickens). Relatively little is known about the microbial communities associated with BCO. This study was conducted to increase our understanding of the microbial factors associated with BCO using a culture-independent approach. Using Illumina sequencing of the hyper-variable region V6 in the 16S rRNA gene, we characterized the bacterial communities in 97 femoral or tibial heads from normal and lame broilers carefully selected to represent diverse variations in age, line, lesion type, floor type, clinical status and bone type. Our in-depth survey based on 14 million assembled sequence reads revealed that complex bacterial communities exist in all samples, including macroscopically normal bones from clinically healthy birds. Overall, Proteobacteria (mean 90.9%) comprised the most common phylum, followed by Firmicutes (6.1%) and Actinobacteria (2.6%), accounting for more than 99% of all reads. Statistical analyses demonstrated that there are differences in bacterial communities in different types of bones (femur vs. tibia), lesion types (macroscopically normal femora or tibiae vs. those with pathognomonic BCO lesions), and among individual birds. This analysis also showed that BCO samples overrepresented genera Staphylococcus, whose species have been frequently isolated in BCO samples in previous studies. Rarefaction analysis demonstrated the general tendency that increased severities of BCO lesions were associated with reduced species diversity in both femoral and tibial samples when compared to macroscopically normal samples. These observations suggest that certain bacterial subgroups are preferentially selected in association with the development of BCO lesions. Understanding the microbial species associated with BCO will identify opportunities for understanding and modulating the pathogenesis of this form of lameness in

PecS and PecT coregulate the synthesis of HrpN and pectate lyases, two virulence determinants in Erwinia chrysanthemi 3937.

PubMed

Nasser, William; Reverchon, Sylvie; Vedel, Regine; Boccara, Martine

2005-11-01

Erwinia chrysanthemi strain 3937 is a necrotrophic bacterial plant pathogen. Pectinolytic enzymes and, in particular, pectate lyases play a key role in soft rot symptoms; however, the efficient colonization of plants by E. chrysanthemi requires additional factors. These factors include HrpN (harpin), a heat-stable, glycine-rich hydrophilic protein, which is secreted by the type III secretion system. We investigated the expression of hrpN in E. chrysanthemi 3937 in various environmental conditions and different regulatory backgrounds. Using lacZ fusions, hrpN expression was markedly influenced by the carbon source, osmolarity, growth phase, and growth substrate. hrpN was repressed when pectinolysis started and negatively regulated by the repressors of pectate lyase synthesis, PecS and PecT. Primer extension data and in vitro DNA-protein interaction experiments support a model whereby PecS represses hrpN expression by binding to the hrpN regulatory region and inhibiting transcript elongation. The results suggest coordinated regulation of HrpN and pectate lyases by PecS and PecT. A putative model of the synthesis of these two virulence factors in E. chrysanthemi during pathogenesis is presented.

Bacterial pathogen manipulation of host membrane trafficking.

PubMed

Asrat, Seblewongel; de Jesús, Dennise A; Hempstead, Andrew D; Ramabhadran, Vinay; Isberg, Ralph R

2014-01-01

Pathogens use a vast number of strategies to alter host membrane dynamics. Targeting the host membrane machinery is important for the survival and pathogenesis of several extracellular, vacuolar, and cytosolic bacteria. Membrane manipulation promotes bacterial replication while suppressing host responses, allowing the bacterium to thrive in a hostile environment. This review provides a comprehensive summary of various strategies used by both extracellular and intracellular bacteria to hijack host membrane trafficking machinery. We start with mechanisms used by bacteria to alter the plasma membrane, delve into the hijacking of various vesicle trafficking pathways, and conclude by summarizing bacterial adaptation to host immune responses. Understanding bacterial manipulation of host membrane trafficking provides insights into bacterial pathogenesis and uncovers the molecular mechanisms behind various processes within a eukaryotic cell.

Riboregulation of bacterial and archaeal transposition.

PubMed

Ellis, Michael J; Haniford, David B

2016-05-01

The coexistence of transposons with their hosts depends largely on transposition levels being tightly regulated to limit the mutagenic burden associated with frequent transposition. For 'DNA-based' (class II) bacterial transposons there is growing evidence that regulation through small noncoding RNAs and/or the RNA-binding protein Hfq are prominent mechanisms of defense against transposition. Recent transcriptomics analyses have identified many new cases of antisense RNAs (asRNA) that potentially could regulate the expression of transposon-encoded genes giving the impression that asRNA regulation of DNA-based transposons is much more frequent than previously thought. Hfq is a highly conserved bacterial protein that plays a central role in posttranscriptional gene regulation and stress response pathways in many bacteria. Three different mechanisms for Hfq-directed control of bacterial transposons have been identified to date highlighting the versatility of this protein as a regulator of bacterial transposons. There is also evidence emerging that some DNA-based transposons encode RNAs that could regulate expression of host genes. In the case of IS200, which appears to have lost its ability to transpose, contributing a regulatory RNA to its host could account for the persistence of this mobile element in a wide range of bacterial species. It remains to be seen how prevalent these transposon-encoded RNA regulators are, but given the relatively large amount of intragenic transcription in bacterial genomes, it would not be surprising if new examples are forthcoming. WIREs RNA 2016, 7:382-398. doi: 10.1002/wrna.1341 For further resources related to this article, please visit the WIREs website. © 2016 Wiley Periodicals, Inc.

Dietary and developmental shifts in butterfly-associated bacterial communities

PubMed Central

2018-01-01

Bacterial communities associated with insects can substantially influence host ecology, evolution and behaviour. Host diet is a key factor that shapes bacterial communities, but the impact of dietary transitions across insect development is poorly understood. We analysed bacterial communities of 12 butterfly species across different developmental stages, using amplicon sequencing of the 16S rRNA gene. Butterfly larvae typically consume leaves of a single host plant, whereas adults are more generalist nectar feeders. Thus, we expected bacterial communities to vary substantially across butterfly development. Surprisingly, only few species showed significant dietary and developmental transitions in bacterial communities, suggesting weak impacts of dietary transitions across butterfly development. On the other hand, bacterial communities were strongly influenced by butterfly species and family identity, potentially due to dietary and physiological variation across the host phylogeny. Larvae of most butterfly species largely mirrored bacterial community composition of their diets, suggesting passive acquisition rather than active selection. Overall, our results suggest that although butterflies harbour distinct microbiomes across taxonomic groups and dietary guilds, the dramatic dietary shifts that occur during development do not impose strong selection to maintain distinct bacterial communities across all butterfly hosts. PMID:29892359

Chitin-induced and CHITIN ELICITOR RECEPTOR KINASE1 (CERK1) phosphorylation-dependent endocytosis of Arabidopsis thaliana LYSIN MOTIF-CONTAINING RECEPTOR-LIKE KINASE5 (LYK5).

PubMed

Erwig, Jan; Ghareeb, Hassan; Kopischke, Michaela; Hacke, Ronja; Matei, Alexandra; Petutschnig, Elena; Lipka, Volker

2017-07-01

To detect potential pathogens, plants perceive the fungal polysaccharide chitin through receptor complexes containing lysin motif receptor-like kinases (LysM-RLKs). To investigate the ligand-induced spatial dynamics of chitin receptor components, we studied the subcellular behaviour of two Arabidopsis thaliana LysM-RLKs involved in chitin signalling, CHITIN ELICITOR RECEPTOR KINASE1 (CERK1) and LYSIN MOTIF-CONTAINING RECEPTOR-LIKE KINASE5. We performed standard and quantitative confocal laser scanning microscopy on stably transformed A. thaliana plants expressing fluorescently tagged CERK1 and LYK5 from their native promoters. Microscopy approaches were complemented by biochemical analyses in plants and in vitro. Both CERK1 and LYK5 localized to the plasma membrane and showed constitutive endomembrane trafficking. After chitin treatment, however, CERK1 remained at the plasma membrane while LYK5 relocalized into mobile intracellular vesicles. Detailed analyses revealed that chitin perception transiently induced the internalization of LYK5 into late endocytic compartments. Plants that lacked CERK1 or expressed an enzymatically inactive CERK1 variant did not exhibit chitin-induced endocytosis of LYK5. CERK1 could phosphorylate LYK5 in vitro and chitin treatment induced CERK1-dependent phosphorylation of LYK5 in planta. Our results suggest that chitin-induced phosphorylation by CERK1 triggers LYK5 internalization. Thus, our work identifies phosphorylation as a key regulatory step in endocytosis of plant RLKs and also provides evidence for receptor complex dissociation after ligand perception. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

The bacterial meningitis score to distinguish bacterial from aseptic meningitis in children from Sao Paulo, Brazil.

PubMed

Mekitarian Filho, Eduardo; Horita, Sérgio Massaru; Gilio, Alfredo Elias; Alves, Anna Cláudia Dominguez; Nigrovic, Lise E

2013-09-01

In a retrospective cohort of 494 children with meningitis in Sao Paulo, Brazil, the Bacterial Meningitis Score identified all the children with bacterial meningitis (sensitivity 100%, 95% confidence interval: 92-100% and negative predictive value 100%, 95% confidence interval: 98-100%). Addition of cerebrospinal fluid lactate to the score did not improve clinical prediction rule performance.

Biochemical basis of improvement of defense in tomato plant against Fusarium wilt by CaCl2.

PubMed

Chakraborty, Nilanjan; Chandra, Swarnendu; Acharya, Krishnendu

2017-07-01

The objective of this study was to investigate the effectiveness of calcium chloride (CaCl 2 ), as potential elicitor, on tomato plants against Fusarium oxysporum f. sp. lycopersici . Foliar application of CaCl 2 showed significant reduction of wilt incidence after challenge inoculation. Increased production of defense and antioxidant enzymes was observed in elicitor treated sets over control. Simultaneously, altered amount of phenolic acids were analyzed spectrophotometrically and by using high performance liquid chromatography. Significant induction of defense-related genes expressions was measured by semi-quantitative RT-PCR. Greater lignifications by microscopic analysis were also recorded in elicitor treated plants. Simultaneously, generation of nitric oxide (NO) in elicitor treated plants was confirmed by spectrophotometrically and microscopically by using membrane permeable fluorescent dye. Furthermore, plants treated with potential NO donor and NO modulators showed significant alteration of all those aforesaid defense molecules. Transcript analysis of nitrate reductase and calmodulin gene showed positive correlation with elicitor treatment. Furthermore, CaCl 2 treatment showed greater seedling vigor index, mean trichome density etc. The result suggests that CaCl 2 have tremendous potential to elicit defense responses as well as plant growth in co-relation with NO, which ultimately leads to resistance against the wilt pathogen.

Combing bacterial turbulence.

NASA Astrophysics Data System (ADS)

Sokolov, Andrey; Nishiguchi, Daiki; Aronson, Igor

Living systems represented by ensembles of motile organisms demonstrate a transition from a chaotic motion to a highly ordered state. Examples of such living systems include suspensions of bacteria, schools of fish, flocks of birds and even crowds of people. In spite of significant differences in interacting mechanisms and motion scales, ordered living systems have many similarities: short-range alignment of organism, turbulent-like motion, emergence of large-scale flows and dynamic vortices. In this work, we rectify a turbulent dynamics in suspensions of swimming bacteria Bacillus subtilis by imposing periodical constraints on bacterial motion. Bacteria, swimming between periodically placed microscopic vertical pillars, may self-organize in a stable lattice of vortices. We demonstrate the emergence of a strong anti-ferromagnetic order of bacterial vortices in a rectangular lattice of pillars. Hydrodynamic interaction between vortices increases the stability of an emerged pattern. The highest stability of vortices in the anti-ferromagnetic lattice and the fastest vortices speed were observed in structures with the periods comparable with a correlation length of bacterial unconstrained motion. A.S and I.A were supported by the US DOE, Office of Basic Energy Sciences, Division of Materials Science And Engineering, under contract No. DE AC02-06CH11357 and D.N was supported by ALPS and JSPS Grant No. 26-9915.

Neglected Bacterial Zoonoses

PubMed Central

Chikeka, Ijeuru; Dumler, J. Stephen

2015-01-01

Bacterial zoonoses comprise a group of diseases in humans or animals acquired by direct contact with or by oral consumption of contaminated animal materials, or via arthropod vectors. Among neglected infections, bacterial zoonoses are among the most neglected given emerging data on incidence and prevalence as causes of acute febrile illness, even in areas where recognized neglected tropical diseases occur frequently. While many other bacterial infections could also be considered in this neglected category, five distinct infections stand out because they are globally distributed, are acute febrile diseases, have high rates of morbidity and case fatality, and are reported as commonly as malaria, typhoid or dengue virus infections in carefully designed studies in which a broad spectrum diagnoses are actively sought. Thus, this review will focus attention on leptospirosis, relapsing fever borreliosis, and rickettsioses, including scrub typhus, murine typhus and spotted fever group rickettsiosis. Of greatest interest is the lack of distinguishing clinical features among these infections when in humans, which confounds diagnosis where laboratory confirmation is lacking, and in regions where clinical diagnosis is often attributed to one of several perceived more common threats. As diseases such as malaria come under improved control, the real impact of these common and under-recognized infections will become evident, as will the requirement for the strategies and allocation of resources for their control. PMID:25964152

Synthetic analogs of bacterial quorum sensors

DOEpatents

Iyer, Rashi [Los Alamos, NM; Ganguly, Kumkum [Los Alamos, NM; Silks, Louis A [Los Alamos, NM

2011-12-06

Bacterial quorum-sensing molecule analogs having the following structures: ##STR00001## and methods of reducing bacterial pathogenicity, comprising providing a biological system comprising pathogenic bacteria which produce natural quorum-sensing molecule; providing a synthetic bacterial quorum-sensing molecule having the above structures and introducing the synthetic quorum-sensing molecule into the biological system comprising pathogenic bacteria. Further is provided a method of targeted delivery of an antibiotic, comprising providing a synthetic quorum-sensing molecule; chemically linking the synthetic quorum-sensing molecule to an antibiotic to produce a quorum-sensing molecule-antibiotic conjugate; and introducing the conjugate into a biological system comprising pathogenic bacteria susceptible to the antibiotic.

Synthetic analogs of bacterial quorum sensors

DOEpatents

Iyer, Rashi S.; Ganguly, Kumkum; Silks, Louis A.

2013-01-08

Bacterial quorum-sensing molecule analogs having the following structures: ##STR00001## and methods of reducing bacterial pathogenicity, comprising providing a biological system comprising pathogenic bacteria which produce natural quorum-sensing molecule; providing a synthetic bacterial quorum-sensing molecule having the above structures and introducing the synthetic quorum-sensing molecule into the biological system comprising pathogenic bacteria. Further is provided a method of targeted delivery of an antibiotic, comprising providing a synthetic quorum-sensing molecule; chemically linking the synthetic quorum-sensing molecule to an antibiotic to produce a quorum-sensing molecule-antibiotic conjugate; and introducing the conjugate into a biological system comprising pathogenic bacteria susceptible to the antibiotic.

New perspectives on bacterial ferredoxin evolution

NASA Technical Reports Server (NTRS)

George, D. G.; Hunt, L. T.; Yeh, L.-S. L.; Barker, W. C.

1985-01-01

Ferredoxins are low-molecular-weight, nonheme, iron proteins which function as electron carriers in a wide variety of electron transport chains. Howard et al. (1983) have suggested that the amino end of Azotobacter vinelandii ferredoxin shows a greater similarity to the carboxyl end of ferredoxin from Chromatium vinosum and that their half-chain sequences are homologous when the half-chains of either species are considered in inverse order. Examination of this proposition has made it necessary to reevaluate previous conclusions concerning the evolution of bacterial ferredoxin. Attention is given to the properties of the bacterial ferredoxin sequences, and the evolution of the bacterial ferredoxins.

Bacterial detection of platelets: current problems and possible resolutions.

PubMed

Blajchman, Morris A; Beckers, Erik A M; Dickmeiss, Ebbe; Lin, Lilly; Moore, Gillian; Muylle, Ludo

2005-10-01

The greatest transfusion-transmitted disease risk facing a transfusion recipient is that of bacterial sepsis. The prevalence of bacterial contamination in platelets and red blood cells is approximately 1 in 3,000 units transfused. The available data indicate that transfusion-associated sepsis develops after 1 in 25,000 platelet transfusions and 1 in 250,000 red blood cell transfusions. One of the most widely used strategies for decreasing bacterial sepsis risk is bacterial detection. A roundtable meeting of experts was convened during the XXVIII Annual Congress of the International Society of Blood Transfusion (Edinburgh, UK, July 2004) to provide a forum for experts to share their experiences in the routine bacterial detection of platelet products. This article summarizes the presentations, discussions, and recommendations of the panel. The data presented indicate that some of the current bacterial screening technology is useful for blocking the issuance of platelet units that contain relatively high levels of contaminating bacteria. Platelet units are usually released based on a test-negative status, which often become test-positive only upon longer storage. These data thus suggest that bacterial screening may not prevent all transfusion-transmitted bacterial infections. Two transfusion-transmitted case reports further highlighted the limitation of the routine bacterial screening of platelet products. It was felt that newer technologies, such as pathogen inactivation, may represent a more reliable process, with a higher level of safety. The panel thus recommended that the Transfusion Medicine community may need to change its thinking (paradigm) about bacterial detection, toward the possibility of the pathogen inactivation of blood products, to deal with the bacterial contamination issue. It was suggested, where permitted by regulatory agencies, that blood centers should consider adopting first-generation pathogen inactivation systems as a more effective approach

Bacterial vaginosis and preterm birth.

PubMed

Manns-James, Laura

2011-01-01

Although it has been clear for more than 2 decades that bacterial vaginosis increases the risk for preterm birth in some women, it is not yet fully understood why this association exists or how best to modify the risk. Incomplete understanding of this polymicrobial condition and difficulties in classification contribute to the challenge. The relationship between altered vaginal microflora and preterm birth is likely mediated by host immune responses. Because treatment of bacterial vaginosis during pregnancy does not improve preterm birth rates, and may in fact increase them, screening and treatment of asymptomatic pregnant women is discouraged. Symptomatic women should be treated for symptom relief. This article reviews the pathophysiology of bacterial vaginosis and controversy surrounding management during pregnancy. Agents currently recommended for treatment of this condition are reviewed. © 2011 by the American College of Nurse-Midwives.

The Burden of Bacterial Vaginosis: Women’s Experience of the Physical, Emotional, Sexual and Social Impact of Living with Recurrent Bacterial Vaginosis

PubMed Central

Bilardi, Jade E.; Walker, Sandra; Temple-Smith, Meredith; McNair, Ruth; Mooney-Somers, Julie; Bellhouse, Clare; Fairley, Christopher K.; Chen, Marcus Y.; Bradshaw, Catriona

2013-01-01

Background Bacterial vaginosis is a common vaginal infection, causing an abnormal vaginal discharge and/or odour in up to 50% of sufferers. Recurrence is common following recommended treatment. There are limited data on women’s experience of bacterial vaginosis, and the impact on their self-esteem, sexual relationships and quality of life. The aim of this study was to explore the experiences and impact of recurrent bacterial vaginosis on women. Methods A social constructionist approach was chosen as the framework for the study. Thirty five women with male and/or female partners participated in semi-structured interviews face-to-face or by telephone about their experience of recurrent bacterial vaginosis. Results Recurrent bacterial vaginosis impacted on women to varying degrees, with some women reporting it had little impact on their lives but most reporting it had a moderate to severe impact. The degree to which it impacted on women physically, emotionally, sexually and socially often depended on the frequency of episodes and severity of symptoms. Women commonly reported that symptoms of bacterial vaginosis made them feel embarrassed, ashamed, ‘dirty’ and very concerned others may detect their malodour and abnormal discharge. The biggest impact of recurrent bacterial vaginosis was on women’s self-esteem and sex lives, with women regularly avoiding sexual activity, in particular oral sex, as they were too embarrassed and self-conscious of their symptoms to engage in these activities. Women often felt confused about why they were experiencing recurrent bacterial vaginosis and frustrated at their lack of control over recurrence. Conclusion Women’s experience of recurrent bacterial vaginosis varied broadly and significantly in this study. Some women reported little impact on their lives but most reported a moderate to severe impact, mainly on their self-esteem and sex life. Further support and acknowledgement of these impacts are required when managing women

Precise, High-throughput Analysis of Bacterial Growth.

PubMed

Kurokawa, Masaomi; Ying, Bei-Wen

2017-09-19

Bacterial growth is a central concept in the development of modern microbial physiology, as well as in the investigation of cellular dynamics at the systems level. Recent studies have reported correlations between bacterial growth and genome-wide events, such as genome reduction and transcriptome reorganization. Correctly analyzing bacterial growth is crucial for understanding the growth-dependent coordination of gene functions and cellular components. Accordingly, the precise quantitative evaluation of bacterial growth in a high-throughput manner is required. Emerging technological developments offer new experimental tools that allow updates of the methods used for studying bacterial growth. The protocol introduced here employs a microplate reader with a highly optimized experimental procedure for the reproducible and precise evaluation of bacterial growth. This protocol was used to evaluate the growth of several previously described Escherichia coli strains. The main steps of the protocol are as follows: the preparation of a large number of cell stocks in small vials for repeated tests with reproducible results, the use of 96-well plates for high-throughput growth evaluation, and the manual calculation of two major parameters (i.e., maximal growth rate and population density) representing the growth dynamics. In comparison to the traditional colony-forming unit (CFU) assay, which counts the cells that are cultured in glass tubes over time on agar plates, the present method is more efficient and provides more detailed temporal records of growth changes, but has a stricter detection limit at low population densities. In summary, the described method is advantageous for the precise and reproducible high-throughput analysis of bacterial growth, which can be used to draw conceptual conclusions or to make theoretical observations.

Minerals in soil select distinct bacterial communities in their microhabitats.

PubMed

Carson, Jennifer K; Campbell, Louise; Rooney, Deirdre; Clipson, Nicholas; Gleeson, Deirdre B

2009-03-01

We tested the hypothesis that different minerals in soil select distinct bacterial communities in their microhabitats. Mica (M), basalt (B) and rock phosphate (RP) were incubated separately in soil planted with Trifolium subterraneum, Lolium rigidum or left unplanted. After 70 days, the mineral and soil fractions were separated by sieving. Automated ribosomal intergenic spacer analysis was used to determine whether the bacterial community structure was affected by the mineral, fraction and plant treatments. Principal coordinate plots showed clustering of bacterial communities from different fraction and mineral treatments, but not from different plant treatments. Permutational multivariate anova (permanova) showed that the microhabitats of M, B and RP selected bacterial communities different from each other in unplanted and L. rigidum, and in T. subterraneum, bacterial communities from M and B differed (P<0.046). permanova also showed that each mineral fraction selected bacterial communities different from the surrounding soil fraction (P<0.05). This study shows that the structure of bacterial communities in soil is influenced by the mineral substrates in their microhabitat and that minerals in soil play a greater role in bacterial ecology than simply providing an inert matrix for bacterial growth. This study suggests that mineral heterogeneity in soil contributes to the spatial variation in bacterial communities.

Bacterial strategies of resistance to antimicrobial peptides.

PubMed

Joo, Hwang-Soo; Fu, Chih-Iung; Otto, Michael

2016-05-26

Antimicrobial peptides (AMPs) are a key component of the host's innate immune system, targeting invasive and colonizing bacteria. For successful survival and colonization of the host, bacteria have a series of mechanisms to interfere with AMP activity, and AMP resistance is intimately connected with the virulence potential of bacterial pathogens. In particular, because AMPs are considered as potential novel antimicrobial drugs, it is vital to understand bacterial AMP resistance mechanisms. This review gives a comparative overview of Gram-positive and Gram-negative bacterial strategies of resistance to various AMPs, such as repulsion or sequestration by bacterial surface structures, alteration of membrane charge or fluidity, degradation and removal by efflux pumps.This article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'. © 2016 The Author(s).

9 CFR 113.64 - General requirements for live bacterial vaccines.

Code of Federal Regulations, 2014 CFR

2014-01-01

... bacterial vaccines. 113.64 Section 113.64 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... STANDARD REQUIREMENTS Live Bacterial Vaccines § 113.64 General requirements for live bacterial vaccines... bacterial vaccine shall meet the requirements in this section. (a) Purity test. Final container samples of...

9 CFR 113.64 - General requirements for live bacterial vaccines.

Code of Federal Regulations, 2012 CFR

2012-01-01

... bacterial vaccines. 113.64 Section 113.64 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... STANDARD REQUIREMENTS Live Bacterial Vaccines § 113.64 General requirements for live bacterial vaccines... bacterial vaccine shall meet the requirements in this section. (a) Purity test. Final container samples of...

9 CFR 113.64 - General requirements for live bacterial vaccines.

Code of Federal Regulations, 2013 CFR

2013-01-01

... bacterial vaccines. 113.64 Section 113.64 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... STANDARD REQUIREMENTS Live Bacterial Vaccines § 113.64 General requirements for live bacterial vaccines... bacterial vaccine shall meet the requirements in this section. (a) Purity test. Final container samples of...

Raw Cow Milk Bacterial Population Shifts Attributable to Refrigeration

PubMed Central

Lafarge, Véronique; Ogier, Jean-Claude; Girard, Victoria; Maladen, Véronique; Leveau, Jean-Yves; Gruss, Alexandra; Delacroix-Buchet, Agnès

2004-01-01

We monitored the dynamic changes in the bacterial population in milk associated with refrigeration. Direct analyses of DNA by using temporal temperature gel electrophoresis (TTGE) and denaturing gradient gel electrophoresis (DGGE) allowed us to make accurate species assignments for bacteria with low-GC-content (low-GC%) (<55%) and medium- or high-GC% (>55%) genomes, respectively. We examined raw milk samples before and after 24-h conservation at 4°C. Bacterial identification was facilitated by comparison with an extensive bacterial reference database (∼150 species) that we established with DNA fragments of pure bacterial strains. Cloning and sequencing of fragments missing from the database were used to achieve complete species identification. Considerable evolution of bacterial populations occurred during conservation at 4°C. TTGE and DGGE are shown to be a powerful tool for identifying the main bacterial species of the raw milk samples and for monitoring changes in bacterial populations during conservation at 4°C. The emergence of psychrotrophic bacteria such as Listeria spp. or Aeromonas hydrophila is demonstrated. PMID:15345453

Fungal and Bacterial Pigments: Secondary Metabolites with Wide Applications

PubMed Central

Narsing Rao, Manik Prabhu; Xiao, Min; Li, Wen-Jun

2017-01-01

The demand for natural colors is increasing day by day due to harmful effects of some synthetic dyes. Bacterial and fungal pigments provide a readily available alternative source of naturally derived pigments. In contrast to other natural pigments, they have enormous advantages including rapid growth, easy processing, and independence of weather conditions. Apart from colorant, bacterial and fungal pigments possess many biological properties such as antioxidant, antimicrobial and anticancer activity. This review outlines different types of pigments. It lists some bacterial and fungal pigments and current bacterial and fungal pigment status and challenges. It also focuses on possible fungal and bacterial pigment applications. PMID:28690593

Survivial Strategies in Bacterial Range Expansions

NASA Astrophysics Data System (ADS)

Frey, Erwin

2014-03-01

Bacterial communities represent complex and dynamic ecological systems. Different environmental conditions as well as bacterial interactions determine the establishment and sustainability of bacterial diversity. In this talk we discuss the competition of three Escherichia coli strains during range expansions on agar plates. In this bacterial model system, a colicin E2 producing strain C competes with a colicin resistant strain R and with a colicin sensitive strain S for new territory. Genetic engineering allows us to tune the growth rates of the strains and to study distinct ecological scenarios. These scenarios may lead to either single-strain dominance, pairwise coexistence, or to the coexistence of all three strains. In order to elucidate the survival mechanisms of the individual strains, we also developed a stochastic agent-based model to capture the ecological scenarios in silico. In a combined theoretical and experimental approach we are able to show that the level of biodiversity depends crucially on the composition of the inoculum, on the relative growth rates of the three strains, and on the effective reach of colicin toxicity.

Acute bacterial and viral meningitis.

PubMed

Bartt, Russell

2012-12-01

Most cases of acute meningitis are infectious and result from a potentially wide range of bacterial and viral pathogens. The organized approach to the patient with suspected meningitis enables the prompt administration of antibiotics, possibly corticosteroids, and diagnostic testing with neuroimaging and spinal fluid analysis. Acute meningitis is infectious in most cases and caused by a potentially wide range of bacterial and viral pathogens. Shifts in the epidemiology of bacterial pathogens have been influenced by changes in vaccines and their implementation. Seasonal and environmental changes influence the likely viral and rickettsial pathogens. The organized approach to the patient with suspected meningitis enables the prompt administration of antibiotics, possibly corticosteroids, and diagnostic testing with neuroimaging and spinal fluid analysis. Pertinent testing and treatment can vary with the clinical presentation, season, and possible exposures. This article reviews the epidemiology, clinical presentation, diagnosis, and treatment of acute meningitis.

Evolving issues in understanding and treating bacterial vaginosis.

PubMed

Marrazzo, Jeanne M

2004-12-01

Bacterial vaginosis is a synergistic polymicrobial syndrome characterized by depletion of Lactobacillus spp., especially those that produce hydrogen peroxide, and an intense increase in the quantity of commensal vaginal anaerobic bacteria to 100- to 1000-fold above normal levels. While the bacterial spectrum of these organisms has long been known to include Gardnerella vaginalis, Prevotella spp., anaerobic Gram-positive cocci, Mobiluncus spp. and Mycoplasma hominis, innovative use of molecular diagnostics has identified novel species apparently associated with this syndrome, including Atopobium vaginalis. Effecting resolution of bacterial vaginosis is important, in particular for the 8 to 23% of women afflicted with symptomatic disease during their reproductive years. Bacterial vaginosis has been consistently associated with numerous adverse sequelae related to the upper genital tract, including pelvic inflammatory disease and postsurgical infection in the setting of invasive gynecologic procedures, and may increase women's risk of acquiring HIV infection. Pregnant women with bacterial vaginosis experience a higher rate of preterm delivery and low-birth-weight infants. While antibiotics with activity against anaerobes--typically, metronidazole and clindamycin applied vaginally or taken orally--are the mainstays of therapy, bacterial vaginosis frequently recurs. For these reasons, innovative approaches to therapy are urgently required.

Comprehensive phylogenetic analysis of bacterial reverse transcriptases.

PubMed

Toro, Nicolás; Nisa-Martínez, Rafael

2014-01-01

Much less is known about reverse transcriptases (RTs) in prokaryotes than in eukaryotes, with most prokaryotic enzymes still uncharacterized. Two surveys involving BLAST searches for RT genes in prokaryotic genomes revealed the presence of large numbers of diverse, uncharacterized RTs and RT-like sequences. Here, using consistent annotation across all sequenced bacterial species from GenBank and other sources via RAST, available from the PATRIC (Pathogenic Resource Integration Center) platform, we have compiled the data for currently annotated reverse transcriptases from completely sequenced bacterial genomes. RT sequences are broadly distributed across bacterial phyla, but green sulfur bacteria and cyanobacteria have the highest levels of RT sequence diversity (≤85% identity) per genome. By contrast, phylum Actinobacteria, for which a large number of genomes have been sequenced, was found to have a low RT sequence diversity. Phylogenetic analyses revealed that bacterial RTs could be classified into 17 main groups: group II introns, retrons/retron-like RTs, diversity-generating retroelements (DGRs), Abi-like RTs, CRISPR-Cas-associated RTs, group II-like RTs (G2L), and 11 other groups of RTs of unknown function. Proteobacteria had the highest potential functional diversity, as they possessed most of the RT groups. Group II introns and DGRs were the most widely distributed RTs in bacterial phyla. Our results provide insights into bacterial RT phylogeny and the basis for an update of annotation systems based on sequence/domain homology.

Comprehensive Phylogenetic Analysis of Bacterial Reverse Transcriptases

PubMed Central

Toro, Nicolás; Nisa-Martínez, Rafael

2014-01-01

Much less is known about reverse transcriptases (RTs) in prokaryotes than in eukaryotes, with most prokaryotic enzymes still uncharacterized. Two surveys involving BLAST searches for RT genes in prokaryotic genomes revealed the presence of large numbers of diverse, uncharacterized RTs and RT-like sequences. Here, using consistent annotation across all sequenced bacterial species from GenBank and other sources via RAST, available from the PATRIC (Pathogenic Resource Integration Center) platform, we have compiled the data for currently annotated reverse transcriptases from completely sequenced bacterial genomes. RT sequences are broadly distributed across bacterial phyla, but green sulfur bacteria and cyanobacteria have the highest levels of RT sequence diversity (≤85% identity) per genome. By contrast, phylum Actinobacteria, for which a large number of genomes have been sequenced, was found to have a low RT sequence diversity. Phylogenetic analyses revealed that bacterial RTs could be classified into 17 main groups: group II introns, retrons/retron-like RTs, diversity-generating retroelements (DGRs), Abi-like RTs, CRISPR-Cas-associated RTs, group II-like RTs (G2L), and 11 other groups of RTs of unknown function. Proteobacteria had the highest potential functional diversity, as they possessed most of the RT groups. Group II introns and DGRs were the most widely distributed RTs in bacterial phyla. Our results provide insights into bacterial RT phylogeny and the basis for an update of annotation systems based on sequence/domain homology. PMID:25423096

Metamorphosis of a butterfly-associated bacterial community.

PubMed

Hammer, Tobin J; McMillan, W Owen; Fierer, Noah

2014-01-01

Butterflies are charismatic insects that have long been a focus of biological research. They are also habitats for microorganisms, yet these microbial symbionts are little-studied, despite their likely importance to butterfly ecology and evolution. In particular, the diversity and composition of the microbial communities inhabiting adult butterflies remain uncharacterized, and it is unknown how the larval (caterpillar) and adult microbiota compare. To address these knowledge gaps, we used Illumina sequencing of 16S rRNA genes from internal bacterial communities associated with multiple life stages of the neotropical butterfly Heliconius erato. We found that the leaf-chewing larvae and nectar- and pollen-feeding adults of H. erato contain markedly distinct bacterial communities, a pattern presumably rooted in their distinct diets. Larvae and adult butterflies host relatively small and similar numbers of bacterial phylotypes, but few are common to both stages. The larval microbiota clearly simplifies and reorganizes during metamorphosis; thus, structural changes in a butterfly's bacterial community parallel those in its own morphology. We furthermore identify specific bacterial taxa that may mediate larval and adult feeding biology in Heliconius and other butterflies. Although male and female Heliconius adults differ in reproductive physiology and degree of pollen feeding, bacterial communities associated with H. erato are not sexually dimorphic. Lastly, we show that captive and wild individuals host different microbiota, a finding that may have important implications for the relevance of experimental studies using captive butterflies.

Metamorphosis of a Butterfly-Associated Bacterial Community

PubMed Central

Hammer, Tobin J.; McMillan, W. Owen; Fierer, Noah

2014-01-01

Butterflies are charismatic insects that have long been a focus of biological research. They are also habitats for microorganisms, yet these microbial symbionts are little-studied, despite their likely importance to butterfly ecology and evolution. In particular, the diversity and composition of the microbial communities inhabiting adult butterflies remain uncharacterized, and it is unknown how the larval (caterpillar) and adult microbiota compare. To address these knowledge gaps, we used Illumina sequencing of 16S rRNA genes from internal bacterial communities associated with multiple life stages of the neotropical butterfly Heliconius erato. We found that the leaf-chewing larvae and nectar- and pollen-feeding adults of H. erato contain markedly distinct bacterial communities, a pattern presumably rooted in their distinct diets. Larvae and adult butterflies host relatively small and similar numbers of bacterial phylotypes, but few are common to both stages. The larval microbiota clearly simplifies and reorganizes during metamorphosis; thus, structural changes in a butterfly's bacterial community parallel those in its own morphology. We furthermore identify specific bacterial taxa that may mediate larval and adult feeding biology in Heliconius and other butterflies. Although male and female Heliconius adults differ in reproductive physiology and degree of pollen feeding, bacterial communities associated with H. erato are not sexually dimorphic. Lastly, we show that captive and wild individuals host different microbiota, a finding that may have important implications for the relevance of experimental studies using captive butterflies. PMID:24466308

SIMPLAS: A Simulation of Bacterial Plasmid Maintenance.

ERIC Educational Resources Information Center

Dunn, A.; And Others

1988-01-01

This article describes a computer simulation of bacterial physiology during growth in a chemostat. The program was designed to help students to appreciate and understand the related effects of parameters which influence plasmid persistence in bacterial populations. (CW)

Identifying Bacterial Immune Evasion Proteins Using Phage Display.

PubMed

Fevre, Cindy; Scheepmaker, Lisette; Haas, Pieter-Jan

2017-01-01

Methods aimed at identification of immune evasion proteins are mainly rely on in silico prediction of sequence, structural homology to known evasion proteins or use a proteomics driven approach. Although proven successful these methods are limited by a low efficiency and or lack of functional identification. Here we describe a high-throughput genomic strategy to functionally identify bacterial immune evasion proteins using phage display technology. Genomic bacterial DNA is randomly fragmented and ligated into a phage display vector that is used to create a phage display library expressing bacterial secreted and membrane bound proteins. This library is used to select displayed bacterial secretome proteins that interact with host immune components.

Bacterial copper storage proteins.

PubMed

Dennison, Christopher; David, Sholto; Lee, Jaeick

2018-03-30

Copper is essential for most organisms as a cofactor for key enzymes involved in fundamental processes such as respiration and photosynthesis. However, copper also has toxic effects in cells, which is why eukaryotes and prokaryotes have evolved mechanisms for safe copper handling. A new family of bacterial proteins uses a Cys-rich four-helix bundle to safely store large quantities of Cu(I). The work leading to the discovery of these proteins, their properties and physiological functions, and how their presence potentially impacts the current views of bacterial copper handling and use are discussed in this review. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Effects of bacterial pollution caused by a strong typhoon event and the restoration of a recreational beach: Transitions of fecal bacterial counts and bacterial flora in beach sand.

PubMed

Suzuki, Yoshihiro; Teranishi, Kotaro; Matsuwaki, Tomonori; Nukazawa, Kei; Ogura, Yoshitoshi

2018-05-28

To determine the effects of bacteria pollution associated with a strong typhoon event and to assess the restoration of the normal bacterial flora, we used conventional filtration methods and nextgeneration sequencing of 16S rRNA genes to analyze the transition of fecal and total bacterial counts in water and core sand samples collected from a recreational beach. Immediately after the typhoon event, Escherichia coli counts increased to 82 CFU/100 g in the surface beach sand. E. coli was detected through the surface to sand 85-cm deep at the land side point (10-m land side from the high-water line). However, E. coli disappeared within a month from the land side point. The composition of the bacterial flora in the beach sand at the land point was directly influenced by the typhoon event. Pseudomonas was the most prevalent genus throughout the sand layers (0-102-cm deep) during the typhoon event. After 3 months, the population of Pseudomonas significantly decreased, and the predominant genus in the surface layer was Kaistobacter, although Pseudomonas was the major genus in the 17- to 85-cm layer. When the beach conditions stabilized, the number of pollutant Pseudomonas among the 10 most abundant genera decreased to lower than the limit of detection. The bacterial population of the sand was subsequently restored to the most populous pre-event orders at the land point. A land-side beach, where users directly contact the sand, was significantly affected by bacterial pollution caused by a strong typhoon event. We show here that the normal bacterial flora of the surface sand was restored within 1 month. Copyright © 2018 Elsevier B.V. All rights reserved.

Acute Bacterial Prostatitis: Diagnosis and Management.

PubMed

Coker, Timothy J; Dierfeldt, Daniel M

2016-01-15

Acute bacterial prostatitis is an acute infection of the prostate gland that causes pelvic pain and urinary tract symptoms, such as dysuria, urinary frequency, and urinary retention, and may lead to systemic symptoms, such as fevers, chills, nausea, emesis, and malaise. Although the true incidence is unknown, acute bacterial prostatitis is estimated to comprise approximately 10% of all cases of prostatitis. Most acute bacterial prostatitis infections are community acquired, but some occur after transurethral manipulation procedures, such as urethral catheterization and cystoscopy, or after transrectal prostate biopsy. The physical examination should include abdominal, genital, and digital rectal examination to assess for a tender, enlarged, or boggy prostate. Diagnosis is predominantly made based on history and physical examination, but may be aided by urinalysis. Urine cultures should be obtained in all patients who are suspected of having acute bacterial prostatitis to determine the responsible bacteria and its antibiotic sensitivity pattern. Additional laboratory studies can be obtained based on risk factors and severity of illness. Radiography is typically unnecessary. Most patients can be treated as outpatients with oral antibiotics and supportive measures. Hospitalization and broad-spectrum intravenous antibiotics should be considered in patients who are systemically ill, unable to voluntarily urinate, unable to tolerate oral intake, or have risk factors for antibiotic resistance. Typical antibiotic regimens include ceftriaxone and doxycycline, ciprofloxacin, and piperacillin/tazobactam. The risk of nosocomial bacterial prostatitis can be reduced by using antibiotics, such as ciprofloxacin, before transrectal prostate biopsy.

Neglected bacterial zoonoses.

PubMed

Chikeka, I; Dumler, J S

2015-05-01

Bacterial zoonoses comprise a group of diseases in humans or animals acquired by direct contact with or by oral consumption of contaminated animal materials, or via arthropod vectors. Among neglected infections, bacterial zoonoses are among the most neglected given emerging data on incidence and prevalence as causes of acute febrile illness, even in areas where recognized neglected tropical diseases occur frequently. Although many other bacterial infections could also be considered in this neglected category, five distinct infections stand out because they are globally distributed, are acute febrile diseases, have high rates of morbidity and case fatality, and are reported as commonly as malaria, typhoid or dengue virus infections in carefully designed studies in which broad-spectrum diagnoses are actively sought. This review will focus attention on leptospirosis, relapsing fever borreliosis and rickettsioses, including scrub typhus, murine typhus and spotted fever group rickettsiosis. Of greatest interest is the lack of distinguishing clinical features among these infections when in humans, which confounds diagnosis where laboratory confirmation is lacking, and in regions where clinical diagnosis is often attributed to one of several perceived more common threats. As diseases such as malaria come under improved control, the real impact of these common and under-recognized infections will become evident, as will the requirement for the strategies and allocation of resources for their control. Copyright © 2015 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

[Revised Japanese guidelines for the clinical management of bacterial meningitis].

PubMed

Ishikawa, Harumi; Kamei, Satoshi

2014-01-01

Improvement of outcomes represents the most important problem in the treatment of bacterial meningitis. To achieve such improvement, revision of the guidelines for the clinical management of bacterial meningitis in Japan has been carried out, and these revised Japanese guidelines will soon be published. The choice of specific antimicrobial agents for initial treatment in bacterial meningitis is influenced by a number of factors, including patient age, systemic symptoms, and local patterns of bacterial resistance. In the revised Japanese guidelines, antimicrobial agents based on current knowledge of the epidemiology in Japan are recommended. Bacterial meningitis is a medical emergency, and patients with this disease require immediate medical assessment and appropriate treatment. Rapid diagnosis and treatment of bacterial meningitis reduces mortality and neurological sequelae. We describe the revised Japanese guidelines for the clinical management of bacterial meningitis 2014, with a focus on adults.

Predictive value of decoy receptor 3 in postoperative nosocomial bacterial meningitis.

PubMed

Liu, Yong-Juan; Shao, Li-Hua; Wang, Qian; Zhang, Jian; Ma, Rui-Ping; Liu, Hai-Hong; Dong, Xiao-Meng; Ma, Li-Xian

2014-11-03

Nosocomial bacterial meningitis requires timely treatment, but what is difficult is the prompt and accurate diagnosis of this disease. The aim of this study was to assess the potential role of decoy receptor 3 (DcR3) levels in the differentiation of bacterial meningitis from non-bacterial meningitis. A total of 123 patients were recruited in this study, among them 80 patients being with bacterial meningitis and 43 patients with non-bacterial meningitis. Bacterial meningitis was confirmed by bacterial culture of cerebrospinal fluid (CSF) culture and enzyme-linked immunosorbent assay (ELISA) was used to detect the level of DcR3 in CSF. CSF levels of DcR3 were statistically significant between patients with bacterial meningitis and those with non-bacterial meningitis (p<0.001). A total of 48.75% of patients with bacterial meningitis received antibiotic>24 h before CSF sampling, which was much higher than that of non-bacterial meningitis. CSF leucocyte count yielded the highest diagnostic value, with an area under the receiver operating characteristic curve (ROC) of 0.928, followed by DcR3. At a critical value of 0.201 ng/mL for DcR3, the sensitivity and specificity were 78.75% and 81.40% respectively. DcR3 in CSF may be a valuable predictor for differentiating patients with bacterial meningitis from those with non-bacterial meningitis. Further studies are needed for the validation of this study.

Predictive Value of Decoy Receptor 3 in Postoperative Nosocomial Bacterial Meningitis

PubMed Central

Liu, Yong-Juan; Shao, Li-Hua; Wang, Qian; Zhang, Jian; Ma, Rui-Ping; Liu, Hai-Hong; Dong, Xiao-Meng; Ma, Li-Xian

2014-01-01

Nosocomial bacterial meningitis requires timely treatment, but what is difficult is the prompt and accurate diagnosis of this disease. The aim of this study was to assess the potential role of decoy receptor 3 (DcR3) levels in the differentiation of bacterial meningitis from non-bacterial meningitis. A total of 123 patients were recruited in this study, among them 80 patients being with bacterial meningitis and 43 patients with non-bacterial meningitis. Bacterial meningitis was confirmed by bacterial culture of cerebrospinal fluid (CSF) culture and enzyme-linked immunosorbent assay (ELISA) was used to detect the level of DcR3 in CSF. CSF levels of DcR3 were statistically significant between patients with bacterial meningitis and those with non-bacterial meningitis (p < 0.001). A total of 48.75% of patients with bacterial meningitis received antibiotic >24 h before CSF sampling, which was much higher than that of non-bacterial meningitis. CSF leucocyte count yielded the highest diagnostic value, with an area under the receiver operating characteristic curve (ROC) of 0.928, followed by DcR3. At a critical value of 0.201 ng/mL for DcR3, the sensitivity and specificity were 78.75% and 81.40% respectively. DcR3 in CSF may be a valuable predictor for differentiating patients with bacterial meningitis from those with non-bacterial meningitis. Further studies are needed for the validation of this study. PMID:25372942

Bacterial selection by mycospheres of Atlantic Rainforest mushrooms.

PubMed

Halsey, Joshua Andrew; de Cássia Pereira E Silva, Michele; Andreote, Fernando Dini

2016-10-01

This study focuses on the selection exerted on bacterial communities in the mycospheres of mushrooms collected in the Brazilian Atlantic Rainforest. A total of 24 paired samples (bulk soil vs. mycosphere) were assessed to investigate potential interactions between fungi and bacteria present in fungal mycospheres. Prevalent fungal families were identified as Marasmiaceae and Lepiotaceae (both Basidiomycota) based on ITS partial sequencing. We used culture-independent techniques to analyze bacterial DNA from soil and mycosphere samples. Bacterial communities in the samples were distinguished based on overall bacterial, alphaproteobacterial, and betaproteobacterial PCR-DGGE patterns, which were different in fungi belonging to different taxa. These results were confirmed by pyrosequencing the V4 region of the 16S rRNA gene (based on five bulk soil vs. mycosphere pairs), which revealed the most responsive bacterial families in the different conditions generated beneath the mushrooms, identified as Bradyrhizobiaceae, Burkholderiaceae, and Pseudomonadaceae. The bacterial families Acetobacteraceae, Chrhoniobacteraceae, Planctomycetaceae, Conexibacteraceae, and Burkholderiaceae were found in all mycosphere samples, composing the core mycosphere microbiome. Similarly, some bacterial groups identified as Koribacteriaceae, Acidobacteria (Solibacteriaceae) and an unclassified group of Acidobacteria were preferentially present in the bulk soil samples (found in all of them). In this study we depict the mycosphere effect exerted by mushrooms inhabiting the Brazilian Atlantic Rainforest, and identify the bacteria with highest response to such a specific niche, possibly indicating the role bacteria play in mushroom development and dissemination within this yet-unexplored environment.

Silver-nanoparticle-coated biliary stent inhibits bacterial adhesion in bacterial cholangitis in swine.

PubMed

Wen, Wei; Ma, Li-Mei; He, Wei; Tang, Xiao-Wei; Zhang, Yin; Wang, Xiang; Liu, Li; Fan, Zhi-Ning

2016-02-01

One of the major limitations of biliary stents is the stent occlusion, which is closely related to the over-growth of bacteria. This study aimed to evaluate the feasibility of a novel silver-nanoparticle-coated polyurethane (Ag/PU) stent in bacterial cholangitis model in swine. Ag/PU was designed by coating silver nanoparticles on polyurethane (PU) stent. Twenty-four healthy pigs with bacterial cholangitis using Ag/PU and PU stents were randomly divided into an Ag/PU stent group (n=12) and a PU stent group (n=12), respectively. The stents were inserted by standard endoscopic retrograde cholangiopancreatography. Laboratory assay was performed for white blood cell (WBC) count, alanine aminotransferase (ALT), interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha) at baseline time, 8 hours, 1, 2, 3, and 7 days after stent placements. The segment of bile duct containing the stent was examined histologically ex vivo. Implanted biliary stents were examined by a scan electron microscope. The amount of silver release was also measured in vitro. The number of inflammatory cells and level of ALT, IL-1beta and TNF-alpha were significantly lower in the Ag/PU stent group than in the PU stent group. Hyperplasia of the mucosa was more severe in the PU stent group than in the Ag/PU stent group. In contrast to the biofilm of bacteria on the PU stent, fewer bacteria adhered to the Ag/PU stent. PU biliary stents modified with silver nanoparticles are able to alleviate the inflammation of pigs with bacterial cholangitis. Silver-nanoparticle-coated stents are resistant to bacterial adhesion.

Bacterial Communities in Women with Bacterial Vaginosis: High Resolution Phylogenetic Analyses Reveal Relationships of Microbiota to Clinical Criteria

PubMed Central

Srinivasan, Sujatha; Hoffman, Noah G.; Morgan, Martin T.; Matsen, Frederick A.; Fiedler, Tina L.; Hall, Robert W.; Ross, Frederick J.; McCoy, Connor O.; Bumgarner, Roger; Marrazzo, Jeanne M.; Fredricks, David N.

2012-01-01

Background Bacterial vaginosis (BV) is a common condition that is associated with numerous adverse health outcomes and is characterized by poorly understood changes in the vaginal microbiota. We sought to describe the composition and diversity of the vaginal bacterial biota in women with BV using deep sequencing of the 16S rRNA gene coupled with species-level taxonomic identification. We investigated the associations between the presence of individual bacterial species and clinical diagnostic characteristics of BV. Methodology/Principal Findings Broad-range 16S rRNA gene PCR and pyrosequencing were performed on vaginal swabs from 220 women with and without BV. BV was assessed by Amsel’s clinical criteria and confirmed by Gram stain. Taxonomic classification was performed using phylogenetic placement tools that assigned 99% of query sequence reads to the species level. Women with BV had heterogeneous vaginal bacterial communities that were usually not dominated by a single taxon. In the absence of BV, vaginal bacterial communities were dominated by either Lactobacillus crispatus or Lactobacillus iners. Leptotrichia amnionii and Eggerthella sp. were the only two BV-associated bacteria (BVABs) significantly associated with each of the four Amsel’s criteria. Co-occurrence analysis revealed the presence of several sub-groups of BVABs suggesting metabolic co-dependencies. Greater abundance of several BVABs was observed in Black women without BV. Conclusions/Significance The human vaginal bacterial biota is heterogeneous and marked by greater species richness and diversity in women with BV; no species is universally present. Different bacterial species have different associations with the four clinical criteria, which may account for discrepancies often observed between Amsel and Nugent (Gram stain) diagnostic criteria. Several BVABs exhibited race-dependent prevalence when analyzed in separate groups by BV status which may contribute to increased incidence of BV in

Cytosolic Access of Intracellular Bacterial Pathogens: The Shigella Paradigm.

PubMed

Mellouk, Nora; Enninga, Jost

2016-01-01

Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it.

Distinct Habitats Select Particular Bacterial Communities in Mangrove Sediments.

PubMed

Rocha, Lidianne L; Colares, Geórgia B; Nogueira, Vanessa L R; Paes, Fernanda A; Melo, Vânia M M

2016-01-01

We investigated the relationship among environmental variables, composition, and structure of bacterial communities in different habitats in a mangrove located nearby to an oil exploitation area, aiming to retrieve the natural pattern of bacterial communities in this ecosystem. The T-RFLP analysis showed a high diversity of bacterial populations and an increase in the bacterial richness from habitats closer to the sea and without vegetation (S1) to habitats covered by Avicennia schaueriana (S2) and Rhizophora mangle (S3). Environmental variables in S1 and S2 were more similar than in S3; however, when comparing the bacterial compositions, S2 and S3 shared more OTUs between them, suggesting that the presence of vegetation is an important factor in shaping these bacterial communities. In silico analyses of the fragments revealed a high diversity of the class Gammaproteobacteria in the 3 sites, although in general they presented quite different bacterial composition, which is probably shaped by the specificities of each habitat. This study shows that microhabitats inside of a mangrove ecosystem harbor diverse and distinct microbiota, reinforcing the need to conserve these ecosystems as a whole.

Distinct Habitats Select Particular Bacterial Communities in Mangrove Sediments

PubMed Central

Rocha, Lidianne L.; Colares, Geórgia B.; Nogueira, Vanessa L. R.; Paes, Fernanda A.; Melo, Vânia M. M.

2016-01-01

We investigated the relationship among environmental variables, composition, and structure of bacterial communities in different habitats in a mangrove located nearby to an oil exploitation area, aiming to retrieve the natural pattern of bacterial communities in this ecosystem. The T-RFLP analysis showed a high diversity of bacterial populations and an increase in the bacterial richness from habitats closer to the sea and without vegetation (S1) to habitats covered by Avicennia schaueriana (S2) and Rhizophora mangle (S3). Environmental variables in S1 and S2 were more similar than in S3; however, when comparing the bacterial compositions, S2 and S3 shared more OTUs between them, suggesting that the presence of vegetation is an important factor in shaping these bacterial communities. In silico analyses of the fragments revealed a high diversity of the class Gammaproteobacteria in the 3 sites, although in general they presented quite different bacterial composition, which is probably shaped by the specificities of each habitat. This study shows that microhabitats inside of a mangrove ecosystem harbor diverse and distinct microbiota, reinforcing the need to conserve these ecosystems as a whole. PMID:26989418

A uniform bacterial growth potential assay for different water types.

PubMed

Farhat, Nadia; Hammes, Frederik; Prest, Emmanuelle; Vrouwenvelder, Johannes

2018-06-06

The bacterial growth potential is important to understand and manage bacterial regrowth-related water quality concerns. Bacterial growth potential depends on growth promoting/limiting compounds, therefore, nutrient availability is the key factor governing bacterial growth potential. Selecting proper tools for bacterial growth measurement is essential for routine implementation of the growth potential measurement. This study proposes a growth potential assay that is universal and can be used for different water types and soil extract without restrictions of pure culture or cultivability of the bacterial strain. The proposed assay measures the sample bacterial growth potential by using the indigenous community as inocula. Flow cytometry (FCM) and adenosine tri-phosphate (ATP) were used to evaluate the growth potential of six different microbial communities indigenous to the sample being analyzed, with increasing carbon concentrations. Bottled mineral water, non-chlorinated tap water, seawater, river water, wastewater effluent and a soil organic carbon extract were analyzed. Results showed that indigenous bacterial communities followed normal batch growth kinetics when grown on naturally present organic carbon. Indigenous bacterial growth could detect spiked organic carbon concentrations as low as 10 μg/L. The indigenous community in all samples responded proportionally to the increase in acetate-carbon and proportional growth could be measured with both FCM and ATP. Bacterial growth was proportional to the carbon concentration but not the same proportion factor for the different water samples tested. The effect of inoculating the same water with different indigenous microbial communities on the growth potential was also examined. The FCM results showed that the highest increase in total bacterial cell concentration was obtained with bacteria indigenous to the water sample. The growth potential assay using indigenous bacterial community revealed consistent results

Physical stress and bacterial colonization

PubMed Central

Otto, Michael

2014-01-01

Bacterial surface colonizers are subject to a variety of physical stresses. During the colonization of human epithelia such as on the skin or the intestinal mucosa, bacteria mainly have to withstand the mechanical stress of being removed by fluid flow, scraping, or epithelial turnover. To that end, they express a series of molecules to establish firm attachment to the epithelial surface, such as fibrillar protrusions (pili) and surface-anchored proteins that bind to human matrix proteins. In addition, some bacteria – in particular gut and urinary tract pathogens – use internalization by epithelial cells and other methods such as directed inhibition of epithelial turnover to ascertain continued association with the epithelial layer. Furthermore, many bacteria produce multi-layered agglomerations called biofilms with a sticky extracellular matrix, providing additional protection from removal. This review will give an overview over the mechanisms human bacterial colonizers have to withstand physical stresses with a focus on bacterial adhesion. PMID:25212723

Acute bacterial meningitis in adults.

PubMed

McGill, Fiona; Heyderman, Robert S; Panagiotou, Stavros; Tunkel, Allan R; Solomon, Tom

2016-12-17

Over the past several decades, the incidence of bacterial meningitis in children has decreased but there remains a significant burden of disease in adults, with a mortality of up to 30%. Although the pathogenesis of bacterial meningitis is not completely understood, knowledge of bacterial invasion and entry into the CNS is improving. Clinical features alone cannot determine whether meningitis is present and analysis of cerebrospinal fluid is essential for diagnosis. Newer technologies, such as multiplex PCR, and novel diagnostic platforms that incorporate proteomics and genetic sequencing, might help provide a quicker and more accurate diagnosis. Even with appropriate antimicrobial therapy, mortality is high and so attention has focused on adjunctive therapies; adjunctive corticosteroids are beneficial in certain circumstances. Any further improvements in outcome are likely to come from either modulation of the host response or novel approaches to therapy, rather than new antibiotics. Ultimately, the best hope to reduce the disease burden is with broadly protective vaccines. Copyright © 2016 Elsevier Ltd. All rights reserved.

Contrasting ability to take up leucine and thymidine among freshwater bacterial groups: implications for bacterial production measurements

PubMed Central

Pérez, María Teresa; Hörtnagl, Paul; Sommaruga, Ruben

2010-01-01

We examined the ability of different freshwater bacterial groups to take up leucine and thymidine in two lakes. Utilization of both substrates by freshwater bacteria was examined at the community level by looking at bulk incorporation rates and at the single-cell level by combining fluorescent in situ hybridization and signal amplification by catalysed reporter deposition with microautoradiography. Our results showed that leucine was taken up by 70–80% of Bacteria-positive cells, whereas only 15–43% of Bacteria-positive cells were able to take up thymidine. When a saturating substrate concentration in combination with a short incubation was used, 80–90% of Betaproteobacteria and 67–79% of Actinobacteria were positive for leucine uptake, whereas thymidine was taken up by < 10% of Betaproteobacteria and by < 1% of the R-BT subgroup that dominated this bacterial group. Bacterial abundance was a good predictor of the relative contribution of bacterial groups to leucine uptake, whereas when thymidine was used Actinobacteria represented the large majority (> 80%) of the cells taking up this substrate. Increasing the substrate concentration to 100 nM did not affect the percentage of R-BT cells taking up leucine (> 90% even at low concentrations), but moderately increased the fraction of thymidine-positive R-BT cells to a maximum of 35% of the hybridized cells. Our results show that even at very high concentrations, thymidine is not taken up by all, otherwise active, bacterial cells. PMID:19725866

Enzymatic hydrolysis of biomimetic bacterial cellulose-hemicellulose composites.

PubMed

Penttilä, Paavo A; Imai, Tomoya; Hemming, Jarl; Willför, Stefan; Sugiyama, Junji

2018-06-15

The production of biofuels and other chemicals from lignocellulosic biomass is limited by the inefficiency of enzymatic hydrolysis. Here a biomimetic composite material consisting of bacterial cellulose and wood-based hemicelluloses was used to study the effects of hemicelluloses on the enzymatic hydrolysis with a commercial cellulase mixture. Bacterial cellulose synthesized in the presence of hemicelluloses, especially xylan, was found to be more susceptible to enzymatic hydrolysis than hemicellulose-free bacterial cellulose. The reason for the easier hydrolysis could be related to the nanoscale structure of the substrate, particularly the packing of cellulose microfibrils into ribbons or bundles. In addition, small-angle X-ray scattering was used to show that the average nanoscale morphology of bacterial cellulose remained unchanged during the enzymatic hydrolysis. The reported easier enzymatic hydrolysis of bacterial cellulose produced in the presence of wood-based xylan offers new insights to overcome biomass recalcitrance through genetic engineering. Copyright © 2018 Elsevier Ltd. All rights reserved.

The Differential Effects of Anesthetics on Bacterial Behaviors

PubMed Central

Chamberlain, Matthew; Koutsogiannaki, Sophia; Schaefers, Matthew; Babazada, Hasan; Liu, Renyu; Yuki, Koichi

2017-01-01

Volatile anesthetics have been in clinical use for a long period of time and are considered to be promiscuous by presumably interacting with several ion channels in the central nervous system to produce anesthesia. Because ion channels and their existing evolutionary analogues, ion transporters, are very important in various organisms, it is possible that volatile anesthetics may affect some bacteria. In this study, we hypothesized that volatile anesthetics could affect bacterial behaviors. We evaluated the impact of anesthetics on bacterial growth, motility (swimming and gliding) and biofilm formation of four common bacterial pathogens in vitro. We found that commonly used volatile anesthetics isoflurane and sevoflurane affected bacterial motility and biofilm formation without any effect on growth of the common bacterial pathogens studied here. Using available Escherichia coli gene deletion mutants of ion transporters and in silico molecular docking, we suggested that these altered behaviors might be at least partly via the interaction of volatile anesthetics with ion transporters. PMID:28099463

Bacterial desorption from food container and food processing surfaces.

PubMed

McEldowney, S; Fletcher, M

1988-03-01

The desorption ofStaphylococcus aureus, Acinetobacter calcoaceticus, and a coryneform from the surfaces of materials used for manufacturing food containers (glass, tin plate, and polypropylene) or postprocess canning factory conveyor belts (stainless steel and nylon) was investigated. The effect of time, pH, temperature, and adsorbed organic layers on desorption was studied.S. aureus did not detach from the substrata at any pH investigated (between pH 5 and 9).A. calcoaceticus and the coryneform in some cases detached, depending upon pH and substratum composition. The degree of bacterial detachment from the substrata was not related to bacterial respiration at experimental pH values. Bacterial desorption was not affected by temperature (4-30°C) nor by an adsorbed layer of peptone and yeast extract on the substrata. The results indicate that bacterial desorption, hence bacterial removal during cleaning or their transfer via liquids flowing over colonized surfaces, is likely to vary with the surface composition and the bacterial species colonizing the surfaces.

Impairment of the Bacterial Biofilm Stability by Triclosan

PubMed Central

Hubas, Cédric; Behrens, Sebastian; Ricciardi, Francesco; Paterson, David M.

2012-01-01

The accumulation of the widely-used antibacterial and antifungal compound triclosan (TCS) in freshwaters raises concerns about the impact of this harmful chemical on the biofilms that are the dominant life style of microorganisms in aquatic systems. However, investigations to-date rarely go beyond effects at the cellular, physiological or morphological level. The present paper focuses on bacterial biofilms addressing the possible chemical impairment of their functionality, while also examining their substratum stabilization potential as one example of an important ecosystem service. The development of a bacterial assemblage of natural composition – isolated from sediments of the Eden Estuary (Scotland, UK) – on non-cohesive glass beads (<63 µm) and exposed to a range of triclosan concentrations (control, 2 – 100 µg L−1) was monitored over time by Magnetic Particle Induction (MagPI). In parallel, bacterial cell numbers, division rate, community composition (DGGE) and EPS (extracellular polymeric substances: carbohydrates and proteins) secretion were determined. While the triclosan exposure did not prevent bacterial settlement, biofilm development was increasingly inhibited by increasing TCS levels. The surface binding capacity (MagPI) of the assemblages was positively correlated to the microbial secreted EPS matrix. The EPS concentrations and composition (quantity and quality) were closely linked to bacterial growth, which was affected by enhanced TCS exposure. Furthermore, TCS induced significant changes in bacterial community composition as well as a significant decrease in bacterial diversity. The impairment of the stabilization potential of bacterial biofilm under even low, environmentally relevant TCS levels is of concern since the resistance of sediments to erosive forces has large implications for the dynamics of sediments and associated pollutant dispersal. In addition, the surface adhesive capacity of the biofilm acts as a sensitive measure of

Risk factors for community-acquired bacterial meningitis.

PubMed

Lundbo, Lene Fogt; Benfield, Thomas

2017-06-01

Bacterial meningitis is a significant burden of disease and mortality in all age groups worldwide despite the development of effective conjugated vaccines. The pathogenesis of bacterial meningitis is based on complex and incompletely understood host-pathogen interactions. Some of these are pathogen-specific, while some are shared between different bacteria. We searched the database PubMed to identify host risk factors for bacterial meningitis caused by the pathogens Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae type b, because they are three most common causative bacteria beyond the neonatal period. We describe a number of risk factors; including socioeconomic factors, age, genetic variation of the host and underlying medical conditions associated with increased susceptibility to invasive bacterial infections in both children and adults. As conjugated vaccines are available for these infections, it is of utmost importance to identify high risk patients to be able to prevent invasive disease.

Probing Prokaryotic Social Behaviors with Bacterial “Lobster Traps”

PubMed Central

Connell, Jodi L.; Wessel, Aimee K.; Parsek, Matthew R.; Ellington, Andrew D.; Whiteley, Marvin; Shear, Jason B.

2010-01-01

Bacteria are social organisms that display distinct behaviors/phenotypes when present in groups. These behaviors include the abilities to construct antibiotic-resistant sessile biofilm communities and to communicate with small signaling molecules (quorum sensing [QS]). Our understanding of biofilms and QS arises primarily from in vitro studies of bacterial communities containing large numbers of cells, often greater than 108 bacteria; however, in nature, bacteria often reside in dense clusters (aggregates) consisting of significantly fewer cells. Indeed, bacterial clusters containing 101 to 105 cells are important for transmission of many bacterial pathogens. Here, we describe a versatile strategy for conducting mechanistic studies to interrogate the molecular processes controlling antibiotic resistance and QS-mediated virulence factor production in high-density bacterial clusters. This strategy involves enclosing a single bacterium within three-dimensional picoliter-scale microcavities (referred to as bacterial “lobster traps”) defined by walls that are permeable to nutrients, waste products, and other bioactive small molecules. Within these traps, bacteria divide normally into extremely dense (1012 cells/ml) clonal populations with final population sizes similar to that observed in naturally occurring bacterial clusters. Using these traps, we provide strong evidence that within low-cell-number/high-density bacterial clusters, QS is modulated not only by bacterial density but also by population size and flow rate of the surrounding medium. We also demonstrate that antibiotic resistance develops as cell density increases, with as few as ~150 confined bacteria exhibiting an antibiotic-resistant phenotype similar to biofilm bacteria. Together, these findings provide key insights into clinically relevant phenotypes in low-cell-number/high-density bacterial populations. PMID:21060734

Community-Acquired Bacterial Meningitis in Alcoholic Patients

PubMed Central

Weisfelt, Martijn; de Gans, Jan; van der Ende, Arie; van de Beek, Diederik

2010-01-01

Background Alcoholism is associated with susceptibility to infectious disease, particularly bacterial pneumonia. In the present study we described characteristics in alcoholic patients with bacterial meningitis and delineate the differences with findings in non-alcoholic adults with bacterial meningitis. Methods/Principal Findings This was a prospective nationwide observational cohort study including patients aged >16 years who had bacterial meningitis confirmed by culture of cerebrospinal fluid (696 episodes of bacterial meningitis occurring in 671 patients). Alcoholism was present in 27 of 686 recorded episodes of bacterial meningitis (4%) and alcoholics were more often male than non-alcoholics (82% vs 48%, P = 0.001). A higher proportion of alcoholics had underlying pneumonia (41% vs 11% P<0.001). Alcoholics were more likely to have meningitis due to infection with Streptococcus pneumoniae (70% vs 50%, P = 0.01) and Listeria monocytogenes (19% vs 4%, P = 0.005), whereas Neisseria meningitidis was more common in non-alcoholic patients (39% vs 4%, P = 0.01). A large proportion of alcoholics developed complications during clinical course (82% vs 62%, as compared with non-alcoholics; P = 0.04), often cardiorespiratory failure (52% vs 28%, as compared with non-alcoholics; P = 0.01). Alcoholic patients were at risk for unfavourable outcome (67% vs 33%, as compared with non-alcoholics; P<0.001). Conclusions/Significance Alcoholic patients are at high risk for complications resulting in high morbidity and mortality. They are especially at risk for cardiorespiratory failure due to underlying pneumonia, and therefore, aggressive supportive care may be crucial in the treatment of these patients. PMID:20161709

Determinants of bacterial communities in Canadian agroforestry systems.

PubMed

Banerjee, Samiran; Baah-Acheamfour, Mark; Carlyle, Cameron N; Bissett, Andrew; Richardson, Alan E; Siddique, Tariq; Bork, Edward W; Chang, Scott X

2016-06-01

Land-use change is one of the most important factors influencing soil microbial communities, which play a pivotal role in most biogeochemical and ecological processes. Using agroforestry systems as a model, this study examined the effects of land uses and edaphic properties on bacterial communities in three agroforestry types covering a 270 km soil-climate gradient in Alberta, Canada. Our results demonstrate that land-use patterns exert stronger effects on soil bacterial communities than soil zones in these agroforestry systems. Plots with trees in agroforestry systems promoted greater bacterial abundance and to some extent species richness, which was associated with more nutrient-rich soil resources. While Acidobacteria, Actinobacteria and Alphaproteobacteria were the dominant bacterial phyla and subphyla across land uses, Arthrobacter, Acidobacteria_Gp16, Burkholderia, Rhodanobacter and Rhizobium were the keystone taxa in these agroforestry systems. Soil pH and carbon contents emerged as the major determinants of bacterial community characteristics. We found non-random co-occurrence and modular patterns of soil bacterial communities, and these patterns were controlled by edaphic factors and not their taxonomy. Overall, this study highlights the drivers and co-occurrence patterns of soil microbial communities in agroforestry systems. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

CHANGES IN BACTERIAL COMPOSITION OF BIOFILM IN A ...

EPA Pesticide Factsheets

This study examined the development of bacterial biofilms within a metropolitan distribution system. The distribution system is fed with different source water (i.e., groundwater, GW and surface water, SW) and undergoes different treatment processes in separate facilities. The biofilm community was characterized using 16S rRNA gene clone libraries and functional potential analysis, generated from total DNA extracted from coupons in biofilm annular reactors fed with onsite drinking water for up to eighteen months. Significant differences in the bacterial community structure were observed between GW and SW. Representatives that explained the dissimilarity between service areas were associated with Betaproteobacteria, Alphaproteobacteria, Actinobacteria, Gammaproteobacteria, and Firmicutes. After nine months the biofilm bacterial community from both areas were dominated by Mycobacterium species. The distribution of the dominant OTU (Mycobacterium) positively correlated with the drinking water distribution system (DWDS) temperature, but no clear relationship was seen with free chlorine residual, pH, turbidity or total organic carbon (TOC). The results suggest that biofilm microbial communities harbor distinct and diverse bacterial communities, and that source water, treatment processes and environmental conditions may play an important role in shaping the bacterial community in the distribution system. On the other hand, several bacterial groups were present i

Phage Life Cycles Behind Bacterial Biodiversity.

PubMed

Olszak, Tomasz; Latka, Agnieszka; Roszniowski, Bartosz; Valvano, Miguel A; Drulis-Kawa, Zuzanna

2017-11-24

Bacteriophages (phages or bacterial viruses) are the most abundant biological entities in our planet; their influence reaches far beyond the microorganisms they parasitize. Phages are present in every environment and shape up every bacterial population in both active and passive ways. They participate in the circulation of organic matter and drive the evolution of microorganisms by horizontal gene transfer at unprecedented scales. The mass flow of genetic information in the microbial world influences the biosphere and poses challenges for science and medicine. The genetic flow, however, depends on the fate of the viral DNA injected into the bacterial cell. The archetypal notion of phages only engaging in predatorprey relationships is slowly fading. Because of their varied development cycles, environmental conditions, and the diversity of microorganisms they parasitize, phages form a dense and highly complex web of dependencies, which has important consequences for life on Earth. The sophisticated phage-bacteria interplay includes both aggressive action (bacterial lysis) and "diplomatic negotiations" (prophage domestication). Here, we review the most important mechanisms of interactions between phages and bacteria and their evolutionary consequences influencing their biodiversity. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Bacterial enzymes involved in lignin degradation.

PubMed

de Gonzalo, Gonzalo; Colpa, Dana I; Habib, Mohamed H M; Fraaije, Marco W

2016-10-20

Lignin forms a large part of plant biomass. It is a highly heterogeneous polymer of 4-hydroxyphenylpropanoid units and is embedded within polysaccharide polymers forming lignocellulose. Lignin provides strength and rigidity to plants and is rather resilient towards degradation. To improve the (bio)processing of lignocellulosic feedstocks, more effective degradation methods of lignin are in demand. Nature has found ways to fully degrade lignin through the production of dedicated ligninolytic enzyme systems. While such enzymes have been well thoroughly studied for ligninolytic fungi, only in recent years biochemical studies on bacterial enzymes capable of lignin modification have intensified. This has revealed several types of enzymes available to bacteria that enable them to act on lignin. Two major classes of bacterial lignin-modifying enzymes are DyP-type peroxidases and laccases. Yet, recently also several other bacterial enzymes have been discovered that seem to play a role in lignin modifications. In the present review, we provide an overview of recent advances in the identification and use of bacterial enzymes acting on lignin or lignin-derived products. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

Temporal Relationships Exist Between Cecum, Ileum, and Litter Bacterial Microbiomes in a Commercial Turkey Flock, and Subtherapeutic Penicillin Treatment Impacts Ileum Bacterial Community Establishment

PubMed Central

Danzeisen, Jessica L.; Clayton, Jonathan B.; Huang, Hu; Knights, Dan; McComb, Brian; Hayer, Shivdeep S.; Johnson, Timothy J.

2015-01-01

Gut health is paramount for commercial poultry production, and improved methods to assess gut health are critically needed to better understand how the avian gastrointestinal tract matures over time. One important aspect of gut health is the totality of bacterial populations inhabiting different sites of the avian gastrointestinal tract, and associations of these populations with the poultry farm environment, since these bacteria are thought to drive metabolism and prime the developing host immune system. In this study, a single flock of commercial turkeys was followed over the course of 12 weeks to examine bacterial microbiome inhabiting the ceca, ileum, and corresponding poultry litter. Furthermore, the effects of low-dose, growth-promoting penicillin treatment (50 g/ton) in feed on the ileum bacterial microbiome were also examined during the early brood period. The cecum and ileum bacterial communities of turkeys were distinct, yet shifted in parallel to one another over time during bird maturation. Corresponding poultry litter was also distinct yet more closely represented the ileal bacterial populations than cecal bacterial populations, and also changed parallel to ileum bacterial populations over time. Penicillin applied at low dose in feed significantly enhanced early weight gain in commercial poults, and this correlated with predictable shifts in the ileum bacterial populations in control versus treatment groups. Overall, this study identified the dynamics of the turkey gastrointestinal microbiome during development, correlations between bacterial populations in the gastrointestinal tract and the litter environment, and the impact of low-dose penicillin on modulation of bacterial communities in the ileum. Such modulations provide a target for alternatives to low-dose antibiotics. PMID:26664983

Cognitive outcome in adults after bacterial meningitis

PubMed Central

Hoogman, Martine; van de Beek, Diederik; Weisfelt, Martijn; de Gans, Jan; Schmand, Ben

2007-01-01

Objective To evaluate cognitive outcome in adult survivors of bacterial meningitis. Methods Data from three prospective multicentre studies were pooled and reanalysed, involving 155 adults surviving bacterial meningitis (79 after pneumococcal and 76 after meningococcal meningitis) and 72 healthy controls. Results Cognitive impairment was found in 32% of patients and this proportion was similar for survivors of pneumococcal and meningococcal meningitis. Survivors of pneumococcal meningitis performed worse on memory tasks (p<0.001) and tended to be cognitively slower than survivors of meningococcal meningitis (p = 0.08). We found a diffuse pattern of cognitive impairment in which cognitive speed played the most important role. Cognitive performance was not related to time since meningitis; however, there was a positive association between time since meningitis and self‐reported physical impairment (p<0.01). The frequency of cognitive impairment and the numbers of abnormal test results for patients with and without adjunctive dexamethasone were similar. Conclusions Adult survivors of bacterial meningitis are at risk of cognitive impairment, which consists mainly of cognitive slowness. The loss of cognitive speed is stable over time after bacterial meningitis; however, there is a significant improvement in subjective physical impairment in the years after bacterial meningitis. The use of dexamethasone was not associated with cognitive impairment. PMID:17353256

Emerging bacterial pathogens: the past and beyond.

PubMed

Vouga, M; Greub, G

2016-01-01

Since the 1950s, medical communities have been facing with emerging and reemerging infectious diseases, and emerging pathogens are now considered to be a major microbiologic public health threat. In this review, we focus on bacterial emerging diseases and explore factors involved in their emergence as well as future challenges. We identified 26 major emerging and reemerging infectious diseases of bacterial origin; most of them originated either from an animal and are considered to be zoonoses or from water sources. Major contributing factors in the emergence of these bacterial infections are: (1) development of new diagnostic tools, such as improvements in culture methods, development of molecular techniques and implementation of mass spectrometry in microbiology; (2) increase in human exposure to bacterial pathogens as a result of sociodemographic and environmental changes; and (3) emergence of more virulent bacterial strains and opportunistic infections, especially affecting immunocompromised populations. A precise definition of their implications in human disease is challenging and requires the comprehensive integration of microbiological, clinical and epidemiologic aspects as well as the use of experimental models. It is now urgent to allocate financial resources to gather international data to provide a better understanding of the clinical relevance of these waterborne and zoonotic emerging diseases. Copyright © 2015. Published by Elsevier Ltd.

BACTERIAL WATERBORNE PATHOGENS

EPA Science Inventory

Bacterial pathogens are examples of classical etiological agents of waterborne disease. While these agents no longer serve as major threats to U.S. water supplies, they are still important pathogens in areas with substandard sanitation and poor water treatment facilities. In th...

Bacterial leaf spot

USDA-ARS?s Scientific Manuscript database

Bacterial leaf spot has been reported in Australia (Queensland), Egypt, El Salvador, India, Japan, Nicaragua, Sudan, and the United States (Florida, Iowa, Kansas, Maryland, and Wisconsin). It occasionally causes locally severe defoliation and post-emergence damping-off and stunting. The disease is...

Structure of bacterial lipopolysaccharides.

PubMed

Caroff, Martine; Karibian, Doris

2003-11-14

Bacterial lipopolysaccharides are the major components of the outer surface of Gram-negative bacteria They are often of interest in medicine for their immunomodulatory properties. In small amounts they can be beneficial, but in larger amounts they may cause endotoxic shock. Although they share a common architecture, their structural details exert a strong influence on their activity. These molecules comprise: a lipid moiety, called lipid A, which is considered to be the endotoxic component, a glycosidic part consisting of a core of approximately 10 monosaccharides and, in "smooth-type" lipopolysaccharides, a third region, named O-chain, consisting of repetitive subunits of one to eight monosaccharides responsible for much of the immunospecificity of the bacterial cell.

Compatible bacterial mixture, tolerant to desiccation, improves maize plant growth.

PubMed

Molina-Romero, Dalia; Baez, Antonino; Quintero-Hernández, Verónica; Castañeda-Lucio, Miguel; Fuentes-Ramírez, Luis Ernesto; Bustillos-Cristales, María Del Rocío; Rodríguez-Andrade, Osvaldo; Morales-García, Yolanda Elizabeth; Munive, Antonio; Muñoz-Rojas, Jesús

2017-01-01

Plant growth-promoting rhizobacteria (PGPR) increase plant growth and crop productivity. The inoculation of plants with a bacterial mixture (consortium) apparently provides greater benefits to plant growth than inoculation with a single bacterial strain. In the present work, a bacterial consortium was formulated containing four compatible and desiccation-tolerant strains with potential as PGPR. The formulation had one moderately (Pseudomonas putida KT2440) and three highly desiccation-tolerant (Sphingomonas sp. OF178, Azospirillum brasilense Sp7 and Acinetobacter sp. EMM02) strains. The four bacterial strains were able to adhere to seeds and colonize the rhizosphere of plants when applied in both mono-inoculation and multi-inoculation treatments, showing that they can also coexist without antagonistic effects in association with plants. The effects of the bacterial consortium on the growth of blue maize were evaluated. Seeds inoculated with either individual bacterial strains or the bacterial consortium were subjected to two experimental conditions before sowing: normal hydration or desiccation. In general, inoculation with the bacterial consortium increased the shoot and root dry weight, plant height and plant diameter compared to the non-inoculated control or mono-inoculation treatments. The bacterial consortium formulated in this work had greater benefits for blue maize plants even when the inoculated seeds underwent desiccation stress before germination, making this formulation attractive for future field applications.

Compatible bacterial mixture, tolerant to desiccation, improves maize plant growth

PubMed Central

Molina-Romero, Dalia; Baez, Antonino; Quintero-Hernández, Verónica; Castañeda-Lucio, Miguel; Fuentes-Ramírez, Luis Ernesto; Bustillos-Cristales, María del Rocío; Rodríguez-Andrade, Osvaldo; Morales-García, Yolanda Elizabeth; Munive, Antonio

2017-01-01

Plant growth-promoting rhizobacteria (PGPR) increase plant growth and crop productivity. The inoculation of plants with a bacterial mixture (consortium) apparently provides greater benefits to plant growth than inoculation with a single bacterial strain. In the present work, a bacterial consortium was formulated containing four compatible and desiccation-tolerant strains with potential as PGPR. The formulation had one moderately (Pseudomonas putida KT2440) and three highly desiccation-tolerant (Sphingomonas sp. OF178, Azospirillum brasilense Sp7 and Acinetobacter sp. EMM02) strains. The four bacterial strains were able to adhere to seeds and colonize the rhizosphere of plants when applied in both mono-inoculation and multi-inoculation treatments, showing that they can also coexist without antagonistic effects in association with plants. The effects of the bacterial consortium on the growth of blue maize were evaluated. Seeds inoculated with either individual bacterial strains or the bacterial consortium were subjected to two experimental conditions before sowing: normal hydration or desiccation. In general, inoculation with the bacterial consortium increased the shoot and root dry weight, plant height and plant diameter compared to the non-inoculated control or mono-inoculation treatments. The bacterial consortium formulated in this work had greater benefits for blue maize plants even when the inoculated seeds underwent desiccation stress before germination, making this formulation attractive for future field applications. PMID:29117218

Marine bacterial degradation of brominated methanes

USGS Publications Warehouse

Goodwin, K.D.; Lidstrom, M.E.; Oremland, R.S.

1997-01-01

Brominated methanes are ozone-depleting compounds whose natural sources include marine algae such as kelp. Brominated methane degradation by bacteria was investigated to address whether bacterial processes might effect net emission of these compounds to the atmosphere. Bacteria in seawater collected from California kelp beds degraded CH2Br2 but not CHBr3. Specific inhibitors showed that methanotrophs and nitrifiers did not significantly contribute to CH2Br2 removal. A seawater enrichment culture oxidized 14CH2Br2 to 14CO2 as well as 14CH3Br to 14CO2. The rates of CH2Br2 degradation in laboratory experiments suggest that bacterial degradation of CH2Br2 in a kelp bed accounts for <1% of the CH2Br2 produced by the kelp. However, the half-life of CH2Br2 due to bacterial removal appears faster than hydrolysis and within an order of magnitude of volatilization to the atmosphere.Brominated methanes are ozone-depleting compounds whose natural sources include marine algae such as kelp. Brominated methane degradation by bacteria was investigated to address whether bacterial processes might effect net emission of these compounds to the atmosphere. Bacteria in seawater collected from California kelp beds degraded CH2Br2 but not CHBr3. Specific inhibitors showed that methanotrophs and nitrifiers did not significantly contribute to CH2Br2 removal. A seawater enrichment culture oxidized 14CH2Br2 to 14CO2 as well as 14CH3Br to 14CO2. The rates of CH2Br2 degradation in laboratory experiments suggest that bacterial degradation of CH2Br2 in a kelp bed accounts for <1% of the CH2Br2 produced by the kelp. However, the half-life of CH2Br2 due to bacterial removal appears faster than hydrolysis and within an order of magnitude of volatilization to the atmosphere.

Inflammatory response in mixed viral-bacterial community-acquired pneumonia.

PubMed

Bello, Salvador; Mincholé, Elisa; Fandos, Sergio; Lasierra, Ana B; Ruiz, María A; Simon, Ana L; Panadero, Carolina; Lapresta, Carlos; Menendez, Rosario; Torres, Antoni

2014-07-29

The role of mixed pneumonia (virus+bacteria) in community-acquired pneumonia (CAP) has been described in recent years. However, it is not known whether the systemic inflammatory profile is different compared to monomicrobial CAP. We wanted to investigate this profile of mixed viral-bacterial infection and to compare it to monomicrobial bacterial or viral CAP. We measured baseline serum procalcitonin (PCT), C reactive protein (CRP), and white blood cell (WBC) count in 171 patients with CAP with definite etiology admitted to a tertiary hospital: 59 (34.5%) bacterial, 66 (39.%) viral and 46 (27%) mixed (viral-bacterial). Serum PCT levels were higher in mixed and bacterial CAP compared to viral CAP. CRP levels were higher in mixed CAP compared to the other groups. CRP was independently associated with mixed CAP. CRP levels below 26 mg/dL were indicative of an etiology other than mixed in 83% of cases, but the positive predictive value was 45%. PCT levels over 2.10 ng/mL had a positive predictive value for bacterial-involved CAP versus viral CAP of 78%, but the negative predictive value was 48%. Mixed CAP has a different inflammatory pattern compared to bacterial or viral CAP. High CRP levels may be useful for clinicians to suspect mixed CAP.

Normal bacterial flora from vaginas of Criollo Limonero cows.

PubMed

Zambrano-Nava, Sunny; Boscán-Ocando, Julio; Nava, Jexenia

2011-02-01

In order to describe the normal bacterial flora in vaginas of Criollo Limonero cows, 51 healthy multiparous cows, at least 90-day postpartum, were selected. Duplicated swabs (N = 102) were taken from the vaginal fornix of cows to perform aerobic and anaerobic cultures as well as conventional biochemical tests. Out of 102 swabs, bacterial growth was obtained in 55 (53.9%) while the remaining 47 (46.1%) did not exhibited any bacterial growth. Of the 55 bacterial growths, 23 (41.8%) were aerobic whereas 32 (58.1%) were anaerobic. Likewise, 29 (52.72%) of bacterial growths were pure and 26 (47.27%) were mixed. Under both aerobic and anaerobic conditions, Gram positive bacteria were predominant (81.82% and 73.08%, respectively) over Gram negative bacteria (18.18% and 26.92%, respectively). Isolated bacteria were Arcanobacterium pyogenes (22.92%), Staphylococcus aureus (15.63%), Staphylococcus coagulase negative (17.71%), Erysipelothrix rhusiopathiae (6.25%), Bacteroides spp. (13.54%), and Peptostreptococcus spp. (7.29%). In conclusion, normal vaginal bacterial flora of Criollo Limonero cows was predominantly Gram positive and included A. pyogenes, S. aureus, coagulase negative Staphylococcus, E. rhusiopathiae, Bacteroides spp., and Peptostreptococcus spp. In Criollo Limonero cattle, adaptive aspects such as development of humoral and physical mechanisms for defense, and bacterial adaptation to host deserve research attention.

Applications of bacterial cellulose and its composites in biomedicine.

PubMed

Rajwade, J M; Paknikar, K M; Kumbhar, J V

2015-03-01

Bacterial cellulose produced by few but specific microbial genera is an extremely pure natural exopolysaccharide. Besides providing adhesive properties and a competitive advantage to the cellulose over-producer, bacterial cellulose confers UV protection, ensures maintenance of an aerobic environment, retains moisture, protects against heavy metal stress, etc. This unique nanostructured matrix is being widely explored for various medical and nonmedical applications. It can be produced in various shapes and forms because of which it finds varied uses in biomedicine. The attributes of bacterial cellulose such as biocompatibility, haemocompatibility, mechanical strength, microporosity and biodegradability with its unique surface chemistry make it ideally suited for a plethora of biomedical applications. This review highlights these qualities of bacterial cellulose in detail with emphasis on reports that prove its utility in biomedicine. It also gives an in-depth account of various biomedical applications ranging from implants and scaffolds for tissue engineering, carriers for drug delivery, wound-dressing materials, etc. that are reported until date. Besides, perspectives on limitations of commercialisation of bacterial cellulose have been presented. This review is also an update on the variety of low-cost substrates used for production of bacterial cellulose and its nonmedical applications and includes patents and commercial products based on bacterial cellulose.

Cytosolic Access of Intracellular Bacterial Pathogens: The Shigella Paradigm

PubMed Central

Mellouk, Nora; Enninga, Jost

2016-01-01

Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it. PMID:27092296

Bacterial carbon utilization in vertical subsurface flow constructed wetlands.

PubMed

Tietz, Alexandra; Langergraber, Günter; Watzinger, Andrea; Haberl, Raimund; Kirschner, Alexander K T

2008-03-01

Subsurface vertical flow constructed wetlands with intermittent loading are considered as state of the art and can comply with stringent effluent requirements. It is usually assumed that microbial activity in the filter body of constructed wetlands, responsible for the removal of carbon and nitrogen, relies mainly on bacterially mediated transformations. However, little quantitative information is available on the distribution of bacterial biomass and production in the "black-box" constructed wetland. The spatial distribution of bacterial carbon utilization, based on bacterial (14)C-leucine incorporation measurements, was investigated for the filter body of planted and unplanted indoor pilot-scale constructed wetlands, as well as for a planted outdoor constructed wetland. A simple mass-balance approach was applied to explain the bacterially catalysed organic matter degradation in this system by comparing estimated bacterial carbon utilization rates with simultaneously measured carbon reduction values. The pilot-scale constructed wetlands proved to be a suitable model system for investigating microbial carbon utilization in constructed wetlands. Under an ideal operating mode, the bulk of bacterial productivity occurred within the first 10cm of the filter body. Plants seemed to have no significant influence on productivity and biomass of bacteria, as well as on wastewater total organic carbon removal.

Proteome analysis of Arabidopsis seedlings exposed to bacterial volatiles.

PubMed

Kwon, Young Sang; Ryu, Choong-Min; Lee, Soohyun; Park, Hyo Bee; Han, Ki Soo; Lee, Jung Han; Lee, Kyunghee; Chung, Woo Sik; Jeong, Mi-Jeong; Kim, Hee Kyu; Bae, Dong-Won

2010-11-01

Plant root-associated bacteria (rhizobacteria) elicit plant basal immunity referred to as induced systemic resistance (ISR) against multiple pathogens. Among multi-bacterial determinants involving such ISR, the induction of ISR and promotion of growth by bacterial volatile compounds was previously reported. To exploit global de novo expression of plant proteins by bacterial volatiles, proteomic analysis was performed after exposure of Arabidopsis plants to the rhizobacterium Bacillus subtilis GB03. Ethylene biosynthesis enzymes were significantly up-regulated. Analysis by quantitative reverse transcriptase polymerase chain reaction confirmed that ethylene biosynthesis-related genes SAM-2, ACS4, ACS12, and ACO2 as well as ethylene response genes, ERF1, GST2, and CHIB were up-regulated by the exposure to bacterial volatiles. More interestingly, the emission of bacterial volatiles significantly up-regulated both key defense mechanisms mediated by jasmonic acid and salicylic acid signaling pathways. In addition, high accumulation of antioxidant proteins also provided evidence of decreased sensitivity to reactive oxygen species during the elicitation of ISR by bacterial volatiles. The present results suggest that the proteomic analysis of plant defense responses in bacterial volatile-mediated ISR can reveal the mechanisms of plant basal defenses orchestrated by endogenous ethylene production pathways and the generation of reactive oxygen species.

Sugarbeet Cultivar Evaluation for Bacterial Root Rot

USDA-ARS?s Scientific Manuscript database

Bacterial root rot of sugarbeet caused by Leuconostoc mesenteroides subsp. dextranicum is a disease problem recently described in the United States. To ameliorate the impact of bacterial root rot on sucrose loss in the field, storage piles, and factories, studies were conducted to establish an assa...

Isolation of cell-free bacterial inclusion bodies.

PubMed

Rodríguez-Carmona, Escarlata; Cano-Garrido, Olivia; Seras-Franzoso, Joaquin; Villaverde, Antonio; García-Fruitós, Elena

2010-09-17

Bacterial inclusion bodies are submicron protein clusters usually found in recombinant bacteria that have been traditionally considered as undesirable products from protein production processes. However, being fully biocompatible, they have been recently characterized as nanoparticulate inert materials useful as scaffolds for tissue engineering, with potentially wider applicability in biomedicine and material sciences. Current protocols for inclusion body isolation from Escherichia coli usually offer between 95 to 99% of protein recovery, what in practical terms, might imply extensive bacterial cell contamination, not compatible with the use of inclusion bodies in biological interfaces. Using an appropriate combination of chemical and mechanical cell disruption methods we have established a convenient procedure for the recovery of bacterial inclusion bodies with undetectable levels of viable cell contamination, below 10⁻¹ cfu/ml, keeping the particulate organization of these aggregates regarding size and protein folding features. The application of the developed protocol allows obtaining bacterial free inclusion bodies suitable for use in mammalian cell cultures and other biological interfaces.

Bacterial computing with engineered populations.

PubMed

Amos, Martyn; Axmann, Ilka Maria; Blüthgen, Nils; de la Cruz, Fernando; Jaramillo, Alfonso; Rodriguez-Paton, Alfonso; Simmel, Friedrich

2015-07-28

We describe strategies for the construction of bacterial computing platforms by describing a number of results from the recently completed bacterial computing with engineered populations project. In general, the implementation of such systems requires a framework containing various components such as intracellular circuits, single cell input/output and cell-cell interfacing, as well as extensive analysis. In this overview paper, we describe our approach to each of these, and suggest possible areas for future research. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Bacterial vaginosis in threatened preterm, preterm and term labour.

PubMed

Chawanpaiboon, Saifon; Pimol, Kanjana

2010-12-01

To present the prevalence of bacterial vaginosis in threatened preterm, preterm, and term labor and results after treatment. Forty-four, 50, and 56 pregnant women with threatened preterm, preterm, and term labor respectively were participated. Bacterial vaginosis was diagnosed by Amsel's criteria. Treatment by metronidazole or clindamycin was used. A case record form recorded maternal age, obstetric history, gestational age at admission and delivery, examination data, the route of delivery, and the newborn birth weight and conditions. The patients in threatened preterm labor group had significantly positive bacterial vaginosis when compared to those in the term labor group. Prevalence of bacterial vaginosis in threatened preterm, preterm, and term labor were presented The prevalence of bacterial vaginosis in both preterm labor groups was higher than in the term labor group.

Bacterial Pathogens versus Autophagy: Implications for Therapeutic Interventions

PubMed Central

Kimmey, Jacqueline M.; Stallings, Christina L.

2016-01-01

Research in recent years has focused significantly on the role of selective macroautophagy in targeting intracellular pathogens for lysosomal degradation, a process termed xenophagy. In this review we evaluate the proposed roles for xenophagy in controlling bacterial infection, highlighting the concept that successful pathogens have evolved ways to subvert or exploit this defense, minimizing the actual effectiveness of xenophagy in innate immunity. Instead, studies in animal models have revealed that autophagy-associated proteins often function outside of xenophagy to influence bacterial pathogenesis. In light of current efforts to manipulate autophagy and the development of host-directed therapies to fight bacterial infections, we also discuss the implications stemming from the complicated relationship that exists between autophagy and bacterial pathogens. PMID:27866924

Urban aerosols harbor diverse and dynamic bacterial populations

PubMed Central

Brodie, Eoin L.; DeSantis, Todd Z.; Parker, Jordan P. Moberg; Zubietta, Ingrid X.; Piceno, Yvette M.; Andersen, Gary L.

2007-01-01

Considering the importance of its potential implications for human health, agricultural productivity, and ecosystem stability, surprisingly little is known regarding the composition or dynamics of the atmosphere's microbial inhabitants. Using a custom high-density DNA microarray, we detected and monitored bacterial populations in two U.S. cities over 17 weeks. These urban aerosols contained at least 1,800 diverse bacterial types, a richness approaching that of some soil bacterial communities. We also reveal the consistent presence of bacterial families with pathogenic members including environmental relatives of select agents of bioterrorism significance. Finally, using multivariate regression techniques, we demonstrate that temporal and meteorological influences can be stronger factors than location in shaping the biological composition of the air we breathe. PMID:17182744

Bacterial community changes in an industrial algae production system.

PubMed

Fulbright, Scott P; Robbins-Pianka, Adam; Berg-Lyons, Donna; Knight, Rob; Reardon, Kenneth F; Chisholm, Stephen T

2018-04-01

While microalgae are a promising feedstock for production of fuels and other chemicals, a challenge for the algal bioproducts industry is obtaining consistent, robust algae growth. Algal cultures include complex bacterial communities and can be difficult to manage because specific bacteria can promote or reduce algae growth. To overcome bacterial contamination, algae growers may use closed photobioreactors designed to reduce the number of contaminant organisms. Even with closed systems, bacteria are known to enter and cohabitate, but little is known about these communities. Therefore, the richness, structure, and composition of bacterial communities were characterized in closed photobioreactor cultivations of Nannochloropsis salina in F/2 medium at different scales, across nine months spanning late summer-early spring, and during a sequence of serially inoculated cultivations. Using 16S rRNA sequence data from 275 samples, bacterial communities in small, medium, and large cultures were shown to be significantly different. Larger systems contained richer bacterial communities compared to smaller systems. Relationships between bacterial communities and algae growth were complex. On one hand, blooms of a specific bacterial type were observed in three abnormal, poorly performing replicate cultivations, while on the other, notable changes in the bacterial community structures were observed in a series of serial large-scale batch cultivations that had similar growth rates. Bacteria common to the majority of samples were identified, including a single OTU within the class Saprospirae that was found in all samples. This study contributes important information for crop protection in algae systems, and demonstrates the complex ecosystems that need to be understood for consistent, successful industrial algae cultivation. This is the first study to profile bacterial communities during the scale-up process of industrial algae systems.

Predicted Bacterial Interactions Affect in Vivo Microbial Colonization Dynamics in Nematostella

PubMed Central

Domin, Hanna; Zurita-Gutiérrez, Yazmín H.; Scotti, Marco; Buttlar, Jann; Hentschel Humeida, Ute; Fraune, Sebastian

2018-01-01

The maintenance and resilience of host-associated microbiota during development is a fundamental process influencing the fitness of many organisms. Several host properties were identified as influencing factors on bacterial colonization, including the innate immune system, mucus composition, and diet. In contrast, the importance of bacteria–bacteria interactions on host colonization is less understood. Here, we use bacterial abundance data of the marine model organism Nematostella vectensis to reconstruct potential bacteria–bacteria interactions through co-occurrence networks. The analysis indicates that bacteria–bacteria interactions are dynamic during host colonization and change according to the host’s developmental stage. To assess the predictive power of inferred interactions, we tested bacterial isolates with predicted cooperative or competitive behavior for their ability to influence bacterial recolonization dynamics. Within 3 days of recolonization, all tested bacterial isolates affected bacterial community structure, while only competitive bacteria increased bacterial diversity. Only 1 week after recolonization, almost no differences in bacterial community structure could be observed between control and treatments. These results show that predicted competitive bacteria can influence community structure for a short period of time, verifying the in silico predictions. However, within 1 week, the effects of the bacterial isolates are neutralized, indicating a high degree of resilience of the bacterial community. PMID:29740401

Collective chemotaxis and segregation of active bacterial colonies

NASA Astrophysics Data System (ADS)

Amar, M. Ben

2016-02-01

Still recently, bacterial fluid suspensions have motivated a lot of works, both experimental and theoretical, with the objective to understand their collective dynamics from universal and simple rules. Since some species are active, most of these works concern the strong interactions that these bacteria exert on a forced flow leading to instabilities, chaos and turbulence. Here, we investigate the self-organization of expanding bacterial colonies under chemotaxis, proliferation and eventually active-reaction. We propose a simple model to understand and quantify the physical properties of these living organisms which either give cohesion or on the contrary dispersion to the colony. Taking into account the diffusion and capture of morphogens complicates the model since it induces a bacterial density gradient coupled to bacterial density fluctuations and dynamics. Nevertheless under some specific conditions, it is possible to investigate the pattern formation as a usual viscous fingering instability. This explains the similarity and differences of patterns according to the physical bacterial suspension properties and explain the factors which favor compactness or branching.

[Combination therapy of chronic bacterial prostatitis].

PubMed

Khryanin, A A; Reshetnikov, O V

2016-08-01

The article discusses the possible etiological factors in the development of chronic bacterial prostatitis. The authors presented a comparative long-term analysis of morbidity from non-viral sexually transmitted infections (STIs) in Russia. Against the background of general decline in STIs incidence, a significant percentage of them is made up by urogenital trichomoniasis. The findings substantiated the advantages of combination therapy (ornidazole and ofloxacin) for bacterial urinary tract infections.

Quantitative PCR Method for Diagnosis of Citrus Bacterial Canker†

PubMed Central

Cubero, J.; Graham, J. H.; Gottwald, T. R.

2001-01-01

For diagnosis of citrus bacterial canker by PCR, an internal standard is employed to ensure the quality of the DNA extraction and that proper requisites exist for the amplification reaction. The ratio of PCR products from the internal standard and bacterial target is used to estimate the initial bacterial concentration in citrus tissues with lesions. PMID:11375206

Arginine Metabolism in Bacterial Pathogenesis and Cancer Therapy

PubMed Central

Xiong, Lifeng; Teng, Jade L. L.; Botelho, Michael G.; Lo, Regina C.; Lau, Susanna K. P.; Woo, Patrick C. Y.

2016-01-01

Antibacterial resistance to infectious diseases is a significant global concern for health care organizations; along with aging populations and increasing cancer rates, it represents a great burden for government healthcare systems. Therefore, the development of therapies against bacterial infection and cancer is an important strategy for healthcare research. Pathogenic bacteria and cancer have developed a broad range of sophisticated strategies to survive or propagate inside a host and cause infection or spread disease. Bacteria can employ their own metabolism pathways to obtain nutrients from the host cells in order to survive. Similarly, cancer cells can dysregulate normal human cell metabolic pathways so that they can grow and spread. One common feature of the adaption and disruption of metabolic pathways observed in bacterial and cancer cell growth is amino acid pathways; these have recently been targeted as a novel approach to manage bacterial infections and cancer therapy. In particular, arginine metabolism has been illustrated to be important not only for bacterial pathogenesis but also for cancer therapy. Therefore, greater insights into arginine metabolism of pathogenic bacteria and cancer cells would provide possible targets for controlling of bacterial infection and cancer treatment. This review will summarize the recent progress on the relationship of arginine metabolism with bacterial pathogenesis and cancer therapy, with a particular focus on arginase and arginine deiminase pathways of arginine catabolism. PMID:26978353

S1PR3 Signaling Drives Bacterial Killing and Is Required for Survival in Bacterial Sepsis.

PubMed

Hou, JinChao; Chen, QiXing; Wu, XiaoLiang; Zhao, DongYan; Reuveni, Hadas; Licht, Tamar; Xu, MengLong; Hu, Hu; Hoeft, Andreas; Ben-Sasson, Shmuel A; Shu, Qiang; Fang, XiangMing

2017-12-15

Efficient elimination of pathogenic bacteria is a critical determinant in the outcome of sepsis. Sphingosine-1-phosphate receptor 3 (S1PR3) mediates multiple aspects of the inflammatory response during sepsis, but whether S1PR3 signaling is necessary for eliminating the invading pathogens remains unknown. To investigate the role of S1PR3 in antibacterial immunity during sepsis. Loss- and gain-of-function experiments were performed using cell and murine models. S1PR3 levels were determined in patients with sepsis and healthy volunteers. S1PR3 protein levels were up-regulated in macrophages upon bacterial stimulation. S1pr3 -/- mice showed increased mortality and increased bacterial burden in multiple models of sepsis. The transfer of wild-type bone marrow-derived macrophages rescued S1pr3 -/- mice from lethal sepsis. S1PR3-overexpressing macrophages further ameliorated the mortality rate of sepsis. Loss of S1PR3 led to markedly decreased bacterial killing in macrophages. Enhancing endogenous S1PR3 activity using a peptide agonist potentiated the macrophage bactericidal function and improved survival rates in multiple models of sepsis. Mechanically, the reactive oxygen species levels were decreased and phagosome maturation was delayed in S1pr3 -/- macrophages due to impaired recruitment of vacuolar protein-sorting 34 to the phagosomes. In addition, S1RP3 expression levels were elevated in monocytes from patients with sepsis. Higher levels of monocytic S1PR3 were associated with efficient intracellular bactericidal activity, better immune status, and preferable outcomes. S1PR3 signaling drives bacterial killing and is essential for survival in bacterial sepsis. Interventions targeting S1PR3 signaling could have translational implications for manipulating the innate immune response to combat pathogens.

Aspergillus niger Enhance Bioactive Compounds Biosynthesis As Well As Expression of Functional Genes in Adventitious Roots of Glycyrrhiza uralensis Fisch.

PubMed

Li, Jing; Wang, Juan; Li, Jinxin; Liu, Dahui; Li, Hongfa; Gao, Wenyuan; Li, Jianli; Liu, Shujie

2016-02-01

In the present study, the culture conditions for the accumulation of Glycyrrhiza uralensis adventitious root metabolites in balloon-type bubble bioreactors (BTBBs) have been optimized. The results of the culture showed that the best culture conditions were a cone angle of 90° bioreactor and 0.4-0.6-0.4-vvm aeration volume. Aspergillus niger can be used as a fungal elicitor to enhance the production of defense compounds in plants. With the addition of a fungal elicitor (derived from Aspergillus niger), the maximum accumulation of total flavonoids (16.12 mg g(-1)) and glycyrrhetinic acid (0.18 mg g(-1)) occurred at a dose of 400 mg L(-1) of Aspergillus niger resulting in a 3.47-fold and 1.8-fold increase over control roots. However, the highest concentration of polysaccharide (106.06 mg g(-1)) was achieved with a mixture of elicitors (Aspergillus niger and salicylic acid) added to the medium, resulting in a 1.09-fold increase over Aspergillus niger treatment alone. Electrospray ionization tandem mass spectrometry (ESI-MS(n)) analysis was performed, showing that seven compounds were present after treatment with the elicitors, including uralsaponin B, licorice saponin B2, liquiritin, and (3R)-vestitol, only identified in the mixed elicitor treatment group. It has also been found that elicitors (Aspergillus niger and salicylic acid) significantly upregulated the expression of the cinnamate 4-hydroxylase (C4H), β-amyrin synthase (β-AS), squalene epoxidase (SE) and a cytochrome P450 monooxygenase (CYP72A154) genes, which are involved in the biosynthesis of bioactive compounds, and increased superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activity.

Antibiotics for treating bacterial vaginosis in pregnancy.

PubMed

McDonald, H; Brocklehurst, P; Parsons, J; Vigneswaran, R

2003-01-01

Bacterial vaginosis is an imbalance of the normal vaginal flora with an overgrowth of anaerobic bacteria and a lack of the normal lactobacillary flora. Bacterial vaginosis during pregnancy has been associated with poor perinatal outcome and, in particular, preterm birth. Identification and treatment may reduce the risk of preterm birth and its consequences. To assess the effects of antibiotic treatment of bacterial vaginosis in pregnancy. We searched the Cochrane Pregnancy and Childbirth Group trials register (September 2002). Randomized trials comparing antibiotic treatment with placebo or no treatment, or comparing two or more antibiotic regimens in pregnant women with bacterial vaginosis. Two reviewers assessed trials and extracted data independently. Study authors were contacted for additional information. Ten trials involving 4249 women were included; all were of good quality. Antibiotic therapy was effective at eradicating bacterial vaginosis during pregnancy (odds ratio (OR) 0.21, 95% confidence interval (CI) 0.18 to 0.24, eight trials of 3825 women). Treatment did not significantly reduce the risk of preterm birth before 37 weeks (OR 0.95, 95% CI 0.82 to 1.10, eight trials of 4062 women), 34 weeks (OR 1.20, 95% CI 0.69 to 2.07, five trials of 851 women), or 32 weeks (OR 1.08, 95% CI 0.70 to 1.68, three trials of 3080 women). However, antibiotic treatment did significantly decrease the risk of preterm prelabour rupture of membranes (OR 0.32, 95% CI 0.15 to 0.67, three trials of 562 women). In women with a previous preterm birth, treatment did not affect the risk of subsequent preterm birth (OR 0.83, 95% CI 0.59 to 1.17, five trials of 622 women) but it did decrease the risk of preterm prelabour rupture of membranes (OR 0.14, 95% CI 0.05 to 0.38, two trials of 114 women) and low birthweight (OR 0.31, 95% CI 0.13 to 0.75, five trials of 622 women). Antibiotic treatment can eradicate bacterial vaginosis in pregnancy. However, the current evidence does not

Coupled effects of chemotaxis and growth on traveling bacterial waves.

PubMed

Yan, Zhifeng; Bouwer, Edward J; Hilpert, Markus

2014-08-01

Traveling bacterial waves are capable of improving contaminant remediation in the subsurface. It is fairly well understood how bacterial chemotaxis and growth separately affect the formation and propagation of such waves. However, their interaction is not well understood. We therefore perform a modeling study to investigate the coupled effects of chemotaxis and growth on bacterial migration, and examine their effects on contaminant remediation. We study the waves by using different initial electron acceptor concentrations for different bacteria and substrate systems. Three types of traveling waves can occur: a chemotactic wave due to the biased movement of chemotactic bacteria resulting from metabolism-generated substrate concentration gradients; a growth/decay/motility wave due to a dynamic equilibrium between bacterial growth, decay and random motility; and an integrated wave due to the interaction between bacterial chemotaxis and growth. Chemotaxis hardly enhances the bacterial propagation if it is too weak to form a chemotactic wave or its wave speed is less than half of the growth/decay/motility wave speed. However, chemotaxis significantly accelerates bacterial propagation once its wave speed exceeds the growth/decay/motility wave speed. When convection occurs, it speeds up the growth/decay/motility wave but slows down or even eliminates the chemotactic wave due to the dispersion. Bacterial survival proves particularly important for bacterial propagation. Therefore we develop a conceptual model to estimate the speed of growth/decay/motility waves. Copyright © 2014 Elsevier B.V. All rights reserved.

Contribution of Progranulin to Protective Lung Immunity During Bacterial Pneumonia.

PubMed

Zou, Shan; Luo, Qin; Song, Zhixin; Zhang, Liping; Xia, Yun; Xu, Huajian; Xiang, Yu; Yin, Yibing; Cao, Ju

2017-06-01

Progranulin (PGRN) is an important immunomodulatory factor in a variety of inflammatory diseases. However, its role in pulmonary immunity against bacterial infection remains unknown. Pneumonia was induced in PGRN-deficient and normal wild-type mice using Pseudomonas aeruginosa or Staphylococcus aureus, and we assessed the effects of PGRN on survival, bacterial burden, cytokine and chemokine production, and pulmonary leukocyte recruitment after bacterial pneumonia. Patients with community-acquired pneumonia displayed elevated PGRN levels. Likewise, mice with Gram-negative and Gram-positive pneumonia had increased PGRN production in the lung and circulation. Progranulin deficiency led to increased bacterial growth and dissemination accompanied by enhanced lung injury and mortality in bacterial pneumonia, which was associated with impaired recruitment of macrophages and neutrophils in the lung. The reduced number of pulmonary macrophages and neutrophils observed in PGRN-deficient mice was related to a reduction of CCL2 and CXCL1 in the lungs after bacterial pneumonia. Importantly, therapeutic administration of PGRN improved mortality in severe bacterial pneumonia. This study supports a novel role for PGRN in pulmonary immunity and suggests that treatment with PGRN may be a viable therapy for bacterial pneumonia. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

Bacterial Sepsis in Patients with Visceral Leishmaniasis in Northwest Ethiopia

PubMed Central

Takele, Yegnasew; Woldeyohannes, Desalegn; Tiruneh, Moges; Mohammed, Rezika; Lynen, Lutgarde; van Griensven, Johan

2014-01-01

Background and Objectives. Visceral leishmaniasis (VL) is one of the neglected diseases affecting the poorest segment of world populations. Sepsis is one of the predictors for death of patients with VL. This study aimed to assess the prevalence and factors associated with bacterial sepsis, causative agents, and their antimicrobial susceptibility patterns among patients with VL. Methods. A cross-sectional study was conducted among parasitologically confirmed VL patients suspected of sepsis admitted to the University of Gondar Hospital, Northwest Ethiopia, from February 2012 to May 2012. Blood cultures and other clinical samples were collected and cultured following the standard procedures. Results. Among 83 sepsis suspected VL patients 16 (19.3%) had culture confirmed bacterial sepsis. The most frequently isolated organism was Staphylococcus aureus (68.8%; 11/16), including two methicillin-resistant isolates (MRSA). Patients with focal bacterial infection were more likely to have bacterial sepsis (P < 0.001). Conclusions. The prevalence of culture confirmed bacterial sepsis was high, predominantly due to S. aureus. Concurrent focal bacterial infection was associated with bacterial sepsis, suggesting that focal infections could serve as sources for bacterial sepsis among VL patients. Careful clinical evaluation for focal infections and prompt initiation of empiric antibiotic treatment appears warranted in VL patients. PMID:24895569

Comparative Genomic Analyses of the Bacterial Phosphotransferase System

PubMed Central

Barabote, Ravi D.; Saier, Milton H.

2005-01-01

We report analyses of 202 fully sequenced genomes for homologues of known protein constituents of the bacterial phosphoenolpyruvate-dependent phosphotransferase system (PTS). These included 174 bacterial, 19 archaeal, and 9 eukaryotic genomes. Homologues of PTS proteins were not identified in archaea or eukaryotes, showing that the horizontal transfer of genes encoding PTS proteins has not occurred between the three domains of life. Of the 174 bacterial genomes (136 bacterial species) analyzed, 30 diverse species have no PTS homologues, and 29 species have cytoplasmic PTS phosphoryl transfer protein homologues but lack recognizable PTS permeases. These soluble homologues presumably function in regulation. The remaining 77 species possess all PTS proteins required for the transport and phosphorylation of at least one sugar via the PTS. Up to 3.2% of the genes in a bacterium encode PTS proteins. These homologues were analyzed for family association, range of protein types, domain organization, and organismal distribution. Different strains of a single bacterial species often possess strikingly different complements of PTS proteins. Types of PTS protein domain fusions were analyzed, showing that certain types of domain fusions are common, while others are rare or prohibited. Select PTS proteins were analyzed from different phylogenetic standpoints, showing that PTS protein phylogeny often differs from organismal phylogeny. The results document the frequent gain and loss of PTS protein-encoding genes and suggest that the lateral transfer of these genes within the bacterial domain has played an important role in bacterial evolution. Our studies provide insight into the development of complex multicomponent enzyme systems and lead to predictions regarding the types of protein-protein interactions that promote efficient PTS-mediated phosphoryl transfer. PMID:16339738

Distinct antimicrobial peptide expression determines host species-specific bacterial associations

PubMed Central

Franzenburg, Sören; Walter, Jonas; Künzel, Sven; Wang, Jun; Baines, John F.; Bosch, Thomas C. G.; Fraune, Sebastian

2013-01-01

Animals are colonized by coevolved bacterial communities, which contribute to the host’s health. This commensal microbiota is often highly specific to its host-species, inferring strong selective pressures on the associated microbes. Several factors, including diet, mucus composition, and the immune system have been proposed as putative determinants of host-associated bacterial communities. Here we report that species-specific antimicrobial peptides account for different bacterial communities associated with closely related species of the cnidarian Hydra. Gene family extensions for potent antimicrobial peptides, the arminins, were detected in four Hydra species, with each species possessing a unique composition and expression profile of arminins. For functional analysis, we inoculated arminin-deficient and control polyps with bacterial consortia characteristic for different Hydra species and compared their selective preferences by 454 pyrosequencing of the bacterial microbiota. In contrast to control polyps, arminin-deficient polyps displayed decreased potential to select for bacterial communities resembling their native microbiota. This finding indicates that species-specific antimicrobial peptides shape species-specific bacterial associations. PMID:24003149

Morphodynamics of growing bacterial colony

NASA Astrophysics Data System (ADS)

Ghosh, Pushpita; Perlekar, Prasad; Rana, Navdeep

Self-organization into multicellular communities is a natural trend of most of the bacteria. Mutual interactions and competition among the bacterial cells in such multicellular organization play essential role in governing the spatiotemporal dynamics. We here present the spatiotemporal dynamics of growing bacterial colony using theory and a particle-based or individual-based simulation model of nonmotile cells growing utilizing a diffusing nutrient/food on a semi-solid surface by their growth and division forces and by pushing each-other through sliding motility. We show how the resource competition over a fixed amount of food, the diffusion coefficient of the nutrient and the random genetic noise govern the morphodynamics of a single species and a well-mixed two-species bacterial colonies. Our results show that for a very low initial food concentrations, colony develops fingering pattern at the front, while for intermediate values of initial food sources, the colony undergoes transitions to branched structures at the periphery and for very high values of food colony develops smoother fronts.

Bacterial sex in dental plaque.

PubMed

Olsen, Ingar; Tribble, Gena D; Fiehn, Nils-Erik; Wang, Bing-Yan

2013-01-01

Genes are transferred between bacteria in dental plaque by transduction, conjugation, and transformation. Membrane vesicles can also provide a mechanism for horizontal gene transfer. DNA transfer is considered bacterial sex, but the transfer is not parallel to processes that we associate with sex in higher organisms. Several examples of bacterial gene transfer in the oral cavity are given in this review. How frequently this occurs in dental plaque is not clear, but evidence suggests that it affects a number of the major genera present. It has been estimated that new sequences in genomes established through horizontal gene transfer can constitute up to 30% of bacterial genomes. Gene transfer can be both inter- and intrageneric, and it can also affect transient organisms. The transferred DNA can be integrated or recombined in the recipient's chromosome or remain as an extrachromosomal inheritable element. This can make dental plaque a reservoir for antimicrobial resistance genes. The ability to transfer DNA is important for bacteria, making them better adapted to the harsh environment of the human mouth, and promoting their survival, virulence, and pathogenicity.

Pediatric bacterial meningitis in French Guiana.

PubMed

Elenga, N; Sicard, S; Cuadro-Alvarez, E; Long, L; Njuieyon, F; Martin, E; Kom-Tchameni, R; Balcaen, J; Moreau, B; Boukhari, R

2015-01-01

Controlling vaccine-preventable infectious diseases is a public health priority in French Guiana but there is currently no epidemiological data on pediatric bacterial meningitis in this overseas department. Our aim was to describe data related to pediatric bacterial meningitis in French Guiana and compare it with that of metropolitan France. We conducted a multicenter retrospective study from 2000 to 2010 to describe the clinical picture, biological data, epidemiology, and outcome of pediatric bacterial meningitis case patients in French Guiana. The median age of bacterial meningitis patients was 6months [0-15] and the sex ratio 1.06. We observed a total of 60 bacterial meningitis case patients. Most presented with pneumococcal meningitis (24 patients; 40%); 11 with Haemophilus influenzae type b meningitis (23%), five with group B streptococcal meningitis (8.5%), and five others (8.5%) with staphylococcal meningitis (three patients presented with coagulase-negative staphylococci and two with Staphylococcus aureus). Only one patient presented with group B meningococcal meningitis, an 18-month-old infant. We recorded 14 deaths (overall case fatality: 23%); eight were due to Streptococcus pneumoniae (case fatality: 33%). The overall sequelae rate was 28%. It was 32% for patients presenting with pneumococcal meningitis. We observed that 38% of children who had never been vaccinated were infected by a vaccine-preventable bacterium. We observed many differences in the distribution of the bacteria and in the patients' prognosis when comparing the French Guiana data with that of metropolitan France. Improving vaccination coverage would decrease the incidence of H. influenzae meningitis. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Bacterial Genome Instability

PubMed Central

Darmon, Elise

2014-01-01

SUMMARY Bacterial genomes are remarkably stable from one generation to the next but are plastic on an evolutionary time scale, substantially shaped by horizontal gene transfer, genome rearrangement, and the activities of mobile DNA elements. This implies the existence of a delicate balance between the maintenance of genome stability and the tolerance of genome instability. In this review, we describe the specialized genetic elements and the endogenous processes that contribute to genome instability. We then discuss the consequences of genome instability at the physiological level, where cells have harnessed instability to mediate phase and antigenic variation, and at the evolutionary level, where horizontal gene transfer has played an important role. Indeed, this ability to share DNA sequences has played a major part in the evolution of life on Earth. The evolutionary plasticity of bacterial genomes, coupled with the vast numbers of bacteria on the planet, substantially limits our ability to control disease. PMID:24600039

Biosensors for Whole-Cell Bacterial Detection

PubMed Central

Rushworth, Jo V.; Hirst, Natalie A.; Millner, Paul A.

2014-01-01

SUMMARY Bacterial pathogens are important targets for detection and identification in medicine, food safety, public health, and security. Bacterial infection is a common cause of morbidity and mortality worldwide. In spite of the availability of antibiotics, these infections are often misdiagnosed or there is an unacceptable delay in diagnosis. Current methods of bacterial detection rely upon laboratory-based techniques such as cell culture, microscopic analysis, and biochemical assays. These procedures are time-consuming and costly and require specialist equipment and trained users. Portable stand-alone biosensors can facilitate rapid detection and diagnosis at the point of care. Biosensors will be particularly useful where a clear diagnosis informs treatment, in critical illness (e.g., meningitis) or to prevent further disease spread (e.g., in case of food-borne pathogens or sexually transmitted diseases). Detection of bacteria is also becoming increasingly important in antibioterrorism measures (e.g., anthrax detection). In this review, we discuss recent progress in the use of biosensors for the detection of whole bacterial cells for sensitive and earlier identification of bacteria without the need for sample processing. There is a particular focus on electrochemical biosensors, especially impedance-based systems, as these present key advantages in terms of ease of miniaturization, lack of reagents, sensitivity, and low cost. PMID:24982325

Future challenges in the elimination of bacterial meningitis.

PubMed

Bottomley, Matthew J; Serruto, Davide; Sáfadi, Marco Aurélio Palazzi; Klugman, Keith P

2012-05-30

Despite the widespread implementation of several effective vaccines over the past few decades, bacterial meningitis caused by Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis and Group B Streptococcus (GBS) still results in unacceptably high levels of human mortality and morbidity. A residual disease burden due to bacterial meningitis is also apparent due to a number of persistent or emerging pathogens, including Mycobacterium tuberculosis, Escherichia coli, Staphylococcus aureus, Salmonella spp. and Streptococcus suis. Here, we review the current status of bacterial meningitis caused by these pathogens, highlighting how past and present vaccination programs have attempted to counter these pathogens. We discuss how improved pathogen surveillance, implementation of current vaccines, and development of novel vaccines may be expected to further reduce bacterial meningitis and related diseases in the future. Copyright © 2011 Elsevier Ltd. All rights reserved.

Composition and variation of sediment bacterial and nirS-harboring bacterial communities at representative sites of the Bohai Gulf coastal zone, China.

PubMed

Guan, Xiangyu; Zhu, Lingling; Li, Youxun; Xie, Yuxuan; Zhao, Mingzhang; Luo, Ximing

2014-04-01

With rapid urbanization, anthropogenic activities are increasingly influencing the natural environment of the Bohai Bay. In this study, the composition and variation of bacterial and nirS-harboring bacterial communities in the coastal zone sediments of the Bohai Gulf were analyzed using PCR-based clone libraries. A total of 95 genera were detected in the bacterial communities, with Proteobacteria (72.1 %), Acidobacteria (10.5 %), Firmicutes (1.7 %), Bacteroidetes (1.4 %), Chloroflexi (0.7 %) and Planctomycetes (0.7 %) being the dominated phyla. The NirS sequences were divided into nine Clusters (A-I). Canonical correlation analysis showed that the bacterial or denitrifying communities were correlated with different environmental factors, such as total organic carbon, total nitrogen, ammonium, sulfate, etc. Furthermore, bacterial communities' composition and diversity are influenced by oil exploration, sewage discharge and other anthropogenic activities in the coastal area of the Bohai Sea. Thus, this study provided useful information on further research on regional or global environmental control and restore.

Analysis of PAMP-Triggered ROS Burst in Plant Immunity.

PubMed

Sang, Yuying; Macho, Alberto P

2017-01-01

The plant perception of pathogen-associated molecular patterns triggers a plethora of cellular immune responses. One of these responses is a rapid and transient burst of reactive oxygen species (ROS) mediated by plasma membrane-localized NADPH oxidases. The ROS burst requires a functional receptor complex and the contribution of several additional regulatory components. In laboratory conditions, the ROS burst can be detected a few minutes after the treatment with an immunogenic microbial elicitor. For these reasons, the elicitor-triggered ROS burst has been often exploited as readout to probe the contribution of plant components to early immune responses. Here, we describe a detailed protocol for the measurement of elicitor-triggered ROS burst in a simple, fast, and easy manner.

The role of respiratory viruses in the etiology of bacterial pneumonia

PubMed Central

Lee, Kyu Han; Gordon, Aubree; Foxman, Betsy

2016-01-01

Pneumonia is the leading cause of death among children less than 5 years old worldwide. A wide range of viral, bacterial and fungal agents can cause pneumonia: although viruses are the most common etiologic agent, the severity of clinical symptoms associated with bacterial pneumonia and increasing antibiotic resistance makes bacterial pneumonia a major public health concern. Bacterial pneumonia can follow upper respiratory viral infection and complicate lower respiratory viral infection. Secondary bacterial pneumonia is a major cause of influenza-related deaths. In this review, we evaluate the following hypotheses: (i) respiratory viruses influence the etiology of pneumonia by altering bacterial community structure in the upper respiratory tract (URT) and (ii) respiratory viruses promote or inhibit colonization of the lower respiratory tract (LRT) by certain bacterial species residing in the URT. We conducted a systematic review of the literature to examine temporal associations between respiratory viruses and bacteria and a targeted review to identify potential mechanisms of interactions. We conclude that viruses both alter the bacterial community in the URT and promote bacterial colonization of the LRT. However, it is uncertain whether changes in the URT bacterial community play a substantial role in pneumonia etiology. The exception is Streptococcus pneumoniae where a strong link between viral co-infection, increased carriage and pneumococcal pneumonia has been established. PMID:26884414

[The range of antagonistic effects of Lactobacillus bacterial strains on etiologic agents of bacterial vaginosis].

PubMed

Strus, M; Malinowska, M

1999-01-01

Bacterial vaginosis is caused by uncontrolled sequential overgrowth of some anaerobic bacteria: Gardnerella vaginalis, Prevotella bivia, Bacteroides spp., Peptostreptococcus spp., Mobiluncus sp. usually occurring in stable numbers in the bacterial flora of healthy women. On the other hand, different species of bacteria belonging to the genus Lactobacillus, most frequently L. plantarum, L. rhamnosus and L. acidophilus, form a group of aerobic bacteria dominating in the same environment. The diversity and density of their populations depend on the age and health conditions. Thanks to their antagonistic and adherence properties bacteria of the genus Lactobacillus can maintain a positive balance role in this ecosystem. The aim of this study was to assess the antagonistic properties of Lactobacillus strains isolated from the vagina of healthy women against most common agents of bacterial vaginosis. It was found that nearly all of the tested Lactobacillus strains exerted distinct antagonistic activity against anaerobic bacteria: Gardnerella vaginalis, Prevotella bivia and Peptostreptococcus anaerobius and quite a number also against Gram-negative rods, while only some of them were able to inhibit Gram-positive aerobic cocci as Enterococcus faecalis or Staphylococcus aureus.

Insights from 20 years of bacterial genome sequencing

DOE PAGES

Land, Miriam L.; Hauser, Loren; Jun, Se-Ran; ...

2015-02-27

Since the first two complete bacterial genome sequences were published in 1995, the science of bacteria has dramatically changed. Using third-generation DNA sequencing, it is possible to completely sequence a bacterial genome in a few hours and identify some types of methylation sites along the genome as well. Sequencing of bacterial genome sequences is now a standard procedure, and the information from tens of thousands of bacterial genomes has had a major impact on our views of the bacterial world. In this review, we explore a series of questions to highlight some insights that comparative genomics has produced. To date,more » there are genome sequences available from 50 different bacterial phyla and 11 different archaeal phyla. However, the distribution is quite skewed towards a few phyla that contain model organisms. But the breadth is continuing to improve, with projects dedicated to filling in less characterized taxonomic groups. The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas system provides bacteria with immunity against viruses, which outnumber bacteria by tenfold. How fast can we go? Second-generation sequencing has produced a large number of draft genomes (close to 90 % of bacterial genomes in GenBank are currently not complete); third-generation sequencing can potentially produce a finished genome in a few hours, and at the same time provide methlylation sites along the entire chromosome. The diversity of bacterial communities is extensive as is evident from the genome sequences available from 50 different bacterial phyla and 11 different archaeal phyla. Genome sequencing can help in classifying an organism, and in the case where multiple genomes of the same species are available, it is possible to calculate the pan- and core genomes; comparison of more than 2000 Escherichia coli genomes finds an E. coli core genome of about 3100 gene families and a total of about 89,000 different gene families. Why do we care about

Insights from 20 years of bacterial genome sequencing

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

Land, Miriam L.; Hauser, Loren; Jun, Se-Ran

Since the first two complete bacterial genome sequences were published in 1995, the science of bacteria has dramatically changed. Using third-generation DNA sequencing, it is possible to completely sequence a bacterial genome in a few hours and identify some types of methylation sites along the genome as well. Sequencing of bacterial genome sequences is now a standard procedure, and the information from tens of thousands of bacterial genomes has had a major impact on our views of the bacterial world. In this review, we explore a series of questions to highlight some insights that comparative genomics has produced. To date,more » there are genome sequences available from 50 different bacterial phyla and 11 different archaeal phyla. However, the distribution is quite skewed towards a few phyla that contain model organisms. But the breadth is continuing to improve, with projects dedicated to filling in less characterized taxonomic groups. The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas system provides bacteria with immunity against viruses, which outnumber bacteria by tenfold. How fast can we go? Second-generation sequencing has produced a large number of draft genomes (close to 90 % of bacterial genomes in GenBank are currently not complete); third-generation sequencing can potentially produce a finished genome in a few hours, and at the same time provide methlylation sites along the entire chromosome. The diversity of bacterial communities is extensive as is evident from the genome sequences available from 50 different bacterial phyla and 11 different archaeal phyla. Genome sequencing can help in classifying an organism, and in the case where multiple genomes of the same species are available, it is possible to calculate the pan- and core genomes; comparison of more than 2000 Escherichia coli genomes finds an E. coli core genome of about 3100 gene families and a total of about 89,000 different gene families. Why do we care about

Metallization of bacterial cellulose for electrical and electronic device manufacture

DOEpatents

Evans, Barbara R [Oak Ridge, TN; O'Neill, Hugh M [Knoxville, TN; Jansen, Valerie Malyvanh [Memphis, TN; Woodward, Jonathan [Knoxville, TN

2011-06-07

A method for the deposition of metals in bacterial cellulose and for the employment of the metallized bacterial cellulose in the construction of fuel cells and other electronic devices is disclosed. The method for impregnating bacterial cellulose with a metal comprises placing a bacterial cellulose matrix in a solution of a metal salt such that the metal salt is reduced to metallic form and the metal precipitates in or on the matrix. The method for the construction of a fuel cell comprises placing a hydrated bacterial cellulose support structure in a solution of a metal salt such that the metal precipitates in or on the support structure, inserting contact wires into two pieces of the metal impregnated support structure, placing the two pieces of metal impregnated support structure on opposite sides of a layer of hydrated bacterial cellulose, and dehydrating the three layer structure to create a fuel cell.

Metallization of bacterial cellulose for electrical and electronic device manufacture

DOEpatents

Evans, Barbara R [Oak Ridge, TN; O'Neill, Hugh M [Knoxville, TN; Jansen, Valerie Malyvanh [Memphis, TN; Woodward, Jonathan [Knoxville, TN

2010-09-28

A method for the deposition of metals in bacterial cellulose and for the employment of the metallized bacterial cellulose in the construction of fuel cells and other electronic devices is disclosed. The method for impregnating bacterial cellulose with a metal comprises placing a bacterial cellulose matrix in a solution of a metal salt such that the metal salt is reduced to metallic form and the metal precipitates in or on the matrix. The method for the construction of a fuel cell comprises placing a hydrated bacterial cellulose support structure in a solution of a metal salt such that the metal precipitates in or on the support structure, inserting contact wires into two pieces of the metal impregnated support structure, placing the two pieces of metal impregnated support structure on opposite sides of a layer of hydrated bacterial cellulose, and dehydrating the three layer structure to create a fuel cell.

Differential signatures of bacterial and mammalian IMP dehydrogenase enzymes.

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

Zhang, R.; Evans, G.; Rotella, F.

1999-06-01

IMP dehydrogenase (IMPDH) is an essential enzyme of de novo guanine nucleotide synthesis. IMPDH inhibitors have clinical utility as antiviral, anticancer or immunosuppressive agents. The essential nature of this enzyme suggests its therapeutic applications may be extended to the development of antimicrobial agents. Bacterial IMPDH enzymes show bio- chemical and kinetic characteristics that are different than the mammalian IMPDH enzymes, suggesting IMPDH may be an attractive target for the development of antimicrobial agents. We suggest that the biochemical and kinetic differences between bacterial and mammalian enzymes are a consequence of the variance of specific, identifiable amino acid residues. Identification ofmore » these residues or combination of residues that impart this mammalian or bacterial enzyme signature is a prerequisite for the rational identification of agents that specifically target the bacterial enzyme. We used sequence alignments of IMPDH proteins to identify sequence signatures associated with bacterial or eukaryotic IMPDH enzymes. These selections were further refined to discern those likely to have a role in catalysis using information derived from the bacterial and mammalian IMPDH crystal structures and site-specific mutagenesis. Candidate bacterial sequence signatures identified by this process include regions involved in subunit interactions, the active site flap and the NAD binding region. Analysis of sequence alignments in these regions indicates a pattern of catalytic residues conserved in all enzymes and a secondary pattern of amino acid conservation associated with the major phylogenetic groups. Elucidation of the basis for this mammalian/bacterial IMPDH signature will provide insight into the catalytic mechanism of this enzyme and the foundation for the development of highly specific inhibitors.« less

Changes in rhizosphere bacterial gene expression following glyphosate treatment.

PubMed

Newman, Molli M; Lorenz, Nicola; Hoilett, Nigel; Lee, Nathan R; Dick, Richard P; Liles, Mark R; Ramsier, Cliff; Kloepper, Joseph W

2016-05-15

In commercial agriculture, populations and interactions of rhizosphere microflora are potentially affected by the use of specific agrichemicals, possibly by affecting gene expression in these organisms. To investigate this, we examined changes in bacterial gene expression within the rhizosphere of glyphosate-tolerant corn (Zea mays) and soybean (Glycine max) in response to long-term glyphosate (PowerMAX™, Monsanto Company, MO, USA) treatment. A long-term glyphosate application study was carried out using rhizoboxes under greenhouse conditions with soil previously having no history of glyphosate exposure. Rhizosphere soil was collected from the rhizoboxes after four growing periods. Soil microbial community composition was analyzed using microbial phospholipid fatty acid (PLFA) analysis. Total RNA was extracted from rhizosphere soil, and samples were analyzed using RNA-Seq analysis. A total of 20-28 million bacterial sequences were obtained for each sample. Transcript abundance was compared between control and glyphosate-treated samples using edgeR. Overall rhizosphere bacterial metatranscriptomes were dominated by transcripts related to RNA and carbohydrate metabolism. We identified 67 differentially expressed bacterial transcripts from the rhizosphere. Transcripts downregulated following glyphosate treatment involved carbohydrate and amino acid metabolism, and upregulated transcripts involved protein metabolism and respiration. Additionally, bacterial transcripts involving nutrients, including iron, nitrogen, phosphorus, and potassium, were also affected by long-term glyphosate application. Overall, most bacterial and all fungal PLFA biomarkers decreased after glyphosate treatment compared to the control. These results demonstrate that long-term glyphosate use can affect rhizosphere bacterial activities and potentially shift bacterial community composition favoring more glyphosate-tolerant bacteria. Copyright © 2016 The Authors. Published by Elsevier B.V. All

[Spontaneous bacterial peritonitis: impact of microbiological changes].

PubMed

Almeida, Paulo Roberto Lerias de; Camargo, Nutianne Schneider; Arenz, Maximilhano; Tovo, Cristiane Valle; Galperim, Bruno; Behar, Paulo

2007-01-01

Spontaneous bacterial peritonitis is a serious complication in cirrhotic patients, and the changes in the microbiological characteristics reported in the last years are impacting the choice of antibiotic used in the treatment. To evaluate the change in the epidemiology and antibiotic resistance of the bacteria causing spontaneous bacterial peritonitis in a 7 years period. All the cases of cirrhotic patients with spontaneous bacterial peritonitis with positive cultural examination were retrospectively studied. Two periods were evaluated: 1997-1998 and 2002-2003. The most frequent infecting organisms and the sensitivity in vitro to antibiotics were registered. In the first period (1997-1998) there were 33 cases, 3 (9%) with polymicrobial infection. The most common were: E.coli in 13 (36,11%), Staphylococcus coagulase-negative in 6 (16,66%), K. pneumoniae in 5 (13,88%), S. aureus in 4 (11,11%) and S. faecalis in 3 (8,33%). In 2003-2004, there were 43 cases, 2 (5%) with polymicrobial infection. The most frequent were: Staphylococus coagulase-negative in 16 (35,55%), S. aureus in 8 (17,77%), E. coli in 7 (15,55%) and K. pneumoniae in 3 (6,66%). No one was using antibiotic prophilaxys. The prevalence of S. aureus methicillin-resitant to quinolone and trimethoprim-sulfamethoxazole changed from 25% to 50%, and vancomicin was the only one with absolute activity during all the period. In the same way, the prevalence of E. coli resistant to third generation cephalosporin and to quinolone changed from 0% to 16%. There was a modification of the bacterial population causing spontaneous bacterial peritonitis, with high frequency of gram-positive organisms, as well as an increase in the resistance to the traditionally recommended antibiotics. This study suggests a probable imminent inclusion of a drug against gram-positive organisms in the empiric treatment of spontaneous bacterial peritonitis.

Interventions for treating bacterial vaginosis in pregnancy.

PubMed

Brocklehurst, P; Hannah, M; McDonald, H

2000-01-01

Bacterial vaginosis has been associated with poor perinatal outcome. Since the infections are amenable to treatment, identification during pregnancy and treatment may reduce the risk of preterm birth and its consequences. The objective of this review was to assess the effects of antibiotic treatment of bacterial vaginosis in pregnancy. We searched the Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register. Randomised trials comparing one antibiotic regimen with placebo or no treatment, or which compare two or more alternative antibiotic regimens in pregnant women with bacterial vaginosis. Trial quality assessments and data extraction were done independently by three reviewers. Study authors were contacted for additional information. Five trials involving 1504 women were included. These trials were of good quality. Antibiotic therapy was highly effective at eradicating infection during pregnancy as judged by 'test-of-cure' following therapy (odds ratio 0.22, 95% confidence interval 0.17 to 0.27). The effect of treating bacterial vaginosis during pregnancy showed a trend to less births before 37 weeks gestation (odds ratio 0.78, 95% confidence interval 0.60 to 1.02). The prevention of preterm birth less than 37 weeks gestation was most marked in the subgroup of women with a previous preterm birth (odds ratio 0.37, 95% confidence interval 0.23 to 0. 60). The current evidence does not support screening and treating all pregnant women for bacterial vaginosis to prevent preterm birth and its consequences. For women with a history of a previous preterm birth there is some suggestion that detection and treatment of bacterial vaginosis early in pregnancy may prevent a proportion of these women having a further preterm birth. It is not known whether this is associated with an improvement in neonatal well-being.

Antimicrobial effect against different bacterial strains and bacterial adaptation to essential oils used as feed additives.

PubMed

Melo, Antonio Diego Brandão; Amaral, Amanda Figueiredo; Schaefer, Gustavo; Luciano, Fernando Bittencourt; de Andrade, Carla; Costa, Leandro Batista; Rostagno, Marcos Horácio

2015-10-01

The aim of this study was to evaluate the antimicrobial activity and determine the minimum bactericidal concentration (MBC) of the essential oils derived from Origanum vulgare (oregano), Melaleuca alternifolia (tea tree), Cinnamomum cassia (cassia), and Thymus vulgaris (white thyme) against Salmonella Typhimurium, Salmonella Enteritidis, Escherichia coli, Staphylococcus aureus and Enterococcus faecalis. The study also investigated the ability of these different bacterial strains to develop adaptation after repetitive exposure to sub-lethal concentrations of these essential oils. The MBC of the essential oils studied was determined by disc diffusion and broth dilution methods. All essential oils showed antimicrobial effect against all bacterial strains. In general, the development of adaptation varied according to the bacterial strain and the essential oil (tea tree > white thyme > oregano). Therefore, it is important to use essential oils at efficient bactericidal doses in animal feed, food, and sanitizers, since bacteria can rapidly develop adaptation when exposed to sub-lethal concentrations of these oils.

Antimicrobial effect against different bacterial strains and bacterial adaptation to essential oils used as feed additives

PubMed Central

Melo, Antonio Diego Brandão; Amaral, Amanda Figueiredo; Schaefer, Gustavo; Luciano, Fernando Bittencourt; de Andrade, Carla; Costa, Leandro Batista; Rostagno, Marcos Horácio

2015-01-01

The aim of this study was to evaluate the antimicrobial activity and determine the minimum bactericidal concentration (MBC) of the essential oils derived from Origanum vulgare (oregano), Melaleuca alternifolia (tea tree), Cinnamomum cassia (cassia), and Thymus vulgaris (white thyme) against Salmonella Typhimurium, Salmonella Enteritidis, Escherichia coli, Staphylococcus aureus and Enterococcus faecalis. The study also investigated the ability of these different bacterial strains to develop adaptation after repetitive exposure to sub-lethal concentrations of these essential oils. The MBC of the essential oils studied was determined by disc diffusion and broth dilution methods. All essential oils showed antimicrobial effect against all bacterial strains. In general, the development of adaptation varied according to the bacterial strain and the essential oil (tea tree > white thyme > oregano). Therefore, it is important to use essential oils at efficient bactericidal doses in animal feed, food, and sanitizers, since bacteria can rapidly develop adaptation when exposed to sub-lethal concentrations of these oils. PMID:26424908

Bacterial conjunctivitis in childhood: etiology, clinical manifestations, diagnosis, and management.

PubMed

Leung, Alexander Kc; Hon, Kam Lun; Wong, Alex H C; Wong, Andrew S

2018-01-29

Bacterial conjunctivitis is a common reason for children to be seen in pediatric practices A correct diagnosis is important so that appropriate treatment can be instituted. To provide an update on the evaluation, diagnosis, and treatment of bacterial conjunctivitis in children. A PubMed search was completed in Clinical Queries using the key term "bacterial conjunctivitis". Patents were searched using the key term "bacterial conjunctivitis" from www.freepatentsonline.com and www.google.com/patents. In the neonatal period, bacterial conjunctivitis is rare and the most common cause of organism is Staphylococcus aureus, followed by Chlamydia trachomatis. In infants and older children, bacterial conjunctivitis is most often caused by Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis. Clinically, bacterial conjunctivitis is characterized by a purulent eye discharge, or sticky eyes on awakening, a foreign body sensation and conjunctival injection (pink eye). The diagnosis is made clinically. Cultures are unnecessary. Some authors suggest a watchful observation approach as most cases of bacterial conjunctivitis are self-limited. A Cochrane review suggests the use of antibiotic eye drops is associated with modestly improved rates of clinical and microbiological omission as compared to the use of placebo. Various investigators have also disclosed patents for the treatment of conjunctivitis. The present consensus supports the use of topical antibiotics for bacterial conjunctivitis. Topical antibiotics shorten the course of the disease, reduce discomfort, prevent person-to-person transmission and reduce the rate of reinfection. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Palladium-bacterial cellulose membranes for fuel cells.

PubMed

Evans, Barbara R; O'Neill, Hugh M; Malyvanh, Valerie P; Lee, Ida; Woodward, Jonathan

2003-07-01

Bacterial cellulose is a versatile renewable biomaterial that can be used as a hydrophilic matrix for the incorporation of metals into thin, flexible, thermally stable membranes. In contrast to plant cellulose, we found it catalyzed the deposition of metals within its structure to generate a finely divided homogeneous catalyst layer. Experimental data suggested that bacterial cellulose possessed reducing groups capable of initiating the precipitation of palladium, gold, and silver from aqueous solution. Since the bacterial cellulose contained water equivalent to at least 200 times the dry weight of the cellulose, it was dried to a thin membranous structure suitable for the construction of membrane electrode assemblies (MEAs). Results of our study with palladium-cellulose showed that it was capable of catalyzing the generation of hydrogen when incubated with sodium dithionite and generated an electrical current from hydrogen in an MEA containing native cellulose as the polyelectrolyte membrane (PEM). Advantages of using native and metallized bacterial cellulose membranes in an MEA over other PEMs such as Nafion 117 include its higher thermal stability to 130 degrees C and lower gas crossover.

Biomimicry of quorum sensing using bacterial lifecycle model.

PubMed

Niu, Ben; Wang, Hong; Duan, Qiqi; Li, Li

2013-01-01

Recent microbiologic studies have shown that quorum sensing mechanisms, which serve as one of the fundamental requirements for bacterial survival, exist widely in bacterial intra- and inter-species cell-cell communication. Many simulation models, inspired by the social behavior of natural organisms, are presented to provide new approaches for solving realistic optimization problems. Most of these simulation models follow population-based modelling approaches, where all the individuals are updated according to the same rules. Therefore, it is difficult to maintain the diversity of the population. In this paper, we present a computational model termed LCM-QS, which simulates the bacterial quorum-sensing (QS) mechanism using an individual-based modelling approach under the framework of Agent-Environment-Rule (AER) scheme, i.e. bacterial lifecycle model (LCM). LCM-QS model can be classified into three main sub-models: chemotaxis with QS sub-model, reproduction and elimination sub-model and migration sub-model. The proposed model is used to not only imitate the bacterial evolution process at the single-cell level, but also concentrate on the study of bacterial macroscopic behaviour. Comparative experiments under four different scenarios have been conducted in an artificial 3-D environment with nutrients and noxious distribution. Detailed study on bacterial chemotatic processes with quorum sensing and without quorum sensing are compared. By using quorum sensing mechanisms, artificial bacteria working together can find the nutrient concentration (or global optimum) quickly in the artificial environment. Biomimicry of quorum sensing mechanisms using the lifecycle model allows the artificial bacteria endowed with the communication abilities, which are essential to obtain more valuable information to guide their search cooperatively towards the preferred nutrient concentrations. It can also provide an inspiration for designing new swarm intelligence optimization algorithms

Biomimicry of quorum sensing using bacterial lifecycle model

PubMed Central

2013-01-01

Background Recent microbiologic studies have shown that quorum sensing mechanisms, which serve as one of the fundamental requirements for bacterial survival, exist widely in bacterial intra- and inter-species cell-cell communication. Many simulation models, inspired by the social behavior of natural organisms, are presented to provide new approaches for solving realistic optimization problems. Most of these simulation models follow population-based modelling approaches, where all the individuals are updated according to the same rules. Therefore, it is difficult to maintain the diversity of the population. Results In this paper, we present a computational model termed LCM-QS, which simulates the bacterial quorum-sensing (QS) mechanism using an individual-based modelling approach under the framework of Agent-Environment-Rule (AER) scheme, i.e. bacterial lifecycle model (LCM). LCM-QS model can be classified into three main sub-models: chemotaxis with QS sub-model, reproduction and elimination sub-model and migration sub-model. The proposed model is used to not only imitate the bacterial evolution process at the single-cell level, but also concentrate on the study of bacterial macroscopic behaviour. Comparative experiments under four different scenarios have been conducted in an artificial 3-D environment with nutrients and noxious distribution. Detailed study on bacterial chemotatic processes with quorum sensing and without quorum sensing are compared. By using quorum sensing mechanisms, artificial bacteria working together can find the nutrient concentration (or global optimum) quickly in the artificial environment. Conclusions Biomimicry of quorum sensing mechanisms using the lifecycle model allows the artificial bacteria endowed with the communication abilities, which are essential to obtain more valuable information to guide their search cooperatively towards the preferred nutrient concentrations. It can also provide an inspiration for designing new swarm

A Computer Simulation of Bacterial Growth During Food-Processing

DTIC Science & Technology

1974-11-01

1 AD A TECHNICAL REPORT A COMPUTER SIMULATION OF BACTERIAL GROWTH DURING FOOD PROCESSING =r= by Edward W. Ross, Jr. Approved for public...COMPUTER SIMULATION OF BACTERIAL GROWTH DURING FOOD - PROCESSING Edward W. Ross, Jr. Army Natick Laboratories Natick, Massachusetts Novembe...CATALOG NUMBER 4. TITLE fand SubtKUJ "A Computer Sinulatlon of Bacterial Growth During Food - Processing " 5. TYPE OF REPORT A PERIOD COVERED 6

Hijacking Complement Regulatory Proteins for Bacterial Immune Evasion.

PubMed

Hovingh, Elise S; van den Broek, Bryan; Jongerius, Ilse

2016-01-01

The human complement system plays an important role in the defense against invading pathogens, inflammation and homeostasis. Invading microbes, such as bacteria, directly activate the complement system resulting in the formation of chemoattractants and in effective labeling of the bacteria for phagocytosis. In addition, formation of the membrane attack complex is responsible for direct killing of Gram-negative bacteria. In turn, bacteria have evolved several ways to evade complement activation on their surface in order to be able to colonize and invade the human host. One important mechanism of bacterial escape is attraction of complement regulatory proteins to the microbial surface. These molecules are present in the human body for tight regulation of the complement system to prevent damage to host self-surfaces. Therefore, recruitment of complement regulatory proteins to the bacterial surface results in decreased complement activation on the microbial surface which favors bacterial survival. This review will discuss recent advances in understanding the binding of complement regulatory proteins to the bacterial surface at the molecular level. This includes, new insights that have become available concerning specific conserved motives on complement regulatory proteins that are favorable for microbial binding. Finally, complement evasion molecules are of high importance for vaccine development due to their dominant role in bacterial survival, high immunogenicity and homology as well as their presence on the bacterial surface. Here, the use of complement evasion molecules for vaccine development will be discussed.

Hijacking Complement Regulatory Proteins for Bacterial Immune Evasion

PubMed Central

Hovingh, Elise S.; van den Broek, Bryan; Jongerius, Ilse

2016-01-01

The human complement system plays an important role in the defense against invading pathogens, inflammation and homeostasis. Invading microbes, such as bacteria, directly activate the complement system resulting in the formation of chemoattractants and in effective labeling of the bacteria for phagocytosis. In addition, formation of the membrane attack complex is responsible for direct killing of Gram-negative bacteria. In turn, bacteria have evolved several ways to evade complement activation on their surface in order to be able to colonize and invade the human host. One important mechanism of bacterial escape is attraction of complement regulatory proteins to the microbial surface. These molecules are present in the human body for tight regulation of the complement system to prevent damage to host self-surfaces. Therefore, recruitment of complement regulatory proteins to the bacterial surface results in decreased complement activation on the microbial surface which favors bacterial survival. This review will discuss recent advances in understanding the binding of complement regulatory proteins to the bacterial surface at the molecular level. This includes, new insights that have become available concerning specific conserved motives on complement regulatory proteins that are favorable for microbial binding. Finally, complement evasion molecules are of high importance for vaccine development due to their dominant role in bacterial survival, high immunogenicity and homology as well as their presence on the bacterial surface. Here, the use of complement evasion molecules for vaccine development will be discussed. PMID:28066340

[Etiology of bacterial vaginosis (non-specific vaginitis)].

PubMed

Lefèvre, J C; Jean, M; Averous, S; Viraben, R; Blanc, C; Bauriaud, R; Lareng, M B

1985-01-01

56 women who were diagnosed bioclinically as having a bacterial vaginal infection were studied, as were 35 women as a control group. The study was a semi-quantitative analysis of the vaginal bacterial flora, both aerobic and anaerobic. It shows that Gardnerella vaginalis and anaerobic bacteria such as Peptococcus, Peptostreptococcus, Bacteroïdes, Veillonella and Mobiluncus were associated in a statistically significant way with bacterial vaginitis. On the other hand Lactobacilli were less frequently found (p less than 0.001) than in the control group of women. The way in which the microbial flora is changed has been observed during attacks of vaginitis and is discussed, as is the importance of making the diagnosis and of treating this syndrome.

Evolvable social agents for bacterial systems modeling.

PubMed

Paton, Ray; Gregory, Richard; Vlachos, Costas; Saunders, Jon; Wu, Henry

2004-09-01

We present two approaches to the individual-based modeling (IbM) of bacterial ecologies and evolution using computational tools. The IbM approach is introduced, and its important complementary role to biosystems modeling is discussed. A fine-grained model of bacterial evolution is then presented that is based on networks of interactivity between computational objects representing genes and proteins. This is followed by a coarser grained agent-based model, which is designed to explore the evolvability of adaptive behavioral strategies in artificial bacteria represented by learning classifier systems. The structure and implementation of the two proposed individual-based bacterial models are discussed, and some results from simulation experiments are presented, illustrating their adaptive properties.

Urinary tract infections and bacterial prostatitis in men.

PubMed

Wagenlehner, Florian M E; Weidner, Wolfgang; Pilatz, Adrian; Naber, Kurt G

2014-02-01

The purpose of this review is to highlight advances in research on urinary tract infections (UTIs) and bacterial prostatitis in men in the preceding year. The antiseptic properties of the prostate secretions might be an important factor for prevention of recurrency. Risk factors for UTI in men include prostate enlargement and urological interventions, such as transrectal prostate biopsy. Preventive treatment of prostate enlargement has been demonstrated to reduce frequency of UTI. Ensuing infections after prostate biopsy, such as UTI and bacterial prostatitis, are increasing due to increasing rates of fluoroquinolone resistance. The increasing global antibiotic resistance also significantly affects management of UTI in men, and therefore calls for alternative strategies.Apart from prevention of complicating factors leading to UTI, a more thorough understanding of the pathophysiology may play a more important role in the future, to define new targets for treatment. Interesting results that might interfere with the intracellular mucosal bacterial load in the bladder wall have been found in the last years. UTI in men and bacterial prostatitis are currently underrepresented in the medical literature. Increasing antibacterial resistance calls for novel strategies in the prevention and management of UTI and bacterial prostatitis in men.

Widespread presence of "bacterial-like" PPP phosphatases in eukaryotes.

PubMed

Andreeva, Alexandra V; Kutuzov, Mikhail A

2004-11-19

In eukaryotes, PPP (protein phosphatase P) family is one of the two known protein phosphatase families specific for Ser and Thr. The role of PPP phosphatases in multiple signaling pathways in eukaryotic cell has been extensively studied. Unlike eukaryotic PPP phosphatases, bacterial members of the family have broad substrate specificity or may even be Tyr-specific. Moreover, one group of bacterial PPPs are diadenosine tetraphosphatases, indicating that bacterial PPP phosphatases may not necessarily function as protein phosphatases. We describe the presence in eukaryotes of three groups of expressed genes encoding "non-conventional" phosphatases of the PPP family. These enzymes are more closely related to bacterial PPP phosphatases than to the known eukaryotic members of the family. One group, found exclusively in land plants, is most closely related to PPP phosphatases from some alpha-Proteobacteria, including Rhizobiales, Rhodobacterales and Rhodospirillaceae. This group is therefore termed Rhizobiales / Rhodobacterales / Rhodospirillaceae-like phosphatases, or Rhilphs. Phosphatases of the other group are found in Viridiplantae, Rhodophyta, Trypanosomatidae, Plasmodium and some fungi. They are structurally related to phosphatases from psychrophilic bacteria Shewanella and Colwellia, and are termed Shewanella-like phosphatases, or Shelphs. Phosphatases of the third group are distantly related to ApaH, bacterial diadenosine tetraphosphatases, and are termed ApaH-like phosphatases, or Alphs. Patchy distribution of Alphs in animals, plants, fungi, diatoms and kinetoplasts suggests that these phosphatases were present in the common ancestor of eukaryotes but were independently lost in many lineages. Rhilphs, Shelphs and Alphs form PPP clades, as divergent from "conventional" eukaryotic PPP phosphatases as they are from each other and from major bacterial clades. In addition, comparison of primary structures revealed a previously unrecognised (I/L/V)D(S/T)G motif

Pyrosequencing analysis of bacterial diversity in dental unit waterlines.

PubMed

Costa, Damien; Mercier, Anne; Gravouil, Kevin; Lesobre, Jérôme; Delafont, Vincent; Bousseau, Anne; Verdon, Julien; Imbert, Christine

2015-09-15

Some infections cases due to exposure to output water from dental unit waterlines (DUWL) have been reported in the literature. However, this type of healthcare-associated risk has remained unclear and up until now the overall bacterial composition of DUWL has been poorly documented. In this study, 454 high-throughput pyrosequencing was used to investigate the bacterial community in seven dental offices (N = 7) and to identify potential bacterial pathogenic sequences. Dental unit waters (DUW) were collected from the tap water supplying units (Incoming Water; IW) to the output exposure point of the turbine handpiece (Output water; OW) following a stagnation period (OWS), and immediately after the last patient of the sampling day (OWA). A high bacterial diversity was revealed in DUW with 394 operational taxonomic units detected at the genus level. In addition to the inter-unit variability observed, results showed increased total bacterial cell concentration and shifts in bacterial community composition and abundance at the genus level, mainly within the Gamma- and Alpha-Proteobacteria class, as water circulated in the dental unit (DU). Results showed that 96.7%, 96.8% and 97.4% of the total sequences from IW, OWS and OWA respectively were common to the 3 defined water groups, thereby highlighting a common core microbiome. Results also suggested that stagnation and DU maintenance practices were critical to composition of the bacterial community. The presence of potentially pathogenic genera was detected, including Pseudomonas and Legionella spp. Emerging and opportunistic pathogenic genera such as Mycobacterium, Propionibacterium and Stenotrophomonas were likewise recovered in DUW. For the first time, an exhaustive evaluation of the bacterial communities present in DUW was performed taking into account the circulation of water within the DU. This study highlights an ignored diversity of the DUWL bacterial community. Our findings also contribute to a better

Infection of orthopedic implants with emphasis on bacterial adhesion process and techniques used in studying bacterial-material interactions

PubMed Central

Ribeiro, Marta; Monteiro, Fernando J.; Ferraz, Maria P.

2012-01-01

Staphylococcus comprises up to two-thirds of all pathogens in orthopedic implant infections and they are the principal causative agents of two major types of infection affecting bone: septic arthritis and osteomyelitis, which involve the inflammatory destruction of joint and bone. Bacterial adhesion is the first and most important step in implant infection. It is a complex process influenced by environmental factors, bacterial properties, material surface properties and by the presence of serum or tissue proteins. Properties of the substrate, such as chemical composition of the material, surface charge, hydrophobicity, surface roughness and the presence of specific proteins at the surface, are all thought to be important in the initial cell attachment process. The biofilm mode of growth of infecting bacteria on an implant surface protects the organisms from the host immune system and antibiotic therapy. The research for novel therapeutic strategies is incited by the emergence of antibiotic-resistant bacteria. This work will provide an overview of the mechanisms and factors involved in bacterial adhesion, the techniques that are currently being used studying bacterial-material interactions as well as provide insight into future directions in the field. PMID:23507884

Glycerol as an additional carbon source for bacterial cellulose synthesis

NASA Astrophysics Data System (ADS)

Agustin, Y. E.; Padmawijaya, K. S.; Rixwari, H. F.; Yuniharto, V. A. S.

2018-03-01

Bacterial cellulose, the fermentation result of Acetobacter xylinus can be produced when glycerol was used as an additional carbon source. In this research, bacterial cellulose produced in two different fermentation medium, Hestrin and Scharmm (HS) medium and HS medium with additional MgSO4. Concentration of glycerol that used in this research were 0%; 5%; 10%; and 15% (v/v). The optimum conditions of bacterial cellulose production on each experiment variations determined by characterization of the mechanical properties, including thickness, tensile strength and elongation. Fourier Transform Infra Red Spectroscopy (FTIR) revealed the characterization of bacterial cellulose. Results showed that the growth rate of bacterial cellulose in HS-MgSO4-glycerol medium was faster than in HS-glycerol medium. Increasing concentrations of glycerol will lower the value of tensile strength and elongation. Elongation test showed that the elongation bacterial cellulose (BC) with the addition of 4.95% (v/v) glycerol in the HS-MgSO4 medium is the highest elongation value. The optimum bacterial cellulose production was achieved when 4.95% (v/v) of glycerol added into HS-MgSO4 medium with stress at break of 116.885 MPa and 4.214% elongation.

Morphomechanics of bacterial biofilms undergoing anisotropic differential growth

NASA Astrophysics Data System (ADS)

Zhang, Cheng; Li, Bo; Huang, Xiao; Ni, Yong; Feng, Xi-Qiao

2016-10-01

Growing bacterial biofilms exhibit a number of surface morphologies, e.g., concentric wrinkles, radial ridges, and labyrinthine networks, depending on their physiological status and nutrient access. We explore the mechanisms underlying the emergence of these greatly different morphologies. Ginzburg-Landau kinetic method and Fourier spectral method are integrated to simulate the morphological evolution of bacterial biofilms. It is shown that the morphological instability of biofilms is triggered by the stresses induced by anisotropic and heterogeneous bacterial expansion, and involves the competition between membrane energy and bending energy. Local interfacial delamination further enriches the morphologies of biofilms. Phase diagrams are established to reveal how the anisotropy and spatial heterogeneity of growth modulate the surface patterns. The mechanics of three-dimensional microbial morphogenesis may also underpin self-organization in other development systems and provide a potential strategy for engineering microscopic structures from bacterial aggregates.

Apparatus and method for automated monitoring of airborne bacterial spores

NASA Technical Reports Server (NTRS)

Ponce, Adrian (Inventor)

2009-01-01

An apparatus and method for automated monitoring of airborne bacterial spores. The apparatus is provided with an air sampler, a surface for capturing airborne spores, a thermal lysis unit to release DPA from bacterial spores, a source of lanthanide ions, and a spectrometer for excitation and detection of the characteristic fluorescence of the aromatic molecules in bacterial spores complexed with lanthanide ions. In accordance with the method: computer-programmed steps allow for automation of the apparatus for the monitoring of airborne bacterial spores.

Benthic bacterial diversity in submerged sinkhole ecosystems.

PubMed

Nold, Stephen C; Pangborn, Joseph B; Zajack, Heidi A; Kendall, Scott T; Rediske, Richard R; Biddanda, Bopaiah A

2010-01-01

Physicochemical characterization, automated ribosomal intergenic spacer analysis (ARISA) community profiling, and 16S rRNA gene sequencing approaches were used to study bacterial communities inhabiting submerged Lake Huron sinkholes inundated with hypoxic, sulfate-rich groundwater. Photosynthetic cyanobacterial mats on the sediment surface were dominated by Phormidium autumnale, while deeper, organically rich sediments contained diverse and active bacterial communities.

Interspecies chemical communication in bacterial development.

PubMed

Straight, Paul D; Kolter, Roberto

2009-01-01

Our view of bacteria, from the earliest observations through the heyday of antibiotic discovery, has shifted dramatically. We recognize communities of bacteria as integral and functionally important components of diverse habitats, ranging from soil collectives to the human microbiome. To function as productive communities, bacteria coordinate metabolic functions, often requiring shifts in growth and development. The hallmark of cellular development, which we characterize as physiological change in response to environmental stimuli, is a defining feature of many bacterial interspecies interactions. Bacterial communities rely on chemical exchanges to provide the cues for developmental change. Traditional methods in microbiology focus on isolation and characterization of bacteria in monoculture, separating the organisms from the surroundings in which interspecies chemical communication has relevance. Developing multispecies experimental systems that incorporate knowledge of bacterial physiology and metabolism with insights from biodiversity and metagenomics shows great promise for understanding interspecies chemical communication in the microbial world.

Bacterial Responses to Reactive Chlorine Species

PubMed Central

Gray, Michael J.; Wholey, Wei-Yun; Jakob, Ursula

2013-01-01

Hypochlorous acid (HOCl), the active ingredient of household bleach, is the most common disinfectant in medical, industrial, and domestic use and plays an important role in microbial killing in the innate immune system. Given the critical importance of the antimicrobial properties of chlorine to public health, it is surprising how little is known about the ways in which bacteria sense and respond to reactive chlorine species (RCS). Although the literature on bacterial responses to reactive oxygen species (ROS) is enormous, work addressing bacterial responses to RCS has begun only recently. Transcriptomic and proteomic studies now provide new insights into how bacteria mount defenses against this important class of antimicrobial compounds. In this review, we summarize the current knowledge, emphasizing the overlaps between RCS stress responses and other more well-characterized bacterial defense systems, and identify outstanding questions that represent productive avenues for future research. PMID:23768204

Chemical sensing in mammalian host-bacterial commensal associations

USDA-ARS?s Scientific Manuscript database

The mammalian gastrointestinal (GI) tract is colonized by a complex consortium of bacterial species. Bacteria engage in chemical signaling to coordinate population-wide behavior. However, it is unclear if chemical sensing plays a role in establishing mammalian host–bacterial commensal relationships....

Formation of bacterial nanocells

NASA Astrophysics Data System (ADS)

Vainshtein, Mikhail; Kudryashova, Ekaterina; Suzina, Natalia; Ariskina, Elena; Voronkov, Vadim

1998-07-01

Existence of nanobacteria received increasing attention both in environmental microbiology/geomicro-biology and in medical microbiology. In order to study a production of nanoforms by typical bacterial cells. Effects of different physical factors were investigated. Treatment of bacterial cultures with microwave radiation, or culturing in field of electric current resulted in formation a few types of nanocells. The number and type of nanoforms were determined with type and dose of the treatment. The produced nanoforms were: i) globules, ii) clusters of the globules--probably produced by liaison, iii) nanocells coated with membrane. The viability of the globules is an object opened for doubts. The nanocells discovered multiplication and growth on solidified nutrient media. The authors suggest that formation of nanocells is a common response of bacteria to stress-actions produced by different agents.

Fungal corneal ulcer and bacterial orbital cellulitis occur as complications of bacterial endophthalmitis after cataract surgery in an immunocompetent patient.

PubMed

Kim, Eun Chul; Kim, Man Soo; Kang, Nam Yeo

2013-03-01

To report a case of fungal corneal ulcer and bacterial orbital cellulitis as complications of bacterial endophthalmitis following cataract surgery. A 51-year-old man underwent anterior chamber irrigation and aspiration in the left eye one day after cataract surgery because of bacterial endophthalmitis. Marked lid swelling with purulent discharge was developed after 5 days. Slit lamp examination showed generalized corneal ulcer and pus in the total anterior chamber. A computerized tomography scan showed left retrobulbar fat stranding with thickened optic disc. Streptococcus pneumonia was cultured from corneal scraping, vireous, and subconjunctival pus. The patient improved gradually with antibiotics treatments, but the corneal ulcer did not fully recover 2 months after cataract surgery. Candida albicans was detected in repetitive corneal culture. After antifungal and antibacterial therapy, the corneal epithelium had healed, but phthisis bulbi had developed. Fungal corneal ulcer and bacterial orbital cellulitis can occur as complications of endophthalmitis in an immunocompetent patient.

Antibiotics for treating bacterial vaginosis in pregnancy.

PubMed

McDonald, H M; Brocklehurst, P; Gordon, A

2007-01-24

Bacterial vaginosis is an imbalance of the normal vaginal flora with an overgrowth of anaerobic bacteria and a lack of the normal lactobacillary flora. Bacterial vaginosis during pregnancy has been associated with poor perinatal outcome and, in particular, preterm birth (PTB). Identification and treatment may reduce the risk of PTB and its consequences. To assess the effects of antibiotic treatment of bacterial vaginosis in pregnancy. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (May 2006). Randomized trials comparing antibiotic treatment with placebo or no treatment, or comparing two or more antibiotic regimens in pregnant women with bacterial vaginosis or intermediate vaginal flora. Two review authors assessed trials and extracted data independently. We contacted study authors for additional information. We included fifteen trials of good quality, involving 5888 women. Antibiotic therapy was effective at eradicating bacterial vaginosis during pregnancy (Peto odds ratio (OR) 0.17, 95% confidence interval (CI) 0.15 to 0.20; 10 trials, 4357 women). Treatment did not reduce the risk of PTB before 37 weeks (Peto OR 0.91, 95% CI 0.78 to 1.06; 15 trials, 5888 women), or the risk of preterm prelabour rupture of membranes (PPROM) (Peto OR 0.88, 95% CI 0.61 to 1.28; four trials, 2579 women). However, treatment before 20 weeks' gestation may reduce the risk of preterm birth less than 37 weeks (Peto OR 0.63, 95% CI 0.48 to 0.84; five trials, 2387 women). In women with a previous PTB, treatment did not affect the risk of subsequent PTB (Peto OR 0.83, 95% CI 0.59 to 1.17, five trials of 622); however, it may decrease the risk of PPROM (Peto OR 0.14, 95% CI 0.05 to 0.38) and low birthweight (Peto OR 0.31, 95% CI 0.13 to 0.75)(two trials, 114 women). In women with abnormal vaginal flora (intermediate flora or bacterial vaginosis) treatment may reduce the risk of PTB before 37 weeks (Peto OR 0.51, 95% CI 0.32 to 0.81; two trials, 894 women

Antibiotics for treating bacterial vaginosis in pregnancy.

PubMed

McDonald, H; Brocklehurst, P; Parsons, J

2005-01-25

Bacterial vaginosis is an imbalance of the normal vaginal flora with an overgrowth of anaerobic bacteria and a lack of the normal lactobacillary flora. Bacterial vaginosis during pregnancy has been associated with poor perinatal outcome and, in particular, preterm birth. Identification and treatment may reduce the risk of preterm birth and its consequences. To assess the effects of antibiotic treatment of bacterial vaginosis in pregnancy. We searched the Cochrane Pregnancy and Childbirth Group trials register (May 2004). Randomized trials comparing antibiotic treatment with placebo or no treatment, or comparing two or more antibiotic regimens in pregnant women with bacterial vaginosis or intermediate vaginal flora. Two reviewers assessed trials and extracted data independently. We contacted study authors for additional information. Thirteen trials involving 5300 women were included; all were of good quality. Antibiotic therapy was effective at eradicating bacterial vaginosis during pregnancy (odds ratio (OR) 0.21, 95% confidence interval (CI) 0.19 to 0.24, nine trials of 3895 women). Treatment was not significant in reducing the risk of preterm birth before 37 weeks (OR 0.87, 95% CI 0.74 to 1.03, thirteen trials of 5300 women, and there was significant heterogeneity between trials, p-value 0.002), preterm birth before 34 weeks (OR 1.22, 95% CI 0.67 to 2.19, five trials of 851 women), preterm birth before 32 weeks (OR 1.14, 95% CI 0.76 to 1.70, four trials of 3565 women), or the risk of preterm prelabour rupture of membranes (OR 0.88, 95% CI 0.61 to 1.28, four trials of 2579 women). In women with a previous preterm birth, treatment did not affect the risk of subsequent preterm birth (OR 0.83, 95% CI 0.59 to 1.17, five trials of 622 women, with significant heterogeneity between these trials); however, it may decrease the risk of preterm prelabour rupture of membranes (OR 0.14, 95% CI 0.05 to 0.38, two trials of 114 women, and low birthweight (OR 0.31, 95% CI 0.13 to

Poisons, ruffles and rockets: bacterial pathogens and the host cell cytoskeleton.

PubMed

Steele-Mortimer, O; Knodler, L A; Finlay, B B

2000-02-01

The cytoskeleton of eukaryotic cells is affected by a number of bacterial and viral pathogens. In this review we consider three recurring themes of cytoskeletal involvement in bacterial pathogenesis: 1) the effect of bacterial toxins on actin-regulating small GTP-binding proteins; 2) the invasion of non-phagocytic cells by the bacterial induction of ruffles at the plasma membrane; 3) the formation of actin tails and pedestals by intracellular and extracellular bacteria, respectively. Considerable progress has been made recently in the characterization of these processes. It is becoming clear that bacterial pathogens have developed a variety of sophisticated mechanisms for utilizing the complex cytoskeletal system of host cells. These bacterially-induced processes are now providing unique insights into the regulation of fundamental eukaryotic mechanisms.

Outcomes of bacterial meningitis in children.

PubMed

Briand, C; Levy, C; Baumie, F; Joao, L; Béchet, S; Carbonnelle, E; Grimprel, E; Cohen, R; Gaudelus, J; de Pontual, L

2016-06-01

Pediatricians are well aware of the immediate risks of bacterial meningitis in children. However, the long-term outcome of the disease has not been extensively studied. We aimed: (i) to evaluate the duration and quality of the long-term follow-up of children diagnosed with bacterial meningitis in a general pediatric department, (ii) to estimate the incidence of sequelae at the various stages of follow-up, and (iii) to compare our data with that of other studies. We conducted a retrospective study and included 34 children (3 months-15 years) who had been hospitalized for bacterial meningitis in the pediatric department of a University Hospital between January 1st, 2001 and December 31st, 2013. Overall, 32% of patients presented with sequelae and 15% with seizures. Only one patient presented with hearing loss, but 23.5% of patients did not have any hearing test performed. Seven patients had a neuropsychological assessment performed and no severe neuropsychological sequela was observed in this group. The average follow-up duration increased during the study period (from 23 to 49months). The long-term follow-up modalities observed in other studies were highly variable. Assessing the incidence and severity of sequelae was therefore difficult. A standardized follow-up should be implemented by way of a national surveillance network of children presenting with bacterial meningitis. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Bacterial Acclimation Inside an Aqueous Battery.

PubMed

Dong, Dexian; Chen, Baoling; Chen, P

2015-01-01

Specific environmental stresses may lead to induced genomic instability in bacteria, generating beneficial mutants and potentially accelerating the breeding of industrial microorganisms. The environmental stresses inside the aqueous battery may be derived from such conditions as ion shuttle, pH gradient, free radical reaction and electric field. In most industrial and medical applications, electric fields and direct currents are used to kill bacteria and yeast. However, the present study focused on increasing bacterial survival inside an operating battery. Using a bacterial acclimation strategy, both Escherichia coli and Bacillus subtilis were acclimated for 10 battery operation cycles and survived in the battery for over 3 days. The acclimated bacteria changed in cell shape, growth rate and colony color. Further analysis indicated that electrolyte concentration could be one of the major factors determining bacterial survival inside an aqueous battery. The acclimation process significantly improved the viability of both bacteria E. coli and B. subtilis. The viability of acclimated strains was not affected under battery cycle conditions of 0.18-0.80 mA cm(-2) and 1.4-2.1 V. Bacterial addition within 1.0×10(10) cells mL(-1) did not significantly affect battery performance. Because the environmental stress inside the aqueous battery is specific, the use of this battery acclimation strategy may be of great potential for the breeding of industrial microorganisms.

Bacterial Acclimation Inside an Aqueous Battery

PubMed Central

Dong, Dexian; Chen, Baoling; Chen, P.

2015-01-01

Specific environmental stresses may lead to induced genomic instability in bacteria, generating beneficial mutants and potentially accelerating the breeding of industrial microorganisms. The environmental stresses inside the aqueous battery may be derived from such conditions as ion shuttle, pH gradient, free radical reaction and electric field. In most industrial and medical applications, electric fields and direct currents are used to kill bacteria and yeast. However, the present study focused on increasing bacterial survival inside an operating battery. Using a bacterial acclimation strategy, both Escherichia coli and Bacillus subtilis were acclimated for 10 battery operation cycles and survived in the battery for over 3 days. The acclimated bacteria changed in cell shape, growth rate and colony color. Further analysis indicated that electrolyte concentration could be one of the major factors determining bacterial survival inside an aqueous battery. The acclimation process significantly improved the viability of both bacteria E. coli and B. subtilis. The viability of acclimated strains was not affected under battery cycle conditions of 0.18-0.80 mA cm-2 and 1.4-2.1 V. Bacterial addition within 1.0×1010 cells mL-1 did not significantly affect battery performance. Because the environmental stress inside the aqueous battery is specific, the use of this battery acclimation strategy may be of great potential for the breeding of industrial microorganisms. PMID:26070088

[Bacterial meningitis in adults in emergency and rescue services].

PubMed

Klein, M; Pfister, H-W

2016-10-01

The cardinal symptoms of bacterial meningitis are headache, fever, impaired consciousness and nuchal stiffness (meningism); however, the diagnosis of acute bacterial meningitis can only be confirmed or ruled out by investigation of cerebrospinal fluid. The recommended empirical antibiotic regimen for community-acquired acute bacterial meningitis in adults in Germany is a combination of ceftriaxone and ampicillin plus adjuvant dexamethasone. An important influenceable factor for treatment success of acute bacterial meningitis is a rapid induction of antibiotic therapy, which must be initiated directly after lumbar puncture. When this is delayed for any reason, e. g. because of the necessity of cerebral computed tomography imaging before lumbar puncture, antibiotics should be started even before acquisition of cerebrospinal fluid.

Bacterial contamination, bacterial profile and antimicrobial susceptibility pattern of isolates from stethoscopes at Jimma University Specialized Hospital.

PubMed

Shiferaw, Teklu; Beyene, Getenet; Kassa, Tesfaye; Sewunet, Tsegaye

2013-12-13

Hospital acquired infections are recognized as critical public health problems. Infections are frequently caused by organisms residing in healthcare environment, including contaminated medical equipment like Stethoscopes. To determine bacterial contamination, bacterial profile and anti-microbial susceptibility pattern of the isolates from stethoscopes at Jimma University Specialized Hospital. Cross-sectional study conducted from May to September 2011 at Jimma University Specialized Hospital. One hundred seventy-six stethoscopes owned by Health Care Workers (HCWs) and Medical students were randomly selected and studied. Self-administered structured questionnaire was used to collect socio-demographic data. Specimen was collected using moisten sterile cotton swab and 1 ml normal saline was used to transport the specimen, all laboratory investigations were done following standard microbiological techniques, at Microbiology Laboratory, Jimma University. SPSS windows version 16 used for data analysis and P <0.05 was considered statistically significant. A total, of 151 (85.8%) stethoscopes were contaminated. A total of 256 bacterial strains and a mean of 1.44×104 CFUs/diaphragm of stethoscopes was isolated. Of the 256 isolates, 133 (52%) were potential pathogens like S. aureus, Klebsiella spp., Citrobacter spp., Salmonella spp., Proteus spp., Enterobacter spp., P. aeruginosa and E. coli. All strains were resistant to multiple classes of antibiotics (two to eight classes of antibiotics). Disinfection practice was poor. Disinfection practice was found to be associated with bacterial contamination of stethoscopes (P < 0.05). High contamination rate 100 (90.9%) was observed among stethoscopes that had never been disinfected; while the least contamination 29 (72.2%) was found on those disinfected a week or less before the survey. Bacterial contamination of the stethoscope was significant. The isolates were potential pathogens and resistant to multiple classes of

Receptors, mediators, and mechanisms involved in bacterial sepsis and septic shock.

PubMed

Van Amersfoort, Edwin S; Van Berkel, Theo J C; Kuiper, Johan

2003-07-01

Bacterial sepsis and septic shock result from the overproduction of inflammatory mediators as a consequence of the interaction of the immune system with bacteria and bacterial wall constituents in the body. Bacterial cell wall constituents such as lipopolysaccharide, peptidoglycans, and lipoteichoic acid are particularly responsible for the deleterious effects of bacteria. These constituents interact in the body with a large number of proteins and receptors, and this interaction determines the eventual inflammatory effect of the compounds. Within the circulation bacterial constituents interact with proteins such as plasma lipoproteins and lipopolysaccharide binding protein. The interaction of the bacterial constituents with receptors on the surface of mononuclear cells is mainly responsible for the induction of proinflammatory mediators by the bacterial constituents. The role of individual receptors such as the toll-like receptors and CD14 in the induction of proinflammatory cytokines and adhesion molecules is discussed in detail. In addition, the roles of a number of other receptors that bind bacterial compounds such as scavenger receptors and their modulating role in inflammation are described. Finally, the therapies for the treatment of bacterial sepsis and septic shock are discussed in relation to the action of the aforementioned receptors and proteins.

Bacterial identification and subtyping using DNA microarray and DNA sequencing.

PubMed

Al-Khaldi, Sufian F; Mossoba, Magdi M; Allard, Marc M; Lienau, E Kurt; Brown, Eric D

2012-01-01

The era of fast and accurate discovery of biological sequence motifs in prokaryotic and eukaryotic cells is here. The co-evolution of direct genome sequencing and DNA microarray strategies not only will identify, isotype, and serotype pathogenic bacteria, but also it will aid in the discovery of new gene functions by detecting gene expressions in different diseases and environmental conditions. Microarray bacterial identification has made great advances in working with pure and mixed bacterial samples. The technological advances have moved beyond bacterial gene expression to include bacterial identification and isotyping. Application of new tools such as mid-infrared chemical imaging improves detection of hybridization in DNA microarrays. The research in this field is promising and future work will reveal the potential of infrared technology in bacterial identification. On the other hand, DNA sequencing by using 454 pyrosequencing is so cost effective that the promise of $1,000 per bacterial genome sequence is becoming a reality. Pyrosequencing technology is a simple to use technique that can produce accurate and quantitative analysis of DNA sequences with a great speed. The deposition of massive amounts of bacterial genomic information in databanks is creating fingerprint phylogenetic analysis that will ultimately replace several technologies such as Pulsed Field Gel Electrophoresis. In this chapter, we will review (1) the use of DNA microarray using fluorescence and infrared imaging detection for identification of pathogenic bacteria, and (2) use of pyrosequencing in DNA cluster analysis to fingerprint bacterial phylogenetic trees.

Gene calling and bacterial genome annotation with BG7.

PubMed

Tobes, Raquel; Pareja-Tobes, Pablo; Manrique, Marina; Pareja-Tobes, Eduardo; Kovach, Evdokim; Alekhin, Alexey; Pareja, Eduardo

2015-01-01

New massive sequencing technologies are providing many bacterial genome sequences from diverse taxa but a refined annotation of these genomes is crucial for obtaining scientific findings and new knowledge. Thus, bacterial genome annotation has emerged as a key point to investigate in bacteria. Any efficient tool designed specifically to annotate bacterial genomes sequenced with massively parallel technologies has to consider the specific features of bacterial genomes (absence of introns and scarcity of nonprotein-coding sequence) and of next-generation sequencing (NGS) technologies (presence of errors and not perfectly assembled genomes). These features make it convenient to focus on coding regions and, hence, on protein sequences that are the elements directly related with biological functions. In this chapter we describe how to annotate bacterial genomes with BG7, an open-source tool based on a protein-centered gene calling/annotation paradigm. BG7 is specifically designed for the annotation of bacterial genomes sequenced with NGS. This tool is sequence error tolerant maintaining their capabilities for the annotation of highly fragmented genomes or for annotating mixed sequences coming from several genomes (as those obtained through metagenomics samples). BG7 has been designed with scalability as a requirement, with a computing infrastructure completely based on cloud computing (Amazon Web Services).

Warfare between Host Immunity and Bacterial Weapons.

PubMed

Yu, Manda; Lai, Erh-Min

2017-01-11

Bacterial pathogens deploy protein secretion systems to facilitate infection and colonization of their hosts. In this issue of Cell Host & Microbe, Chen et al. (2017) report a new role for a type VI secretion effector in promoting bacterial colonization by preventing inflammasome activation induced by a type III secretion system. Copyright © 2017 Elsevier Inc. All rights reserved.

Bacterial group II introns: not just splicing.

PubMed

Toro, Nicolás; Jiménez-Zurdo, José Ignacio; García-Rodríguez, Fernando Manuel

2007-04-01

Group II introns are both catalytic RNAs (ribozymes) and mobile retroelements that were discovered almost 14 years ago. It has been suggested that eukaryotic mRNA introns might have originated from the group II introns present in the alphaproteobacterial progenitor of the mitochondria. Bacterial group II introns are of considerable interest not only because of their evolutionary significance, but also because they could potentially be used as tools for genetic manipulation in biotechnology and for gene therapy. This review summarizes what is known about the splicing mechanisms and mobility of bacterial group II introns, and describes the recent development of group II intron-based gene-targetting methods. Bacterial group II intron diversity, evolutionary relationships, and behaviour in bacteria are also discussed.

Bacterial nucleotide-based second messengers.

PubMed

Pesavento, Christina; Hengge, Regine

2009-04-01

In all domains of life nucleotide-based second messengers transduce signals originating from changes in the environment or in intracellular conditions into appropriate cellular responses. In prokaryotes cyclic di-GMP has emerged as an important and ubiquitous second messenger regulating bacterial life-style transitions relevant for biofilm formation, virulence, and many other bacterial functions. This review describes similarities and differences in the architecture of the cAMP, (p)ppGpp, and c-di-GMP signaling systems and their underlying signaling principles. Moreover, recent advances in c-di-GMP-mediated signaling will be presented and the integration of c-di-GMP signaling with other nucleotide-based signaling systems will be discussed.

Method for construction of bacterial strains with increased succinic acid production

DOEpatents

Donnelly, Mark I.; Sanville-Millard, Cynthia; Chatterjee, Ranjini

2000-01-01

A fermentation process for producing succinic acid is provided comprising selecting a bacterial strain that does not produce succinic acid in high yield, disrupting the normal regulation of sugar metabolism of said bacterial strain, and combining the mutant bacterial strain and selected sugar in anaerobic conditions to facilitate production of succinic acid. Also provided is a method for changing low yield succinic acid producing bacteria to high yield succinic acid producing bacteria comprising selecting a bacterial strain having a phosphotransferase system and altering the phosphotransferase system so as to allow the bacterial strain to simultaneously metabolize different sugars.

Metal adsorption onto bacterial surfaces: development of a predictive approach

NASA Astrophysics Data System (ADS)

Fein, Jeremy B.; Martin, Aaron M.; Wightman, Peter G.

2001-12-01

Aqueous metal cation adsorption onto bacterial surfaces can be successfully modeled by means of a surface complexation approach. However, relatively few stability constants for metal-bacterial surface complexes have been measured. In order to determine the bacterial adsorption behavior of cations that have not been studied in the laboratory, predictive techniques are required that enable estimation of the stability constants of bacterial surface complexes. In this study, we use a linear free-energy approach to compare previously measured stability constants for Bacillus subtilis metal-carboxyl surface complexes with aqueous metal-organic acid anion stability constants. The organic acids that we consider are acetic, oxalic, citric, and tiron. We add to this limited data set by conducting metal adsorption experiments onto Bacillus subtilis, determining bacterial surface stability constants for Co, Nd, Ni, Sr, and Zn. The adsorption behavior of each of the metals studied here was described well by considering metal-carboxyl bacterial surface complexation only, except for the Zn adsorption behavior, which required carboxyl and phosphoryl complexation to obtain a suitable fit to the data. The best correlation between bacterial carboxyl surface complexes and aqueous organic acid anion stability constants was obtained by means of metal-acetate aqueous complexes, with a linear correlation coefficient of 0.97. This correlation applies only to unhydrolyzed aqueous cations and only to carboxyl binding of those cations, and it does not predict the binding behavior under conditions where metal binding to other bacterial surface site types occurs. However, the relationship derived in this study permits estimation of the carboxyl site adsorption behavior of a wide range of aqueous metal cations for which there is an absence of experimental data. This technique, coupled with the observation of similar adsorption behaviors across bacterial species (Yee and Fein, 2001), enables

Biliary bacterial factors determine the path of gallstone formation.

PubMed

Stewart, Lygia; Grifiss, J McLeod; Jarvis, Gary A; Way, Lawrence W

2006-11-01

Bacteria cause pigment gallstones and can act as a nidus for cholesterol gallstone formation. Bacterial factors that facilitate gallstone formation include beta-glucuronidase (bG), phospholipase (PhL), and slime. The current study sought to determine whether bacterial factors influence the path of gallstone formation. A total of 382 gallstones were cultured and/or examined using scanning electron microscopy (SEM). Bacteria were tested for bG and slime production. Gallstone composition was determined using infrared spectrography. Ca-palmitate presence documented bacterial PhL production. Groups were identified based upon bacterial factors present: slime and bGPhL (slime/bGPhL), bGPhL only, and slime only. Influence of bacterial stone-forming factors on gallstone composition and morphology was analyzed. Bacteria were present in 75% of pigment, 76% of mixed, and 20% of cholesterol stones. Gallstones with bGPhL producing bacteria contained more pigment (71% vs. 26%, P < .0001). The slime/bGPhL group was associated (79%) with pigment stones, bGPhL was associated (56%) with mixed stones, while slime (or none) only was associated (67%) with cholesterol stones (P < .031, all comparisons). Bacterial properties determined the path of gallstone formation. Bacteria that produced all stone-forming factors promoted pigment stone formation, while those that produced only bGPhL promoted mixed stone formation. Bacteria that only produced slime lacked the ability to generate pigment solids, and consequently were more common in the centers of cholesterol stones. This shows how bacterial characteristics may govern the process of gallstone formation.

Colourful parrot feathers resist bacterial degradation

PubMed Central

Burtt, Edward H.; Schroeder, Max R.; Smith, Lauren A.; Sroka, Jenna E.; McGraw, Kevin J.

2011-01-01

The brilliant red, orange and yellow colours of parrot feathers are the product of psittacofulvins, which are synthetic pigments known only from parrots. Recent evidence suggests that some pigments in bird feathers function not just as colour generators, but also preserve plumage integrity by increasing the resistance of feather keratin to bacterial degradation. We exposed a variety of colourful parrot feathers to feather-degrading Bacillus licheniformis and found that feathers with red psittacofulvins degraded at about the same rate as those with melanin and more slowly than white feathers, which lack pigments. Blue feathers, in which colour is based on the microstructural arrangement of keratin, air and melanin granules, and green feathers, which combine structural blue with yellow psittacofulvins, degraded at a rate similar to that of red and black feathers. These differences in resistance to bacterial degradation of differently coloured feathers suggest that colour patterns within the Psittaciformes may have evolved to resist bacterial degradation, in addition to their role in communication and camouflage. PMID:20926430

Arthropod-borne bacterial diseases in pregnancy.

PubMed

Dotters-Katz, Sarah K; Kuller, Jeffrey; Heine, R Phillips

2013-09-01

Arthropod-borne bacterial diseases affect more than 25,000 Americans every year and thousands more around the world. These infections present a diagnostic dilemma for clinicians because they mimic many other pathologic conditions and are often low on or absent from the differential diagnosis list. Diagnosis is particularly challenging during pregnancy, as these infections may mimic common pregnancy-specific conditions, such as typical and atypical preeclampsia, or symptoms of pregnancy itself. Concerns regarding the safety in pregnancy of some indicated antibiotics add a therapeutic challenge for the prescriber, requiring knowledge of alternative therapeutic options for many arthropod-borne bacterial diseases. Physicians, especially those in endemic areas, must keep this class of infections in mind, particularly when the presentation does not appear classic for more commonly seen conditions. This article discusses presentation, diagnosis, and treatment of the most common of these arthropod-borne bacterial diseases, including Lyme disease, Rocky Mountain spotted fever, tick-borne relapsing fever, typhus, plague, cat-scratch disease, and Carrión disease.

Co-acclimation of bacterial communities under stresses of hydrocarbons with different structures

PubMed Central

Wang, Hui; Wang, Bin; Dong, Wenwen; Hu, Xiaoke

2016-01-01

Crude oil is a complex mixture of hydrocarbons with different structures; its components vary in bioavailability and toxicity. It is important to understand how bacterial communities response to different hydrocarbons and their co-acclimation in the process of degradation. In this study, microcosms with the addition of structurally different hydrocarbons were setup to investigate the successions of bacterial communities and the interactions between different bacterial taxa. Hydrocarbons were effectively degraded in all microcosms after 40 days. High-throughput sequencing offered a great quantity of data for analyzing successions of bacterial communities. The results indicated that the bacterial communities responded dramatically different to various hydrocarbons. KEGG database and PICRUSt were applied to predict functions of individual bacterial taxa and networks were constructed to analyze co-acclimations between functional bacterial groups. Almost all functional genes catalyzing degradation of different hydrocarbons were predicted in bacterial communities. Most of bacterial taxa were believed to conduct biodegradation processes via interactions with each other. This study addressed a few investigated area of bacterial community responses to structurally different organic pollutants and their co-acclimation and interactions in the process of biodegradation. The study could provide useful information to guide the bioremediation of crude oil pollution. PMID:27698451

An active bacterial community linked to high chl-a concentrations in Antarctic winter-pack ice and evidence for the development of an anaerobic sea-ice bacterial community.

PubMed

Eronen-Rasimus, Eeva; Luhtanen, Anne-Mari; Rintala, Janne-Markus; Delille, Bruno; Dieckmann, Gerhard; Karkman, Antti; Tison, Jean-Louis

2017-10-01

Antarctic sea-ice bacterial community composition and dynamics in various developmental stages were investigated during the austral winter in 2013. Thick snow cover likely insulated the ice, leading to high (<4 μg l -1 ) chlorophyll-a (chl-a) concentrations and consequent bacterial production. Typical sea-ice bacterial genera, for example, Octadecabacter, Polaribacter and Glaciecola, often abundant in spring and summer during the sea-ice algal bloom, predominated in the communities. The variability in bacterial community composition in the different ice types was mainly explained by the chl-a concentrations, suggesting that as in spring and summer sea ice, the sea-ice bacteria and algae may also be coupled during the Antarctic winter. Coupling between the bacterial community and sea-ice algae was further supported by significant correlations between bacterial abundance and production with chl-a. In addition, sulphate-reducing bacteria (for example, Desulforhopalus) together with odour of H 2 S were observed in thick, apparently anoxic ice, suggesting that the development of the anaerobic bacterial community may occur in sea ice under suitable conditions. In all, the results show that bacterial community in Antarctic sea ice can stay active throughout the winter period and thus possible future warming of sea ice and consequent increase in bacterial production may lead to changes in bacteria-mediated processes in the Antarctic sea-ice zone.

Hydrodebridement of wounds: effectiveness in reducing wound bacterial contamination and potential for air bacterial contamination.

PubMed

Bowling, Frank L; Stickings, Daryl S; Edwards-Jones, Valerie; Armstrong, David G; Boulton, Andrew Jm

2009-05-08

The purpose of this study was to assess the level of air contamination with bacteria after surgical hydrodebridement and to determine the effectiveness of hydro surgery on bacterial reduction of a simulated infected wound. Four porcine samples were scored then infected with a broth culture containing a variety of organisms and incubated at 37 degrees C for 24 hours. The infected samples were then debrided with the hydro surgery tool (Versajet, Smith and Nephew, Largo, Florida, USA). Samples were taken for microbiology, histology and scanning electron microscopy pre-infection, post infection and post debridement. Air bacterial contamination was evaluated before, during and after debridement by using active and passive methods; for active sampling the SAS-Super 90 air sampler was used, for passive sampling settle plates were located at set distances around the clinic room. There was no statistically significant reduction in bacterial contamination of the porcine samples post hydrodebridement. Analysis of the passive sampling showed a significant (p < 0.001) increase in microbial counts post hydrodebridement. Levels ranging from 950 colony forming units per meter cubed (CFUs/m3) to 16780 CFUs/m3 were observed with active sampling of the air whilst using hydro surgery equipment compared with a basal count of 582 CFUs/m3. During removal of the wound dressing, a significant increase was observed relative to basal counts (p < 0.05). Microbial load of the air samples was still significantly raised 1 hour post-therapy. The results suggest a significant increase in bacterial air contamination both by active sampling and passive sampling. We believe that action might be taken to mitigate fallout in the settings in which this technique is used.

Mechanical influences in bacterial morphogenesis and cell division

NASA Astrophysics Data System (ADS)

Sun, Sean

2010-03-01

Bacterial cells utilize a ring-like organelle (the Z-ring) to accomplish cell division. The Z-ring actively generates a contractile force and influences cell wall growth. We will discuss a general model of bacterial morphogenesis where mechanical forces are coupled to the growth dynamics of the cell wall. The model suggests a physical mechanism that determines the shapes of bacteria cells. The roles of several bacterial cytoskeletal proteins and the Z-ring are discussed. We will also explore molecular mechanisms of force generation by the Z-ring and how cells can generate mechanical forces without molecular motors.

Spontaneous bacterial peritonitis

PubMed Central

Koulaouzidis, Anastasios; Bhat, Shivaram; Saeed, Athar A

2009-01-01

Since its initial description in 1964, research has transformed spontaneous bacterial peritonitis (SBP) from a feared disease (with reported mortality of 90%) to a treatable complication of decompensated cirrhosis, albeit with steady prevalence and a high recurrence rate. Bacterial translocation, the key mechanism in the pathogenesis of SBP, is only possible because of the concurrent failure of defensive mechanisms in cirrhosis. Variants of SBP should be treated. Leucocyte esterase reagent strips have managed to shorten the ‘tap-to-shot’ time, while future studies should look into their combined use with ascitic fluid pH. Third generation cephalosporins are the antibiotic of choice because they have a number of advantages. Renal dysfunction has been shown to be an independent predictor of mortality in patients with SBP. Albumin is felt to reduce the risk of renal impairment by improving effective intravascular volume, and by helping to bind pro-inflammatory molecules. Following a single episode of SBP, patients should have long-term antibiotic prophylaxis and be considered for liver transplantation. PMID:19266595

New target for inhibition of bacterial RNA polymerase: 'switch region'.

PubMed

Srivastava, Aashish; Talaue, Meliza; Liu, Shuang; Degen, David; Ebright, Richard Y; Sineva, Elena; Chakraborty, Anirban; Druzhinin, Sergey Y; Chatterjee, Sujoy; Mukhopadhyay, Jayanta; Ebright, Yon W; Zozula, Alex; Shen, Juan; Sengupta, Sonali; Niedfeldt, Rui Rong; Xin, Cai; Kaneko, Takushi; Irschik, Herbert; Jansen, Rolf; Donadio, Stefano; Connell, Nancy; Ebright, Richard H

2011-10-01

A new drug target - the 'switch region' - has been identified within bacterial RNA polymerase (RNAP), the enzyme that mediates bacterial RNA synthesis. The new target serves as the binding site for compounds that inhibit bacterial RNA synthesis and kill bacteria. Since the new target is present in most bacterial species, compounds that bind to the new target are active against a broad spectrum of bacterial species. Since the new target is different from targets of other antibacterial agents, compounds that bind to the new target are not cross-resistant with other antibacterial agents. Four antibiotics that function through the new target have been identified: myxopyronin, corallopyronin, ripostatin, and lipiarmycin. This review summarizes the switch region, switch-region inhibitors, and implications for antibacterial drug discovery. Copyright © 2011 Elsevier Ltd. All rights reserved.

Hydration dynamics promote bacterial coexistence on rough surfaces

PubMed Central

Wang, Gang; Or, Dani

2013-01-01

Identification of mechanisms that promote and maintain the immense microbial diversity found in soil is a central challenge for contemporary microbial ecology. Quantitative tools for systematic integration of complex biophysical and trophic processes at spatial scales, relevant for individual cell interactions, are essential for making progress. We report a modeling study of competing bacterial populations cohabiting soil surfaces subjected to highly dynamic hydration conditions. The model explicitly tracks growth, motion and life histories of individual bacterial cells on surfaces spanning dynamic aqueous networks that shape heterogeneous nutrient fields. The range of hydration conditions that confer physical advantages for rapidly growing species and support competitive exclusion is surprisingly narrow. The rapid fragmentation of soil aqueous phase under most natural conditions suppresses bacterial growth and cell dispersion, thereby balancing conditions experienced by competing populations with diverse physiological traits. In addition, hydration fluctuations intensify localized interactions that promote coexistence through disproportional effects within densely populated regions during dry periods. Consequently, bacterial population dynamics is affected well beyond responses predicted from equivalent and uniform hydration conditions. New insights on hydration dynamics could be considered in future designs of soil bioremediation activities, affect longevity of dry food products, and advance basic understanding of bacterial diversity dynamics and its role in global biogeochemical cycles. PMID:23051694

Soil bacterial community shifts associated with sugarcane straw removal

NASA Astrophysics Data System (ADS)

Pimentel, Laisa; Gumiere, Thiago; Andreote, Fernando; Cerri, Carlos

2017-04-01

In Brazil, the adoption of the mechanical unburned sugarcane harvest potentially increase the quantity of residue left in the field after harvesting. Economically, this material has a high potential for second generation ethanol (2G) production. However, crop residues have an essential role in diverse properties and processes in the soil. The greater part of the uncertainties about straw removal for 2G ethanol production is based on its effects in soil microbial community. In this sense, it is important to identify the main impacts of sugarcane straw removal on soil microbial community. Therefore, we conducted a field study, during one year, in Valparaíso (São Paulo state - Brazil) to evaluate the effects of straw decomposition on soil bacterial community. Specifically, we wanted: i) to compare the rates of straw removal and ii) to evaluate the effects of straw decomposition on soil bacterial groups over one year. The experiment was in a randomized block design with treatments arranged in strip plot. The treatments are different rates of sugarcane straw removal, namely: no removal, 50, 75 and 100% of straw removal. Soil sampling was carried out at 0, 4, 8 and 12 months after the sugarcane harvest (August 2015). Total DNA was extracted from soil using the PowersoilTM DNA Isolation kit. And the abundance of bacterial in each soil sample was estimated via quantification of 16S rRNA gene. The composition of the bacterial communities was estimated via terminal restriction fragment length polymorphism (T-RFLP) analysis, and the T-RF sizes were performed on a 3500 Genetic Analyzer. Finally, the results were examined with GeneMapper 4.1 software. There was bacterial community shifts through the time and among the rates of sugarcane straw removal. Bacterial community was firstly determined by the time scale, which explained 29.16% of total variation. Rates of straw removal explained 11.55% of shifts on bacterial community. Distribution through the time is an important

Skin bacterial flora as a potential risk factor predisposing to late bacterial infection after cross-linked hyaluronic acid gel augmentation.

PubMed

Netsvyetayeva, Irina; Marusza, Wojciech; Olszanski, Romuald; Szyller, Kamila; Krolak-Ulinska, Aneta; Swoboda-Kopec, Ewa; Sierdzinski, Janusz; Szymonski, Zachary; Mlynarczyk, Grazyna

2018-01-01

Cross-linked hyaluronic acid (HA) gel is widely used in esthetic medicine. Late bacterial infection (LBI) is a rare, but severe complication after HA augmentation. The aim of this study was to determine whether patients who underwent the HA injection procedure and developed LBI had qualitatively different bacterial flora on the skin compared to patients who underwent the procedure without any complications. The study group comprised 10 previously healthy women with recently diagnosed, untreated LBI after HA augmentation. The control group comprised 17 healthy women who had a similar amount of HA injected with no complications. To assess the difference between the two groups, their skin flora was cultured from nasal swabs, both before and after antibiotic treatment in the study group. A significant increase in the incidence of Staphylococcus epidermidis was detected in the control group ( P =0.000) compared to the study group. The study group showed a significantly higher incidence of Staphylococcus aureus ( P =0.005), Klebsiella pneumoniae ( P =0.006), Klebsiella oxytoca ( P =0.048), and Staphylococcus haemolyticus ( P =0.048) compared to the control group. The bacterial flora on the skin differed in patients with LBI from the control group. The control group's bacterial skin flora was dominated by S. epidermidis . Patients with LBI had a bacterial skin flora dominated by potentially pathogenic bacteria.

Factors influencing bacterial adhesion to contact lenses.

PubMed

Dutta, Debarun; Cole, Nerida; Willcox, Mark

2012-01-01

The process of any contact lens related keratitis generally starts with the adhesion of opportunistic pathogens to contact lens surface. This article focuses on identifying the factors which have been reported to affect bacterial adhesion to contact lenses. Adhesion to lenses differs between various genera/species/strains of bacteria. Pseudomonas aeruginosa, which is the predominant causative organism, adheres in the highest numbers to both hydrogel and silicone hydrogel lenses in vitro. The adhesion of this strain reaches maximum numbers within 1h in most in vitro studies and a biofilm has generally formed within 24 h of cells adhering to the lens surface. Physical and chemical properties of contact lens material affect bacterial adhesion. The water content of hydroxyethylmethacrylate (HEMA)-based lenses and their iconicity affect the ability of bacteria to adhere. The higher hydrophobicity of silicone hydrogel lenses compared to HEMA-based lenses has been implicated in the higher numbers of bacteria that can adhere to their surfaces. Lens wear has different effects on bacterial adhesion, partly due to differences between wearers, responses of bacterial strains and the ability of certain tear film proteins when bound to a lens surface to kill certain types of bacteria.

Bacterial responses to antibiotics and their combinations.

PubMed

Mitosch, Karin; Bollenbach, Tobias

2014-12-01

Antibiotics affect bacterial cell physiology at many levels. Rather than just compensating for the direct cellular defects caused by the drug, bacteria respond to antibiotics by changing their morphology, macromolecular composition, metabolism, gene expression and possibly even their mutation rate. Inevitably, these processes affect each other, resulting in a complex response with changes in the expression of numerous genes. Genome-wide approaches can thus help in gaining a comprehensive understanding of bacterial responses to antibiotics. In addition, a combination of experimental and theoretical approaches is needed for identifying general principles that underlie these responses. Here, we review recent progress in our understanding of bacterial responses to antibiotics and their combinations, focusing on effects at the levels of growth rate and gene expression. We concentrate on studies performed in controlled laboratory conditions, which combine promising experimental techniques with quantitative data analysis and mathematical modeling. While these basic research approaches are not immediately applicable in the clinic, uncovering the principles and mechanisms underlying bacterial responses to antibiotics may, in the long term, contribute to the development of new treatment strategies to cope with and prevent the rise of resistant pathogenic bacteria.

Bacterial Sphingomyelinases and Phospholipases as Virulence Factors

PubMed Central

Flores-Díaz, Marietta; Monturiol-Gross, Laura; Naylor, Claire

2016-01-01

SUMMARY Bacterial sphingomyelinases and phospholipases are a heterogeneous group of esterases which are usually surface associated or secreted by a wide variety of Gram-positive and Gram-negative bacteria. These enzymes hydrolyze sphingomyelin and glycerophospholipids, respectively, generating products identical to the ones produced by eukaryotic enzymes which play crucial roles in distinct physiological processes, including membrane dynamics, cellular signaling, migration, growth, and death. Several bacterial sphingomyelinases and phospholipases are essential for virulence of extracellular, facultative, or obligate intracellular pathogens, as these enzymes contribute to phagosomal escape or phagosomal maturation avoidance, favoring tissue colonization, infection establishment and progression, or immune response evasion. This work presents a classification proposal for bacterial sphingomyelinases and phospholipases that considers not only their enzymatic activities but also their structural aspects. An overview of the main physiopathological activities is provided for each enzyme type, as are examples in which inactivation of a sphingomyelinase- or a phospholipase-encoding gene impairs the virulence of a pathogen. The identification of sphingomyelinases and phospholipases important for bacterial pathogenesis and the development of inhibitors for these enzymes could generate candidate vaccines and therapeutic agents, which will diminish the impacts of the associated human and animal diseases. PMID:27307578

Factors influencing bacterial adhesion to contact lenses

PubMed Central

Dutta, Debarun; Willcox, Mark

2012-01-01

The process of any contact lens related keratitis generally starts with the adhesion of opportunistic pathogens to contact lens surface. This article focuses on identifying the factors which have been reported to affect bacterial adhesion to contact lenses. Adhesion to lenses differs between various genera/species/strains of bacteria. Pseudomonas aeruginosa, which is the predominant causative organism, adheres in the highest numbers to both hydrogel and silicone hydrogel lenses in vitro. The adhesion of this strain reaches maximum numbers within 1h in most in vitro studies and a biofilm has generally formed within 24 h of cells adhering to the lens surface. Physical and chemical properties of contact lens material affect bacterial adhesion. The water content of hydroxyethylmethacrylate (HEMA)-based lenses and their iconicity affect the ability of bacteria to adhere. The higher hydrophobicity of silicone hydrogel lenses compared to HEMA-based lenses has been implicated in the higher numbers of bacteria that can adhere to their surfaces. Lens wear has different effects on bacterial adhesion, partly due to differences between wearers, responses of bacterial strains and the ability of certain tear film proteins when bound to a lens surface to kill certain types of bacteria. PMID:22259220

Mathematical Modelling of Bacterial Populations in Bio-remediation Processes

NASA Astrophysics Data System (ADS)

Vasiliadou, Ioanna A.; Vayenas, Dimitris V.; Chrysikopoulos, Constantinos V.

2011-09-01

An understanding of bacterial behaviour concerns many field applications, such as the enhancement of water, wastewater and subsurface bio-remediation, the prevention of environmental pollution and the protection of human health. Numerous microorganisms have been identified to be able to degrade chemical pollutants, thus, a variety of bacteria are known that can be used in bio-remediation processes. In this study the development of mathematical models capable of describing bacterial behaviour considered in bio-augmentation plans, such as bacterial growth, consumption of nutrients, removal of pollutants, bacterial transport and attachment in porous media, is presented. The mathematical models may be used as a guide in designing and assessing the conditions under which areas contaminated with pollutants can be better remediated.

Interference in Bacterial Quorum Sensing: A Biopharmaceutical Perspective

PubMed Central

Rémy, Benjamin; Mion, Sonia; Plener, Laure; Elias, Mikael; Chabrière, Eric; Daudé, David

2018-01-01

Numerous bacteria utilize molecular communication systems referred to as quorum sensing (QS) to synchronize the expression of certain genes regulating, among other aspects, the expression of virulence factors and the synthesis of biofilm. To achieve this process, bacteria use signaling molecules, known as autoinducers (AIs), as chemical messengers to share information. Naturally occurring strategies that interfere with bacterial signaling have been extensively studied in recent years, examining their potential to control bacteria. To interfere with QS, bacteria use quorum sensing inhibitors (QSIs) to block the action of AIs and quorum quenching (QQ) enzymes to degrade signaling molecules. Recent studies have shown that these strategies are promising routes to decrease bacterial pathogenicity and decrease biofilms, potentially enhancing bacterial susceptibility to antimicrobial agents including antibiotics and bacteriophages. The efficacy of QSIs and QQ enzymes has been demonstrated in various animal models and are now considered in the development of new medical devices against bacterial infections, including dressings, and catheters for enlarging the therapeutic arsenal against bacteria. PMID:29563876

Towards revealing the structure of bacterial inclusion bodies.

PubMed

Wang, Lei

2009-01-01

Protein aggregation is a widely observed phenomenon in human diseases, biopharmaceutical production, and biological research. Protein aggregates are generally classified as highly ordered, such as amyloid fibrils, or amorphous, such as bacterial inclusion bodies. Amyloid fibrils are elongated filaments with diameters of 6-12 nm, they are comprised of residue-specific cross-beta structure, and display characteristic properties, such as binding with amyloid-specific dyes. Amyloid fibrils are associated with dozens of human pathological conditions, including Alzheimer disease and prion diseases. Distinguished from amyloid fibrils, bacterial inclusion bodies display apparent amorphous morphology. Inclusion bodies are formed during high-level recombinant protein production, and formation of inclusion bodies is a major concern in biotechnology. Despite of the distinctive morphological difference, bacterial inclusion bodies have been found to have some amyloid-like properties, suggesting that they might contain structures similar to amyloid-like fibrils. Recent structural data further support this hypothesis, and this review summarizes the latest progress towards revealing the structural details of bacterial inclusion bodies.

Procalcitonin as a potential predicting factor for prognosis in bacterial meningitis.

PubMed

Park, Bong Soo; Kim, Si Eun; Park, Si Hyung; Kim, Jinseung; Shin, Kyong Jin; Ha, Sam Yeol; Park, JinSe; Kim, Sung Eun; Lee, Byung In; Park, Kang Min

2017-02-01

We investigated the potential role of serum procalcitonin in differentiating bacterial meningitis from viral meningitis, and in predicting the prognosis in patients with bacterial meningitis. This was a retrospective study of 80 patients with bacterial meningitis (13 patients died). In addition, 58 patients with viral meningitis were included as the disease control groups for comparison. The serum procalcitonin level was measured in all patients at admission. Differences in demographic and laboratory data, including the procalcitonin level, were analyzed between the groups. We used the mortality rate during hospitalization as a marker of prognosis in patients with bacterial meningitis. Multiple logistic regression analysis showed that high serum levels of procalcitonin (>0.12ng/mL) were an independently significant variable for differentiating bacterial meningitis from viral meningitis. The risk of having bacterial meningitis with high serum levels of procalcitonin was at least 6 times higher than the risk of having viral meningitis (OR=6.76, 95% CI: 1.84-24.90, p=0.004). In addition, we found that high levels of procalcitonin (>7.26ng/mL) in the blood were an independently significant predictor for death in patients with bacterial meningitis. The risk of death in patients with bacterial meningitis with high serum levels of procalcitonin may be at least 9 times higher than those without death (OR=9.09, 95% CI: 1.74-47.12, p=0.016). We found that serum procalcitonin is a useful marker for differentiating bacterial meningitis from viral meningitis, and it is also a potential predicting factor for prognosis in patients with bacterial meningitis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Control of bacterial adhesion and growth on honeycomb-like patterned surfaces.

PubMed

Yang, Meng; Ding, Yonghui; Ge, Xiang; Leng, Yang

2015-11-01

It is a great challenge to construct a persistent bacteria-resistant surface even though it has been demonstrated that several surface features might be used to control bacterial behavior, including surface topography. In this study, we develop micro-scale honeycomb-like patterns of different sizes (0.5-10 μm) as well as a flat area as the control on a single platform to evaluate the bacterial adhesion and growth. Bacteria strains, Escherichia coli and Staphylococcus aureus with two distinct shapes (rod and sphere) are cultured on the platforms, with the patterned surface-up and surface-down in the culture medium. The results demonstrate that the 1 μm patterns remarkably reduce bacterial adhesion and growth while suppressing bacterial colonization when compared to the flat surface. The selective adhesion of the bacterial cells on the patterns reveals that the bacterial adhesion is cooperatively mediated by maximizing the cell-substrate contact area and minimizing the cell deformation, from a thermodynamic point of view. Moreover, study of bacterial behaviors on the surface-up vs. surface-down samples shows that gravity does not apparently affect the spatial distribution of the adherent cells although it indeed facilitates bacterial adhesion. Furthermore, the experimental results suggest that two major factors, i.e. the availability of energetically favorable adhesion sites and the physical confinements, contribute to the anti-bacterial nature of the honeycomb-like patterns. Copyright © 2015 Elsevier B.V. All rights reserved.

Cerebrospinal fluid ferritin in children with viral and bacterial meningitis.

PubMed

Rezaei, M; Mamishi, S; Mahmoudi, S; Pourakbari, B; Khotaei, G; Daneshjou, K; Hashemi, N

2013-01-01

Despite the fact that the prognosis of bacterial meningitis has been improved by the influence of antibiotics, this disease is still one of the significant causes of morbidity and mortality in children. Rapid differentiation between bacterial and aseptic meningitis, and the need for immediate antibiotic treatment in the former, is crucial in the prognosis of these patients. Ferritin is one of the most sensitive biochemical markers investigated in cerebrospinal fluid (CSF) for the early diagnosis of bacterial meningitis. The present study aims to evaluate the diagnostic capability of CSF ferritin in differentiating bacterial and viral meningitis in the paediatric setting. A cross-sectional study was carried out in the referral Children's Medical Center Hospital, Tehran, during 2008 and 2009. According to the inclusion criteria, CSF samples from 42 patients with suspected meningitis were obtained and divided into two meningitis groups, bacterial (n = 18) and viral (n = 24). Ferritin and other routine determinants (i.e., leucocytes, protein and glucose) were compared between the two groups. Ferritin concentration in the bacterial meningitis group was 106.39 +/- 86.96 ng/dL, which was considerably higher than in the viral meningitis group (10.17 +/- 14.09, P < 0.001). Mean CSF protein concentration and cell count were significantly higher in the bacterial meningitis group and showed a positive correlation with CSF ferritin. In conclusion, this study suggests that CSF ferritin concentration is an accurate test for the early differentiation of bacterial and aseptic meningitis; however, further investigation on a larger cohort of patients is required to confirm this finding.

Temperature adaptation of bacterial communities in experimentally warmed forest soils.

PubMed

Rousk, Johannes; Frey, Serita D; Bååth, Erland

2012-10-01

A detailed understanding of the influence of temperature on soil microbial activity is critical to predict future atmospheric CO 2 concentrations and feedbacks to anthropogenic warming. We investigated soils exposed to 3-4 years of continuous 5 °C-warming in a field experiment in a temperate forest. We found that an index for the temperature adaptation of the microbial community, T min for bacterial growth, increased by 0.19 °C per 1 °C rise in temperature, showing a community shift towards one adapted to higher temperature with a higher temperature sensitivity (Q 10(5-15 °C) increased by 0.08 units per 1 °C). Using continuously measured temperature data from the field experiment we modelled in situ bacterial growth. Assuming that warming did not affect resource availability, bacterial growth was modelled to become 60% higher in warmed compared to the control plots, with the effect of temperature adaptation of the community only having a small effect on overall bacterial growth (<5%). However, 3 years of warming decreased bacterial growth, most likely due to substrate depletion because of the initially higher growth in warmed plots. When this was factored in, the result was similar rates of modelled in situ bacterial growth in warmed and control plots after 3 years, despite the temperature difference. We conclude that although temperature adaptation for bacterial growth to higher temperatures was detectable, its influence on annual bacterial growth was minor, and overshadowed by the direct temperature effect on growth rates. © 2012 Blackwell Publishing Ltd.

Investigation of multimodal forward scatter phenotyping from bacterial colonies

NASA Astrophysics Data System (ADS)

Kim, Huisung

A rapid, label-free, and elastic light scattering (ELS) based bacterial colony phenotyping technology, bacterial rapid detection using optical scattering technology (BARDOT) provides a successful classification of several bacterial genus and species. For a thorough understanding of the phenomena and overcoming the limitations of the previous design, five additional modalities from a bacterial colony: 3D morphology, spatial optical density (OD) distribution, spectral forward scattering pattern, spectral OD, and surface backward reflection pattern are proposed to enhance the classification/identification ratio, and the feasibilities of each modality are verified. For the verification, three different instruments: integrated colony morphology analyzer (ICMA), multi-spectral BARDOT (MS-BARDOT) , and multi-modal BARDOT (MM-BARDOT) are proposed and developed. The ICMA can measure 3D morphology and spatial OD distribution of the colony simultaneously. A commercialized confocal displacement meter is used to measure the profiles of the bacterial colonies, together with a custom built optical density measurement unit to interrogate the biophysics behind the collective behavior of a bacterial colony. The system delivers essential information related to the quantitative growth dynamics (height, diameter, aspect ratio, optical density) of the bacterial colony, as well as, a relationship in between the morphological characteristics of the bacterial colony and its forward scattering pattern. Two different genera: Escherichia coli O157:H7 EDL933, and Staphylococcus aureus ATCC 25923 are selected for the analysis of the spatially resolved growth dynamics, while, Bacillus spp. such as B. subtilis ATCC 6633, B. cereus ATCC 14579, B. thuringiensis DUP6044, B. polymyxa B719W, and B. megaterium DSP 81319, are interrogated since some of the Bacillus spp. provides strikingly different characteristics of ELS patterns, and the origin of the speckle patterns are successfully correlated with

Detection of bacterial DNA by PCR in dogs with stifle pathology.

PubMed

Bhandal, Jitender; Hayashi, Kei; Kim, Sun-Young; Klein, Martha; Wong, Alice; Toupadakis, Chrisoula A; Muir, Peter; Yellowley, Clare E

2013-10-01

To determine presence of bacterial DNA in canine stifles with cranial cruciate ligament rupture (CCLR) and medial patellar luxation (MPL) compared to normal canine stifles (control). Prospective clinical study. Dogs (n = 44). Dogs of varying age, breed, sex, and weight residing in California were assessed for stifle pathology (CCLR, MPL, or normal control). Synovial fluid of all stifles was assessed for the presence of bacterial DNA using broad-ranging 16S rRNA primers and PCR. Bacterial DNA was detected in normal control stifles and those with CCLR and MPL. There were no statistical differences in the copy numbers of bacterial DNA in the stifle synovial fluid among groups (P > .05); however, synovial fluid specimens from dogs with stifle pathology (CCLR and MPL combined) tended to have higher copy numbers of bacterial DNA than those from controls (P = .06). There was no significant difference in the number of bacterial DNA between the CCLR and MPL groups (P = .57). The copy numbers of bacterial DNA had a weak positive significant correlation with the duration of lameness in CCLR group (P < .05). Increased detection of bacterial DNA in the stifle synovial fluid may indicate joint pathology but not be directly linked to a specific joint disease. © Copyright 2013 by The American College of Veterinary Surgeons.

Bacterial contamination of platelet components not detected by BacT/ALERT®.

PubMed

Abela, M A; Fenning, S; Maguire, K A; Morris, K G

2018-02-01

To investigate the possible causes for false negative results in BacT/ALERT ® 3D Signature System despite bacterial contamination of platelet units. The Northern Ireland Blood Transfusion Service (NIBTS) routinely extends platelet component shelf life to 7 days. Components are sampled and screened for bacterial contamination using an automated microbial detection system, the BacT/ALERT ® 3D Signature System. We report on three platelet components with confirmed bacterial contamination, which represent false negative BacT/ALERT ® results and near-miss serious adverse events. NIBTS protocols for risk reduction of bacterial contamination of platelet components are described. The methodology for bacterial detection using BacT/ALERT ® is outlined. Laboratory tests, relevant patient details and relevant follow-up information are analysed. In all three cases, Staphylococcus aureus was isolated from the platelet residue and confirmed on terminal sub-culture using BacT/ALERT ® . In two cases, S. aureus with similar genetic makeup was isolated from the donors. Risk reduction measures for bacterial contamination of platelet components are not always effective. Automated bacterial culture detection does not eliminate the risk of bacterial contamination. Visual inspection of platelet components prior to release, issue and administration remains an important last line of defence. © 2017 British Blood Transfusion Society.

Temporal variability of bacterial communities in cryoconite on an alpine glacier.

PubMed

Franzetti, Andrea; Navarra, Federico; Tagliaferri, Ilario; Gandolfi, Isabella; Bestetti, Giuseppina; Minora, Umberto; Azzoni, Roberto Sergio; Diolaiuti, Guglielmina; Smiraglia, Claudio; Ambrosini, Roberto

2017-04-01

Cryoconite holes, that is, small ponds that form on glacier surface, are considered the most biologically active environments on glaciers. Bacterial communities in these environments have been extensively studied, but often through snapshot studies based on the assumption of a general stability of community structure. In this study, the temporal variation of bacterial communities in cryoconite holes on the Forni Glacier (Italian Alps) was investigated by high throughput DNA sequencing. A temporal change of bacterial communities was observed with autotrophic Cyanobacteria populations dominating communities after snowmelt, and heterotrophic Sphingobacteriales populations increasing in abundance later in the season. Bacterial communities also varied according to hole depth and area, amount of organic matter in the cryoconite and oxygen concentration. However, variation in environmental features explained a lower fraction of the variation in bacterial communities than temporal variation. Temporal change along ablation season seems therefore more important than local environmental conditions in shaping bacterial communities of cryoconite of the Forni Glacier. These findings challenge the assumption that bacterial communities of cryoconite holes are stable. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

Strontium Incorporation Into Calcite Generated by Bacterial Ureolysis

NASA Astrophysics Data System (ADS)

Fujita, Y.; Ingram, J. A.; Cortez, M. M.; Redden, G. D.; Smith, R. W.

2002-12-01

Strontium incorporation into calcite generated by bacterial ureolytic activity was investigated as part of a larger effort to evaluate the use of in situ urea hydrolysis for accelerating co-precipitation of trace metals and radionuclides in contaminated aquifers. 90Sr, a uranium fission product with a half-life of 29 years, is a significant subsurface contaminant at several Department of Energy facilities and could be immobilized using this remediation strategy. Experiments were conducted in a medium designed to simulate the groundwater of the Snake River Plain Aquifer in eastern Idaho, amended with strontium. Initially the solution was undersaturated with respect to calcite. As a model ureolytic organism, we used Bacillus pasteurii, a well-characterized bacterium known for high urease activity and previously shown to induce calcite precipitation in urea-amended medium. To gain information on the effect of the bacterial surfaces, we also looked at precipitation in the presence of a bacterial species that did not hydrolyze urea, as well as in the absence of bacteria. In the absence of bacterial ureolysis, carbonate precipitation was induced by addition of ammonium carbonate. All products were identified as calcite by X-ray diffraction. Strontium uptake was observed in all cases, but was greatest in the system including bacterial ureolysis. Sputter depth element profiling by time-of-flight secondary ion mass spectrometry (TOF-SIMS) confirmed this finding, showing highest Sr:Ca ratios in the bacterially generated calcite throughout the depth (~350 nm) investigated. Environmental Scanning Electron Microscopy (ESEM) of the solids revealed regular crystals containing the outlines of embedded or entombed bacterial cells, suggesting that calcite precipitated directly on the cell surfaces when present. Analysis by X-ray Absorption Near Edge Spectroscopy (XANES) indicated that in both the biotically and abiotically generated calcites the Sr was incorporated into the calcite

Bacterial DNA Detected in Japanese Rice Wines and the Fermentation Starters.

PubMed

Terasaki, Momoka; Fukuyama, Akari; Takahashi, Yurika; Yamada, Masato; Nishida, Hiromi

2017-12-01

As Japanese rice wine (sake) brewing is not done aseptically, bacterial contamination is conceivable during the process of sake production. There are two types of the fermentation starter, sokujo-moto and yamahai-moto (kimoto). We identified bacterial DNA found in various sakes, the sokujo-moto and the yamahai-moto making just after sake yeast addition. Each sake has a unique variety of bacterial DNA not observed in other sakes. Although most bacterial DNA sequences detected in the sokujo-moto were found in sakes of different sake breweries, most bacterial DNA sequences detected in the yamahai-moto at the early stage of the starter fermentation were not detected in any sakes. Our findings demonstrate that various bacteria grow and then die during the process of sake brewing, as indicated by the presence of trace levels of bacterial DNA.

Ellipsometric Measurement of Bacterial Films at Metal-Electrolyte Interfaces

PubMed Central

Busalmen, J. P.; de Sánchez, S. R.; Schiffrin, D. J.

1998-01-01

Ellipsometric measurements were used to monitor the formation of a bacterial cell film on polarized metal surfaces (Al-brass and Ti). Under cathodic polarization bacterial attachment was measured from changes in the ellipsometric angles. These were fitted to an effective medium model for a nonabsorbing bacterial film with an effective refractive index (nf) of 1.38 and a thickness (df) of 160 ± 10 nm. From the optical measurements a surface coverage of 17% was estimated, in agreement with direct microscopic observations. The influence of bacteria on the formation of oxide films was monitored by ellipsometry following the film growth in situ. A strong inhibition of metal oxide film formation was observed, which was assigned to the decrease in oxygen concentration due to the presence of bacteria. It is shown that the irreversible adhesion of bacteria to the surface can be monitored ellipsometrically. Electrophoretic mobility is proposed as one of the factors determining bacterial attachment. The high sensitivity of ellipsometry and its usefulness for the determination of growth of interfacial bacterial films is demonstrated. PMID:9758786

Future direction in marine bacterial agarases for industrial applications.

PubMed

Jahromi, Saeid Tamadoni; Barzkar, Noora

2018-06-16

The marine ecosystem has been known to be a rich source of novel enzymes. Agarase is a key enzyme that can hydrolyze agar in the marine environment. Marine bacterial agarase has been isolated from various sources, such as sediments, coastal water, and deep sea and from the surface of crustaceans and seaweeds. This review presents an account of the agarase production of marine bacteria. General information about agar, agarase, isolation, and purification of marine bacterial agarases; the biochemical properties of native agarase from marine bacteria; the biochemical properties of recombinant marine bacterial agarases from engineered microorganisms; and the industrial future of marine bacterial agarases is analyzed. With recent biotechnological processes, researchers need novel functional enzymes like agarase from marine resources, such as marine bacteria, that can be used for diverse applications in the biotechnological industry. Marine bacterial agarases might be of significant interest to the industry because they are safe and are a natural source. This review highlights the potential of marine bacteria as important sources of agarase for application in various industries.

Carbon nanomaterials alter plant physiology and soil bacterial community composition in a rice-soil-bacterial ecosystem.

PubMed

Hao, Yi; Ma, Chuanxin; Zhang, Zetian; Song, Youhong; Cao, Weidong; Guo, Jing; Zhou, Guopeng; Rui, Yukui; Liu, Liming; Xing, Baoshan

2018-01-01

The aim of this study was to compare the toxicity effects of carbon nanomaterials (CNMs), namely fullerene (C 60 ), reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs), on a mini-ecosystem of rice grown in a loamy potted soil. We measured plant physiological and biochemical parameters and examined bacterial community composition in the CNMs-treated plant-soil system. After 30 days of exposure, all the three CNMs negatively affected the shoot height and root length of rice, significantly decreased root cortical cells diameter and resulted in shrinkage and deformation of cells, regardless of exposure doses (50 or 500 mg/kg). Additionally, at the high exposure dose of CNM, the concentrations of four phytohormones, including auxin, indoleacetic acid, brassinosteroid and gibberellin acid 4 in rice roots significantly increased as compared to the control. At the high exposure dose of MWCNTs and C 60 , activities of the antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD) in roots increased significantly. High-throughput sequencing showed that three typical CNMs had little effect on shifting the predominant soil bacterial species, but the presence of CNMs significantly altered the composition of the bacterial community. Our results indicate that different CNMs indeed resulted in environmental toxicity to rice and soil bacterial community in the rhizosphere and suggest that CNMs themselves and their incorporated products should be reasonably used to control their release/discharge into the environment to prevent their toxic effects on living organisms and the potential risks to food safety. Copyright © 2017 Elsevier Ltd. All rights reserved.

Phylogenetic and Protein Sequence Analysis of Bacterial Chemoreceptors.

PubMed

Ortega, Davi R; Zhulin, Igor B

2018-01-01

Identifying chemoreceptors in sequenced bacterial genomes, revealing their domain architecture, inferring their evolutionary relationships, and comparing them to chemoreceptors of known function become important steps in genome annotation and chemotaxis research. Here, we describe bioinformatics procedures that enable such analyses, using two closely related bacterial genomes as examples.

Factors contributing to bacterial bulb rots of onion

USDA-ARS?s Scientific Manuscript database