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Trehalose accumulation, invertase activity and physiological characteristics of 86 yeast isolates from short fermentative cycles during the production of cachaça in three artisanal distilleries of the State of Minas Gerais were studied. Among these isolates, 70% were able to grow at temperatures between 40 and 42ºC. Only Saccharomyces cerevisiae isolates were able to grow over 40ºC. Lower temperatures (As características fisiológicas, acúmulo de trealose e produção de invertase de 86 leveduras isoladas do ciclo fermentativo durante a produção artesanal de cachaça em três destilarias no Estado de Minas Gerais foram estudadas. Destes isolados 70% foram capazes de crescer acima de 40 e 42ºC. Somente os isolados de Saccharomyces cerevisiae foram capazes de crescer acima de 40ºC. Baixas temperaturas (

M . A . D I A S , I . C . A . L A C E R D A , P . F . P I M E N T E L , H . F . D E C A S T R O A N D C . A . R O S A . 2002. Aims: The aim was to investigate the biosorption of chromium, nickel and iron from metallurgical effluents, produced by a steel foundry, using a strain of Aspergillus terreus immobilized in polyurethane foam. Methods and Results: A. terreus UFMG-F01 was immobilized in polyurethane foam and subjected to biosorption tests with metallurgical effluents. Maximal metal uptake values of 164AE 5m g g )1 iron, 96AE 5m g g )1 chromium and 19AE 6m g g )1 nickel were attained in a culture medium containing 100% of effluent stream supplemented with 1% of glucose, after 6 d of incubation. Conclusions: Microbial populations in metal-polluted environments include fungi that have adapted to otherwise toxic concentrations of heavy metals and have become metal resistant. In this work, a strain of A. terreus was successfully used as a metal biosorbent for the treatment of metallurgical effluents. Significance and Impact of the Study: A. terreus UFMG-F01 was shown to have good biosorption properties with respect to heavy metals. The low cost and simplicity of this technique make its use ideal for the treatment of effluents from steel foundries.

Five strains of Rhodotorula mucilaginosa were tested for the ability to accumulate free and complexed silver ions by metabolism-dependent and -independent processes. The ability to take up Ag+ was observed in both live and dead biomass, whereas silver dicyanide [Ag (CN)2-] uptake was strictly glucose dependent. In contrast to Ag (CN)2-, glucose addition inhibited by 16 to 25% the Ag+ uptake rate of living UFMG - Y02, Y27, and Y35 cells, while strains CBS 316 and UFMG-Y01 showed an improved uptake rate of about 115% and 13%, respectively. The Langmuir sorption model was used to evaluate the silver sorption capability of the R. mucilaginosa strains. The calculated q max value suggested that R. mucilaginosa strains UFMG-Y27 had the highest loading capacity. The type strain CBS 316 had the lowest q max but showed the highest affinity for silver ions. The results provided by the Fourier Transform Infra Red analysis (FTIR) suggest that C=O groups represent the main reactive site for silver uptake by the strain UFMG-Y27.Quatro linhagens de Rhodotorula mucilaginosa e uma linhagem padrão dessa mesma espécie foram investigadas quanto a habilidade de acumular íons de prata livres (Ag+) e complexados [Ag (CN)2-], através de processos dependentes e independentes do metabolismo. A habilidade de acumular Ag+ foi observada em ambas as células, vivas e mortas. Contudo, o acúmulo de Ag (CN)2- foi um processo estritamente dependente de energia. Durante os estudos que avaliaram a dependência de uma fonte energética para o acumulo de íons de prata livres (Ag+) foi observado que a adição de glicose resultou na diminuição do acúmulo de Ag+ por três linhagens (UFMG -- Y02, 27 and 35). Ao passo que as linhagens CBS 316 e UFMG -- Y01 apresentaram aumento do acúmulo desse metal. A analise dos resultados de biossorção através do modelo de Langmuir, sugerem que a linhagem UFMG -- Y27 possui a maior capacidade de acúmulo de prata (carga). Enquanto que a linhagem padrão CBS 316 apresentou a menor capacidade de carga e a maior afinidade por ions de prata. Analises de infra vermelho da biomassa fúngica, com e sem prata, mostraram que os grupamentos C=O foram os principais sítios de ligação desse metal pela linhagem UFMG -- Y27.

Five strains of Rhodotorula mucilaginosa were tested for the ability to accumulate free and complexed silver ions by metabolism-dependent and -independent processes. The ability to take up Ag+ was observed in both live and dead biomass, whereas silver dicyanide [Ag (CN)2-] uptake was strictly glucose dependent. In contrast to Ag (CN)2-, glucose addition inhibited by 16 to 25% the Ag+ uptake rate of living UFMG - Y02, Y27, and Y35 cells, while strains CBS 316 and UFMG-Y01 showed an improved uptake rate of about 115% and 13%, respectively. The Langmuir sorption model was used to evaluate the silver sorption capability of the R. mucilaginosa strains. The calculated q max value suggested that R. mucilaginosa strains UFMG-Y27 had the highest loading capacity. The type strain CBS 316 had the lowest q max but showed the highest affinity for silver ions. The results provided by the Fourier Transform Infra Red analysis (FTIR) suggest that C=O groups represent the main reactive site for silver uptake by the strain UFMG-Y27. Quatro linhagens de Rhodotorula mucilaginosa e uma linhagem padrão dessa mesma espécie foram investigadas quanto a habilidade de acumular íons de prata livres (Ag+) e complexados [Ag (CN)2-], através de processos dependentes e independentes do metabolismo. A habilidade de acumular Ag+ foi observada em ambas as células, vivas e mortas. Contudo, o acúmulo de Ag (CN)2- foi um processo estritamente dependente de energia. Durante os estudos que avaliaram a dependência de uma fonte energética para o acumulo de íons de prata livres (Ag+) foi observado que a adição de glicose resultou na diminuição do acúmulo de Ag+ por três linhagens (UFMG -- Y02, 27 and 35). Ao passo que as linhagens CBS 316 e UFMG -- Y01 apresentaram aumento do acúmulo desse metal. A analise dos resultados de biossorção através do modelo de Langmuir, sugerem que a linhagem UFMG -- Y27 possui a maior capacidade de acúmulo de prata (carga). Enquanto que a linhagem padrão CBS 316 apresentou a menor capacidade de carga e a maior afinidade por ions de prata. Analises de infra vermelho da biomassa fúngica, com e sem prata, mostraram que os grupamentos C=O foram os principais sítios de ligação desse metal pela linhagem UFMG -- Y27.

A mixed culture and a pure bacterial strain (BMV8) were isolated from a bioreactor for thiocyanate treatment. Both cultures removed 5 mM of thiocyanate from the medium in 36 hours. The mixed culture was able to tolerate concentrations up to 60 mM. The efficiency of thiocyanate degradation decreased when the cells were immobilized. Uma cultura mixta e uma linhagem bacteriana pura foram isoladas de um bioreator para tratamento de tiocianato. As culturas removeram 5mM de tiocianato do meio em 36 horas. A cultura mixta foi capaz de tolerar concentrações superiores a 60mM. A eficiência da degradação de tiocianato diminuiu quando as células foram imobilizadas.

Trehalose accumulation, invertase activity and physiological characteristics of 86 yeast isolates from short fermentative cycles during the production of cachaça in three artisanal distilleries of the State of Minas Gerais were studied. Among these isolates, 70% were able to grow at temperatures between 40 and 42ºC. Only Saccharomyces cerevisiae isolates were able to grow over 40ºC. Lower temperatures (

Thiocyanate is frequently found in industrial wastewater such as those from coal, gold and silver mining. Although the microbial degradation of thiocyanate has been well documented, scarce information is available on the heterotrophic degradation of thiocyanate. A pure bacteria strain (BMV8) and a mixed culture of bacteria and fungi were isolated by an enrichment method from a fixed bed bioreactor for cyanide and thiocyanate removal and they were able to metabolize thiocyanate heterotrophically as a nitrogen source. The efficiency of thiocyanate biodegradation decreased when the cells were immobilized in citric pectin. The immobilized mixed culture was able to degrade thiocyanate more efficiently than the BMV8 strain.

Metal ion adsorption by microorganisms is commonly denoted as biosorption and does not depend on cellular metabolic activity. In this work the biomass of the fungus Aspergillus niger was tested for the capacity to accumulate cadmium in the presence and absence of an organic ligand (citrate). An overall improvement on the Cd sorption capacity of at least 15% was achieved with caustic treatment. The present work elucidates, to some extent, the effects of caustic treatment on the biosorption of Cd by A. niger in terms of improvement of the metal uptake as well as some changes in the biomass sites due to both the treatment and the presence of the metal.

The capacity of waste biomasses from sugar-cane aguardente, a traditional Brazilian spirit, for metal biosorption was assessed. Free biomass and biomass immobilized onto chitin and Dowex (ion-exchange resin) were utilized to remove chromium, iron and nickel from both synthetic solutions and stainless steel effluents. The best performance in terms of metal sorbed was observed in with free biomass, with the following adsorption capacity: 70% chromium, 50% iron and 20% nickel at pH 4.0.