The yeast flora of some decaying mushrooms on trunks of living trees

Several ascomycetous and basidiomycetous yeasts were isolated from rotten mushrooms on the trunks of beech and tamarisk trees. One strain, identified as the novel species Cryptococcus allantoinivorans, assimilated allantoin as the sole carbon source. Phylogenetically it belongs to the C. laurentii complex, Papiliotrema bandonii being the closest relative. Some ascomycetous strains could not be distinguished from Pichia guillermondii, but deviated considerably in rDNA sequences. In addition to these species, both decaying mushrooms were inhabited by more common species, viz. Candida albicans, C. saitoana, Rhodotorula mucilaginosa, Trichosporon asahii, T. multisporum and T. porosum. The basidiomycetous yeasts, except R. mucilaginosa, assimilated some polysaccharides of plant origin.     

Isolation and characterization of ethanol-producing yeasts from fruits and tree barks

Aims:  Isolation and identification of yeasts converting xylose to ethanol.
Methods and Results:  A total of 374 yeasts were isolated from a variety of rotten fruits and barks of trees. Out of these, 27 yeast strains were able to assimilate xylose and produce 0·12–0·38 g of ethanol per gram of xylose. Based on phylogenetic analysis of D1/D2 domain sequence of LSU (Large Subunit) rRNA gene and phenotypic characteristics the ethanol-producing strains were identified as member(s) of the genera Pichia, Candida , Kluyveromyces, Issatchenkia, Zygosacchraomyces , Clavispora, Debaryomyces , Metschnikowia , Rhodotorula and Cryptococcus.
Conclusion:  Yeast strains producing ethanol from xylose have been isolated from a variety of rotten fruits and barks of trees and identified.
Significance and Impact of the Study:  Environmental isolates of yeasts which could convert xylose to ethanol could form the basis for bio-fuel production and proper utilization of xylan rich agricultural and forest wastes.     

Yeast populations on the tropical timber tree species Milicia excelsa

H. LI, E. VEENENDAAL, N.A. AB SHUKOR, J.R. COBBINAH AND C. LEIFERT. 1995. Yeast populations found on the tropical timber tree species Milicia excelsa showed very little diversity at the genus and species level. Of 62 isolates, 87% were Cryptococcus laurentii , 5% Candida humicola , 3% Candida curvata , 1.5% Candida membranaefaciens , 1.5% Rhodotorula minuta and 1.5% Rhodotorula rubra . Approximately half of the Crypt. laurentii strains had unusual metabolic profiles when compared with the Crypt. laurentii strains in the profile library of the APILAB yeast identification software. All isolated strains were non-pathogenic and did not show antagonism against Botrytis cinerea in an in vitro plate assay. However, three strains of Crypt. laurentii suppressed disease development of B. cinerea in a leaf disk bio-assay. This indicates that protection of leaves against opportunistic fungal diseases may be part of the ecological function of Crypt. laurentii populations on Milicia leaves and the potential of this yeast species for biological control.     

Effect of foliar disease on the epiphytic yeast communities of creeping bentgrass and tall fescue

The effect of mechanical wounding or foliar diseases caused by Sclerotinia homoeocarpa or Rhizoctonia solani on the epiphytic yeast communities on creeping bentgrass and tall fescue were determined by leaf washing and dilution plating. Total yeast communities on healthy bentgrass and tall fescue leaves ranged from 7.9 x 103 to 1.4 x 105 CFU.cm-2 and from 2.4 x 103 to 1.6 x 104 CFU.cm-2, respectively. Mechanically wounded leaves (1 of 2 trials) and leaves with disease lesions (11 of 12 trials) supported significantly larger communities of phylloplane yeasts. Total yeast communities on S. homoeocarpa infected or R. solani infected bentgrass leaves were 3.6-10.2 times and 6.2-6.4 times larger, respectively, than the communities on healthy leaves. In general, healthy and diseased bentgrass leaves supported larger yeast communities than healthy or diseased tall fescue leaves. We categorized the majority of yeasts as white-pigmented species, including Cryptococcus laurentii, Cryptococcus flavus, Pseudozyma antarctica, Pseudozyma aphidis, and Pseudozyma parantarctica. The percentage of pink yeasts in the total yeast community ranged from 2.6% to 9.9% on healthy leaves and increased to 32.0%-44.7% on S. homoeocarpa infected leaves. Pink-pigmented yeasts included Rhodotorula glutinis, Rhodotorula mucilaginosa, Sakaguchia dacryoidea, and Sporidiobolus pararoseus. Foliar disease significantly affected community size and composition of epiphytic yeasts on bentgrass and tall fescue.     

Utilization of nitriles by yeasts isolated from a Brazilian gold mine

Yeast strains from the genera Candida, Debaryomyces, Aureobasidium, Geotrichum, Pichia, Rhodotorula, Tremella, Hanseniaspora, and Cryptococcus were isolated from samples of a gold mine from liquid extraction circuit. These strains were tested for their ability to utilize acetonitrile at 12 mM as the sole nitrogen source. The yeasts that grew using acetonitrile at 12 mM were tested in the presence of acetonitrile, isobutyronitrile, methacrylnitrile, and propionitrile at concentrations of 12, 24, 48, 97, and 120 mM. One strain was selected for each nitrile and the concentration of nitrile in which the best growth occurred. Cryptococcus sp. strain UFMG-Y28 had a better growth on 120 mM propionitrile and 97 mM acetonitrile, Rhodotorula glutinis strain UFMG-Y5 on 48 mM methacrylnitrile, and Cryptococcus flavus strain UFMG-Y61 on 120 mM isobutyronitrile. The utilization of different nitriles and amides by yeast strains involves hydrolysis in a two-step reaction mediated by both inducible and intracellular nitrile hydratase and amidase.     

醇化烟叶酵母菌分离鉴定及其生物学特性研究

采用涂布培养法和富集培养法对醇化烟叶样品中酵母菌进行了分离,富集培养法分离到23株,涂布培养法分离到6株。29株酵母菌的生物学特性研究表明,其中果胶酶、蛋白酶、淀粉酶、脂酶、纤维素酶、酚类利用、木质素利用、尼古丁降解、发酵产物气味等试验呈阳性的菌株数分别是1、10、0、3、10、22、1、21和29株。利用ATB系统,将ATY1、ATY8和ATY27等3株酵母菌分别鉴定为黏红酵母(Rhodotorula glutinis)、罗伦隐球酵母(Cryptococcus laurentii)和粗壮假丝酵母(Candida valida),各菌株鉴定结果的符合率分别为99.4%、98.2%和89.9%。研究结果表明,醇化烟叶中酵母菌种群数量较小,但酵母菌的生物学特性有利于烟叶醇化,值得进一步深入研究。     

三种拮抗酵母菌对苹果采后青霉病的抑制效果

从苹果果实上分离获得的50余种酵母菌中筛选出了能够有效地抑制苹果青霉病(Penicilium expansum Link)的丝孢酵母(Trichosporon pullulans (Lindner.) Diddens and Lodder)、罗伦隐球酵母(Cryptococcus laurentii (Kuffer.) Skinner)和粘红酵母(Rhodotorula glutinis (Fresen.) F. C. Harrison).其中,抑病效果最好的T. pullulans 是一种用于采后果实生物防治的新型拮抗菌.研究了这三种拮抗菌不同浓度处理和外加营养物质以及与钙配合使用对苹果青霉病的抑病效果.实验结果表明:酵母菌浓度越高,抑病作用越强;外源营养物质的加入削弱了酵母菌的拮抗效果;在C. laurentii的细胞悬浮液中加入0.18 mol/L 的CaCl2能显著提高其抑病能力,但增加CaCl2 对T. pullulans 和R. glutinis 的抑病效果却没有明显作用.     

Seasonal dynamics in a yeast population on the Oxalis acetosella L. leaves

Analysis of an epiphytic yeast population on the leaves of the evergreen common wood sorrel Oxalis acetosella L. throughout a year showed that the density and the species composition of this population underwent regular seasonal changes. There were almost no yeasts on the young spring leaves. However, the yeast population on the mature leaves tended to increase in the autumn, reaching a maximum after the formation of continuous snow cover. Then the yeast population on the leaves tended to decrease, reaching a minimum in the spring. The species diversity of the yeasts was maximum in the autumn. The population of the epiphytic yeast species Cystofilobasidium capitatum, Rhodotorula fujisanensis, Leucosporium scottii, and Cryptococcus flavus peaked in the autumn. On the other hand, the population of the widespread epiphytic species Cryptococcus laurentii on the wood sorrel leaves peaked in January. The relative abundance of the red-pigmented phytobionts Rhodotorula glutinis and Sporobolomyces roseus virtually did not change throughout the year. The relative abundance of the euribiotic species Cryptococcus albidus showed irregular monthly variations. The data obtained show that the epiphytic microbial population of various plants can be comprehensively studied only by analyzing this population throughout the vegetative period of the plants.     

Presence of pathogenic yeasts in the feces of the semi-domesticated pigeon (Columba livia, Gmelin 1789, urban type) from the city of Turin

The results of a survey on the presence of pathogenic yeasts in pigeon droppings collected in Turin, are shown. The study was carried out in 8 densely populated areas, where human-animal contact is highest. A total of 427 pigeon dropping samples, most of which fresh, were collected. 550 yeast colonies, clinically interesting or at least pathologically significant, were isolated by the identification routine methods. The yeasts belong to the following species: Candida albicans, C. humicola, C. krusei, C. guillermondii, C. lypolitica, C. lambica, C. parapsilosis, C. tropicalis, C. rugosa, C. zeylanoides, Cryptococcus albidus, C. laurentii, C. neoformans, Hansenula anomala, Geotrichum sp., Kloekera apiculata, Rhodotorula glutinis, R. rubra, Saccharomyces cerevisiae, Torulopsis candida, T. glabrata, Trichosporon beigelii, T. capitatum, T. cutaneum, T. pullulans.     

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%。     

Alkalitolerant yeasts from natural biotopes

Using a solid nutrient medium containing alkaline buffer (pH 10) and an antibiotic, alkalitolerant yeasts were isolated from samples of soda-rich saline soils (solonchaks) of Armenia (Arazdayan) and the Transbaikal Region (the Kungur Steppe). The species diversity of the yeast populations of the tested soda-rich soils was relatively insignificant. They only contained alkalitolerant representatives of asporogenic capsulated yeasts belonging to the species Cryptococcus laurentii, C. albidus, Rhodotorula glutinis, R. mucilaginosa, and Sporobolomyces roseus. C. laurentii representatives clearly dominated the isolates obtained, their number exceeding that of the other species by 2-3 orders of magnitude. All of the isolates grew on acidic wort agar, suggesting that they did not include obligate alkaliphiles.     

Effects of pesticides on yeasts isolated from agricultural soil

The effect of six various pesticides on the growth of yeasts isolated from agricultural soil was investigated. Two herbicides (with the effective substances lactofen and metazachlor), two fungicides (with the effective substances fluquinconazole and prochloraz), and two insecticides (with the effective substances cypermethrin + chlorpyrifos and triazamate) were tested. It is evident that there are considerable differences in inhibition effects of studied pesticides. The fungicide with the effective substance prochloraz inhibited the growth of majority of yeast strains. The insecticide triazamate at concentration 0.6 mM restricted or inhibited growth of all tested strains. The strains of the genus Cryptococcus were the most sensitive to pesticides, while the strains of the species Cystofilobasidium capitatum, Debaryomyces occidentalis var. occidentalis, and Trichosporon cutaneum were the most resistant.     

Yeasts associated with fresh and frozen pulps of Brazilian tropical fruits

The occurrence of yeasts on ripe fruits and frozen pulps of pitanga (Eugenia uniflora L), mangaba (Hancornia speciosa Gom.), umbu (Spondias tuberosa Avr. Cam.), and acerola (Malpighia glaba L) was verified. The incidence of proteolytic, pectinolytic, and mycocinogenic yeasts on these communities was also determined. A total of 480 colonies was isolated and grouped in 405 different strains. These corresponded to 42 ascomycetous and 28 basidiomycetous species. Candida sorbosivorans, Pseudozyma antarctica, C. spandovensis-like, C. spandovensis, Kloeckera apis, C. parapsilosis, Rhodotorula graminis, Kluyveromyces marxianus, Cryptococcus laurentii, Metchnikowia sp (isolated only from pitanga ripe fruits), Issatchenkia occidentalis and C. krusei (isolated only from mangaba frozen pulps), were the most frequent species. The yeast communities from pitanga ripe fruits exhibited the highest frequency of species, followed by communities from acerola ripe fruits and mangaba frozen pulps. Yeast communities from frozen pulp and ripe fruits of umbu had the lowest number of species. Except the yeasts from pitanga, yeast communities from frozen pulp exhibited higher number of yeasts than ripe fruit communities. Mycocinogenic yeasts were found in all of the substrates studied except in communities from umbu ripe fruits and pitanga frozen pulps. Most of the yeasts found to produce mycocins were basidiomycetes and included P. antarctica, Cryptococcus albidus, C. bhutanensis-like, R. graminis and R. mucilaginosa-like from pitanga ripe fruits as well as black yeasts from pitanga and acerola ripe fruits. The umbu frozen pulps community had the highest frequency of proteolytic species. Yeasts able to hydrolyse casein at pH 5.0 represented 38.5% of the species isolated. Thirty-seven percent of yeast isolates were able to hydrolyse casein at pH 7.0. Pectinolytic yeasts were found in all of the communities studied, excepted for those of umbu frozen pulps. The highest frequency of pectinolytic activity was found in mangaba frozen pulp communities. Around 30% of all isolates produced pectinases. The ability to split arbutin was observed in all communities ranging from 8% in yeasts from pitanga frozen pulps to 40.6% in acerola ripe fruit communities. Among 432 species tested, 125 were active for beta-glucosidase production, and Kloeckera apis, P. antarctica, C. sorbosivorans, and C. spandovensis-like were the most active species.     

Apple tissue culture contamination by <Emphasis Type="Italic">Rhodotorula</Emphasis> spp.: Identification and prevention

Summary Shool cultures of apple cv. Pinova were contaminated with faint pink pigmented yeast. Yeast isolates were identified as Rhodotorula slooffiae with standard physiological methods and molecular analysis. Growth of isolated yeasts was tested against different fungicides. The following fungicides inhibited the growth of yeast isolates, and were not phytotoxic to apple shoots at concentrations lower than the minimal phytotoxic concentrations (MPC): ProClin^? 300, mancozeb, triforine, myclobutanil, thiabendazole, mancozeb+zoxamid, and silver nitrate. Some fungicides inhibited growth of yeasts, but were phytotoxic. These included miconazole, PPM^™, copper sulfate, potassium sorbate, and cycloheximide. Benomyl was not phytotoxic, but was effective only at high doses. Decontamination of shoots was achieved using a combination of two treatments. Shoots were first soaked in half-strength Murashige and Skoog (MS) liquid medium containing silver nitrate (588μM) and Silvet 77 (0.01%) for 1–2h, and then transferred to a solidified MS medium containing both mancozeb (15mgl⁻¹) and thiabendazole (40mgl⁻¹).     

On the occurrence of various species of yeast in nature

Summary A number of yeasts were isolated from various natural sources such as slime fluxes of trees, insects and insect frass, flowers and similar substrata. Several of the isolates represented species described in recent years. The additional isolations reported here contributed additional knowledge regarding the natural habitat of some of the species. Conclusions are offered regarding the ecology ofSaccharomyces kluyveri, S. phaselosporus, S. rosei, S. veronae, S. wickerhamii, Hansenula californica, H. mirakii, H. minuta, Pichia kluyveri, P. pastori, P. rhodanensis, P. silvestris, P. vanriji, Candida albicans, C. claussenii, Torulopsis glabrata, T. candida, Cryptococcus albidus, Cr. diffluens, Cr. laurentii, Rhodotorula graminis, Rh. texensis, andAscocybe grovesii. Various other species are listed in tabular form and by isolation source.     

Identity and biodegradative abilities of yeasts isolated from plants growing in an arid climate

Plants harvested in the Canary Islands Lanzarote and Fuerteventura were analyzed for the yeasts inhabiting their surface. Half of the isolates (22 out of 44) were identified as Debaryomyces hansenii. Black ascomycetes, viz. Hortaea werneckii and two Hormonema species were represented by 7 strains. Basidiomycetous yeasts, viz. Cryptococcus sp. (8 strains), Rhodotorula sp. (5 strains), Cerinosterus cyanescens (1 strain) and Pseudozyma sp. (1 strain) constituted a minority of 33%. Thirty strains were screened for their ability to assimilate various plant constituents including lipids of the cuticle and the cell membrane, hemicelluloses, nitrogenous compounds (protein, nucleic acids, amino acids) and benzene compounds. All strains were able to assimilate or to hydrolyze lipids, lecithin included. Many strains of D. hansenii, H. dematioides, H. werneckii, C. cyanescens, Cr. laurentii, Pseudozyma sp. and Rh. glutinis were proteolytic. Hemicelluloses like xylan and pectin were assimilated by black ascomycetous yeasts, Cryptococcus sp., Pseudozyma sp. and Rh. glutinis. Ferulic and hydroxycinnamic acids, gallic and tannic acids were assimilated by some strains of H. dematioides, C. cyanescens, Pseudozyma sp. and Rhodotorula sp.     

Psychrophilic yeasts in glacial environments of Alpine glaciers

The presence of psychrophilic yeasts in supra- and subglacial sediments, ice and meltwater collected from two glaciers of the Italian Alps (Forni and Sforzellina-Ortles-Cevedale group) was investigated. After incubation at 4 degrees C, subglacial sediments contained from 1.3 x 10(3) to 9.6 x 10(3) CFU of yeasts g(-1). The number of yeast cells in supraglacial sediments was c. 10-100-fold lower. A significant proportion of isolated yeasts exhibited one or more extracellular enzymatic activities (starch-degrading, lipolytic, esterolytic, proteolytic and pectinolytic activity) at 4 degrees C. Selected isolates were able to grow at 2 degrees C under laboratory-simulated in situ conditions. In all, 106 isolated yeasts were identified by MSP-PCR fingerprinting and 26S rRNA gene sequencing of the D1/D2 region as belonging to 10 species: Aureobasidium pullulans, Cryptococcus gilvescens (over 50% of the total), Cryptococcus terricolus, Mrakia gelida, Naganishia globosa, Rhodotorula glacialis, Rhodotorula psychrophenolica, Rhodotorula bacarum, Rhodotorula creatinivora and Rhodotorula laryngis. Four strains, all belonging to a new yeast species, yet to be described, were also isolated.     

田间应用拮抗酵母菌对甜樱桃果实采后病害的防治效果

研究了应用拮抗酵母菌丝孢酵母(Trichosporon pullulans(Lindner.)Diddens et Lodder)、罗伦隐球酵母(Cryptococcus laurentii(Kuffer.)Skinner)和粘红酵母(Rhodotorula glutinis(Fresenius)Harrison)后拮抗菌在果实表面的繁殖能力以及对不同贮藏条件下甜樱桃(Pranus avivum L.cv.Hongdeng)果实采后病害的防治效果.酵母菌的使用浓度为1×108CFU/mL.结果表明,田间3种拮抗菌都能够在果实表面增值,但是只有C.laurentii和R.glutinis能够持续稳定地生长.C.laurentii的抑病效果最好,它对田间环境和采后低温低氧及高CO2都具有很强的适应能力.     

The distribution of pyrophosphatidic acid in nature.

The occurrence of a novel phospholipid, pyrophosphatidic acid, in the lipid extracts of yeasts (23 species), bacteria (E. coli), algae (chlorella), mammalia (human, rabbit, guinea pig, and mouse), insect (cockroach), fish (carp), mollusc (clam), and spermatophyta (spinach) was investigated. Pyrophosphatidic acid was found exclusively in the lipid extracts of several kinds of yeast species, but not in other normal living species (animals, plants, and microorganisms) so far investigated. All of the yeast species containing this lipid belong to the asporogenous yeasts (Cryptococcus neoformans CBS-132, Cryptococcus laurentii Z 6-5, Rhodotorula glutinis H 3-9-1, Rhodotorula rubra AY-2, Kloeckera apiculata KK-3, and Trichosporon cutaneum KC 4-3), and ballistosporogenous yeast (Sporobolomyces salmonicolor WF 174). In contrast, no detectable amount of pyrophosphatidic acid was found in the cellular lipids of ascosporogenous yeasts.     

Yeast communities associated with sugarcane in Campos, Rio de Janeiro, Brazil.

Yeast communities associated with sugarcane leaves, stems and rhizosphere during different phases of plant development were studied near Campos, in Rio de Janeiro, Brazil. Atmospheric temperature, soil granulometry and pH, and sugar cane juice degree Brix and pH were determined. Yeast communities associated with sugarcane were obtained after cellular extraction by shaking, blending and shaking plus sonication, and cultured on Yeast Nitrogen Base Agar plus glucose (0.5%) and Yeast Extract-Malt Extract Agar. No significant differences in yeast counts were found among the cellular extraction treatments and culture media. 230 yeast cultures were identified according to standard methods, and distinct yeast communities were found for each substrate studied. The prevalent species isolated from sugarcane were Cryptococcus laurentii, Cryptococcus albidus, Rhodotorula mucilaginosa and Debaryomyces hansenii.