Biomedical subjects

C A Rosa

Publications and source records attributed to C A Rosa.

31 records · Page 2Linked to original sources

PubMed1997

The incidence of killer activity and extracellular proteases in tropical yeast communities.

The presence of killer and proteolytic yeasts was studied among 944 isolates representing 105 species from tropical yeast communities. We found 13 killer toxin producing species, with Pichia kluyveri being the most frequent. Other killer yeast isolates were Candida apis, Candida bombicola, Candida fructus, Candida krusei, Candida sorbosa, Hanseniaspora uvarum, Issatchenkia occidentalis, Kloeckera apis, Kluyveromyces marxianus, Pichia membranaefaciens, Pichia ohmeri-like, and Sporobolomyces roseus. The communities from which killer yeasts were isolated had strains sensitive to them, and there were interspecific and intraspecific differences in the spectra of their killer activities. Pichia kluyveri had the broadest spectra of activity against sensitive isolates, and it apparently produced different toxins. The coexistence of sensitive and killer yeasts using the same substrate suggests that there is spatial separation in microhabitats or temporal separation in different stages of successions. Basidiomycetous yeasts were more frequently proteolytic than ascomycetous yeasts. Extracellular proteases could be important for the yeasts to have access to more nitrogen nutrients and obtain a better balance with available carbon sources.

Endopeptidases↗

PubMed1996

Utilization of acetonitrile and other aliphatic nitriles by a Candida famata strain.

A variant of a yeast strain identified as Candida famata isolated from gold mine effluent was able to grow on acetonitrile, acrylonitrile, butyronitrile, isobutyronitrile, methacrylnitrile, propionitrile, succinonitrile, valeronitrile, acetamide, isobutyamide, and succinamide as sole nitrogen source, after acclimatization. The yeast grew on acetonitrile and acetamide at concentrations up to 4%. The utilisation of acetonitrile and acetamide by the C. famata strain probably involves hydrolysis in a two-step reaction mediated by both inducible and intracellular nitrile hydratase and amidase.

Acetonitriles↗

PubMed1994

Yeast communities of the cactus Pilosocereus 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 moth Sigelgaita sp. in the cactus Pilosocereus arrabidae were surveyed in three restinga ecosystems in Southeastern Brazil. Insects associated with these substrates were sampled to verify the vectoring of yeasts. The cactus Pilosocereus arrabidae was shown to have four different yeast communities associated with it. Necrotic stems had a diverse yeast community with the prevalent species Pichia barkeri, Candida sonorensis, Pichia cactophila, Geotrichum sp., Myxozyma mucilagina and Sporopachydermia sp. A, representing about 80% of the total isolates. Pichia sp. A and a Candida 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 genus Kloeckera, basidiomicetous anamorphs of the genus Cryptococcus, the black yeast Aureobasidium pullulans, Pichia sp. A, a Candida domercqii-like species, and some cactophilic yeasts, especially Clavispora opuntiae. The feeding site of Sigelgaita sp. larvae had Clavispora opuntiae as the prevalent species. Insect vectors are suggested as one the most important factors influencing the composition of these yeast communities.

Animals↗

PubMed1994

Yeast communities of the cactus Pilosocereus arrabidae as resources for larval and adult stages of Drosophila serido.

The feeding behavior of Drosophila serido on the yeast communities of necrotic stem tissue of Pilosocereus arrabidae were studied in a sand dune ecosystem of Rio de Janeiro, Brazil. The prevalence of cactophilic yeasts including Pichia barkeri, Candida sonorensis and Geotrichum sp. in the crops and external surfaces of D. 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 of P. arrabidae. This was probably related to the search for oviposition sites by females. The presence of Pichia thermotolerans-like and Pichia amethionina var pachycereana in the flies, but not in P. arrabidae stems, indicated that D. 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 with P. arrabidae, and preferred P. barkeri and Pichia cactophila as food. Adult flies fed on patches with the most frequent yeasts except for P. 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 of D. serido.

Animals↗

PubMed1993

Yeasts and coliform bacteria of water accumulated in bromeliads of mangrove and sand dune ecosystems of southeast Brazil.

Yeasts and coliform bacteria were isolated from water that accumulated in the central cups and adjacent leaf axilae of two bromeliads, Neoregelia cruenta of a coastal sand dune and Quesnelia quesneliana of a mangrove ecosystem near the city of Rio de Janeiro, Brazil. The mean total coliform counts were above 10,000 per 100 mL for waters of both plants, but the mean fecal coliform counts were only 74 per 100 mL for Q. quesneliana and mostly undetected in water from N. cruenta. Of 90 fecal coliform isolates, 51 were typical of Escherichia coli in colony morphology and indol, methyl red, Volges-Proskauer, and citrate (IMViC) tests. Seven representatives of the typical E. coli cultures were identified as this species, but the identifications of nine other coliform bacteria were mostly dubious. The yeast community of N. cruenta was typical of plant surfaces with basidiomycetous yeasts anamorphs, and the black yeast Aureobasidium pullulans was prevalent. Quesnelia quesneliana had a substantial proportion of ascomycetous yeasts and their anamorphs, including a probable new biotype of Saccharomyces unisporus. Our results suggested that the microbial communities in bromeliad waters are typically autochtonous and not contaminants.

Brazil↗

PubMed1992

Clavispora opuntiae and other yeasts associated with the moth Sigelgaita sp. in the cactus Pilosocereus arrabidae of Rio de Janeiro, Brazil.

Clavispora opuntiae was the prevalent yeast associated with the feeding sites of Sigelgaita sp. larvae in the cactus Pilosocereus arrabidae. Also associated with this habitat were Candida sonorensis, Pichia cactophila, Pichia barkeri, Candida sp. A, Geotrichum sp., Geotrichum sericeum and the yeast like organisms Prototheca zopfii and Acremonium sp. Atypical yeast biotypes that may represent new species of Pichia, Sporopachydermia and Candida were isolated. Mating types of Clavispora opuntiae were at a ratio 70 h- to 3 h- and reduced levels of sporulation suggested low pressure for sexual reproduction in this habitat. Sigelgaita sp. probably was not an important vector for Clavispora opuntiae because it was not isolated from an adult or eggs of this moth.

Animals↗

PubMed1992

Yeasts associated with Drosophila in tropical forests of Rio de Janeiro, Brazil.

The distribution and diversity of yeast species vectored by and from the crop of eight species groups of Drosophila is described for two rain forest sites and an urban wooded area in Rio de Janeiro, Brazil. The typical forest Drosophila groups guarani, tripunctata, and willistoni showed a higher diversity of yeasts than the cosmopolitan melanogaster species group, suggesting different strategies of utilization of substrates. Apiculate yeasts, including Kloeckera apis, Kloeckera javanica, and Kloeckera japonica, were the prevalent species. Geotrichum spp. and Candida citea were also frequent isolates in the forest sites. Similarities between the yeasts from the external surfaces and crops of Drosophila suggested that the feeding substrates were the main source of the yeasts vectored by these flies. Most of the yeasts were strong fermenters and assimilated few compounds, usually sucrose, cellobiose, and glycerol. This indicated a preference of the flies for food sources such as fruits. Some yeasts were primarily isolated from one group of Drosophila; for example, Kloeckera javanica from the melanogaster group, Debaryomyces vanrijiae var. yarrowii from the tripunctata group, and Kluyveromyces delphensis from the willistoni group. These associations and differences in the yeast communities among the fly groups suggested a differentiation of diets and specialization of the yeast-Drosophila association in the tropical forests.

Animals↗

PubMed1975

[Canine leptospirosis in the state of São Paulo (author's transl)].

In this paper the occurrence of leptospirosis was studied by the search of agglutininis antileptospira, in 10 dogs with symptoms of the disease. Another group of 22 animals with hepatic or renal insufficiency was also studied for the correlation between both insufficiency and leptospirosis. Finally, a third group of 40 dogs, clinically normal, was also included in this study. In 60% of suspected cases the clinical diagnosis was confirmed by the presence of specific agglutinins to serotypes icterohaemorrhagiae, canícola, grippotyphosa and bataviae. Among animals with renal or hepatic insufficiency it was found 36.3% of reagents while in the normal group the rate was only 7.5%. The serotype butembo was detected serologically in dogs for the first time in Brazil.

Acute Kidney Injury↗

PubMed1974