Psychrophilic yeasts isolated from marine fish

Yeasts were isolated from marine fish using low incubation temperatures. The isolates were screened for their ability to grow at 4 C and 30 C. Isolates growing at 4 C but not at 30 C were considered to be psychrophilic and were selected for further study. Approximately 25% of the isolates were in this category. The isolates comprised the following genera:Candida, Cryptococcus, Debaryomyces, Rhodotorula, Torulopsis andTrichosporon. Rhodotorula infirmo-miniata accounted for 50% of the isolates andTrichosporon pullulans 10%. Other species were present in numbers below the 10% level. The distribution of the species between the two sample areas is discussed. The vitamin requirements and optimum growth temperatures of the isolates were assessed.     

Yeast community survey in the Tagus estuary

The yeast community in the waters of the Tagus estuary, Portugal, was followed for over a year in order to assess its dynamics. Yeast occurrence and incidence were measured and this information was related to relevant environmental data. Yeast occurrence did not seem to depend upon tides, but river discharge had a dramatic impact both on the density and diversity of the community. The occurrence of some yeasts was partially correlated with faecal pollution indicators. Yeast isolates were characterized by microsatellite primed PCR (MSP-PCR) fingerprinting and rRNA gene sequencing. The principal species found were Candida catenulata, C. intermedia, C. parapsilosis, Clavispora lusitaniae, Debaryomyces hansenii, Pichia guilliermondii, Rhodotorula mucilaginosa and Rhodosporidium diobovatum. The incidence of these species was evaluated against the environmental context of the samples and the current knowledge about the substrates from which they are usually isolated.     

On the intestinal yeast flora of free living hippopotami(Hippopotamus amphibius), wart hogs(Phacochoerus aethiopicus) and bush pigs(Potamochoerus choeropotamus)

Summary From the faeces of 35 free-living hippopotami (Hippopotamus amphibius), sampled in south Mozambique, 13 yeast isolates were obtained, distributed as shown (in brackets) among the following species:Candida guilliermondii (3),C. tropicalis (2),C. krusei (2),C. brumptii (1),Debaryomyces globosus (2),Trichosporon cutaneum (1), not identified (2). From the caecal contents of 9 free-living wart hogs (Phacochoerus aethiopicus), shot in north Mozambique 5 isolates were obtained:C. albicans (2),C. lusitaniae (2),C. parapsilosis (1). From the caecal contents of 9 free-living bush pigs (Potamochoerus choeropotamus), shot in north Mozambique, 18 isolates were obtained:C. krusei (6),C. tropicalis (5),Pichia fermentans (2),C. slooffii (2),C. albicans (1),Torulopsis glabrata (1),Trichosporon cutaneum (1). The low total yeast indices of the hippopotami (0.37) and the wart hogs (0.56) are believed to be correlated with the type of diet of these animals (rich in cellulose, poor in starch and simple carbohydrates). The bush pigs, which like the domestic pig, use a diet rich in starch and simple carbohydrates, had a very high total yeast index (2.00).Candida slooffii an obligate saprophyte of the digestive tract of domestic swine was found in two of the bush pig samples.     

Ascospore formation in yeasts related to Torulopsis candida

Ascospore formation was found in the type strains Torulopsis famata (Harrison) Lodder et Kreger van Rij, T. minor (Pollaci et Nannizi) Lodder and Candida flareri (Ciferri et Redaelli) Langeron et Guerra. The names of these species should be considered as a synonym of Debaryomyces hansenii (Zopf) Lodder et Kreger van Rij.     

Occurrence and Growth of Yeasts in Yogurts

Yogurts purchased from retail outlets were examined for the presence of yeasts by being plated onto oxytetracycline malt extract agar. Of the 128 samples examined, 45% exhibited yeast counts above 10³ cells per g. A total of 73 yeast strains were isolated and identified as belonging to the genera Torulopsis, Kluyveromyces, Saccharomyces, Candida, Rhodotorula, Pichia, Debaryomyces, and Sporobolomyces. Torulopsis candida and Kluyveromyces fragilis were the most frequently isolated species, followed by Saccharomyces cerevisiae, Rhodotorula rubra, Kluyveromyces lactis, and Torulopsis versatilis. The growth of yeasts in yogurts was related to the ability of the yeasts to grow at refrigeration temperatures, to ferment lactose and sucrose, and to hydrolyze milk casein. Most yeast isolates grew in the presence of 100 μg of sorbate and benzoate preservatives per ml. Higher yeast counts from yogurts were obtained when the yogurts were plated onto oxytetracycline malt extract agar than when they were plated onto acidified malt extract agar.     

The utilization of creatine and creatinine by some Debaryomyces species

Summary Strains of Debaryomyces hansenii, Deb. kloeckeri, Deb. subglobosus, Deb. nicotianae and their imperfect forms Torulopsis famata and T. candida were found to be able to use creatine and creatinine as a sole source of nitrogen. Most strains could assimilate creatine when tested by the auxanographic method, while creatinine was only assimilated in liquid medium. In several instances the reaction with creatine in the auxanogram was positive, and in the liquid medium negative.We have considered the taxonomic value of the utilization of creatine and creatine in the first place for distinction between the four Debaryomyces species, and in the second place for the differentiation of the four species as a group from other species.     

The oral yeast flora of 10-year-old schoolchildren

The yeast flora of the hard palate mucosa and pooled saliva of 122 schoolchildren (average age 9 years 10 months, 63 males, 59 females) has been studied in detail. Of the population sampled, 71.3% carried oral yeasts. The carriage was approximately 3 times greater in females than in males. The yeast isolates were Candida albicans 71% Saccharomyces spp. 19.7% and Candida tropicalis 8.6%. No isolates of Torulopsis spp. or Rhodotorula spp. were recovered. 71.5% of the Candida albicans isolates were serotype A and 26.3% were serotype B.     

致病酵母菌基因组多态性及亲缘关系的研究

致病酵母是条件致病菌感染中最常见的菌群。其属间、种间及种内的分型具有重要的流行病学及临床意义。以随机扩增多态性(Randomly Amplified Polymorphism DNA markers,RAPD)的方法对48株临床上常见的酵母菌属间、种间及种内基因组型的多态性进行了研究,并以多种引物扩增带型的相似性系数的高低来评价酵母菌之间的亲缘关系。结果表明:RAPD带型可清楚的显示出假丝酵母(Candida)及相关酵母属间、种间及种内的差异,亲缘关系的研究表明假丝酵母属与隐球菌属(Cryptococcus)、丝孢酵母属(Trichosporon)的相似性系数为80％,除季也蒙假丝酵母(C. guilliermondii)外,假丝酵母属中不同种间的相似性系数为82％～87％,同种不同株间的相似性系数>90％。大多数属、种基因组分型的结果和形态学分类结果相符。     

Ecology of pathogenic yeasts in Amazonian soil.

In an investigation of Amazonian soil as a natural reservoir for pathogenic fungi, 1,949 soil samples collected from diverse geographical and ecological settings of the Brazilian Amazon Basin were analyzed for the presence of non-keratinophilic fungi by the indirect mouse inoculation procedure and for the presence of keratinophilic fungi by the hair bait technique. All soil samples were acidic with low pH values. From 12% of the soil samples, 241 yeast and yeastlike isolates pertaining to six genera and 82 species were recovered, of which 63% were Torulopsis and 26% were Candida species. Nine fungi with known pathogenic potentials were encountered among 43% (104) of the isolates: T. glabrata, C. guilliermondii, C. albicans, C. pseudotropicalis, C. stellatoidea, C. tropicalis, Rhodotorula rubra, and Wangiella dermatitidis. The yeast flora was marked by species diversity, low frequency of each species, random geographical distribution, and an apparent lack of species clustering. The composition and distribution of the yeast flora in soil differed from those of the yeast flora harbored by bats, suggesting that the Amazonian external environment and internal bat organs act as independent natural habitats for yeasts.     

Ecology of pathogenic yeasts in Amazonian soil

In an investigation of Amazonian soil as a natural reservoir for pathogenic fungi, 1,949 soil samples collected from diverse geographical and ecological settings of the Brazilian Amazon Basin were analyzed for the presence of non-keratinophilic fungi by the indirect mouse inoculation procedure and for the presence of keratinophilic fungi by the hair bait technique. All soil samples were acidic with low pH values. From 12% of the soil samples, 241 yeast and yeastlike isolates pertaining to six genera and 82 species were recovered, of which 63% were Torulopsis and 26% were Candida species. Nine fungi with known pathogenic potentials were encountered among 43% (104) of the isolates: T. glabrata, C. guilliermondii, C. albicans, C. pseudotropicalis, C. stellatoidea, C. tropicalis, Rhodotorula rubra, and Wangiella dermatitidis. The yeast flora was marked by species diversity, low frequency of each species, random geographical distribution, and an apparent lack of species clustering. The composition and distribution of the yeast flora in soil differed from those of the yeast flora harbored by bats, suggesting that the Amazonian external environment and internal bat organs act as independent natural habitats for yeasts.     

Numerical taxonomic analysis of imperfect yeast species in Candida and Torulopsis shows no basis for generic separation

A numerical taxonomic analysis was performed on 79 phenotypic characters of 147 imperfect yeast species currently assigned to the genus Candida. The characters used were drawn from two monographs on yeast taxonomy. The analysis revealed 10 clusters of three or more species that were similar at the level of 75% or more, and seven clusters containing only one or two species. None of the 10 major clusters contained exclusively species that were traditionally assigned to the genus Torulopsis, while the 12 Candida species of basidiomycetous affinity fell into three clusters with only one species of ascomycetous affinity included. Statistical determination of the five most important differential characters for each cluster failed to show the property of pseudomycelium/mycelium formation as significant for any cluster. The study provides no evidence to support a distinction between taxa that were formerly divided between the genera Candida and Torulopsis and supports previous proposals that these genera should be fused.     

Response of

The fish prey consumed by New Zealand fur seals (Arctocephalus forsteri) was investigated by analysis of faeces collected between February and August at sites on the east and west coasts of South Island, New Zealand. Twelve species were identified from otoliths recovered from faeces. Lanternfish (Symbolophorus sp. and Lampanyctodes hectoris), the most frequent fish prey, comprised 79% of all otoliths, followed by anchovy (Engraulis australis) at 12%, ahuru (Auchenoceros punctatus) with 3.9%, and hoki (Macruronus novaezelandiae) at 3.7%. Of these species only hoki is commercially important. Regional and seasonal differences in the proportions of species were evident, and the results are compared with those from previous studies.     

Heat Resistance Studies on Yeast spp. Causing Spoilage in Soft Drinks

A test method to investigate the heat resistance of yeasts has been developed. The method was used to study the heat resistance of 120 yeast strains, representative of the fungal flora in soft drinks and certain acid food products: 35 asporogenous yeast strains ( Brettanomyces, Candida, Kloeckera, Rhodotorula and Torulopsis ) and 85 ascomycetous strains ( Debaryomyces, Hansenula, Kluyveromyces, Lodderomyces, Pichia, Saccharomyces and Saccharomycopsis ) were tested. Generally, asporogenous yeasts were found to be less heat resistant than ascomycetous types. The genus Saccharomyces showed the highest heat resistance, especially strains of the species Sacch. cerevisiae and Sacch. chevalieri . For an evaluation of the practical implications of these results additional studies on environmental factors influencing the heat resistance of ascomycetous yeast species are required.     

Isolation of proteolytic psychrotrophic yeasts from fresh raw seafoods

A total of 103 cultures of yeasts were isolated from seven kinds of fresh raw seafoods. The isolates comprised six genera, Candida, Cryptococcus, Debaryomyces, Rhodotorula, Sterigmatomyces and Trichosporon , and included 21 different species. All the isolates were psychrotrophic yeasts. Proteolytic activities of 50 psychrotrophic strains were studied by use of skim milk within the temperature range of 0–42°C. All the strains showed various degrees of proteolysis. In particular, Candida lipolytica. Trichosporon pullulans and Candida scottii were active species at low temperatures. Sensory spoilage due to the proteolytic yeasts were observed in mackerel homogenates stored at 10°C. C. lipolytica -inoculated homogenates caused spoilage with ammoniacal odours after 1 week of storage. Values of total volatile basic nitrogen at 10°C were highest with C. lipolytica among 35 strains tested, followed by Tr. pullans. Trichosporon cutaneum, C. scottii, Rhodotorula glutinis and Cryptococcus luteolus. Proteolytic psychrotrophic yeasts were widely distributed in raw seafoods.     

Randomly amplified polymorphic DNA (RAPD) PCR for the identification of yeasts isolated from dairy products

In the present work randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) with primers M13 and RF2 was applied to the identification at species level of yeast strains isolated from cheeses. RAPD-PCR analysis of the type strains of different yeast species gave distinctive band profiles that allowed a clear differentiation of all the considered species. Forty-two of the 48 dairy associated yeasts were clearly assigned to the species Saccharomyces cerevisiae, Kluyveromyces marxianus (anamorph Candida kefyr), Kluyveromyces lactis (anamorph Candida sphaerica), Debaryomyces hansenii (anamorph Candida famata), Yarrowia lipolytica and Torulaspora delbrueckii (anamorph Candida colliculosa). The method, which is rapid and easy to perform, could be a useful tool for the identification of yeasts present in dairy products.     

Contribution a l'étude des levures des chais- taxonomie,répartition des levures

Résumé Les populations levuriennes de deux chais de Bourgogne sont étudiées sur deux années d'un point de vue taxonomique et biologique. 122 souches se rapportant à 26 espèces, ont été isolées à partir de la voûte et du sol de la cave, sur les madriers supportant les tonneaux, dans la cuve, sur le pressoir et sur les tonneaux. En dehors d'un certain nombre d'espèces classiques dans ce type d'habitat, telles que Saccharomyces cerevisiae, Pichia membranaefaciens, Hansenula anomala et Kloeckera apiculata, nous avons pu mettre en évidence notamment: Debaryomyces hansenii, Torulopsis Candida, Saccharomyces italicus, ainsi qu'un certain nombre d'espèces appartenant aux genres Pichia, Candida et Trichosporon. La répartition qualitative et quantitative des espèces est également étudiée.

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The yeast populations of two burgundy cellars were studied during two years from a taxonomical and biological point of view. 122 strains distributed among 26 species have been isolated from the vault and ground of the cellar, on the planks supporting the barrels, in the tank, on the winepress and on the barrels. Apart from a number of standard species in this type of habitat such Saccharomy cescerevisiae, Pichia membranaefaciens, Hansenula anomala, Kloeckera apiculata we have encountered the more rare Debaryomyces hansenii, Torulopsis Candida, Saccharomyces italicus as also species of the genus Pichia, Candida, and Trichosporon.

     

A modified method for testing inositol assimilation by Cryptococcus species.

The proposed method for rapid testing of inositol assimilation incorporates shake cultures in an indicator-based broth containing inositol (1%), yeast nitrogen base (0.067%), bromocresol purple, and a heavy inoculum. Of 153 yeast isolates investigated, inositol assimilation was shown with the modified method, as also by the Adams-Cooper procedure, in all the 123 isolates, representing 11 species of Cryptococcus. The results were negative by both the methods in the remaining 30 isolates belonging to Candida, Rhodotorula, Torulopsis, Pichia, Saccharomyces, and Sporobolomyces. The modified method was found to be significantly more effective than the Adams-Cooper procedure; the results could be read within 36 h by the former as against 336 h by the latter method. The superiority of the modified method to the Adams-Cooper procedure is attributed to increased aeration in shake cultures, a heavier inoculum, and reduced concentration of yeast nitrogen base.     

Yeast biodiversity in hydromorphic soils with reference to grass-Sphagnum swamp in Western Siberia and the hammocky tundra region( Barrow, Alaska)]

The microbiological analysis of 78 samples taken from a boreal bog in Western Siberia and from a tundra wetland soil in Alaska showed the presence of 23 yeast species belonging to the genera Bullera, Candida, Cryptococcus, Debaryomyces, Hanseniaspora, Metschnikowia, Mrakia, Pichia, Rhodotorula, Saccharomyces, Sporobolomyces, Torulaspora, and Trichosporon. Peat samples from the boreal bog were dominated by eurytopic anamorphic basidiomycetous species, such as Rhodotorula mucilaginosa and Sporobolomyces roseus, and by the ascomycetous yeasts Candida spp. and Debaryomyces hansenii. These samples also contained two rare ascomycetous species (Candida paludigena and Schizoblastosporion starkeyi-henricii), which so far have been found only in taiga wetland soils. The wetland Alaskan soil was dominated by one yeast species (Cryptococcus gilvescens), which is a typical inhabitant of tundra soils. Therefore, geographic factors may serve for a more reliable prediction of yeast diversity in soils than the physicochemical or ecotopic parameters of these soils.     

Ascomycetous yeasts from tropical intertidal dark mud of southeast Brazilian estuaries

Four different intertidal estuarine sediments had distinct yeast communities. One-hundred-ninety-three yeast isolates were classified in 47 species, with 34 of these in the genus Candida. Candida tropicalis was the only ascomycetous species isolated from all four sites. Other opportunistic pathogens including Candida glabrata, Candida guilliermondii, Candida parapsilosis and Candida krusei were present, especially at the more polluted sites. Pichia species were also frequent isolates with Pichia membranaefaciens, and its anamorph, Candida valida, and other phenotypically similar low assimilation profile species the most frequent. Kluyveromyces aestuarii was prevalent at the only site with well established mangrove vegetation, but not present at the other sites. The sediment yeast communities were distinct from each other, but more similar to each other than to the yeast communities of other ecosystems in the same geographic region.