Yeasts associated with nests of the leaf-cutting ant Atta sexdens rubropilosa Forel, 1908

A total of 137 yeasts associated with the leaf-cutting ant Atta sexdens rubropilosa Forel, 1908 were characterized, being selected 93 for analysis. Twenty four species belonging to seven genera(Candida, Cryptococcus, Rhodotorula, Sporobolomyces, Tremella, Trichosporon, Pichia) were isolated from the different analysed material. The genus Candida was widely distributed, with C. homilentoma, C. colliculosa-like, C. famata and C. colliculosa being the most prevalent. A few isolates did not fit the standard descriptions and probably some of them could be new biotypes or even new species. Three strains of black yeasts were also isolated, and four others were identified as being Candida spp. The effective number of yeast species was higher in newer sponge. The origin, distribution and relative importance of these microorganisms for the ants are discussed.

Effects of cardiomyopathic mutations on the biochemical and biophysical properties of the human alpha-tropomyosin

Mutations in the protein alpha-tropomyosin (Tm) can cause a disease known as familial hypertrophic cardiomyopathy. In order to understand how such mutations lead to protein dysfunction, three point mutations were introduced into cDNA encoding the human skeletal tropomyosin, and the recombinant Tms were produced at high levels in the yeast Pichia pastoris. Two mutations (A63V and K70T) were located in the N-terminal region of Tm and one (E180G) was located close to the calcium-dependent troponin T binding domain. The functional and structural properties of the mutant Tms were compared to those of the wild type protein. None of the mutations altered the head-to-tail polymerization, although slightly higher actin binding was observed in the mutant Tm K70T, as demonstrated in a cosedimentation assay. The mutations also did not change the cooperativity of the thin filament activation by increasing the concentrations of Ca2+. However, in the absence of troponin, all mutant Tms were less effective than the wild type in regulating the actomyosin subfragment 1 Mg2+ ATPase activity. Circular dichroism spectroscopy revealed no differences in the secondary structure of the Tms. However, the thermally induced unfolding, as monitored by circular dichroism or differential scanning calorimetry, demonstrated that the mutants were less stable than the wild type. These results indicate that the main effect of the mutations is related to the overall stability of Tm as a whole, and that the mutations have only minor effects on the cooperative interactions among proteins that constitute the thin filament.

Yeasts and others parameters of pollution of the Ribeirao Claro stream in Rio Claro, São Paulo

The main water source of the Rio Claro municipal district (DAAE) was analysed for determining the level of organic contamination. Temperature, pH, light penetration, conductivity, dissolved oxygen, total dissolved phosphate, ortophosphate, ammonia, heterotrofic bacteria, total coliforms, fecal coliforms, total yeasts and fermentative yeasts were analysed during one year with samples being collected on a monthly basis. Bathing quality of the water from sites 1, 2 and 3 were classified, respectively, as Satisfactory, Very Good and Improper based on fecal coliform counts. Total yeast counts were appropriate as a complement for the appraisal of fresh water contamination by coliform counts. Seventeen yeast species belonging to genera Candida, Cryptococcus, Kloeckera, Pichia and Rhodotorula were found but none of them could be correlated with a level of contamination. Candida famata, C. robusta-like and C. colliculosa were isolated at all of the sites and between the five species found only at the more polluted site, Rhodotorula mucilaginosa was prevalent.

Yeast biodiversity from oleic ecosystems: Study of their biotechnological properties

The aim of this study was to know the yeast biodiversity from fresh olive (Olea europaea L.) fruits, olive paste (crush olives) and olive pomace (solid waste) from Arbequina and Cornicabra varieties. Yeasts were isolated from fruits randomly harvested at various olive groves in the region of Castilla La Mancha (Spain). Olive paste and pomace, a byproduct of the processing of this raw material, were also collected in sterile flasks from different oil mills. Molecular identification methodology used included comparison of polymerase chain reaction (PCR) amplicons of their 5.8S rRNA gene and internal transcribed spacers ITS1 and ITS2 followed by restriction pattern analysis (RFLP). For some species, sequence analysis of the 5.8S rDNA gene was necessary. The results were compared to sequences held in public databases (BLAST). These techniques allowed to identify fourteen different species of yeasts, belonging to seven different genera (Zygosaccharomyces, Pichia, Lachancea, Kluyveromyces, Saccharomyces, Candida, Torulaspora) from the 108 yeast isolates. Species diversity was thus considerable: Pichia caribbica, Zygosaccharomyces fermentati (Lachancea fermentati) and Pichia holstii (Nakazawaea holstii) were the most commonly isolated species, followed by Pichia mississippiensis, Lachancea sp., Kluyveromyces thermotolerans and Saccharomyces rosinii. The biotechnological properties of these isolates, was also studied. For this purpose, the activity of various enzymes (beta-glucosidase, beta-glucanase, carboxymethylcellulase, polygalacturonase, peroxidase and lipase) was evaluated. It was important that none of species showed lipase activity, a few had cellulase and polygalacturonase activities and the majority of them presented beta-glucanase, beta-glucosidase and peroxidase activities. (C) 2010 Elsevier Ltd. All rights reserved.

Phenotypical characterization of Candida spp. isolated from crop of parrots (Amazona spp.)

Renata G. Vieira R.G. & Acqua Coutinho S.D. 2009. Phenotypical characterization of Candida spp. isolated from crop of parrots (Amazona spp.). Pesquisa Veterinaria Brasileira 29(6):452-456. Curso de Pos-Graduagdo em Imunopatologia Veterinaria, Universidade Paulista, Rua Agariba 48, São Paulo, SP 05053010, Brazil. E-mail: selene@uol.com.brThe purpose of this study was to characterize Candida isolates from crop of parrots. Forty baby parrots of genus Amazona, species aestiva and amazonica that were apprehended from wild animal traffic were used: 18 presented ingluvitis and 22 other alterations, but showing general debilitation. Samples were seeded on Sabouraud dextrose agar with chloramphenicol after be obtained by the introduction of urethral probe through the esophagus. Based on morphology and biochemical reactions (API 20C) Candida was confirmed; it was still searched the production of proteinase and phospholipase, virulence factors for Candida species. Candida spp. were isolated from 57.5% parrots, being 72.2% from birds with ingluvitis and 45.5% from without ones. Twenty-five strains of Candida were isolated, 60% and 40%, respectively from parrots with and without ingluvitis, and were speciated: 28% C. humicola, 24% C. parapsilosis, 20% C. guilliermondii, 20% C. famata, and 8% C. albicans. These results demonstrate that C. albicans is not the most frequent species isolated, and it is the first report that shows C. guilliermondii, C. famata, and C. humicola causing infection in parrots. Many isolates presented filamentation (76%), 100% produced proteinase and 68% phospholipase. The observation of Candida spp. producing virulence factors reinforce the pathogenic role of these yeasts in the cases studied.

Culture of Candida in vinasse and molasses: Effect of acid and salt addition on biomass and raw protein production

Species of the genera Candida grown in vinasse and molasses were studied under the following conditions: agitation of containers, pH 4.6, culture time of 24 hours at 30°C. The greatest biomass production of C. krusei grown in vinasse was obtained with the addition of 0.1% H3PO4, and of C. guilliermondii and C. utilis with the addition 0.02% urea plus 0.03% H3PO4. Protein levels near 50% were found in C. utilis in vinasse supplemented either with molasses, with 0.05% MgSO4, or with 0.02% urea plus 0.03% H3PO4. © 1982 Springer-Verlag.

Hyaluronidase and chondroitin sulphatase production by different species of Candida

The production of hyaluronidase and chondroitin sulphatase by Candida albicans, Candida tropicalis, Candida parapsilosis, Candida guilliermondii and Candida krusei was investigated using a complex culture medium (Sabouraud glucose agar) and a chemically defined medium. Among the 63 C. albicans isolates tested, 61 (97.8%) were found to be hyaluronidase and chondroitin sulphatase producers; one isolate produced only chondroitin sulphatase and one other was unable to produce either enzyme. The second major hyaluronidase and chondroitin sulphatase producing species was C. tropicalis followed by C. guilliermondii, C. parapsilosis and C. krusei. Among the C. albicans isolates tested no relation between the source of isolation and the amount of hyaluronidase and chondroitin sulphatase produced was found.

Ascomycetous Yeasts Associated with Naturally Occurring Fruits in a Tropical Rain Forest

Fruits from twenty different species of angiosperms were collected during the period from November, 1991 to January, 1992. Two hundred and two strains of yeasts and yeast-like fungi were isolated, of which 74 % showed ascomycetic affinity. Candida was the predominant genus, followed by (in descending order of occurrence): Cryptococcus, Klœckera, Sporobolomyces, Pichia, Hanseniaspora and Bullera. Black yeasts and other strains showing basidiomycetic affinity were also isolated. The genus Candida represented the highest number of identified species and the greatest variety of associated substrates. Among the ascomycetes and their anamorphs, 38 species were identified, with Klœckera apiculata being the most frequent among the isolates and the one which occurred in the largest variety of substrates. Some of the biotypes designated as Candida sp. A, B, C, D, E, F, G, H, I, and Pichia sp. did not correspond to the standard species description found in the literature, and may represent new species. The strains of yeasts isolated in this study were characterized and incorporated into the Tropical Culture Collection of the Fundação Tropical de Pesquisas e Tecnologia André Tosello, Campinas, São Paulo.

Prevalence of yeasts in the oral cavity of children treated with inhaled corticosteroids

The aim of this study was to observe the prevalence of Candida spp. in the oral cavity of children undergoing treatment with inhaled corticosteroids. Thirty children treated with inhaled corticosteroids and thirty control children were studied. Saliva samples were collected through oral rinses with phosphate buffered saline (PBS). The samples were plated on Sabouraud's dextrose agar and incubated at 37 degrees C for 48 h. After this period, the number of colony-forming units per ml (cfu/ml) of saliva was calculated. The isolates were identified by phenotypic characterization. Candida spp. was isolated from 43.33% of the samples of children treated with corticosteroids, with a mean of 780 cfu/ml of saliva, and from 30% of the samples of the control group, with a mean of 560 cfu/ml of saliva. No significant statistical difference was observed between the groups. C. albicans was the prevalent species in both groups, followed by C. guilliermondii, C. parapsilosis and C. stellatoidea. Furthermore, Rhodotorula rubra and C. lusitaniae were also isolated from the treated group. We concluded that there was no significant increase in the prevalence and number of Candida spp. in the oral cavity of children treated with inhaled corticosteroids.

First isolation of microorganisms from the gut diverticulum of Aedes aegypti (Diptera: Culicidae): New perspectives for an insect-bacteria association

We show for the first time that the ventral diverticulum of the mosquito gut (impermeable sugar storage organ) harbors microorganisms. The gut diverticulum from newly emerged and non-fed Aedes aegypti was dissected under aseptic conditions, homogenized and plated on BHI medium. Microbial isolates were identified by sequencing of 16S rDNA for bacteria and 28S rDNA for yeast. A direct DNA extraction from Ae. aegypti gut diverticulum was also performed. The bacterial isolates were: Bacillus sp., Bacillus subtilis and Serratia sp. The latter was the predominant bacteria found in our isolations. The yeast species identified was Pichia caribbica.

Avaliação do potencial antagônico de leveduras, visando biocontrole de deterioração por penicillium expansum

Considerable losses during apple fruit storage occur due to microbiological diseases, mainly caused by Penicillium expansum, which in addition to fruit pulp deterioration produces patulin, a mycotoxin with carcinogenic and teratogenic activity. Biological control of post-harvest disease by antagonist yeasts focused on killer toxins is an appreciable alternative to the chemical fungicides, due to the low possibility of toxic residues demonstrated during fermentative processes. Twenty out of 44 yeasts (16 isolated from fruits, 10 from corn silage and 18 from laboratory anthill), showed antagonism against spores of P. expansum. The assay in solid medium pointed the strongest nutrient competition antagonism by D. hansenii strain C1 (31 mm inhibition diameter), while D. hansenii strain C7 (15 mm) showed higher antibiosis and parasitism pattern. In the following step the extracellular activity was tested performing the assay with culture supernatant in Yeast Medium agar, where C. guilliermondii P3 was more effective against conidia germination (inhibition rate of 58.15%) while P. ohmeri showed better inhibition on micelial growth (66.17%). The antibiosis showed by both yeasts could suggest probable mechanism associated with killer phenomenon, once both strains were killer positive against sensitive reference strains (S. cerevisiae NCYC 1006 and P. kluyveri CAY-15). In order to enhance the production of antifungal substance, these yeasts were cultivated with P. expansum, but the difference between culture supernatant obtained from yeasts cultivated alone and with mould was not significant (P > 0.05). The results demonstrated that the yeasts application constitute a promising tool, enhancing the biological control of P. expansum in post-harvest diseases of apple fruit.

Identification of Candida species in the clinical laboratory: A review of conventional, commercial, and molecular techniques

In healthy individuals, Candida species are considered commensal yeasts of the oral cavity. However, these microorganisms can also act as opportunist pathogens, particularly the so-called non-albicans Candida species that are increasingly recognized as important agents of human infection. Several surveys have documented increased rates of C. glabrata, C. tropicalis, C. guilliermondii, C. dubliniensis, C. parapsilosis, and C. krusei in local and systemic fungal infections. Some of these species are resistant to antifungal agents. Consequently, rapid and correct identification of species can play an important role in the management of candidiasis. Conventional methods for identification of Candida species are based on morphological and physiological attributes. However, accurate identification of all isolates from clinical samples is often complex and time-consuming. Hence, several manual and automated rapid commercial systems for identifying these organisms have been developed, some of which may have significant sensitivity issues. To overcome these limitations, newer molecular typing techniques have been developed that allow accurate and rapid identification of Candida species. This study reviewed the current state of identification methods for yeasts, particularly Candida species. © 2013 John Wiley & Sons A/S.

Hydroxyurea therapy in sickle cell anemia patients aids to maintain oral fungal colonization balance

Background: The aim of this study was to evaluate the frequency of Candida species and presence of lesions in the oral cavity of patients with sickle cell anemia (SS). Methods: The study included 30 patients diagnosed with sickle cell anemia and taking hydroxyurea for at least 90 days (SS/HU+); and 39 patients with sickle cell anemia and without hydroxyurea therapy (SS/HU-). Two control groups were constituted by healthy individuals matched to the test groups in age, gender, and oral conditions (C/HU+ for SS/HU+ and C/HU- for SS/HU-). Oral clinical examination and anamnesis were performed. Yeasts were collected by oral rinses and identified by API system. Antifungal susceptibility evaluation was performed according to the CLSI methodology. Data obtained for microorganisms counts were compared by Student's t test (SS/HU+ vs. C/HU+ and SS/HU- vs. C/HU-) using MINITAB for Windows 1.4. Significance level was set at 5%. Results: No oral candidosis lesions were detected. Significant differences in yeasts counts were observed between SS/HU- group and the respective control, but there were no differences between SS/HU+ and C/HU+. Candida albicans was the most prevalent species in all groups. Candida famata was observed both in SS and control groups. Candida dubliniensis, Candida glabrata, Candida krusei, Candida tropicalis, Candida pelliculosa, and Candida parapsilosis were observed only in SS groups. Most strains were susceptible to all antifungal agents. Conclusion: Hydroxyurea therapy seems to decrease candidal counts and resistance rate in sickle cell anemia patients. However, further studies should be conducted in the future to confirm this finding. Hydroxyurea therapy in sickle cell anemia patients maintains fungal species balance in oral cavity. © 2013 John Wiley & Sons A/S.

Indução da expressão da Glicerol-3-Fosfato desidrogenase em levedura

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Isolamento e seleção de leveduras fermentadoras de xilose

Pós-graduação em Microbiologia - IBILCE