Valter R. Linardi

Biodegradation of phenol by a filamentous fungi isolated from industrial effluents: identification and degradation potential

Thirty filamentous fungal strains were isolated from effluents of a stainless steel industry (Minas Gerais, Brazil) and tested for phenol tolerance. Fifteen strains of the genera Fusarium sp., Aspergillus sp., Penicillium sp. and Graphium sp. tolerants up to 10 mM of phenol were selected and tested for their ability to degrade phenol. Phenol degradation was a function of strain, time of incubation and initial phenol concentration. FIB4, LEA5 and AE2 strains of Graphium sp. and FE11 of Fusarium sp. presented the highest percentage phenol degradation, with 75% degradation of 10 mM phenol in 168 h for FIB4. A higher starting cell density of Graphium sp. FIB4 lead to a decrease in the time needed for full phenol degradation and increased the phenol degradation rate. All strains exhibited activity of catechol 1,2-dioxygenase and phenol hydroxylase in free cell extracts obtained from cells grown on phenol, suggesting that catechol was oxidized by the ortho type of ring fission. These data reported demonstrate the prospect after the application of filamentous fungal strains in protecting the environment from phenol pollution.

Yeast communities and genetic polymorphism of Saccharomyces cerevisiae strains associated with artisanal fermentation in Brazil

Yeast communities and genetic polymorphism of prevalent Saccharomyces cerevisiae strains isolated from the spontaneous fermentation of the sugarcane juice during the production of aguardente in three distilleries in the state of Minas Gerais, Brazil, were studied. S. cerevisiae was the prevalent species during the process of aguardente production, but Schizosaccharomyces pombe was predominant in old fermentations in one distillery. Transient yeast species were found in a variable number, probably due to the daily addition of sugarcane juice, and they were different for each of the three distilleries studied. PFGE and PCR analysis of the predominant strains of S. cerevisiae isolated from the fermented must showed a high degree of genetic polymorphism among the three distilleries. A high molecular variability of S. cerevisae strains was also observed among strains isolated from the same vat at different fermentation ages. Our results showed that there was a succession of geneticly different strains of S. cerevisae during the process of aguardente production.

Characterization and succession of yeast populations associated with spontaneous fermentations during the production of Brazilian sugar-cane aguardente.

A succession of yeasts was observed during fermentation of aguardente with Saccharomyces cerevisiae being the predominant species. Candida sake, Kluyveromyces marxianus var. drosophilarum and apiculate yeasts were also frequent. Transient yeast species were found in variable numbers, probably due to the daily addition of sugar-cane juice. Killer yeasts were isolated and may have a role in the exclusion of some transient and contaminant species.

Screening of Yeasts from Brazilian Amazon Rain Forest for Extracellular Proteinases Production

Eighty seven yeast strains representing 34 species isolated from Parahancornia amapa fruit and associated Drosophila flies collected in the Brazilian Amazon rain forest, were screened for proteinase production. Proteolytic activity was tested through casein hydrolysis in solid medium supplemented with 0.5% casein and glucose. Among 23 strains, 18 from genus Candida and 5 from Pichia were caseinolytic and produced proteinases in yeast carbon base liquid medium supplemented with casein 0.01%. The proteolytic activity was tested on pH ranging from 2.0 to 9.0 in correspondence to the pH of the cultures media in which the yeasts were grown. Six highly proteolytic strains: Candida parapsilosis AP153A, C. krusei AP176, C. sorbosa DR215, C. sorbosa AP259, C. valida AP209A and C. sorboxylosa AP287 were selected and the pH optima of production and the proteolytic activity were determined. In general the secretion of proteinase was maximum throughout the exponential and the stationary phases. Greater production occurred in acidic culture and high activity was observed at pH 3.0, 4.0 and 5.0.

An outbreak of staphylococcal food poisoning in the Municipality of Passos, MG, Brazil

An outbreak of staphylococcal food poisoning involving 42 people who had eaten a meal at a restaurant in the Municipality of Passos, Minas Gerais, Brazil, is reported. Thirty-one of the individuals became ill with vomiting, diarrhea and dizziness within 30 minutes after eating the meal. The foods suspected were: chicken pancake, rice, beans, tomato sauce and mashed chick-peas. Large numbers (> 2.0x108 CFU/g) of enterotoxigenic staphylococci were present in the chicken pancake. These strains produced enterotoxins A, B and D. Swabs from the nasal cavity and throat and from under the fingernails of food handlers were cultured for the detection of enterotoxigenic staphylococci carriers. Four out of five of them were healthy carriers of enterotoxin A, B, C and D producing Staphylococcus aureus at the sites cultured and one of them was also a nasal carrier of TSST-1 toxin producing S. aureus. These results indicate that the food handlers would have been the source of the food contamination.

Production of fuel alcohol by Saccharomyces strains from tropical habitats

SummaryStrains of Saccharomyces spp. from tropical substrates tolerated temperatures up to 40 ° C, sucrose concentrations up to 50% (w/v) and ethanol concentrations up to 20 g/L in fermentation conditions. Strain TD200 tolerated 20 g/l of ethanol. The ethanol produced by strain DR1459 was comparable to that of industrial strain HTYM-81. These strains have potential use for the production of fuel alcohol.

Metabolism of benzonitrile by Cryptococcus sp. UFMG‐Y28

The yeast Cryptococcus sp. UFMG‐Y28 can utilize benzonitrile as a nitrogen and possible additional carbon source. The kinetics of growth on Yeast Carbon Base (YCB) added of benzonitrile as sole nitrogen source showed that benzonitrile was metabolized to benzoic acid and ammonia. Liquid chromatography analysis indicated that Cryptococccus sp. UFMG‐Y28 metabolized 12 mM benzonitrile to 10 mM benzoic acid. Resting cells cultivated on YCB‐propionitrile medium showed nitrilase activity against benzonitrile. This strain appears to be promising for bioconversion of nitriles to high value acids and for bioremediation of sites contaminated with aliphatic and aromatic nitriles.

The use of acetonitrile as the sole nitrogen and carbon source by Geotrichum sp. JR1

A yeast strain identified as Geotrichum sp. JR1 was able to use acetonitrile as the sole carbon and nitrogen source. The strain grew in 0.5 to 2M acetonitrile. Ammonia generation as enzymatic product during the strain growth indicates the presence of an acetonitrile degrading enzyme. Acetic acid and acetamide were detected during assays with the resting cells cultivated in acetonitrile, indicating the presence of nitrile and amide degrading enzymes. This paper is the first to describe the use of acetonitrile as the sole carbon and nitrogen source by a yeast.

Degradation of phenol by Trichosporon sp. LE3 cells immobilized in alginate.

The degradation of phenol by freely suspended cells of Trichosporon sp. LE3 and alginate‐immobilized cells was studied in batch culture. The alginate concentration (2 or 4%) and the cross‐linking salt used (BaCl2 or CaCl2) affected the rate and percentage of phenol degradation. The highest values were obtained for immobilized cells at 2% calcium alginate, although complete degradation of 15 and 18 mM phenol was not observed. When the cell concentrations in the assays were doubled, the 2% calcium alginate‐immobilized cells were able to degrade up to 30 mM phenol in less than 120 hours, although the free cells did not completely degrade phenol at concentrations above 20 mM. The maximum phenol degradation rate was a strong function of initial phenol concentrations, being the highest values being observed for 20 mM phenol.

Biodegradation of acetonitrile by cells of Candida guilliermondii UFMG-Y65 immobilized in alginate, kappa-carrageenan and citric pectin

Na degradacao de acetonitrila, foram testadas celulas livres de Candida guilliermondii UFMG-Y65 e imobilizadas em diferentes suportes, quais sejam, Ba-alginato, k-carrageno e pectina citrica. A velocidade de degradacao da acetonitrila foi monitorada por 120 h, mediante o crescimento da levedura e geracao de amonia. Diferentes concentracoes de alginato nao afetam a viabilidade das celulas; mas o periodo de incubacao, em solucao de BaCl2, reduziu o numero de celulas vivas. Da mesma forma, a natureza do gel e a estrutura da matriz do suporte, ambas resultantes das condicoes de imobilizacao das celulas, foram de fundamental importância para a atividade catalisadora e sua performance; afetando assim, os padroes de crescimento microbiano e a de atividade enzimatica. As celulas imobilizadas em alginato degradaram acetonitrila com maior eficacia do que as imobilizadas em k-carrageno ou as celulas imobilizadas em pectina citrica.