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.     

Analysis of fatty acid composition of Candida species by gas-liquid chromatography using a polar column

The fatty acid composition of representative Candida species was examined by gas-liquid chromatography (GLC) using a polar column. The major fatty acids were C14:0, C16:0, C18:0 saturated, C16:1 and C18:1 monoenoic series, with or without C18 polyunsaturated acids (C18:2 and C18:3). In Torulopsis glabrata and Saccharomyces cerevisiae the C18:2 and C18:3 acids were not found, but the C10:0 and C12:0 acids were detected in S. cerevisiae. These results indicated that the Candida genus could be distinguished from Torulopsis and Saccharomyces genera by GLC analysis of fatty acids. Quantitative differences in the fatty acid composition between cells grown at high temperature (37 degrees C) and low temperature (25 degrees C) were found generally in Candida species, and the amounts of C18 polyunsaturated acids (C18:2 and C18:3) increased in the cells grown at 25 degrees C. Each Candida species showed a characteristic profile in fatty acid composition. Determination of the cellular fatty acid composition in Candida species is likely to be useful for the grouping or chemotaxonomy of newer isolates of Candida species.     

Evolutionary relationships among pathogenic Candida species and relatives.

Small subunit rRNA sequences have been determined for 10 of the most clinically important pathogenic species of the yeast genus Candida (including Torulopsis [Candida] glabrata and Yarrowia [Candida] lipolytica) and for Hansenula polymorpha. Phylogenetic analyses of these sequences and those of Saccharomyces cerevisiae, Kluyveromyces marxianus var. lactis, and Aspergillus fumigatus indicate that Candida albicans, C. tropicalis, C. parapsilosis, and C. viswanathii form a subgroup within the genus. The remaining significant pathogen, T. glabrata, falls into a second, distinct subgroup and is specifically related to S. cerevisiae and more distantly related to C. kefyr (psuedotropicalis) and K. marxianus var. lactis. The 18S rRNA sequence of Y. lipolytica has evolved rapidly in relation to the other Candida sequences examined and appears to be only distantly related to them. As anticipated, species of several other genera appear to bear specific relationships to members of the genus Candida.     

Search for yeast producers of brassylic and sebacic fatty acids

Yeast cultures belonging to the genera Candida, Torulopsis, Saccharomyces, Debaryomyces, Hansenula, Pichia, and Yarrowia, capable of synthesizing brassylic and sebacic fatty acids, were screened. Overall, about 200 cultures grown in media containing decane or tridecane as a sole source of carbon were tested. On the medium with tridecane, yeasts synthesized insignificant amounts of brassylic acid. Sebacic acid was produced more intensively in the medium with n-decane. The culture Candida tropicalis, displaying the highest ability to synthesize sebacic acid, was selected.     

The in vitro susceptibility of some mycotic agents to a new orally active triazole, itraconazole

The growth-inhibitory effect of itraconazole against 85 strains of mycotic agents belonging to 37 species was studied. MIC values were determined in a microtiter broth dilution method using casitone medium. The widest range of susceptibility was noted for yeasts. More strains of Candida albicans, Candida, spp. and Torulopsis spp. were found to be highly sensitive (MIC = 0.22 mg l-1), a single strain of Candida tropicalis and Rhodotorula glutinis was fully resistant (MIC = 200 mg l-1). Most isolates of yeasts were susceptible at concentrations of 0.19 to 0.78 mg l-1. Itraconazole showed the best activity against the clinical isolates of Aspergillus. Of the 16 strains tested, 12 isolates had MIC values less than or equal to 0.09 mg l-1. The drug was inhibitory for the agents of adiaspiromycosis at a narrow range of concentrations (0.19-0.39 mg l-1). greater variation in the response was noted for Geotrichum candidum (0.045-3.12 mg l-1). Zygomycetous fungi (Mucor, Rhizopus) were mostly highly resistant (100-200 mg l-1). Very susceptible strains of Absidia spp. were an exception. In most genera and species, the results of this study were in agreement with the previously reported data of foreign authors.     

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.     

Ultrastructure of methanol-utilizing yeast cells: appearance of microbodies in relation to high catalase activity.

Nine strains of methanol-utilizing yeasts belonging to the genera Candida, Hansenula, Kloeckera, Pichia, and Torulopsis were examined with respect to the interrelationship between their catalase content and ultrastructure. Methanol-grown cells of all the yeasts tested showed higher catalase activities than the respective ethanol- and glucose-grown cells. In connection with this, occurrence of a specific organelle surrounded by a single-unit membrane ("microbodies") was observed only in the methanol-grown cells. Several morphological differences were observed between the microbodies of methanol-utilizing yeasts and those of hydrocarbon-utilizing yeasts such as Candida tropicalis. That is, microbodies of methanol utilizers were large in size, existed in closely associated forms, and had crystalloid structures. Localization of catalase activity in these microbodies was demonstrated cytochemically by use of 3,3'-diaminobenzidene. Especially, 3,3'-diaminobenzidine reaction product accumulated heavily in crystalloids of yeast microbodies.     

Search for Yeast Producers of Brassylic and Sebacic Fatty Acids

Yeast cultures belonging to the genera Candida, Torulopsis, Saccharomyces, Debaryomyces, Hansenula, Pichia, and Yarrowia, capable of synthesizing brassylic and sebacic fatty acids, were screened. Overall about 200 cultures grown in media containing decane or tridecane as a sole source of carbon were tested. On the medium with tridecane, yeasts synthesized insignificant amounts of brassylic acid. Sebacic acid was produced more intensively in the medium with n-decane. The culture Candida tropicalis, displaying the highest ability to synthesize sebacic acid, was selected.     

A method for the rapid identification of pathogenic yeast-like microorganisms

Summary A new rapid diagnostic method for the identification of pathogenic yeast-like microorganisms is described. By this method in the course of one week these genera can be identified:Candida, Torulopsis, Rhodotorula, Trichosporon, Geotrichum and seven species often found in infectious material, of the genusCandida: C. albicans, C. tropicalis, C. pseudotropicalis, C. krusei, C. guilliermondii, C. pelliculosa andC. parapsilosis.     

我国各类基物上的酵母菌分布及其尿素酶活性

本文讨论了2300株由我国各地分离到的酵母菌和类酵母菌与各类基物的关系。共述及23属,占Lodder(1970)系统的半数以上。在十几类基物中酵母菌的分布各有不同,叶子上有大量掷孢酵母,果实上比其它基物更能获得克勒克酵母属(Kloeckera),在咸腌食品中相对地有较多耐高渗透压的酵母如球拟酵母属(Torulopsis)与德巴利酵母属(Debaryomyces)。对部分属的定种工作也已进行,说明某些属的种在我国均有发现而且为数不少。此外还研究了600余株代表各类酵母的尿素酶活性,结果说明担子菌酵母或系统上接近担子菌的酵母都有尿素酶活性,而子囊菌酵母则无。根据作者的观察子囊菌酵母中裂殖酵母属(Schizosaccharomyces)则常常例外地有尿素酶反应,且常有辅酶Q_(10),从而可见裂殖酵母属有其特有的生物学特性,在系统上很可能与其它子囊菌酵母不同。对属于不完全菌的无孢子酵母也进行了尿素酶活性测定,结果表明它们部分与子囊菌有关,部分与担子菌有关。     

Specific features of fermentation of D-xylose and D-glucose by xylose-assimilating yeasts

The ability to assimilate D-glucose and D-xylose was studied in 21 yeast species of the following genera: Candida, Kluyveromyces, Pachysolen, Pichia, and Torulopsis. All the cultures fermented D-glucose with the formation of ethanol. During the assimilation of D-xylose, ethanol was produced by P. stipitis and C. shehatae, whereas xylitol was produced by C. didensiae, C. intermediae, C. parapsilosis, C. silvanorum, C. tropicalis, K. fragilis, K. marxianus, P. guillermondii, and T. molishiama. The yeast P. tannophilus produced comparable amounts of both alcohols. The possible use of xylose-assimilating yeasts for the production of xylitol and ethanol is discussed.     

Colonization of hospitalized patients with yeast-like organisms

The pharyngeal, fecal and skin carrier rates of yeast-like organisms was determined in 126 patients on the day of admission to a larger Veterans Administration Hospital. None of these patients had been hospitalized or received anti-microbial agents during the previous year Candida and Torulopsis species were most common. A small percentage of patients were carriers of various species belonging to the genera Trichosporon, Rhodotorula, Saccharomyces, Leucosporidium and Endomycopsis. Fifty of the original 126 patients remained hospitalized for a sufficient duration to permit repeat cultures on days 7 and 14. Twenty-five of these patients served as controls and did not receive antibiotics; the other 25 received at least a 4-day course of antibiotic therapy for an underlying infection. Although there was no significant difference in the carrier rates in these 2 groups, organisms other than Candida continued to be isolated from the 50 patients who remained hospitalized for 2 weeks.     

The significance of hydrocarbon assimilation in yeast identification

A large number of yeasts were screened for the ability to assimilate hydrocarbons. Not only representatives of the genusCandida, but also species from other perfect and imperfect genera are able to usen-alkanes as sole carbon and energy source. The significance of this feature in yeast systematics is discussed. In general, all strains of a species share either the ability to assimilate hydrocarbons or the failure to do so. Exceptions are found in species regarded as heterogeneous, likeCandida sake, Candida diddensii andCandida zeylanoides. In cases where the usual criteria used in identification seem to be inadequate, the simple hydrocarbon assimilation test may be useful. Also in subgrouping the generaCandida andTorulopsis the test may be of value, because some perfect genera likeHansenula, Kluyveromyces andSaccharomyces lack hydrocarbon-assimilating representatives.     

The activity of xylose reductase and xylitol dehydrogenase in yeasts

The activity and the cofactor specificity of xylose reductase and xylitol dehydrogenase were studied in extracts of yeasts from the genera Candida, Kluyveromyces, Pachysolen, Pichia, and Torulopsis grown under microaerobic conditions. It was found that xylitol dehydrogenase in all of the yeast species studied is specific for NAD+; xylose reductase in the xylitol-producing species C. didensiae, C. intermediae, C. parapsilosis, C. silvanorum, C. tropicalis, Kl. fragilis, Kl. marxianus, P. guillermondii, and T. molishiama is specific for NADPH; and xylose reductase in the ethanol-producing species P. stipitis, C. shehatae, and Pa. tannophilus is specific for both NADPH and NADH.     

The yeast flora of cocoa bean fermentation in the Ivory Coast

Summary The yeast flora involved in the traditional fermentation process of cocoa during four harvest seasons in the Ivory Coast was studied. Twenty-nine species belonging to 11 genera were identified. The following species were the most frequently isolated:Saccharomyces chevalieri,Pichia membranaefaciens, Candida krusei, Torulopsis holmii, Torulopsis Candida. This flora is similar to that found in other parts of the world.

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Resumen Levaduras en la fermentación del cacao en la Costa de Marfil Se estudiaron las levaduras envueltas en la tradicional fermentación del cacao durante cuatro cosechas consecutivas en la Costa de Marfíl. Las especies aisladas con mayor frecuencia fueron las siguientes:Saccharomyces chevalieri, Pichia membranaefaciens, Candida krusei,Torulopsis holmii, Torulopsis candida. Flora que es similar a la hallada en otras partes del mundo.

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Résumé La flore de levures dans la fermentation des fèves de cacao en Côte d'Ivoire La flore des levures intervenant dans la fermentation traditionnelle du cacao a été étudiée en Côte d'Ivoire au cours de quatre saisons de récolte. Vingt-neuf espèces appartenant à 11 genres ont été identifiées. Les espèces les plus fréquemment isolées sont:Saccharomyces chevalieri, Pichia membranaefaciens, Candida krusei, Torulopsis holmii, Torulopsis Candida. Cette flore est similaire à celles trouvées dans d'autres parties du monde.

     

Molecular typing of Candida spp. by random amplification of polymorphic DNA and analysis of restriction fragment length polymorphism of ribosomal DNA repeats

Random amplification of polymorphic DNA (RAPD) using an arbitrary oligonucleotide primer (5'-CGGTGCGACG) and analysis of restriction fragment length polymorphism of ribosomal DNA (rDNA-RFLP) after digestion of genomic DNA with restriction endonuclease EcoRI were investigated as tools for genotypic delineation beyond the species level of 91 Candida clinical isolates and four reference strains including 33 Candida albicans, 19 Candida tropicalis, 22 Candida krusei and 21 Candida (Torulopsis) glabrata. Results indicated that both techniques can be useful for typing isolates of the above species, although showing a variable discriminative potential with different species. As compared to RAPD fingerprinting, the discriminative potential of rDNA-RFLP appeared to be highest for C. albicans and lowest for C. glabrata, being overall similar for C. krusei and identical for C. tropicalis. A comparative analysis of the results obtained with the two typing techniques showed that, except for C. tropicalis, they were able to provide non-redundant information, and that their use in combination could enhance the discriminative potential for delineation among C. glabrata and C. krusei isolates.     

Contribution to the study of the enzymatic profiles of yeast organisms with medical interest

The enzymatic profiles of several yeastlike organisms were studied using 19 substrates included in the API ZYM system. The isolates evaluated were: 186 Candida albicans, 19 C. stellatoidea, 4 C. tropicalis, 2 C. parapsilosis, 2 C. pseudotropicalis, 1 C. guilliermondii, 3 C. krusei, 11 Torulopsis (Candida) glabrata, 1 Cryptococcus neoformans, 2 Saccharomyces carlsbergensis, 1 Rhodotorula rubra, and 1 R. mucilaginosa. Esterase lipase (C8), leucine arylamidase, acid phosphatase, and phosphoamidase were detected in all of the isolates while trypsin and alpha-galactosidase were not found in any of the isolates using this system. The other enzymes were produced to a variable degree. The different enzymatic profiles might prove useful in the rapid differential diagnosis of genera and species of these yeastlike organisms. To this end, more extensive studies using more isolates of each species will be required, and enzymatic activity should be verified with other techniques and substrates.     

Characteristics of Yeasts Isolated from Pacific Crab Meat

A total of 202 cultures of yeasts were isolated and characterized from king crab and Dungeness crab meat. A yeastlike organism, resembling Aureobasidium pullulans, and 15 different species distributed among the genera Rhodotorula, Cryptococcus, Torulopsis, Candida, and Trichosporon were represented. Nine of the species grew at 5 C or lower. Although two of the species grew at 37 C, none of the isolates had the characteristics of pathogenic species. Members of the Cryptococcus and Candida failed to grow at 37 C. Furthermore, species of the former genus were not pathogenic to mice. The pigmentation of the Rhodotorula cultures decreased in intensity as the incubation temperature was decreased. Biochemical activities of the different species were studied by use of triglycerides, lecithin, and proteins (casein, gelatin, and crab-meat protein) as substrates. Eight of the species could attack triglycerides; eight, lecithin; five, gelatin; one, casein; and one, crab protein. An organism, tentatively identified as Trichosporon sp., was very active in attacking each of the substrates tested and grew well at 0.5 C.     

Isolation of fungi from bats of the Amazon basin.

A total of 2,886 bats captured in the Amazon Basin of Brazil were processed for the isolation of fungi. From the livers, spleens, and lungs of 155 bats (5.4%), 186 fungal isolates of the genera Candida (123 isolates), Trichosporon (26 isolates), Torulopsis (25 isolates), Kluyveromyces (11 isolates), and Geotrichum (1 isolate) were recovered. Seven known pathogenic species were present: Candida parapsilosis, C. guilliermondii, C. albicans, C. stellatoidea, C. pseudotropicalis, Trichosporon beigelii, and Torulopsis glabrata. Twenty-three culture-positive bats showed identical fungal colonization in multiple organs or mixed colonization in a single organ. The fungal isolation rates for individual bat species varied from 1 fungus per 87 bats to 3 fungi per 13 bats, and the mycoflora diversity for members of an individual fungus-bearing bat species varied from 16 fungi per 40 bats to 7 fungi per 6 bats. Of the 38 fungal species isolated, 36 had not been previously described as in vivo bat isolates. Of the 27 culture-positive bat species, 21 had not been previously described as mammalian hosts for medically or nonmedically important fungi.