云南程海湖酵母菌多样性及应用

【目的】针对云南丽江永胜县境内程海湖环境的特殊性,研究高原湖泊环境中酵母菌的多样性,初步探索程海湖环境中酵母菌的利用价值。【方法】对程海湖的湖水和其周边土壤样品中的酵母菌进行分离;应用26S rDNA的D1/D2区域序列分析,并结合形态及生理生化指标对分离获得的酵母菌进行鉴定;采用筛选培养基对已鉴定酵母菌进行产酶定性实验,分析高原湖泊中酵母菌的多样性及可应用性。【结果】分离得到酵母菌64株,对其中63株进行鉴定,归属于9个属22个种(包括4个疑似新种或新变种);地霉属Geotrichum和隐球酵母属Cryptococcus是2种环境中的共有属;在产酶活性筛选中发现有9株产胞外酶活性的菌株,其中YM24373既产蛋白酶又可产淀粉酶。【结论】研究结果显示程海湖中酵母菌组成具有较为丰富的多样性,其应用价值值得进一步研究。     

Leucosporidium fellii sp. nov., a basidiomycetous yeast that degrades L(+)-tartaric acid

A new species of basidiomycetous yeast Leucosporidium fellii was isolated from soil in Portugal on a selective L(+)-tartaric acid medium. This yeast is self-sporulating but forms dikaryotic hyphae with clamp connections and is presumably homothallic. It differs from the type strain of Leucosporidium scottii in its life cycle, assimilation pattern and guanine-cytosine content and from the other described Leucosporidium species by additional characteristics.     

石河子不同树龄蟠桃土壤中可培养酵母多样性分析及功能酵母的筛选

为了探究新疆本土蟠桃园可培养酵母菌多样性,并挖掘功能酵母资源,本研究以新疆石河子蟠桃园3年、8年、15年树龄的根际和非根际土壤以及桃树叶片为材料,经过传统的分离培养方法获得可培养的酵母菌菌株,并进行形态学、生理生化以及26S r DNA的D1/D2区序列分析,共获得可培养酵母菌129株,从属于12个属17个种,其中子囊菌酵母为优势菌群,占分离属的88%,分布于威克汉姆酵母属(Wickerhamomyces),Vanrija属,Barnettozyma属和有孢圆酵母属(Torulaspora)等11个属的15个种。担子菌占分离属的12%,分布于隐球酵母属(Cryptococcus)的2个种。其中优势属威克汉姆酵母属,包括异常威克汉姆酵母(W. anomalus)和W. pijperi两个种,占总比例的33%,优势种异常威克汉姆酵母所占总株数比例为17%。从可培养酵母中共筛选出23株功能酵母,其中富硒酵母21株,优势种为白地霉(Galactomyces candidum),产蛋白酶酵母2株均属于隐球酵母属的Cryptococcus albidus。结果表明,新疆桃园中蕴含丰富的酵母菌资源,非根际土壤中的酵母多样性大于根际及叶片酵母多样性,且分离得到富硒酵母及产蛋白酶酵母。本研究挖掘了新疆本土可培养酵母菌资源,同时也为功能酵母的开发和利用提供理论指导。     

Degradation of benzene compounds by yeasts in acidic soils

Attemps were made to demonstrate the role of yeasts in the degradation of benzene compounds under natural soil conditions. Yeasts were isolated from acidic sandy soil supplied with benzene compounds. For this purpose the slant culture method was used. Growth on the benzene compounds took place on solid growth media at 10°C. Several yeast species were isolated: Leucosporidium scottii, Rhodotorula aurantiaca, Rhodotorula mucilaginosa, Trichosporon dulcitum, Trichosporon moniliiforme and Schizoblastosporion starkeyi-henricii. Cryptococcus humicolus and Cryptococcus laurentii were isolated from liquid enrichment cultures. All these strains assimilated several benzene compounds in pure culture.Cresol removal from contaminated soil was speeded up by inoculation with Rhodotorula aurantiaca G36. It was demonstrated that this yeast utilized this compound in competition with the soil microflora.     

Cell surface topography of Candida and Leucosporidium yeasts as revealed by scanning electron microscopy.

The cell surface topography of the following yeast strains was examined by scanning electron microscopy: Candida slooffii, C. lipolytica, Leucosporidium frigidum, and L. nivalis. Multipolar and lateral budding were observed in the Candida yeasts in contrast to bipolar budding in the Leucosporidium species. The cell surface topography and the morphology of the bud and birth scars in these yeasts differed markedly. Apart from the bud and birth scars, the cells of C. slooffii showed a relatively smooth topography. The bud scars were seen as a circular ridge of wall material surrounding a markedly convex scar plug. Birth scars were raised, rounded structures, which appeared to distend upon cell growth. In contrast, bud scars of C. lipolytica were platelike, lacked a distinct annulus of wall material, and were much less protuberent than those of C. slooffii. Birth scars were a more permanent feature of these cells. The topography of Leucosporidium yeasts was characterized by the presence of numerous protrusions on the cell surface. In some cases, the entire cell surface was covered by these protrusions. There appeared to be some correlations between the age of the cell and the extent of surface protrusions and degree of surface convolution...     

Effect of medium composition on amylase production by some starch-degrading yeasts

Abstract The production of extracellular amylase activity by a number of recently described amyloytic yeast species, viz. Candida homilentoma, C. silvanorum, C. tsukubaensis, Cryptococcus flavus, Leucosporidium capsuligenum, Filobasidium capsuligenum and Trichosporon pullulans , was investigated. The effects on amylase secretion of pH, different carbon sources (glucose, maltose, dextrin, soluble starch) and of various nitrogen sources [yeast nitrogen base, yeast extract, corn steep liquor (CSL)] were compared for these yeasts.     

红富士苹果园酵母多样性研究

从北京顺义和山东泰安红富士苹果园采集果实、叶片、树皮和土壤等不同基物,分离酵母菌,利用26S rDNA的D1/D2区域序列分析并结合形态学特征和SSCP分析对这些菌株进行了分类学研究,探讨了苹果园酵母的物种多样性及其分布。北京苹果园共分离酵母菌129株,鉴定为13属21种,优势属为Pichia（4个种）,Cryptococcus（3个种）,Pseudozyma（3个种）,子囊菌占较大优势,分布于8属12种,占总种数的57.1%。山东苹果园共分离酵母291株,鉴定为13属26种,优势属为假丝酵母Candida（6个种）,毕赤酵母Pichia（4个种）和隐球酵母Cryptococcus（3个种）,并且子囊菌占较大优势,分布于7属17种,占总种数的65.4%。     

A new species of psychrophilic basidiomycetes yeast Leucosporidium fasciculatum sp. Nov

A psychrophilic yeast with a basidiomycetous developmental cycle and properties corresponding to the genus Leucosporidium Fell et al. was isolated from the fruiting body of the edible spring mushroom Gyromitra esculenta Pers. picked near Moscow. However, the isolate differed from all Leucosporidium species described to date in a number of characteristics. The results of the study of the developmental cycle and of the cultural, morphological, physiological, and biochemical properties of the new isolate, strain KBP Y-3696, allow it to be assigned to a new species of the genus Leucosporidium.     

Yeast communities associated with the bulk-soil, rhizosphere and ectomycorrhizosphere of a Nothofagus pumilio forest in northwestern Patagonia, Argentina

Soil microorganisms play an important role in soil quality and they interact closely with vegetation. Little is known about yeast diversity and function in forest soil ecosystems and their interactions with other biotic soil components, particularly in the mycorrhizosphere. We studied the diversity of yeasts inhabiting the bulk-soil, rhizosphere and ectomycorrhizosphere of a Nothofagus pumilio forest in Nahuel Huapi National Park (Bariloche, Argentina). Ectomycorrhizal infection was observed in all N. pumilio trees studied. A total of 126 yeast isolates were obtained, including 18 known and three possibly new species. Basidiomycetous yeasts were predominant in all soil fractions, and the most frequently isolated species was Cryptococcus podzolicus. Diversity indices and multivariate analyses were used to study and compare yeast communities in the bulk-soil, rhizosphere and ectomycorrhizosphere. Yeasts able to ferment glucose were found associated with the rhizosphere. Many of the recovered yeast species were associated with lignocelluloses compound degradation, which suggest that yeast plays an important role as a decomposer in these forest soils. Each soil fraction has a distinct yeast assemblage related to their physiologic capacities and soil nutrient availability.     

Quantitative determination of indole-3-acetic acid in yeasts using high performance liquid chromatography—tandem mass spectrometry

High performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) was applied to the comprehensive analysis of the ability of yeast strains to synthesize a plant hormone indole-3-acetic acid (IAA). A total of 124 strains (37 species) of yeasts isolated from various regions and substrates were studied. Testing of IAA production showed that 92% strains were capable of IAA synthesis. The results indicated that, in general, ascomycetous yeasts were more active auxin producers than basidiomycetous ones. Geographically, strains from tropical regions were the most active IAA producers. Analysis of the substrate variability of the strains showed higher auxin production (on average) by the yeasts isolated from plants compared to the soil isolates, indicating a specific regulatory role of the plant yeast population.     

Study on the effects of near-future ocean acidification on marine yeasts: a microcosm approach

Marine yeasts play an important role in biodegradation and nutrient cycling and are often associated with marine flora and fauna. They show maximum growth at pH levels lower than present-day seawater pH. Thus, contrary to many other marine organisms, they may actually profit from ocean acidification. Hence, we conducted a microcosm study, incubating natural seawater from the North Sea at present-day pH (8.10) and two near-future pH levels (7.81 and 7.67). Yeasts were isolated from the initial seawater sample and after 2 and 4 weeks of incubation. Isolates were classified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and representative isolates were identified by partial sequencing of the large subunit rRNA gene. From the initial seawater sample, we predominantly isolated a yeast-like filamentous fungus related to Aureobasidium pullulans, Cryptococcus sp., Candida sake, and various cold-adapted yeasts. After incubation, we found more different yeast species at near-future pH levels than at present-day pH. Yeasts reacting to low pH were related to Leucosporidium scottii, Rhodotorula mucilaginosa, Cryptococcus sp., and Debaryomyces hansenii. Our results suggest that these yeasts will benefit from seawater pH reductions and give a first indication that the importance of yeasts will increase in a more acidic ocean.     

Leucosporidium egoroviorum f.a., sp. nov., a New Yeast Species Isolated from Zucchini

Microbiology - Leucosporidium egoroviorum f.a., sp. nov., a new anamorphic species of the basidiomycetous yeasts, was isolated as an endophyte from the fruits of Cucurbita pepo subsp. pepo...     

Occurrence and dominance of yeast species in naturally fermented milk from the Tibetan Plateau of China

To determine which yeasts are present in the naturally fermented milks of China, 69 samples made by the nomads of Tibet were collected from the Tibetan Plateau in China. From these samples, 225 strains of yeast were isolated and identified using conventional microbiological analysis and gene sequencing analysis of the D1/D2 domain of the large subunit (26S) ribosomal DNA. The results showed that the total concentration of yeasts in these samples ranged from 5.01 to 8.97 log10 colony-forming units (CFU)/mL (6.91?± 1.02 log10 CFU/mL; mean?± SD). The number of cultivable yeasts was higher in the samples from Qinghai (7.55?± 0.75 log10 CFU/mL) than those from Tibet (6.21?± 0.79 log10 CFU/mL, P?< 0.05). Moreover, there were 15 phylotypes in these 69 samples. Among these phylotypes, Kluyveromyces marxianus (49.3%, frequency percentage), Saccharomyces cerevisiae (62.3%), and Pichia fermentans (46.4%) appeared frequently and can be considered the most common culturable species in naturally fermented milk products. Traditional fermented Mongolian cow milk featured a wide diversity of yeast species, including Issatchenkia orientalis, Kazachstania unisporus, Rhodotorula mucilaginosa, Candida pararugosa, Torulaspora delbrueckii, Geotrichum sp., Kazachstania unisporus, Geotrichum fragrans, Debaryomyces hansenii, Yarrowia lipolytica, Trichosporon gracile, and Pichia membranifaciens. This study provides new data on yeast composition in naturally fermented milk and shows the yeast biodiversity of fermented milk products from the Tibetan Plateau of China.     

Indole-3-Acetic Acid-Producing Yeasts in the Phyllosphere of the Carnivorous Plant Drosera indica L

Yeasts are widely distributed in nature and exist in association with other microorganisms as normal inhabitants of soil, vegetation, and aqueous environments. In this study, 12 yeast strains were enriched and isolated from leaf samples of the carnivorous plant Drosera indica L., which is currently threatened because of restricted habitats and use in herbal industries. According to similarities in large subunit and small subunit ribosomal RNA gene sequences, we identified 2 yeast species in 2 genera of the phylum Ascomycota, and 5 yeast species in 5 genera of the phylum Basidiomycota. All of the isolated yeasts produced indole-3-acetic acid (IAA) when cultivated in YPD broth supplemented with 0.1% L-tryptophan. Growth conditions, such as the pH and temperature of the medium, influenced yeast IAA production. Our results also suggested the existence of a tryptophan-independent IAA biosynthetic pathway. We evaluated the effects of various concentrations of exogenous IAA on yeast growth and observed that IAA produced by wild yeasts modifies auxin-inducible gene expression in Arabidopsis. Our data suggest that yeasts can promote plant growth and support ongoing prospecting of yeast strains for inclusion into biofertilizer for sustainable agriculture.     

Molecular identification and characterization of wine yeasts isolated from Tenerife (Canary Island, Spain)

AIMS: The present study was aimed at the identification, differentiation and characterization of indigenous yeasts isolated from Tenerife vineyards (viticulture region that has never been characterized before). Microbiota were studied from 14 samples taken during fermentations carried out in the 2002 vintage, from 11 wineries belonging to five wine regions on Tenerife Island. METHODS AND RESULTS: Yeasts' strains were identified and characterized through restriction analysis of the 5.8S-internal transcribed spacer region and the mitochondrial DNA. At the beginning of alcoholic fermentation, 26 yeast species were found, where 14 species were present in significant frequencies in only one sample. Likewise, the Saccharomyces cerevisiae strains isolated are very specific, as they were only present in one wine region. CONCLUSIONS: There were isolated specific yeasts from each region on Tenerife Island. The founded yeasts may be responsible for distinctive and interesting properties of the studied wines. SIGNIFICANCE AND IMPACT OF THE STUDY: This study forms part of an extensive taxonomic survey within the ecological framework of vineyards in Tenerife. This investigation is an essential step towards the preservation and exploitation of the hidden oenological potential of the untapped wealth of yeast biodiversity in the grape growing regions of this island. The results obtained demonstrate the value of using molecular genetic methods in taxonomic and ecological surveys. The results also shed some light on the ecology and oenological potential of S. cerevisiae strains isolated from this unique environment.     

Potentially pathogenic yeast isolated from the throat and cloaca of an Arctic colonial seabird: the little auk (Alle alle)

Yeasts are a distinctive group of microfungi, but compared to other microorganisms, their ecological function and biodiversity are poorly known. This is especially so where polar ecosystems are concerned. With climate changes and increasing pollution levels in the Arctic, it can be anticipated that there will be an increase in the prevalence and diversity of fungi colonizing live organisms. With these changes, it is crucial to investigate and monitor species diversity and prevalence of fungi in this fragile environment. In this study, yeasts were examined from throat and cloaca of a small colonial seabird, the little auk (Alle alle), a keystone species in the Arctic ecosystem. Samples were collected from 94 adults and 17 nestlings in breeding colony in Magdalenefjorden (NW Spitsbergen) in 2009. In total, twelve species of yeast from eight genera were found in 12 % of the samples, with the Dipodascus genus being the most prevalent. All yeast species were found in the adults, but only one species, Cryptococcus macerans, was found in a single nestling. In individuals where fungus was isolated, it was only isolated from either the throat or the cloaca, except for two cases, where fungus was found in both throat and cloaca. The presence of yeast was not related to sex but age of the birds, with adults being more prone to colonization by yeasts than the nestlings. The relatively low prevalence and diversity of yeast in little auks suggest that these birds are random carriers of fungi, with minor health impacts.     

云南高原湖泊杞麓湖冬季可培养酵母菌多样性分析

【目的】探究云南杞麓湖酵母菌群落结构及其与环境因子的相互关系。【方法】采用原位培养方法对杞麓湖14个水样进行酵母菌分离,应用26S r DNA D1/D2区域序列分析,并结合形态及生理生化指标将对分离获得的酵母菌进行鉴定,运用软件bio-dap和Canoco分析酵母菌类群的丰富度及其与环境因子间的相互关系。【结果】从杞麓湖中分离得到321株酵母菌,鉴定为14个属27个种和1个潜在的新类群。Rhodosporidium kratochvilovae和出芽短梗霉(Aureobasidium pullulans)是优势种,分别为总菌株数的29.6%和16.8%。水体总磷含量是影响产色素红冬孢酵母属(Rhodosporidium)分布的重要环境因子,而p H为隐球酵母属(Cryptococcus)分布的一个重要选择条件。【结论】杞麓湖酵母菌具有较为丰富的群落多样性。     

Isolation and characterization of thermotolerant yeasts for the production of second-generation bioethanol

The purpose of this study was to isolate, identify, and characterize the thermotolerant yeasts for use in high-temperature ethanol fermentation. Thermotolerant yeasts were isolated and screened from soil samples collected from the Mekong Delta, Vietnam, using the enrichment method. Classification and identification of the selected thermotolerant yeasts were performed using matrix-assisted laser desorption ionization/time-of-fight mass spectrometry (MALDI-TOF/MS) and nucleotide sequencing of the D1/D2 domain of the 26S rDNA and the internal transcribed spacer (ITS) 1 and 2 regions. The ethanol production by the selected thermotolerant yeast was carried out using pineapple waste hydrolysate (PWH) as feedstock. A total of 174 yeast isolates were obtained from 80 soil samples collected from 13 provinces in the Mekong Delta, Vietnam. Using MALDI-TOF/MS and nucleotide sequencing of the D1/D2 domain and the ITS 1 and 2 regions, six different yeast species were identified, including Meyerozyma caribbica, Saccharomyces cerevisiae, Candida tropicalis, Torulaspora globosa, Pichia manshurica, and Pichia kudriavzevii. Among the isolated thermotolerant yeasts, P. kudriavzevii CM4.2 displayed great potential for high-temperature ethanol fermentation. The maximum ethanol concentration (36.91 g/L) and volumetric ethanol productivity (4.10 g/L h) produced at 45 °C by P. kudriavzevii CM4.2 were achieved using PWH containing 103.08 g/L of total sugars as a feedstock. These findings clearly demonstrate that the newly isolated thermotolerant yeast P. kudriavzevii CM4.2 has a high potential for second-generation bioethanol production at high temperature.     

Nucleotide sequence analysis of a variable region of the large subunit rRNA for identification of marine-occurring yeasts

A 230-nucleotide region of the large subunit (LSU) ribosomal RNA was examined to determine whether signature nucleotide sequences could be used for species identifications of basidiomycetous yeasts. Multiple strains of genetically defined heterothallic species ofRhodosporidium, Leucosporidium, Cystofilobasidium, andSporidiobolus demonstrated that nucleotide sequences within these species are homologous and that differences between species range from 1 to 20 or more bases. Also included in this study were several homothallic species of these teleomorphic genera and some anamorphs assigned toRhodotorula andCandida. Those results indicated close relationships among certain homothallic species, particularly in the genusMrakia, and potential relationships of homothallic and anamorphic strains to several teleomorphs. The data suggest that LSU sequences can be used for yeast identifications with the possible exception of closely related homothallic species.     

Diversity of Cryptococcus and Dioszegia yeasts (Basidiomycota) inhabiting arbuscular mycorrhizal roots or spores

The genera Cryptococcus and Dioszegia contain basidiomycetous yeasts found in a wide range of habitats. Primers to amplify the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA (nrDNA) of arbuscular mycorrhizal fungi (AMF) also allow detecting members of this yeast group. Here we report the results of a sequence analysis using maximum parsimony on a set of 50 ITS sequences of yeasts associated with AMF structures (roots of 26 plant species, AM spores) from six field sites in Central Germany. Among 10 separated taxa, respectively five in the Tremellales and two in the Filobasidiales had unknown sequences. Therefore it was not possible to assign these sequences to any known species. The study indicates that exploring the diversity of Cryptococcus and Dioszegia in soil habitats with molecular methods might enlarge the actually estimated biodiversity of the group.