Yeast-like Isolates Research Articles

Chromogenic, Biochemical and Proteomic Identification of Yeast and Yeast-like Microorganisms Isolated from Clinical Samples from Animals of Costa Rica.

Yeast infections are challenging human and animal medicine due to low rates of detection and the emergence of unknown ecology isolates. The aim of this study was to verify the biochemical identification of yeasts and yeast-like microorganisms obtained from animals comparing the results with chromogenic media and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF MS). Between January and August 2023, yeast and yeast-like isolates from samples of animals with suspicion of mycosis were identified using Vitek® 2 Compact, Brilliance® Candida Agar and MALDI Biotyper® MSP. A total of 39 cases were included, and 45 isolations were obtained. Cryptococcus neoformans (15.5%, 7/45), Meyerozyma guilliermondii (13.3%, 6/45), Candida parapsilosis (11.1%, 5/45), Candida albicans and Candida tropicalis (8.9%, each one 4/45) were the most identified organisms. There was full agreement with the three identification methods in 71.1% (32/45) of the isolates, disagreement on species in 17.8% (8/45), disagreement on genus and species in 6.7% (3/45) and, in 4.4% (2/45), there was no matched pattern in MALDI-TOF to compare the results. Biochemical methods are a good option in laboratories where proteomics are not available, and chromogenic media enhances diagnostics by detecting mixed infections. Surveillance must be implemented to improve the detection of agents shared between humans and animals.

Sugarcane: an unexpected habitat for black yeasts in Chaetothyriales

Sugarcane (Saccharum officinarum, Poaceae) is cultivated on a large scale in (sub)tropical regions such as Brazil and has considerable economic value for sugar and biofuel production. The plant is a rich substrate for endo- and epiphytic fungi. Black yeasts in the family Herpotrichiellaceae (Chaetothyriales) are colonizers of human-dominated habitats, particularly those rich in toxins and hydrocarbon pollutants, and may cause severe infections in susceptible human hosts. The present study assessed the diversity of Herpotrichiellaceae associated with sugarcane, using in silico identification and selective isolation. Using metagenomics, we identified 5833 fungal sequences, while 639 black yeast-like isolates were recovered in vitro. In both strategies, the latter fungi were identified as members of the genera Cladophialophora, Exophiala, and Rhinocladiella (Herpotrichiellaceae), Cyphellophora (Cyphellophoraceae), and Knufia (Trichomeriaceae). In addition, we discovered new species of Cladophialophora and Exophiala from sugarcane and its rhizosphere. The first environmental isolation of Cladophialophora bantiana is particularly noteworthy, because this species up to now is exclusively known from the human host where it mostly causes fatal brain disease in otherwise healthy patients.

Analyzing Ash Leaf-Colonizing Fungal Communities for Their Biological Control of Hymenoscyphus fraxineus.

The invasive ascomycete Hymenoscyphus fraxineus has been threatening Fraxinus excelsior populations throughout Europe for over two decades. Since the infection and first colonization by the pathogen occurs in leaves, leaf-colonizing microorganisms have been discussed as a barrier and as possible biocontrol agents against the disease. To identify fungal groups with health-supporting potential, we compared the fungal microbiota of compound leaves from susceptible and tolerant ash trees in four ash stands with high H. fraxineus exposure. The fungal communities were analyzed both culture-independently by ITS2 amplicon sequencing and by the taxonomic classification of 1,704 isolates using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) or sequencing of the entire ITS region. The fungal community structure did not show significant differences depending on the health status. However, for several OTUs and a MALDI group, a significantly higher abundance was found in tolerant ash trees. Thus, the yeast Papiliotrema flavescens was significantly increased and accounted for 12.3% of the mycobiome of tolerant ashes (OTU0003), and it had also a distinctly higher abundance among the isolates. The filamentous ascomycete Sarocladium strictum was increased 24-fold among the isolates of tolerant trees, but its abundance was comparably low. An in vitro screening for the growth inhibition of the pathogen via cocultivation resulted in 28 yeast-like isolates and 79 filamentous fungi with antagonistic activity. A statistical cocultivation test on two H. fraxineus strains confirmed six of the yeast-like isolates that suppressed H. fraxineus significantly, from 39–50%, two of them through a fungicidal effect. The highest inhibition rates among the yeasts were found for three isolates belonging to Aureobasidium pullulans and P. flavescens. The cocultivation test of the filamentous isolates revealed higher effects compared to the yeasts. Four isolates showed significant inhibition of both H. fraxineus strains with a rate of 72–100%, and five further isolates inhibited only one H. fraxineus strain significantly. The most effective isolates were members of the genus Cladosporium. During the next step, in planta tests will be necessary to verify the efficacy of the antagonistic isolates and to assess their suitability as biocontrol agents.

Diversity, Virulence Factors, and Antifungal Susceptibility Patterns of Pathogenic and Opportunistic Yeast Species in Rock Pigeon (Columba livia) Fecal Droppings in Western Saudi Arabia.

Bird fecal matter is considered a potential source of pathogenic microbes such as yeast species that contaminate the environment. Therefore, it needs to be scrutinized to assess potential environmental health risks. The aim of this study was to investigate the diversity of the yeasts in pigeon fecal droppings, their antifungal susceptibility patterns, and virulence factors. We used culturing techniques to detect the yeasts in pigeon fecal droppings. The isolates were then characterized based on colony morphologies, microscopic examinations, and biochemical reactions. The molecular identification of all yeast isolates was performed by sequencing of the amplified ITS gene. Genes encoding virulence factors CAP1, CAP59, and PLB were also detected. Antifungal susceptibility patterns were examined by the disk diffusion method. A total of 46 yeast-like isolates were recovered, and they belonged to nine different genera, namely, Cryptococcus, Saccharomyces, Rhodotorula, Candida, Meyerozyma, Cyberlindnera, Rhodosporidium, Millerozyma, and Lodderomyces. The prevalence of two genera Cryptococcus and Rhodotorula was high. None of the yeast isolates exhibited any resistance to the antifungal drugs tested; however, all pathogenic Cryptococcus species were positive for virulence determinants like urease activity, growth at 37°C, melanin production, the PLB and CAP genes. This is the first report on the molecular diversity of yeast species, particularly, Cryptococcus species and their virulence attributes in pigeon fecal droppings in Saudi Arabia.

Species Identification of Stress Resistance Yeasts Isolated from Banana Waste for Ethanol Production

Banana waste putrefaction was naturally shown the potential activities of microorganisms in fermenting ethanol. Yeasts have been known as one of the potential microorganisms that wildly grown in banana waste that has the ability in producing ethanol. The objectives of the research were to isolate and identify yeasts with stress resistance ability towards high ethanol and glucose in the production of ethanol. Yeasts isolation has been done by using Potato Dextrose Agar/PDA (Oxoid Ltd.) that was modified with 3% yeast extract/YE (Kraft Inc.) and 10 ppm Amoxicillin, then incubated for 48h at room temperature. The yeast-like isolates were identified microscopic and macroscopically then cultured on Nutrient Broth/NB (Oxoid Ltd.) with the addition of 3% yeast extract/YE (Kraft Inc.), 10 ppm Amoxicillin and 30% glucose or ethanol for stress resistance ability test. The resistance ability of yeasts toward high glucose and ethanol media was determined by measuring optical density (OD) on UV-Vis spectrophotometer λ=600nm. The isolates species identified using sequence analysis of the rRNA gene internal transcribed spacer (ITS) region with the primers of ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′), the sequences compared with the GenBank database using the BLAST algorithm. The isolates were mixed and inoculated into banana wastes for 72h then the ethanol contents measured by chromium dichromate oxidation methods every 24h. The results showed that three wild yeasts (B1, B2, B3) were isolated from banana wastes, with the ability to produce ethanol with a concentration of 10.72±2.53% at 48h. Species identification showed that isolate B1, B2, and B3 were 98.99% (295/298), 100% (330/330), 99.71% (695/597) identical with Pichia bruneiensis strain CLIB 1453, Kodamaea ohmeri F3 and Hanseniaspora sp. R2 respectively.

A teleomorph of the ustilaginalean yeast Moesziomyces antarcticus on barnyardgrass in Japan provides bioresources that degrade biodegradable plastics.

The basidiomycetous yeast Moesziomyces antarcticus (often cited as Pseudozyma antarctica), originally isolated from a sediment sample obtained from Lake Vanda in Antarctica, was asexually typified but closely related to the smut fungus Moesziomyces bullatus (Ustilaginales). We found a smut fungus on an ovary of barnyardgrass (Echinochloa crus-galli) in Japan, which had been identified as M. bullatus. The teliospores germinated and formed yeast-like colonies. Physiological and phylogenetic studies revealed that the characteristics of the yeast-like isolates coincided with those of "P. antarctica." We thus recognised the smut fungus as the teleomorph of M. antarcticus, and then emended the description of M. antarcticus based on the holomorph. The identified fungus could degrade certain biodegradable plastics and produce mannosylerythritol lipids (MELs) in similar qualities as the "P. antarctica" type strain. This discovery provides a significant bioresource, as genetically diverse M. antarcticus isolates could be obtained from the smut fungus.

Teleomorph–anamorph connection of Macalpinomyces spermophorus with Pseudozyma tsukubaensis and corresponding erythritol production

A basidiomycetous yeast, Pseudozyma tsukubaensis, has been isolated from a variety of plant materials. Previous molecular phylogenetic analyses have suggested this yeast is an asexual stage of the smut fungus Macalpinomyces spermophorus (synonym Ustilago spermophora, Ustilaginales). To reveal the teleomorph–anamorph connection, yeast-like isolates from germinated teliospores of morphologically identified M. spermophorus on Eragrostis ferruginea from Japan were analyzed. The internal transcribed spacer region of rDNA of the yeast isolates was mostly identical with that of known isolates of P. tsukubaensis. Physiological analysis showed that the characteristics of the yeast isolates correlated well with P. tsukubaensis. These data revealed that P. tsukubaensis is the anamorph of M. spermophorus and should be treated as a synonym of M. spermophorus. In addition, the erythritol-producing ability of the yeast isolates derived from teliospores of M. spermophorus were confirmed by high-performance ion-exchange chromatography and 13C NMR analyses.

Biodiversity Evaluation of Geotrichum candidum Link. Is Arthrosporic Nucleus Number in Geotrichum candidum related to the Fungus Biodiversity?

Abstract Geotrichum candidum species exhibits properties of both moulds and yeasts and its affiliation to one of the groups has been intensively discussed. It is because this filamentous microscopic fungus is displaying substantial morphological variability and wide phenotypic diversity. The present study assesses the variability of arthrosporic nucleus number of twelve isolates of G. candidum originating from artisanal manufacturing and ripened traditional Slovak cheeses. Results showed that arthrospores of the studied isolates contained on average 1.5 ± 0.7 (on the Gorodkova medium) and 1.5 ± 0.6 (on the McClary medium) Hoechst 33258-stained nuclei (range 1–4 nuclei on both agars) after a 7-day cultivation at 25°C. Majority of arthrospores comprised one nucleus, irrespective to the used nutrient-limited medium. Generally, a higher relative nucleus number per arthrospore was exhibited in yeast-like isolates with microscopic structure composed predominantly of spores, while it was lower in vegetative hyphae. These isolates originated from ewe’s lump cheese. Our study reveals that the arthrosporic nucleus number of the G. candidum strains is closely related to morphotype and origin of this yeast.

Urinary Candida isolates from a tertiary care hospital: Speciation and resistance patterns

Background: Candida species (spp.) is an integral member of the human microbiota and is an opportunistic pathogen. This pathogen infects the urinary tract both by ascending the urinary tract and by haematogenous spread. Aim: Speciation and antifungal susceptibility patterns of Candida isolates from urine specimens. Materials and Methods: Yeast-like isolates from urine culture were identified using a Mini-API® (bioMerieux, Marcy-l'Etoile, France) tool with ID 32 C strips (bioMerieux, Marcy-l'Etoile, France) for species identification and ATB Fungus 3 strips (bioMerieux, Marcy-l'Etoile, France) for susceptibility testing to five antifungal agents and results interpreted as per Centers for Disease Control and Prevention (CDC) guidelines. The significance of data was analysed using the chi-square test. Results: Candida spp. isolation was 10.2% (112/1092) and the commonest was Candida tropicalis [54.5% (61/112)], followed by C. glabrata 25% (28/112), and C. albicans, 11.6% (13/112). C. albicans showed good susceptibility to Flucytosine (100%) and Amphotericin B (84.6%) while non-albicans Candida susceptibility was only 82.9% and 60.6%, respectively. Conclusion: Non-albicans Candida have replaced Candida albicans as the more common causative agent. Resistance to both Amphotericin B and Fluconazole is on the rise, requiring the judicial use of antifungals in the immunocompetent and immunocompromised host as therapeutic and prophylactic therapy.

Advances in Identification of Clinical Yeast Isolates by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based identification is being adopted by clinical laboratories for routine identification of microorganisms. To date, the majority of studies have focused on the performance and optimization of MALDI-TOF MS for the identification of bacterial isolates. We review recent literature describing the use of MALDI-TOF MS for the routine identification of a variety of yeasts and yeast-like isolates. Specific topics include the effect of optimized or streamlined extraction methods, modified scoring thresholds, expanded reference libraries, and the possibility of conducting antifungal susceptibility testing using MALDI-TOF MS.

Improved clinical laboratory identification of human pathogenic yeasts by matrix-assisted laser desorption ionization time-of-flight mass spectrometry

The key to therapeutic success with yeast infections is an early onset of antifungal treatment with an appropriate drug regimen. To do this, yeast species identification is necessary, but conventional biochemical and morphological approaches are time-consuming. The recent arrival of biophysical methods, such as matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), in routine diagnostic laboratories holds the promise of significantly speeding up this process. In this study, two commercially available MALDI-TOF MS species identification systems were evaluated for application in clinical diagnostics, using a geographically diverse collection of 1192 clinical yeast and yeast-like isolates. The results were compared with those of the classical differentiation scheme based on microscopic and biochemical characteristics. For 95.1% of the isolates, all three procedures consistently gave the correct species identification, but the rate of misclassification was greatly reduced in both MALDI-TOF MS systems. Furthermore, several closely related species (e.g. Candida orthopsilosis/metapsilosis/parapsilosis or Candida glabrata/bracarensis) could be resolved by both MALDI-TOF MS systems, but not by the biochemical approach. A significant advantage of MALDI-TOF MS over biochemistry in the recognition of isolates novel to the system was observed. Although both MALDI-TOF MS systems employed different approaches in the database structure and showed different susceptibilities to errors in database entries, these were negligible in terms of clinical usefulness. The time-saving benefit of MALDI-TOF MS over biochemical identification will substantially improve fungal diagnostics and patient treatment.

Identification for medically important yeast-like fungal species by sequence analysis of 18S rRNA gene

Objective To compare sequence analysis of the yeast-like fungal isolates with traditional methods and analyze the feasibility of identification of common yeast-like fungal by sequence analysis of gene. Methods 115 yeast-like fungal isolates were collected in the clinical laboratory of Beijing Tongren Hospital. DNA of yeast-like fungal was extracted and then amplified with universal primers of part of 18S rRNA genes followed by sequencing directly. The sequences obtained were submitted to the GenBank (NCBI) to identify the fungi. At the same time, the CHROMagar Candida and Vitek 32 YBC were used to identify the fungi. The identification accuracy with three methods was compared to explore the feasibility of the identification of sequence analysis. Results 18S rRNA gene sequence analysis was compared with traditional method. There were some differences in the identification results of 13 strains. The coincidence rate between CHROMagar Candida and sequence analysis was 89. 2% (91/102) and the coincidence rate between Vitek 32 YBC and sequence analysis was 91.3% (105/115). The positivity rate of species-level identification by CHROMagar Candida , Vitek 32 YBC and the 18S rRNA gene sequence analysis were 88. 7 % ( 102/115 ), 100% ( 115/115 ), 100% ( 115/115 ). Conclusion Identification of medically important yeast-like fungal by sequence analysis of the 18S rRNA gene is reliability. Key words: Yeasts; RNA,ribosomal,18S; Sequence analysis,RNA

Novel precipitated fluorescent substrates for the screening of cellulolytic microorganisms

New substrates, 2-(2′-benzothiazolyl)-phenyl ( BTP) cellooligosaccharides with degree of polymerization (d.p.) 2–4 ( BTPG 2–4) were synthesized for the screening of microbial cellulolytic activity in plate assays. The substrates were very efficient that was shown for several cellulolytic bacteria, including yeast-like isolates from Kamchatka hot springs. Three tested bacterial strains and eighteen of 30 of the yeast isolates showed ability to degrade cellulose with cellobiohydrolase, β-glucosidase and endo-cellulase activities measured with standard substrates. The structures of 2-(2′-benzothiazolyl)-phenyl oligosaccharides were solved by NMR- and mass-spectrometry. The usefulness of the 2-(2′-benzothiazolyl)-phenyl substrates were also shown during purification of the B. polymyxa cellulolytic complex, which consists of at least three types of the enzymes: cellobiohydrolase, endo-β- d-glucanase and β-glucosidase.

Fluconazole resistant opportunistic oro-pharyngeal Candida and non-Candida yeast-like isolates from HIV infected patients attending ARV clinics in Lagos, Nigeria.

Oro-Pharyngeal Candidiasis (OPC) continues to be considered the most common opportunistic fungal disease in HIV/AIDS patients globally. Azole antifungal agent has become important in the treatment of mucosal candidiasis in HIV patients. Presently, antifungal drug resistance is fast becoming a major problem particularly with the immune depleted population. This study was designed to investigate the: existence of OPC, species distribution fluconazole susceptibility profile of yeast cells isolated from oral specimens of HIV/AIDS patients from Lagos Nigeria, between Oct. 2004 and June, 2005. The venous blood samples were screened for HIV antibodies using the Cappillus HIV I and II test kit (Trinity Biotech Plc UK), and Genie II HIV I and II EIA kit (Bio-Rad France). The positive results were subsequently confirmed at the laboratory attached to each of the clinics, using the Nigerian Federal Ministry of Health approved algorithm. The samples from 213 (108 females and 105 males) HIV positive patients were plated onto SD agar. The isolates were identified by morphotyping, microscopy and speciated using germ tube test and battery of biochemical sugar fermentation and assimilation tests. Fluconazole agar diffusion susceptibility testing was carried out on each isolates. Seventy-four (34.7%) isolates were recovered including one person with double isolates. Only 70 (94.6%) of the isolates could be adequately speciated. Candida albicans 30 (40.5%) was the most frequently isolated species, the rest were non-albicans species, with the frequency of C. tropicalis > C. Krusei > C. glabrata and C. neoformans for species for species having up to 4 isolates. Four (30.8%) out of 13 isolates of C. tropicalis showed germ tube formation. While one C. albicans was germ-tube negative. Out of the 74 isolates tested for fluconazole sensitivity, 58 (78.4%) were sensitive, MIC d'' 8 microg/ml, 9 (12.1%) were susceptible Dose Dependent (SDD), MIC 16-32 microg/ml and 7 (9.5%) were resistant, MICs e'' 64 microg/ml. Among the C. albicans isolates, 26 (86.7%) were sensitive to fluconazole. The rank of susceptibility was C. albicans > C. tropicalis > C. Krusei for the most prevalent species. We conclude that fluconazole resistant strains of oro-pharyngeal yeast-like cells exist in about 9.5% of HIV/AIDS patients with the above stated species distribution. We therefore, highlight the need for routine antifungal susceptibility testing on HIV patients with cases of initial or repeat episodes of OPC.

Onychomycosis Incidence in Type 2 Diabetes Mellitus Patients

The onychomycosis incidence was determined in 250 type 2 diabetes mellitus (T2DM) patients who were registered at the Internal Medicine Service from a Mexico city General Hospital throughout a year (January-December 2006). Out of the total of studied T2DM patients, 93 (37.2%) showed ungual dystrophy and from these, in 75.3% a fungal etiology was corroborated. Out of 70 patients, 34 were men and 36 women, with an average of 63.5 years. Correlation between T2DM evolution time and onychomycosis was significant (P < 0.01). Distal-lateral subungual and total dystrophic onychomycosis were the most frequent clinical types (55.1% and 33.7%, respectively). Fifty-eight fungal isolates were obtained; 48.6% corresponded to dermatophytes, Trichophyton rubrum being the first species (37.1%). All these strains corresponded to two morphological varieties: "yellow" and typical downy. From the yeast-like isolates, 12 corresponded to Candida spp., firstly C. albicans and C. parapsilosis; three to Cryptococcus spp. (C. albidus, C. uniguttulatus and C. laurentii); two Trichosporon asahii; and only one to Pichia ohmeri. Six non-dermatophytic molds were isolated: two Chrysosporium keratinophylus, two Scopulariopsis brevicaulis, one Aspergillus fumigatus, and one Acremonium sp. The fungal mixture corresponded to T. mentagrophytes with C. guilliermondii; T. mentagrophytes with C. glabrata; T. rubrum with C. glabrata; T. rubrum with P. ohmeri.

Utilization of Low Molecular Weight Lignin-Related Aromatic Compounds for the Selective Isolation of Yeasts: Rhodotorula vanillica, a New Basidiomycetous Yeast Species

Summary Low molecular weight lignin-related aromatic compounds were used as sole sources of carbon and energy for the selective isolation of yeasts. A total of 227 yeast strains were isolated from terrestrial and aquatic habitats and ascribed to three groups: ascomycetous yeasts (17.6%), ascomycetous yeast-like microorganisms (5.3%) and basidiomycetous yeasts (77.1%). About half of the strains, representing the proportions of the various groups, were identified to the species level. Among the basidiomycetous yeasts, those affiliated to the Ustilaginales were present in higher number (75 strains) than the representatives of the Tremellales/Filobasidiales (16 strains). The ability of each identified isolate to grow in liquid medium with the same composition as the solid selective isolation medium was checked. Only 41% of the ascomycetous yeasts were able to grow, whereas all the ascomycetous yeast-like isolates and 90% of the basidiomycetous yeasts had that capacity. A novel basidiomycetous anamorphic yeast species was found among the strains collected and is described as Rhodotorula vanillica . Conspecificity with the phenotypically similar species Rhodotorula ingeniosa was excluded based on absence of DNA-DNA complementarity.

Evaluation of the MicroScan Rapid Yeast Identification panel

The MicroScan Rapid Yeast Identification (RYI) panel is a 4-h microdilution system for identification of clinical yeastlike isolates. Its accuracy was evaluated by using 357 isolates encompassing 11 genera and 30 species. The RYI panel identifications were compared with those obtained by the API 20C system assisted with morphological characterization on cornmeal-Tween 80 agar. The panels were read both visually and with the AutoScan-4, a computer-controlled microplate reader. Both the RYI panel and the API 20C system correctly identified 78% of the strains within 4 and 72 h, respectively, with no additional tests. Supplementary tests recommended by the manufacturers made it possible to identify up to 96.6% (AutoScan-4) and 98.9% (API 20C) of the strains. The accuracy of the RYI panel was 99.5% with common strains and 92.1% with less common strains. The RYI panel misidentified 10 or 12 strains and failed to identify 2 or 3 strains, depending on whether it was read with the AutoScan-4 or visually. Errors occurred with one strain of Torulopsis glabrata and the less common yeasts T. candida, Candida lusitaniae, C. lambica, C. rugosa, C. stellatoidea, Cryptococcus albidus, C. laurentii, and C. uniguttulatus. Overall, the RYI panel appears to be a reliable system for identification of the more common clinical yeast isolates.

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.

Identification ofCandida albicans, otherCandidaspecies andTorulopsis glabrataby means of immunofluorescence

Specific identification of Candida albicans type A, C. albicans type B, C. tropicalis, C. stellatoidea, and Torulopsis glabrata was effected by means of a pair of fluorescein-labelled immune globulins directed respectively against C. albicans A and T. glabrata. The former, when absorbed with cells of C. stellatoidea, differentiated C. albicans A - C. tropicalis and C. albicans B - C. stellatoidea from all other yeasts tested, while the latter, absorbed with C. albicans A, separated the 2 pairs into their respective components and also identified T. glabrata. The results of immunofluorescence and conventional methods agreed with each other on the identification of more than 95% of 585 routine yeastlike isolates, of which 335 were C. albicans A and 55 C. albicans B.