Sample records for saccharomycetales
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Disseminated yeast (Order Saccharomycetales) infection in a Muscovy duckling (Cairina moschata)
Ravi, Madhu; Hill, Janet E.; Fernando, Champika; Wobeser, Gary
2016-01-01
A Muscovy duckling was presented for necropsy due to ongoing mortalities on a farm. Microscopic examination revealed multisystemic inflammatory lesions with intralesional and intracytoplasmic yeast-like organisms. We identified these agents as yeast belonging to the Order Saccharomycetales based on sequence data obtained from the ribosomal RNA operon. PMID:27807382
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Phylogenetics of Saccharomycetales, the ascomycete yeasts.
Suh, Sung-Oui; Blackwell, Meredith; Kurtzman, Cletus P; Lachance, Marc-André
2006-01-01
Ascomycete yeasts (phylum Ascomycota: subphylum Saccharomycotina: class Saccharomycetes: order Saccharomycetales) comprise a monophyletic lineage with a single order of about 1000 known species. These yeasts live as saprobes, often in association with plants, animals and their interfaces. A few species account for most human mycotic infections, and fewer than 10 species are plant pathogens. Yeasts are responsible for important industrial and biotechnological processes, including baking, brewing and synthesis of recombinant proteins. Species such as Saccharomyces cerevisiae are model organisms in research, some of which led to a Nobel Prize. Yeasts usually reproduce asexually by budding, and their sexual states are not enclosed in a fruiting body. The group also is well defined by synapomorphies visible at the ultrastructural level. Yeast identification and classification changed dramatically with the availability of DNA sequencing. Species identification now benefits from a constantly updated sequence database and no longer relies on ambiguous growth tests. A phylogeny based on single gene analyses has shown the order to be remarkably divergent despite morphological similarities among members. The limits of many previously described genera are not supported by sequence comparisons, and multigene phylogenetic studies are under way to provide a stable circumscription of genera, families and orders. One recent multigene study has resolved species of the Saccharomycetaceae into genera that differ markedly from those defined by analysis of morphology and growth responses, and similar changes are likely to occur in other branches of the yeast tree as additional sequences become available.
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USDA-ARS?s Scientific Manuscript database
We describe the yeast genus Tortispora gen. nov., an early diverging lineage in the Saccharomycetales that features the formation of helical ascospores. The genus is based on 16 strains resembling Candida caseinolytica that were isolated from necrotic plant tissue in warm regions of the New World. B...
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Fungi diversity from different depths and times in chicken manure waste static aerobic composting.
Gu, Wenjie; Lu, Yusheng; Tan, Zhiyuan; Xu, Peizhi; Xie, Kaizhi; Li, Xia; Sun, Lili
2017-09-01
The Dirichlet multinomial mixtures mode was used to analyse illumina sequencing data to reveal both temporal and spatial variations of the fungi community present in the aerobic composting. Results showed that 670 operational taxonomic units (OTUs) were detected, and the dominant phylum was Ascomycota. There were four types of samples fungi communities during the composting process. Samples from the early composting stage were mainly grouped into type I and Saccharomycetales sp. was dominant. Fungi community in the medium composting stage were fallen into type II and III, Sordariales sp. and Acremonium alcalophilum, Saccharomycetales sp. and Scedosporium minutisporum were the dominant OTUs respectively. Samples from the late composting stage were mainly grouped into type IV and Scedosporium minutisporum was the dominant OTU; Scedosporium minutisporum was significantly affected by depth (P<0.05). Results indicate that time and depth both are factors that influence fungi distribution and variation in c waste during static aerobic composting. Copyright © 2017. Published by Elsevier Ltd.
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Statzell-Tallman, Adele; Scorzetti, Gloria; Fell, Jack W
2010-08-01
Three species of yeasts are taxonomically described for strains isolated from marine environments. Candida spencermartinsiae sp. nov. (type strain CBS 10894T =NRRL Y-48663T) and Candida taylorii sp. nov. (type strain CBS 8508T =NRRL Y-27213T) are anamorphic ascomycetous yeasts in a phylogenetic cluster of marine yeasts in the Debaryomyces/Lodderomyces clade of the Saccharomycetales. The two species were isolated from multiple locations among coral reefs and mangrove habitats. Pseudozyma abaconensis sp. nov. (type strain CBS 8380T =NRRL Y-17380T) is an anamorphic basidiomycete that is related to the smut fungi of the genus Ustilago in the Ustilaginales. P. abaconensis was collected from waters adjacent to a coral reef.
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Zhang, Yanyan; Zhu, Xiaoyu; Li, Xiangzhen; Tao, Yong; Jia, Jia; He, Xiaohong
2017-09-15
Famous Chinese strong-flavored liquor (CSFL) is brewed by microbial consortia in a special fermentation pit (FT). However, the fermentation process was not fully understood owing to the complicate community structure and metabolism. In this study, the process-related dynamics of microbial communities and main flavor compounds during the 70-day fermentation process were investigated in a simulated fermentation system. A three-phase model was proposed to characterize the process of the CSFL fermentation. (i) In the early fermentation period (1-23 days), glucose was produced from macromolecular carbohydrates (e.g., starch). The prokaryotic diversity decreased significantly. The Lactobacillaceae gradually predominated in the prokaryotic community. In contrast, the eukaryotic diversity rose remarkably in this stage. Thermoascus, Aspergillus, Rhizopus and unidentified Saccharomycetales were dominant eukaryotic members. (ii) In the middle fermentation period (23-48 days), glucose concentration decreased while lactate acid and ethanol increased significantly. Prokaryotic community was almost dominated by the Lactobacillus, while eukaryotic community was mainly comprised of Thermoascus, Emericella and Aspergillus. (iii) In the later fermentation period (48-70 days), the concentrations of ethyl esters, especially ethyl caproate, increased remarkably. The CSFL fermentation could undergo three stages: saccharification, glycolysis and esterification. Saccharomycetales, Monascus, and Rhizopus were positively correlated to glucose concentration (P < 0.05), highlighting their important roles in the starch saccharification. The Lactobacillaceae, Bacilli, Botryotinia, Aspergillus, unidentified Pleosporales and Capnodiales contributed to the glycolysis and esterification, because they were positively correlated to most organic acids and ethyl esters (P < 0.05). Additionally, four genera, including Emericella, Suillus, Mortierella and Botryotinia, that likely played key roles
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Controls over fungal communities and consequences for nutrient cycling
NASA Astrophysics Data System (ADS)
Treseder, K. K.; Majumder, P.; Bent, E.; Borneman, J.; Allison, S. D.; Hanson, C. A.
2007-12-01
Soils harbor a high diversity of microbes-- as many as 100 species of fungi within a square meter. If different species target different components of litter, a more diverse community of fungi should lead to faster decomposition rates. We examined the hypotheses that variation in substrate use among fungal groups and variation in nitrogen availability are both important controls over the diversity of fungi in an Alaskan boreal forest. Nitrogen availability was considered because microbes are often N-limited, and because humans are altering N availability via anthropogenic N deposition and global warming. We used nucleotide analogs to link fungal groups with their role in decomposition in field samples. Leaf litter collected from the forest floor was supplemented with one of four N-containing compounds. Bromodeoxyuridine (BrdU, a thymidine analog) was also added. After 48 hours incubation, DNA was extracted. Most growing fungi should have assimilated the BrdU into new DNA. Their genetic identity was determined using oligonucleotide fingerprinting of rRNA genes (OFRG). OFRG is an rRNA gene profiling method that sorts genes into taxonomic groups with a high degree of resolution, and has a large capacity for sample processing. Fungal groups that proliferated following the addition of a given compound probably metabolized that compound. We found that fungal taxa varied in their responses to different substrates, indicating that they differed in substrate use. Specifically, community composition of fungi was significantly different among substrate treatments (P < 0.001). In addition, of the 15 dominant taxa, seven displayed significant preferences for one substrate over another. For instance, taxa within the Helotiales preferred glutamate (P = 0.001); Sporidiales, tannin-protein complexes (P = 0.014); Saccharomycetales, arginine (P = 0.042); and Polyporales, arginine and lignocellulose (P = 0.040). In a complementary experiment, we used BrdU labeling to characterize
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Fungi Isolated From House Flies (Diptera: Muscidae) on Penned Cattle in South Texas
Ysquierdo, Cherity A.; Olafson, Pia U.; Thomas, Donald B.
2017-01-01
Abstract Musca domestica L. were collected from cattle diagnosed with bovine ringworm to evaluate the potential of the house fly to disseminate Trichophyton verrucosum E. Bodin, a fungal dermatophyte that is the causative agent for ringworm in cattle. Fungal isolates were cultured from 45 individual flies on supplemented Sabouraud dextrose agar, and isolates were identified using morphological and microscopic approaches. Each isolate was identified further by PCR amplification of the ribosomal DNA locus with fungal-specific primers and subsequent amplicon sequencing. Trichophyton verrucosum was not identified using these approaches. However, 35 different fungal species representing 17 genera were cultured from collected flies, including several species that are allergenic and pathogenic to humans and animals. Several species within the fungal orders Hypocreales, Microascales, Onygenales, Saccharomycetales, Xylaniales, and Agaricales were observed for the first time on house flies. The most frequent fungus recovered was Cladosporium cladosporoides Fresen, which is known to be a ubiquitous, airborne allergen to humans. PMID:28399217
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NASA Astrophysics Data System (ADS)
Zhang, Tao; Fei Wang, Neng; Qin Zhang, Yu; Yu Liu, Hong; Yan Yu, Li
2015-10-01
This study assessed the diversity and distribution of fungal communities in eight marine sediments of Kongsfjorden (Svalbard, High Arctic) using 454 pyrosequencing with fungal-specific primers targeting the internal transcribed spacer (ITS) region of the ribosomal rRNA gene. Sedimentary fungal communities showed high diversity with 42,219 reads belonging to 113 operational taxonomic units (OTUs). Of these OTUs, 62 belonged to the Ascomycota, 26 to Basidiomycota, 2 to Chytridiomycota, 1 to Zygomycota, 1 to Glomeromycota, and 21 to unknown fungi. The major known orders included Hypocreales and Saccharomycetales. The common fungal genera were Pichia, Fusarium, Alternaria, and Malassezia. Interestingly, most fungi occurring in these Arctic sediments may originate from the terrestrial habitats and different basins in Kongsfjorden (i.e., inner basin, central basin, and outer basin) harbor different sedimentary fungal communities. These results suggest the existence of diverse fungal communities in the Arctic marine sediments, which may serve as a useful community model for further ecological and evolutionary study of fungi in the Arctic.
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Ren, Yong-Cheng; Wang, Yun; Chen, Liang; Ke, Tao; Hui, Feng-Li
2014-11-01
Two strains representing Wickerhamiella allomyrinae f.a., sp. nov. were isolated from the gut of Allomyrina dichotoma (Coleoptera: Scarabeidae) collected from the Baotianman National Nature Reserve, Nanyan, Henan Province, China. Sequence analyses of the D1/D2 domains of the LSU rRNA gene revealed that this novel species was located in the Wickerhamiella clade (Saccharomycetes, Saccharomycetales), with three described species of the genus Candida, namely Candida musiphila, Candida spandovensis and Candida sergipensis, as the most closely related species. The novel species differed from these three species by 9.3-9.8% sequence divergence (35-45 nt substitutions) in the D1/D2 sequences. The species could also be distinguished from the closely related species, C. musiphila, C. spandovensis and C. sergipensis, by growth on vitamin-free medium and at 37 °C. The type strain is Wickerhamiella allomyrinae sp. nov. NYNU 13920(T) ( =CICC 33031(T) =CBS 13167(T)). © 2014 IUMS.
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Khunnamwong, Pannida; Lertwattanasakul, Noppon; Jindamorakot, Sasitorn; Limtong, Savitree; Lachance, Marc-André
2015-12-01
Three strains (DMKU-RE28, DMKU-RE43T and DMKU-RE123) of a novel anamorphic yeast species were isolated from rice leaf tissue collected in Thailand. DNA sequence analysis demonstrated that the species forms a sister pair with Candida ranongensis CBS 10861T but differs by 24-30 substitutions in the LSU rRNA gene D1/D2 domains and 30-35 substitutions in the ITS region. A phylogenetic analysis based on both the small and the large rRNA gene subunits confirmed this connection and demonstrated the presence of a clade that also includes Candida catenulata, Candida mesorugosa, Candida neorugosa, Candida pseudorugosa, Candida rugosa and Candida scorzettiae. The clade is not closely affiliated to any known teleomorphic genus, and forms a well-separated lineage from currently recognized genera of the Saccharomycetales. Hence, the genus Diutina gen. nov. is proposed to accommodate members of the clade, including Diutina siamensis f.a. sp. nov. and the preceding seven Candida species. The type strain is DMKU-RE43T ( = CBS 13388T = BCC 61183T = NBRC 109695T).
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Kwasiborski, Anthony; Bajji, Mohammed; Renaut, Jenny; Delaplace, Pierre; Jijakli, M. Haissam
2014-01-01
Yeast Pichia anomala strain Kh6 Kurtzman (Saccharomycetales: Endomycetaceae) exhibits biological control properties that provide an alternative to the chemical fungicides currently used by fruit or vegetable producers against main post-harvest pathogens, such as Botrytis cinerea (Helotiales: Sclerotiniaceae). Using an in situ model that takes into account interactions between organisms and a proteomic approach, we aimed to identify P. anomala metabolic pathways influenced by the presence of B. cinerea. A total of 105 and 60 P. anomala proteins were differentially represented in the exponential and stationary growth phases, respectively. In the exponential phase and in the presence of B. cinerea, the pentose phosphate pathway seems to be enhanced and would provide P. anomala with the needed nucleic acids and energy for the wound colonisation. In the stationary phase, P. anomala would use alcoholic fermentation both in the absence and presence of the pathogen. These results would suggest that the competitive colonisation of apple wounds could be implicated in the mode of action of P. anomala against B. cinerea. PMID:24614090
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Analysis of the yeast short-term Crabtree effect and its origin
Hagman, Arne; Säll, Torbjörn; Piškur, Jure
2014-01-01
The short-term Crabtree effect is defined as the immediate occurrence of aerobic alcoholic fermentation in response to provision of a pulse of excess sugar to sugar-limited yeast cultures. Here we have characterized ten yeast species with a clearly defined phylogenetic relationship. Yeast species were cultivated under glucose-limited conditions, and we studied their general carbon metabolism in response to a glucose pulse. We generated an extensive collection of data on glucose and oxygen consumption, and ethanol and carbon dioxide generation. We conclude that the Pichia,Debaryomyces,Eremothecium and Kluyveromyces marxianus yeasts do not exhibit any significant ethanol formation, while Kluyveromyces lactis behaves as an intermediate yeast, and Lachancea,Torulaspora,Vanderwaltozyma and Saccharomyces yeasts exhibit rapid ethanol accumulation. Based on the present data and our previous data relating to the presence of the long-term Crabtree effect in over 40 yeast species, we speculate that the origin of the short-term effect may coincide with the origin of the long-term Crabtree effect in the Saccharomycetales lineage, occurring ∼ 150 million years ago. PMID:25161062
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Portugal, Cauré; Pinto, Luís; Ribeiro, Miguel; Tenorio, Carmen; Igrejas, Gilberto; Ruiz-Larrea, Fernanda
2015-10-01
Wine microbiota is complex and includes a wide diversity of yeast species. Few of them are able to survive under the restrictive conditions of dry red wines. In our study we detected and identified seven yeast species of the order Saccharomycetales that can be considered potential spoilers of wines due to physiological traits such as acidogenic metabolism and off-odor generation: Arthroascus schoenii, Candida ishiwadae, Meyerozyma guilliermondii, Pichia holstii, Pichia manshurica, Trigonopsis cantarellii, and Trigonopsis variabilis. Based on the prevalence of T. cantarellii isolates in the wine samples of our study, we further characterized this species, determined molecular and phenotypic features, and performed a proteomic analysis to identify differentially expressed proteins at mid-exponential growth phase in the presence of ethanol in the culture broth. This yeast species is shown to be able to grow in the presence of ethanol by expressing heat shock proteins (Hsp70, Hsp71) and a DNA damage-related protein (Rad24), and to be able to confer spoilage characteristics on wine. Copyright © 2015 Elsevier B.V. All rights reserved.
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Developments in Fungal Taxonomy
Guarro, Josep; Gené, Josepa; Stchigel, Alberto M.
1999-01-01
Fungal infections, especially those caused by opportunistic species, have become substantially more common in recent decades. Numerous species cause human infections, and several new human pathogens are discovered yearly. This situation has created an increasing interest in fungal taxonomy and has led to the development of new methods and approaches to fungal biosystematics which have promoted important practical advances in identification procedures. However, the significance of some data provided by the new approaches is still unclear, and results drawn from such studies may even increase nomenclatural confusion. Analyses of rRNA and rDNA sequences constitute an important complement of the morphological criteria needed to allow clinical fungi to be more easily identified and placed on a single phylogenetic tree. Most of the pathogenic fungi so far described belong to the kingdom Fungi; two belong to the kingdom Chromista. Within the Fungi, they are distributed in three phyla and in 15 orders (Pneumocystidales, Saccharomycetales, Dothideales, Sordariales, Onygenales, Eurotiales, Hypocreales, Ophiostomatales, Microascales, Tremellales, Poriales, Stereales, Agaricales, Schizophyllales, and Ustilaginales). PMID:10398676
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Qiu, Xinyun; Zhang, Feng; Yang, Xi; Wu, Na; Jiang, Weiwei; Li, Xia; Li, Xiaoxue; Liu, Yulan
2015-05-27
Intestinal fungi are increasingly believed to greatly influence gut health. However, the effects of fungi on intestinal inflammation and on gut bacterial constitution are not clear. Here, based on pyrosequencing method, we reveal that fungal compositions vary in different intestinal segments (ileum, cecum, and colon), prefer different colonization locations (mucosa and feces), and are remarkably changed during intestinal inflammation in dextran sulfate sodium (DSS)-colitis mouse models compare to normal controls: Penicillium, Wickerhamomyces, Alternaria, and Candida are increased while Cryptococcus, Phialemonium, Wallemia and an unidentified Saccharomycetales genus are decreased in the guts of DSS-colitis mice. Fungi-depleted mice exhibited aggravated acute DSS-colitis associated with gain of Hallella, Barnesiella, Bacteroides, Alistipes, and Lactobacillus and loss of butyrate-producing Clostridium XIVa, and Anaerostipes compare with normal control. In contrast, bacteria-depleted mice show attenuated acute DSS-colitis. Mice with severely chronic recurrent DSS-colitis show increased plasma (1,3)-β-D-glucan level and fungal translocation into the colonic mucosa, mesenteric lymph nodes and spleen. This work demonstrate the different roles of fungi in acute and chronic recurrent colitis: They are important counterbalance to bacteria in maintaining intestinal micro-ecological homeostasis and health in acutely inflamed intestines, but can harmfully translocate into abnormal sites and could aggravate disease severity in chronic recurrent colitis.
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Qiu, Xinyun; Zhang, Feng; Yang, Xi; Wu, Na; Jiang, Weiwei; Li, Xia; Li, Xiaoxue; Liu, Yulan
2015-01-01
Intestinal fungi are increasingly believed to greatly influence gut health. However, the effects of fungi on intestinal inflammation and on gut bacterial constitution are not clear. Here, based on pyrosequencing method, we reveal that fungal compositions vary in different intestinal segments (ileum, cecum, and colon), prefer different colonization locations (mucosa and feces), and are remarkably changed during intestinal inflammation in dextran sulfate sodium (DSS)-colitis mouse models compare to normal controls: Penicillium, Wickerhamomyces, Alternaria, and Candida are increased while Cryptococcus, Phialemonium, Wallemia and an unidentified Saccharomycetales genus are decreased in the guts of DSS-colitis mice. Fungi-depleted mice exhibited aggravated acute DSS-colitis associated with gain of Hallella, Barnesiella, Bacteroides, Alistipes, and Lactobacillus and loss of butyrate-producing Clostridium XIVa, and Anaerostipes compare with normal control. In contrast, bacteria-depleted mice show attenuated acute DSS-colitis. Mice with severely chronic recurrent DSS-colitis show increased plasma (1,3)-β-D-glucan level and fungal translocation into the colonic mucosa, mesenteric lymph nodes and spleen. This work demonstrate the different roles of fungi in acute and chronic recurrent colitis: They are important counterbalance to bacteria in maintaining intestinal micro-ecological homeostasis and health in acutely inflamed intestines, but can harmfully translocate into abnormal sites and could aggravate disease severity in chronic recurrent colitis. PMID:26013555
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Broissin-Vargas, L M; Snell-Castro, R; Godon, J J; González-Ríos, O; Suárez-Quiroz, M L
2018-02-01
The purpose of this study was to evaluate the effect of warehouse storage conditions on the composition of the fungal community of green coffee beans (GCB) that were stored in jute sacks for 1 year. Molecular characterization of the fungal community composition and population dynamics obtained by Q-PCR, CE-SSCP (Simpson's diversity index D) and Illumina MiSeq sequencing indicated that Saccharomycetales dominated during the first 6 months of storage period with species as Meyerozyma guilliermondii and Pichia kluyveri. However, after 6 months of storage, the filamentous genus Wallemia became dominant. Principal components analysis correlated this fungal dynamic with storage conditions and other variables as chromaticity (colour), water activity, moisture content, reducing sugars concentration, fungal infection and ochratoxin A production. This study demonstrated that GCB stored in jute sacks after 6 months of storage lead to fungal population dynamics, decreased chromaticity in GCB by bleaching and, then, affected overall quality. Storage plays an important role in the quality evolution during the handling of the GCB. In this context, the composition of the microbial community could be considered a marker to assess the trade value of the coffee beans. © 2017 The Society for Applied Microbiology.
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Massive programmed translational jumping in mitochondria
Lang, B. Franz; Jakubkova, Michaela; Hegedusova, Eva; Daoud, Rachid; Forget, Lise; Brejova, Brona; Vinar, Tomas; Kosa, Peter; Fricova, Dominika; Nebohacova, Martina; Griac, Peter; Tomaska, Lubomir; Burger, Gertraud; Nosek, Jozef
2014-01-01
Programmed translational bypassing is a process whereby ribosomes “ignore” a substantial interval of mRNA sequence. Although discovered 25 y ago, the only experimentally confirmed example of this puzzling phenomenon is expression of the bacteriophage T4 gene 60. Bypassing requires translational blockage at a “takeoff codon” immediately upstream of a stop codon followed by a hairpin, which causes peptidyl-tRNA dissociation and reassociation with a matching “landing triplet” 50 nt downstream, where translation resumes. Here, we report 81 translational bypassing elements (byps) in mitochondria of the yeast Magnusiomyces capitatus and demonstrate in three cases, by transcript analysis and proteomics, that byps are retained in mitochondrial mRNAs but not translated. Although mitochondrial byps resemble the bypass sequence in the T4 gene 60, they utilize unused codons instead of stops for translational blockage and have relaxed matching rules for takeoff/landing sites. We detected byp-like sequences also in mtDNAs of several Saccharomycetales, indicating that byps are mobile genetic elements. These byp-like sequences lack bypassing activity and are tolerated when inserted in-frame in variable protein regions. We hypothesize that byp-like elements have the potential to contribute to evolutionary diversification of proteins by adding new domains that allow exploration of new structures and functions. PMID:24711422
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Li, Pan; Lin, Weifeng; Liu, Xiong; Wang, Xiaowen; Gan, Xing; Luo, Lixin; Lin, Wei-Tie
2017-02-01
Daqu, a traditional fermentation starter that is used for Chinese liquor and vinegar production, is still manufactured through a traditional spontaneous solid-state fermentation process with no selected microorganisms are intentionally inoculated. The aim of this work was to analyze the microbiota dynamics during the solid-state fermentation process of Daqu using a traditional and bioaugmented inoculation with autochthonous of Bacillus, Pediococcus, Saccharomycopsis and Wickerhamomyces at an industrial scale. Highly similar dynamics of physicochemical parameters, enzymatic activities and microbial communities were observed during the traditional and bioaugmented solid-state fermentation processes. Both in the two cases, groups of Streptophyta, Rickettsiales and Xanthomonadales only dominated the first two days, but Bacillales and Eurotiales became predominant members after 2 and 10 days fermentation, respectively. Phylotypes of Enterobacteriales, Lactobacillales, Saccharomycetales and Mucorales dominated the whole fermentation process. No significant difference (P > 0.05) in microbial structure was observed between the traditional and bioaugmented fermentation processes. However, slightly higher microbial richness was found during the bioaugmented fermentation process after 10 days fermentation. Our results reinforced the microbiota dynamic stability during the solid-state fermentation process of Daqu, and might aid in controlling the traditional Daqu manufacturing process. Copyright © 2016 Elsevier Ltd. All rights reserved.
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Li, Pan; Liang, Hebin; Lin, Wei-Tie; Feng, Feng
2015-01-01
Traditional Chinese solid-state fermented cereal starters contain highly complex microbial communities and enzymes. Very little is known, however, about the microbial dynamics related to environmental conditions, and cellulolytic communities have never been proposed to exist during cereal starter fermentation. In this study, we performed Illumina MiSeq sequencing combined with PCR-denaturing gradient gel electrophoresis to investigate microbiota, coupled with clone library construction to trace cellulolytic communities in both fermentation stages. A succession of microbial assemblages was observed during the fermentation of starters. Lactobacillales and Saccharomycetales dominated the initial stages, with a continuous decline in relative abundance. However, thermotolerant and drought-resistant Bacillales, Eurotiales, and Mucorales were considerably accelerated during the heating stages, and these organisms dominated until the end of fermentation. Enterobacteriales were consistently ubiquitous throughout the process. For the cellulolytic communities, only the genera Sanguibacter, Beutenbergia, Agrobacterium, and Erwinia dominated the initial fermentation stages. In contrast, stages at high incubation temperature induced the appearance and dominance of Bacillus, Aspergillus, and Mucor. The enzymatic dynamics of amylase and glucoamylase also showed a similar trend, with the activities clearly increased in the first 7 days and subsequently decreased until the end of fermentation. Furthermore, β-glucosidase activity continuously and significantly increased during the fermentation process. Evidently, cellulolytic potential can adapt to environmental conditions by changes in the community structure during the fermentation of starters. PMID:26002897
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Yurkov, Andrey M; Dlauchy, Dénes; Péter, Gábor
2017-10-01
In the course of two independent studies three yeasts have been isolated from temperate deciduous trees in Hungary and Germany. Analyses of nucleotide sequences of D1/D2 domains of the 26S rRNA gene (LSU) suggested that these strains belong to the Meyerozyma clade in Debaryomycetaceae (Saccharomycetales). The phylogenetic analysis of a concatenated alignment of the ITS region and LSU gene sequences confirmed the placement of the three strains in the Meyerozyma clade close to Candida elateridarum. If mixed in proper combinations, the strains formed one to two hat shaped ascospores in deliquescent asci. In addition to the ascospore formation, the three studied strains differed from Candida elateridarum and other members of the Meyerozyma clade in terms of ribosomal gene sequence and some physiological properties. To accommodate the above-noted strains, we describe the new species as Meyerozyma amylolytica sp. nov. (holotype: DSM 27310 T ; ex-type cultures: NCAIM Y.02140 T =MUCL 56454 T , allotype: NCAIM Y.01955 A ; ex-allotype culture: DSM 27468), MB 821663. Additionally, we propose the transfer of five non-ascosporic members of the Meyerozyma clade to the genus Meyerozyma as the following new taxonomic combinations Meyerozyma athensensis f.a., comb. nov. (MB 821664), Meyerozyma carpophila f.a., comb. nov. (MB 821665), Meyerozyma elateridarum f.a., comb. nov. (MB 821666), Meyerozyma neustonensis f.a., comb. nov. (MB 821667), and Meyerozyma smithsonii f.a., comb. nov. (MB 821668).
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Zhang, L; Zhou, R; Niu, M; Zheng, J; Wu, C
2015-11-01
Artificial pit muds (APMs) is produced by peats, aged pit muds, yellow and black clays etc. and is one of essential factors for Luzhou-flavour liquor production. The microbial community of APMs significantly influence the quality of Luzhou-flavour liquor. The aim of this study was to investigate the differences in bacterial, archaeal and fungal community of APMs, starters and materials. Multiphase culture-independent technology were employed in this study, including nested PCR-denaturing gradient gel electrophoresis (nested PCR-DGGE), phospholipid fatty acid (PLFA), phospholipid ether lipids (PLEL) and fluorescence in situ hybridization (FISH) analysis. Results suggested that the microbial diversity significantly changed under environmental stress and different culture patterns during APMs cultivation. The dominant bacteria in APMs mainly fell into Clostridiales, Lactobacillales, Bacteroidales and Rhizobiales, Archaea affiliated with Methanomicrobiales and Methanosarcinales, and fungi belonged to Saccharomycetales and Eurotiales. Furthermore, the microbial community structures of APMs cultured by ground pile pattern were more similar with that of aged pit muds, meanwhile, the relative bands intensities of microbes, which are the main contributors for liquor brewing, increased with the culture times. Not only the niche selection and biogeochemical properties of APMs, but also the mutual collaboration and constraint between different microbes may result in enriching different liquor-brewing microbes into APMs. APM cultivation technology was necessary to promote enriching functional liquor-brewing microbes into APMs. These results may facilitate understanding the microbial succession during APMs manufacture. © 2015 The Society for Applied Microbiology.
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Li, Pan; Liang, Hebin; Lin, Wei-Tie; Feng, Feng; Luo, Lixin
2015-08-01
Traditional Chinese solid-state fermented cereal starters contain highly complex microbial communities and enzymes. Very little is known, however, about the microbial dynamics related to environmental conditions, and cellulolytic communities have never been proposed to exist during cereal starter fermentation. In this study, we performed Illumina MiSeq sequencing combined with PCR-denaturing gradient gel electrophoresis to investigate microbiota, coupled with clone library construction to trace cellulolytic communities in both fermentation stages. A succession of microbial assemblages was observed during the fermentation of starters. Lactobacillales and Saccharomycetales dominated the initial stages, with a continuous decline in relative abundance. However, thermotolerant and drought-resistant Bacillales, Eurotiales, and Mucorales were considerably accelerated during the heating stages, and these organisms dominated until the end of fermentation. Enterobacteriales were consistently ubiquitous throughout the process. For the cellulolytic communities, only the genera Sanguibacter, Beutenbergia, Agrobacterium, and Erwinia dominated the initial fermentation stages. In contrast, stages at high incubation temperature induced the appearance and dominance of Bacillus, Aspergillus, and Mucor. The enzymatic dynamics of amylase and glucoamylase also showed a similar trend, with the activities clearly increased in the first 7 days and subsequently decreased until the end of fermentation. Furthermore, β-glucosidase activity continuously and significantly increased during the fermentation process. Evidently, cellulolytic potential can adapt to environmental conditions by changes in the community structure during the fermentation of starters. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
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Bal, Jyotiranjan; Yun, Suk-Hyun; Yeo, Soo-Hwan; Kim, Jung-Mi; Kim, Beom-Tae; Kim, Dae-Hyuk
2017-03-01
The brewing of makgeolli, one of Korea's most popular alcoholic beverages that is gaining popularity globally, is facilitated by nuruk, a traditional Korean cereal starter. The nuruk microbiome greatly influences the fermentation process as well as the nutritional, hygienic, and aromatic qualities of the product. This study is a continuation of our efforts to examine nuruk biodiversity at a depth previously unattainable. In this study, microfloral dynamics in wheat-based nuruk C, composed of traditional ingredients such as barley, green gram, and wheat and fermented under various internal moisture contents of 20% (C20), 26% (C26), and 30% (C30), was evaluated using 454 pyrosequencing during the 30-day fermentation process. Rarefaction analysis and alpha diversity parameters indicated adequate sampling. C20 showed the greatest fungal richness and diversity, C20 and C26 exhibited similar bacterial richness and diversity, while C30 had low fungal and bacterial richness. Fungal taxonomic assignments revealed that the initial moisture content caused selective enrichment of Aspergillus candidus with a decreasing trend during fermentation, whereas Saccharomycetales sp. exhibited increasing relative abundance with increasing moisture content from day 6 of the fermentation process. Depending on initial moisture level, changes in bacterial communities were also observed in the genera Streptomyces, Bacillus, and Staphylococcus, with decreasing trends whereas Saccharopolyspora exhibited a sigmoidal trend with the highest abundance in C26. These findings demonstrate the possible impact of initial moisture content of nuruk on microfloral richness, diversity, and dynamics; this study is thus a step toward our ultimate goal of enhancing the quality of nuruk.
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Eddouzi, Jamel; Hofstetter, Valérie; Groenewald, Marizeth; Manai, Mohamed; Sanglard, Dominique
2013-01-01
From a collection of yeast isolates isolated from patients in Tunisian hospitals between September 2006 and July 2010, the yeast strain JEY63 (CBS 12513), isolated from a 50-year-old male that suffered from oral thrush, could not be identified to the species level using conventional methods used in clinical laboratories. These methods include matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), germ tube formation, and the use of CHROMagar Candida and metabolic galleries. Sequence analysis of the nuclear rRNA (18S rRNA, 5.8S rRNA, and 26S rRNA) and internal transcribed spacer regions (ITS1 and ITS2) indicated that the ribosomal DNA sequences of this species were not yet reported. Multiple gene phylogenic analyses suggested that this isolate clustered at the base of the Dipodascaceae (Saccharomycetales, Saccharomycetes, and Ascomycota). JEY63 was named Candida tunisiensis sp. nov. according to several phenotypic criteria and its geographical origin. C. tunisiensis was able to grow at 42°C and does not form chlamydospores and hyphae but could grow as yeast and pseudohyphal forms. C. tunisiensis exhibited most probably a haploid genome with an estimated size of 10 Mb on at least three chromosomes. Using European Committee for Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) Candida albicans susceptibility breakpoints as a reference, C. tunisiensis was resistant to fluconazole (MIC = 8 μg/ml), voriconazole (MIC = 0.5 μg/ml), itraconazole (MIC = 16 μg/ml), and amphotericin B (MIC = 4 μg/ml) but still susceptible to posaconazole (MIC = 0.008 μg/ml) and caspofungin (MIC = 0.5 μg/ml). In conclusion, MALDI-TOF MS permitted the early selection of an unusual isolate, which was still unreported in molecular databases but could not be unambiguously classified based on phylogenetic approaches.
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Eddouzi, Jamel; Hofstetter, Valérie; Groenewald, Marizeth; Manai, Mohamed
2013-01-01
From a collection of yeast isolates isolated from patients in Tunisian hospitals between September 2006 and July 2010, the yeast strain JEY63 (CBS 12513), isolated from a 50-year-old male that suffered from oral thrush, could not be identified to the species level using conventional methods used in clinical laboratories. These methods include matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS), germ tube formation, and the use of CHROMagar Candida and metabolic galleries. Sequence analysis of the nuclear rRNA (18S rRNA, 5.8S rRNA, and 26S rRNA) and internal transcribed spacer regions (ITS1 and ITS2) indicated that the ribosomal DNA sequences of this species were not yet reported. Multiple gene phylogenic analyses suggested that this isolate clustered at the base of the Dipodascaceae (Saccharomycetales, Saccharomycetes, and Ascomycota). JEY63 was named Candida tunisiensis sp. nov. according to several phenotypic criteria and its geographical origin. C. tunisiensis was able to grow at 42°C and does not form chlamydospores and hyphae but could grow as yeast and pseudohyphal forms. C. tunisiensis exhibited most probably a haploid genome with an estimated size of 10 Mb on at least three chromosomes. Using European Committee for Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) Candida albicans susceptibility breakpoints as a reference, C. tunisiensis was resistant to fluconazole (MIC = 8 μg/ml), voriconazole (MIC = 0.5 μg/ml), itraconazole (MIC = 16 μg/ml), and amphotericin B (MIC = 4 μg/ml) but still susceptible to posaconazole (MIC = 0.008 μg/ml) and caspofungin (MIC = 0.5 μg/ml). In conclusion, MALDI-TOF MS permitted the early selection of an unusual isolate, which was still unreported in molecular databases but could not be unambiguously classified based on phylogenetic approaches. PMID:23077122
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Duniere, L; Jin, L; Smiley, B; Qi, M; Rutherford, W; Wang, Y; McAllister, T
2015-05-01
Bacterial inoculants can improve the conservation and nutritional quality of silages. Inclusion of the yeast Saccharomyces in the diet of dairy cattle has also been reported to be beneficial. The present study assessed the ability of silage to be used as a means of delivering Saccharomyces strains to ruminants. Two strains of Saccharomyces cerevisiae (strain 1 and 3)and 1 strain of Saccharomyces paradoxus (strain 2) were inoculated (10(3) cfu/g) individually onto corn forage that was ensiled in mini silos for 90 d. Fermentation characteristics, aerobic stability, and nutritive value of silages were determined and real-time quantitative PCR (RT-qPCR) was used to quantify S. cerevisiae, S.paradoxus, total Saccharomyces, fungal, and bacterial populations. Fermentation characteristics of silage inoculated with S1 were similar to control silage. Although strain 3 inoculation increased ash and decreased OM contents of silage (P = 0.017), no differences were observed in nutrient composition or fermentation profiles after 90 d of ensiling. Inoculation with Saccharomyces had no detrimental effect on the aerobic stability of silage. In vitro DM disappearance, gas production, and microbial protein synthesis were not affected by yeast inoculation.Saccharomyces strain 1 was quantified throughout ensiling, whereas strain 2 was detected only immediately after inoculation. Saccharomyces cerevisiae strain 3 was quantified until d 7 and detectable 90 d after ensiling. All inoculants were detected and quantified during aerobic exposure. Inoculation with Saccharomyces did not alter lactobacilli populations. Saccharomycetales were detected by RT-qPCR throughout ensiling in all silages. Both S. cerevisiae and S. paradoxus populations increased during aerobic exposure, demonstrating that the density of these yeast strains would increase between the time that silage was removed from storage and the time it was fed.
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López-Miras, María del Mar; Martín-Sánchez, Inés; Yebra-Rodríguez, África; Romero-Noguera, Julio; Bolívar-Galiano, Fernando; Ettenauer, Jörg; Sterflinger, Katja; Piñar, Guadalupe
2013-01-01
In this study, we investigated the microbial community (bacteria and fungi) colonising an oil painting on canvas, which showed visible signs of biodeterioration. A combined strategy, comprising culture-dependent and -independent techniques, was selected. The results derived from the two techniques were disparate. Most of the isolated bacterial strains belonged to related species of the phylum Firmicutes, as Bacillus sp. and Paenisporosarcina sp., whereas the majority of the non-cultivable members of the bacterial community were shown to be related to species of the phylum Proteobacteria, as Stenotrophomonas sp. Fungal communities also showed discrepancies: the isolated fungal strains belonged to different genera of the order Eurotiales, as Penicillium and Eurotium, and the non-cultivable belonged to species of the order Pleosporales and Saccharomycetales. The cultivable microorganisms, which exhibited enzymatic activities related to the deterioration processes, were selected to evaluate their biodeteriorative potential on canvas paintings; namely Arthrobacter sp. as the representative bacterium and Penicillium sp. as the representative fungus. With this aim, a sample taken from the painting studied in this work was examined to determine the stratigraphic sequence of its cross-section. From this information, “mock paintings,” simulating the structure of the original painting, were prepared, inoculated with the selected bacterial and fungal strains, and subsequently examined by micro-Fourier Transform Infrared spectroscopy, in order to determine their potential susceptibility to microbial degradation. The FTIR-spectra revealed that neither Arthrobacter sp. nor Penicillium sp. alone, were able to induce chemical changes on the various materials used to prepare “mock paintings.” Only when inoculated together, could a synergistic effect on the FTIR-spectra be observed, in the form of a variation in band position on the spectrum. PMID:24312203
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Li, Pan; Lin, Weifeng; Liu, Xiong; Wang, Xiaowen; Luo, Lixin
2016-01-01
In this study, we investigated the microbiota dynamics during two industrial-scale traditional solid-state fermentation (SSF) processes of Daqu starters. Similar evolution profiles of environmental parameters, enzymatic activities, microbial amounts, and communities were observed during the medium temperature SSF (MTSSF) and low temperature SSF (LTSSF) processes. Orders of Rickettsiales and Streptophyta only dominated the initial 2 days, and Eurotiales only predominated from days 10 to 24, however, phylotypes of Enterobacteriales, Lactobacillales, Bacillales, Saccharomycetales, and Mucorales both prevailed throughout the MTSSF and LTSSF processes. Nevertheless, the pH in MTSSF process on day 5 were 5.28, while in LTSSF process (4.87) significantly lower (P < 0.05). The glucoamylase activities in MTSSF process dropped from 902.71 to 394.33 mg glucose g-1 h-1 on days 5 to 24, while significantly lower (P < 0.05) in LTSSF process and decreased from 512.25 to 268.69 mg glucose g-1 h-1. The relative abundance of Enterobacteriales and Lactobacillales in MTSSF process constituted from 10.30 to 71.73% and 2.34 to 16.68%, while in LTSSF process ranged from 3.16 to 41.06% and 8.43 to 57.39%, respectively. The relative abundance of Eurotiales in MTSSF process on days 10 to 24 decreased from 36.10 to 28.63%, while obviously higher in LTSSF process and increased from 52.00 to 72.97%. Furthermore, lower bacterial richness but higher fungal richness were displayed, markedly differences in bacterial communities but highly similarities in fungal communities were exhibited, during MTSSF process comparatively to the LTSSF process. Canonical correspondence analysis revealed microbial structure transition happened at thermophilic stages under environmental stress of moisture, pH, acidity, and pile temperature. These profound understanding might help to effectively control the traditional Daqu SSF process by adjusting relevant environmental parameters. PMID:27540378
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Duniere, Lysiane; Xu, Shanwei; Long, Jin; Elekwachi, Chijioke; Wang, Yuxi; Turkington, Kelly; Forster, Robert; McAllister, Tim A
2017-03-03
Describing the microbial populations present in small grain silage and understanding their changes during ensiling is of interest for improving the nutrient value of these important forage crops. Barley, oat and triticale forages as well as an intercropped mixture of the 3 crops were harvested and ensiled in mini silos for a period of 90 days, followed by 14 days of aerobic exposure. Changes in fermentation characteristics and nutritive value were assessed in terminal silages and bacterial and fungal communities during ensiling and aerobic exposure were described using 16S and 18S rDNA sequencing, respectively. All small grain silages exhibited chemical traits that were associated with well ensiled forages, such as low pH value (4.09 ± 0.28) and high levels of lactic acid (59.8 ± 14.59 mg/g DM). The number of microbial core genome operational taxonomic units (OTUs) decreased with time of ensiling. Taxonomic bacterial community profiles were dominated by the Lactobacillales after fermentation, with a notable increase in Bacillales as a result of aerobic exposure. Diversity of the fungal core microbiome was shown to also be reduced during ensiling. Operational taxonomic units assigned to filamentous fungi were found in the core microbiome at ensiling and after aerobic exposure, whereas the Saccharomycetales were the dominate yeast population after 90 days of ensiling and aerobic exposure. Bacterial and fungal orders typically associated with silage spoilage were identified in the core microbiome after aerobic exposure. Next Generation Sequencing was successfully used to describe bacterial communities and the first record of fungal communities throughout the process of ensiling and utilization. Adequately describing the microbial ecology of silages could lead to improved ensiling practices and the selection of silage inoculants that act synergistically with the natural forage microbiome.
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MoSfl1 Is Important for Virulence and Heat Tolerance in Magnaporthe oryzae
Li, Guotian; Zhou, Xiaoying; Kong, Lingan; Wang, Yuling; Zhang, Haifeng; Zhu, Heng; Mitchell, Thomas K.; Dean, Ralph A.; Xu, Jin-Rong
2011-01-01
The formation of appressoria, specialized plant penetration structures of Magnaporthe oryzae, is regulated by the MST11-MST7-PMK1 MAP kinase cascade. One of its downstream transcription factor, MST12, is important for penetration and invasive growth but dispensable for appressorium formation. To identify additional downstream targets that are regulated by Pmk1, in this study we performed phosphorylation assays with a protein microarray composed of 573 M. oryzae transcription factor (TF) genes. Three of the TF genes phosphorylated by Pmk1 in vitro were further analyzed by coimmunoprecipitation assays. One of them, MoSFL1, was found to interact with Pmk1 in vivo. Like other Sfl1 orthologs, the MoSfl1 protein has the HSF-like domain. When expressed in yeast, MoSFL1 functionally complemented the flocculation defects of the sfl1 mutant. In M. oryzae, deletion of MoSFl1 resulted in a significant reduction in virulence on rice and barley seedlings. Consistent with this observation, the Mosfl1 mutant was defective in invasive growth in penetration assays with rice leaf sheaths. In comparison with that of vegetative hyphae, the expression level of MoSFL1 was increased in appressoria and infected rice leaves. The Mosfl1 mutant also had increased sensitivity to elevated temperatures. In CM cultures of the Mosfl1 and pmk1 mutants grown at 30°C, the production of aerial hyphae and melanization were reduced but their growth rate was not altered. When assayed by qRT-PCR, the transcription levels of the MoHSP30 and MoHSP98 genes were reduced 10- and 3-fold, respectively, in the Mosfl1 mutant. SFL1 orthologs are conserved in filamentous ascomycetes but none of them have been functionally characterized in non-Saccharomycetales fungi. MoSfl1 has one putative MAPK docking site and three putative MAPK phosphorylation sites. Therefore, it may be functionally related to Pmk1 in the regulation of invasive growth and stress responses in M. oryzae. PMID:21625508
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Galitskaya, Polina; Biktasheva, Liliya; Saveliev, Anatoly; Grigoryeva, Tatiana; Boulygina, Eugenia; Selivanovskaya, Svetlana
2017-01-01
Composting is viewed as one of the primary methods to treat organic wastes. Co-composting may improve the efficiency of this treatment by establishing the most suitable conditions for decomposers than those present in the individual wastes. Given that bacteria and fungi are the driving agents of composting, information about the composition of their communities and dynamics during composting may improve reproducibility, performance and quality of the final compost as well as help to evaluate the potential human health risk and the choice of the most appropriate application procedure. In this study, the co-composting of mixtures containing two similar components (organic fraction of municipal solid waste and sawdust polluted by oil) and one discriminate component (sewage sludges of different origin) were investigated. Bacterial and fungal community successions in the two mixtures were analyzed during the composting process by determining the change in their structural dynamics using qPCR and 454 pyrosequencing methods in a lab experiment for a period of 270 days. During the initial composting stage, the number of 16S bacterial copies was (3.0±0.2) x 106 and (0.4±0.0) x 107 g-1, and the Rhodospiralles and Lactobacialles orders dominated. Fungal communities had (2.9±0.0) x105 and (6.1±0.2) x105 ITS copies g-1, and the Saccharomycetales order dominated. At the end of the thermophilic stage on the 30th day of composting, bacterial and fungal communities underwent significant changes: dominants changed and their relative abundance decreased. Typical compost residents included Flavobacteriales, Chitinophagaceae and Bacterioidetes for bacteria and Microascaceae, Dothideomycetes, Eurotiomycetes, Sordariomycetes, and Agaricomycetes for fungi. During the later composting stages, the dominating taxa of both bacterial and fungal communities remained, while their relative abundance decreased. In accordance with the change in the dominating OTUs, it was concluded that the
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Galitskaya, Polina; Saveliev, Anatoly; Grigoryeva, Tatiana; Boulygina, Eugenia; Selivanovskaya, Svetlana
2017-01-01
Composting is viewed as one of the primary methods to treat organic wastes. Co-composting may improve the efficiency of this treatment by establishing the most suitable conditions for decomposers than those present in the individual wastes. Given that bacteria and fungi are the driving agents of composting, information about the composition of their communities and dynamics during composting may improve reproducibility, performance and quality of the final compost as well as help to evaluate the potential human health risk and the choice of the most appropriate application procedure. In this study, the co-composting of mixtures containing two similar components (organic fraction of municipal solid waste and sawdust polluted by oil) and one discriminate component (sewage sludges of different origin) were investigated. Bacterial and fungal community successions in the two mixtures were analyzed during the composting process by determining the change in their structural dynamics using qPCR and 454 pyrosequencing methods in a lab experiment for a period of 270 days. During the initial composting stage, the number of 16S bacterial copies was (3.0±0.2) x 106 and (0.4±0.0) x 107 g-1, and the Rhodospiralles and Lactobacialles orders dominated. Fungal communities had (2.9±0.0) x105 and (6.1±0.2) x105 ITS copies g-1, and the Saccharomycetales order dominated. At the end of the thermophilic stage on the 30th day of composting, bacterial and fungal communities underwent significant changes: dominants changed and their relative abundance decreased. Typical compost residents included Flavobacteriales, Chitinophagaceae and Bacterioidetes for bacteria and Microascaceae, Dothideomycetes, Eurotiomycetes, Sordariomycetes, and Agaricomycetes for fungi. During the later composting stages, the dominating taxa of both bacterial and fungal communities remained, while their relative abundance decreased. In accordance with the change in the dominating OTUs, it was concluded that the
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Bio-Heat Is a Key Environmental Driver Shaping the Microbial Community of Medium-Temperature Daqu.
Xiao, Chen; Lu, Zhen-Ming; Zhang, Xiao-Juan; Wang, Song-Tao; Ao, Ling; Shen, Cai-Hong; Shi, Jin-Song; Xu, Zheng-Hong
2017-12-01
"Daqu" is a saccharifying and fermenting agent commonly used in the traditional solid-state fermentation industry (e.g., baijiu and vinegar). The patterns of microbial community succession and flavor formation are highly similar among batches, yet the mechanisms promoting temporal succession in the Daqu microbial ecology remain unclear. Here, we first correlated temporal profiles of microbial community succession with environmental variables (temperature, moisture, and titratable acidity) in medium temperature Daqu (MT-Daqu) throughout fermentation. Temperature dynamics significantly correlated ( P < 0.05) with the quick succession of MT-Daqu microbiota in the first 12 d of fermentation, while the community structure was relatively stable after 12 d. Then, we explored the effect of temperature on the MT-Daqu community assembly. In the first 4 d of fermentation, the rapid propagation of most bacterial taxa and several fungal taxa, including Candida , Wickerhamomyces , and unclassified Dipodascaceae and Saccharomycetales species, significantly increased MT-Daqu temperature to 55°C. Subsequently, sustained bio-heat generated by microbial metabolism (53 to 56°C) within MT-Daqu inhibited the growth of most microbes from day 4 to day 12, while thermotolerant taxa, including Bacillus , unclassified Streptophyta , Weissella , Thermoactinomyces , Thermoascus , and Thermomyces survived or kept on growing. Furthermore, temperature as a major driving force on the shaping of MT-Daqu microbiota was validated. Lowering the fermentation temperature by placing the MT-Daqu in a 37°C incubator resulted in decreased relative abundances of thermotolerant taxa, including Bacillus , Thermoactinomyces , and Thermoascus , in the MT-Daqu microbiota. This study revealed that bio-heat functioned as a primary endogenous driver promoting the formation of functional MT-Daqu microbiota. IMPORTANCE Humans have mastered the Daqu preparation technique of cultivating functional microbiota on