Abstract Yeasts are unicellular fungi widespread in the environment, and studies suggest that there is a positive correlation between yeast and polluted aquatic environments. The aim of this study was to analyze the diversity and resistance of yeasts isolated from water samples collected along the Arroio Dilúvio in Porto Alegre to antifungals. Yeast isolates from the Arroio Dilúvio were subjected to susceptibility assays against antifungals using the minimum inhibitory concentration (MIC) test, and amplification of the ITS1-5.8S-IT2 region; in addition, the ITS-5.8S region was sequenced for some of the isolates. The amplification product was subjected to PCR-RFLP, and the restriction profile allowed the construction of a dendrogram. Susceptibility tests showed a high prevalence of resistance to azole antifungals, where 16.8% of the isolates had a resistance profile to amphotericin B. The sequence analysis allowed the identification of Candida species, including potentially pathogenic species, and species of the Debaryomyces spp. The resistance to antifungals in yeasts isolated from Arroio Dilúvio reinforces the importance of studies of environmental microbiota, and indicates that environmental degradation influences the phenotype displayed.

ABSTRACT During composting processes, the degradation of organic waste is accomplished and driven by a succession of microbial populations exhibiting a broad range of functional competencies. A total of 183 bacteria, isolated from a composting process, were evaluated for cellulase activity at different temperatures (37, 50, 60, and 70°C) and pH values. Out of the 22 isolates that showed activity, isolate 380 showed the highest cellulase activity. Its ability to produce cellulase was evaluated in culture medium supplemented with carboxymethyl cellulose, microcrystalline cellulose, wheat straw, and rice husk. The culture medium supplemented with carboxymethyl cellulose induced higher enzyme activity after 6 hours of incubation (0.12 UEA mL-1 min-1). For wheat straw and rice husk, the results were 0.08 UEA mL-1 min-1 for both, while for microcrystalline cellulose, 0.04 UEA mL-1 min-1 were observed. The highest carboxymethyl cellulase activity was observed at 60°C (0.14 UEA mL-1 min-1) for both crude and partially purified enzyme after 30 and 120 min of incubation, respectively. Alkalinization of the medium was observed during cultivation in all substrates. The cellulase had a molecular mass of 20 kDa determined by SDS-Page. Isolate 380 was identified as Bacillus licheniformis. This work provides a basis for further studies on composting optimization.

A técnica da compostagem é um recurso empregado com o objetivo de reciclar resíduos orgânicos domésticos e sanitizar o lodo produzido nas estações de tratamento de efluentes de esgoto (ETE) podendo-se obter um composto com propriedades de fertilizante agrícola e/ou corretor de solos degradados. A alta temperatura atingida pelo sistema deve ser responsável pela redução de micro-organismos patogênicos presentes no início do processo assegurando, desta forma, a qualidade microbiológica do composto sem oferecer riscos de contaminação, conforme preconiza a Resolução 354/2006 do CONAMA. Objetivou-se, com o trabalho, avaliar a influência da temperatura sobre a redução de Escherichia coli, Salmonella sp., ovos de helmintos e vírus entéricos durante o processo de compostagem, além da contagem de bactérias heterotróficas. Foram realizados testes colimétricos, semeaduras em meios de cultivo, testes de visualização de ovos de helmintos e detecção molecular de vírus entéricos. Os resultados indicaram oscilação nas contagens de E. coli e de bactérias heterotróficas, mesmo após a fase termofílica. Por outro lado, não foi detectada a presença de Salmonella sp., vírus entéricos nem de ovos viáveis de helmintos, ao final do processo.

The composting technique is a promising alternative for the treatment of solid organic residues, along with the sludge produced in sewage treatment plants. The final compost might show fertilizer properties, which can be used to recover poor soils. The high temperatures that the composting process can achieve are responsible for the reduction of the pathogenic microbial population, helminth eggs and virus present in the beginning of the process. This behavior assures the microbial quality of the compost according to the 375/2006 Resolution of the CONAMA. The aim of this study was to evaluate the influence of temperature on Escherichia coli, Salmonella sp., helminth egg and enteric virus presence in the final product from a composting process. For this matter colimetric assays were performed together with the seedling of the samples in different culture media, the assay for helminth eggs visualization under the microscope and the identification of enteric virus. The results showed an oscillation on E. coli and heterotrophic bacteria counts, even after the thermophilic phase. On the other hand, Salmonella sp., helminth eggs and enteric virus were not found in the final compost.

A presença das biovares I e/ou II de Ralstonia solanacearum em uma lavoura de batatas (Solanum tuberosum) tem influência direta no sucesso das medidas adotadas para controlar a murcha bacteriana. As biovares diferem entre si em relação à agressividade, latência e sobrevivência. Assim, um experimento de campo foi conduzido em uma área naturalmente infestada em duas épocas de cultivo com os objetivos de verificar (1) a incidência de biovares I e/ou II, (2) a relação entre biovar e época de plantio e (3) a relação entre biovar e cultivar de batata. Os isolados obtidos de plantas das cultivares Achat, Baronesa, Elvira, Macaca, Monte Bonito e Trapeira foram identificados como biovar I ou II através da PCR, utilizando os oligonucleotídeos iniciadores T3A e T5A. Ambas as biovares foram encontradas na área naturalmente infestada. De 73 isolados de R. solanacearum, 94,5% foram identificados como biovar II e 5,5% como biovar I. A biovar II foi isolada dos cultivos de primavera e de outono, independente da cultivar, mas a I apenas do cultivo de primavera e de plantas assintomáticas das cultivares Achat e Macaca. A maior população da biovar I nestas duas cultivares pode ser uma evidência da possível relação entre biovar e cultivar.

The occurrence of biovars I and/or II of Ralstonia solanacearum in a potato (Solanum tuberosum) field has direct consequences for the success of the measures adopted to control bacterial wilt. Biovars differ regarding aggressiveness, latency and survival. An experiment was conducted in a naturally infested potato field in two seasons to find (1) the incidence of biovars I and II, (2) the relationship between biovar and planting season, and (3) the relationship between biovar and potato cultivar. Bacterial isolates from potato cultivars Achat, Baronesa, Elvira, Macaca, Monte Bonito, and Trapeira were identified as biovar I or II through PCR, using T3A and T5A primers. Both biovars I and II were found in the naturally infested field. Among 73 strains, 5.5 and 94.5 % were identified as biovar I and II, respectively. Biovar II was found in the spring and in the fall, regardless of the cultivar, but biovar I only in the spring season and on symptomless plants of Achat and Macaca cultivars. The highest population of biovar I on these two cultivars may be evidence for a possible relationship between biovar and cultivar.