Allen N. Hagler

Rapid Diazonium Blue B Test to Detect Basidiomycetous Yeasts

More than 100 known eucaryotic microorganisms were examined for capacity to form red to violet pigments with diazonium blue B after alkaline hydrolysis and an ethanol wash. All 50 basidiomycetes gave rapid and unequivocal positive reactions when 1- to 6-day-old cultures were tested, whereas all ascomycetes and algae gave negative reactions. Extracellular enzymes generally considered to be typical of basidiomycetous yeasts were detected in several ascomycetous taxa.

Genetic and molecular delineation of three sibling species in the Hansenula polymorpha complex

Summary Genetic hybridization, molecular karyotyping and UP-PCR analysis showed that the taxonomic complex Hansenula polymorpha De Morais et Maia consists of three biological sibling species. H. angusta Teunisson et al. (= Pichia angusta (Teunisson et al.) Kurtzman) is not synonymous with H. polymorpha and must be reinstated as a separate species. The third sibling species is apparently a new taxon associated with Opuntia cacti. The sibling species are able to cross with each other but their interspecific hybrids are sterile.

Ascomycetous yeast communities of marine invertebrates in a Southeast Brazilian mangrove ecosystem

The ascomycetous yeast communities associated with 3 bivalve mollusk, and 4 crab species were studied in the mangrove at Coroa Grande on Sepetiba Bay in Rio de Janeiro, Brazil. These were made up mostly of diverse but sparse and apparently allochtonous yeast populations. The striking exception was a prevalent population of the speciesKluyveromyces aestuarii, which predominated the yeast communities of 2 detritus feeding crabs,Sesarma rectum andUca spp., and the shipwormNeoteredo reynei. However,K. aestuarii was absent from the omnivorous crabsAratus pisonii andGoniopsis cruentata, and the clamAnomalocardia brasiliana, and was rare in the clamTagelus plebeius from mostly submerged more sandy sediments.Pichia membranaefaciens, Candida valida-like,Candida krusei, Candida sorbosa, Candida colliculosa-like,Candida famata-like,Kloeckera spp.,Candida guilliermondii, Candida albicans, Candida silvae, Geotrichum spp.,Rhodotorula spp.,Cryptococcus spp., and the methylotrophic yeastCandida boidinii were frequently isolated. The 322 ascomycetous yeast cultures representing 252 isolates from crabs and mollusks were classified as 40 species that fit standard descriptions, and 44 putative new species. The ascomycetous yeast communities of the mangrove ecosystem include many new biotypes that require better taxonomic definition.

Heterogeneity of metallo and serine extracellular proteinases in oral clinical isolates of Candida albicans in HIV-positive and healthy children from Rio de Janeiro, Brazil

Candida yeasts frequently cause life-threatening systemic infections in immunocompromised hosts. In the present study, gelatin-SDS-PAGE analysis was used to characterize extracellular proteinases in 44 oral clinical isolates of Candida albicans from HIV-positive (29/50) and healthy children (15/50). Our survey indicates that these oral clinical isolates of C. albicans have complex extracellular proteolytic activity profiles, which illustrates the heterogeneity of this species. We showed four distinct proteolytic patterns composed of distinct serine (30-58 kDa) and metalloproteinase (64-95 kDa) activities, based on the inhibition profile with phenylmethylsulfonyl fluoride and 1,10-phenanthroline, respectively. This is the first report on secreted serine and metalloproteinases present in the culture supernatant fluids of C. albicans; however, we did not observe a significant correlation between proteolytic profile expressed by the C. albicans isolates from HIV-positive children and CD4(+) T cell count and plasma viral load.

Yeast communities of the cactusPilosocereus arrabidae as resources for larval and adult stages ofDrosophila serido

The feeding behavior ofDrosophila serido on the yeast communities of necrotic stem tissue ofPilosocereus arrabidae were studied in a sand dune ecosystem of Rio de Janeiro, Brazil. The prevalence of cactophilic yeasts includingPichia barkeri, Candida sonorensis andGeotrichum sp. in the crops and external surfaces ofD. serido reflected its association with the cactus habitat. The effective number of yeasts vectored on the surface of flies was higher than that in the crops. Also overlap between the yeasts from stems and from crops was partial suggesting selective feeding by the flies in the substrates visited. The females had a higher effective number of yeast species and a lower similarity than males with the yeast community ofP. arrabidae. This was probably related to the search for oviposition sites by females. The presence ofPichia thermotolerans-like andPichia amethionina varpachycereana in the flies, but not inP. arrabidae stems, indicated thatD. serido was not limited to this cactus species. The larvae and adults lived in different patches with the adults feeding in patches with higher yeast species richness. The larvae had a narrower feeding niche and higher overlap withP. arrabidae, and preferredP. barkeri andPichia cactophila as food. Adult flies fed on patches with the most frequent yeasts except forP. cactophila. Pichia caribaea was found in higher frequency in the adult crops than in the stems. Our data suggested that there was food selection and diet partitioning between adult and larval stages ofD. serido.

Phylogeny of Metschnikowia species estimated from partial rRNA sequences

Phylogenetic relationships of species assigned to the genus Metschnikowia were estimated from the extents of divergence among partial sequences of rRNA. The data suggest that the aquatic species (Metschnikowia australis, Metschnikowia bicuspidata, Metschnikowia krissii, and Metschnikowia zobellii) and the terrestrial species (Metschnikowia hawaiiensis, Metschnikowia lunata, Metschnikowia pulcherrima, and Metschnikowia reukaufii) form two groups within the genus. M. lunata and M. hawaiiensis are well separated from other members of the genus, and M. hawaiiensis may be sufficiently divergent that it could be placed in a new genus. Species of the genus Metschnikowia are unique compared with other ascomycetous yeasts because they have a deletion in the large-subunit rRNA sequence that includes nucleotides 434 to 483.

Yeast communities associated with different plant resources in sandy coastal plains of southeastern Brazil

The distribution of yeasts was studied in different plant substrata of beach and restinga ecosystems in southeastern Brazil. Candida sonorensis, Clavispora opuntiae, Pichia barkeri, Pichia cactophila and Geotrichum sp. were generally prevalent in yeast communities associated with necrotic tissues of the cacti Cereus pernambucensis, Selenicereus rizzini, Opuntia vulgaris and Opuntia sp. Cactus yeast communities were unique and no cactophilic yeast species were isolated from plant substrata other than cacti in these ecosystems. Flowers of the cactus Cereus pernambucensis had a highly specific yeast community composed almost exclusively of Pichia sp. C, a Candida domercqii -like species and Candida sp. C. Flowers of Ipomoea litoralis and Ipomoea pes-caprae , and extrafloral nectaries of Senna australis and Senna bicapsularis had communities composed predominantly of basidiomycetous yeast anamorphs. Insect vectors, the chemistry of each plant resource, and environmental conditions of these microhabitats are among the most important factors determining the species composition of these communities.

Mycocinogenic yeasts isolated from Amazon soils of the Maracá Ecological Station, Roraima-Brazil

The 240 yeasts isolated from soils of the Maraca Ecological Station in the Brazilian Amazon were identified and screened for mycocin production. These strains included 82% of ascomycetous and 18% basidiomicetous affinities and the prevalent species were Candida etchellsii, Candida famata, Candida robusta, Candida rugosa, Candida valida, Debaryomyces hansenii, Cryptococcus albidus, Cryptococcus laurentii, Rhodotorula glutinis, Rhodotorula minuta and Rhodotorula mucilaginosa. Mycocins able to kill some yeasts were produced by 6 strains identified as Issatchenkia sp., Saccharomyces exiguus?, Williopsis saturnus, var. subsufficiens, and 3 W. saturnus according to 26S rDNA D1/D2 region sequence and phenotypic data.

Yeast communities of the cactusPilosocereus arrabidae and associated insects in the Sandy Coastal Plains of Southeastern Brazil

The yeast communities from necrotic tissues, decaying flowers and fruits, and from larval feeding sites of the mothSigelgaita sp. in the cactusPilosocereus arrabidae were surveyed in three restinga ecosystems in Southeastern Brazil. Insects associated with these substrates were sampled to verify the vectoring of yeasts. The cactusPilosocereus arrabidae was shown to have four different yeast communities associated with it. Necrotic stems had a diverse yeast community with the prevalent speciesPichia barkeri, Candida sonorensis, Pichia cactophila, Geotrichum sp.,Myxozyma mucilagina andSporopachydermia sp. A, representing about 80% of the total isolates.Pichia sp. A and aCandida domercqii-like species represented more than 90% of the yeast isolates from decaying flowers. Fruits had a heterogeneous yeast community with typical fruit yeasts of the genusKloeckera, basidiomicetous anamorphs of the genusCryptococcus, the black yeastAureobasidium pullulans, Pichia sp. A, aCandida domercqii-like species, and some cactophilic yeasts, especiallyClavispora opuntiae. The feeding site ofSigelgaita sp. larvae hadClavispora opuntiae as the prevalent species. Insect vectors are suggested as one the most important factors influencing the composition of these yeast communities.

Microbial pollution indicators in Brazilian tropical and subtropical marine surface waters

The specificity of indicators that depend on elevated incubation temperature as a selective factor for their enumeration was questioned because of the possibility of interference from autochthonous microorganisms adapted to high ambient temperatures. Lactose-fermenting cultures isolated from fecal coliform tests of tropical marine surface waters were identified as consisting of about 70% Escherichia coli, and most of the remaining cultures being Klebsiella, Enterobacter or Citrobacter species. This confirmed the taxonomic specificity of fecal coliform tests for these waters. Fecal and total coliforms, fecal streptococcus, heterotrophic bacteria and yeast counts had correlations of above 99% confidence levels with most other microbial and chemical parameters studied. Waters with fecal coliform counts above 1000 per 100 ml had increased incidence of presumptive pathogenic yeasts, Pseudomonas aeruginosa and Salmonella. Our data support the use of coliforms or fecal streptococci as indicators of recent fecal pollution in tropical marine waters and yeast or heterotrophic bacteria counts as complementary indicator methods for these waters.