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The production of ethanol by the new yeast Spathaspora arborariae using rice hull hydrolysate (RHH) as substrate, either alone or in co-cultures with Saccharomyces cerevisiae is presented. Cultivations were also carried out in synthetic medium to gather physiological information on these systems, especially concerning their ability to grow and produce ethanol in the presence of acetic acid, furfural, and hydroxymethylfurfural, which are toxic compounds usually present in lignocellulosic hydrolysates. S. arborariae was able to metabolize xilose and glucose present in the hydrolysate, with ethanol yields (Y(P/S)(et)) of 0.45. In co-cultures, ethanol yields peaked to 0.77 and 0.62 in the synthetic medium and in RHH, respectively. When the toxic compounds were added to the synthetic medium, their presence produced negative effects on biomass formation and ethanol productivity. This work shows good prospects for the use of the new yeast S. arborariae alone and in co-cultures with S. cerevisiae for ethanol production.

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The ability of Candida shehatae, Saccharomyces cerevisiae, or the combination of these two yeasts in converting the mixed sugar composition of rice hull hydrolysate (RHH) as substrate for ethanol production is presented. In shake flask experiments, co-cultures showed ethanol yields (YP/S) of 0.42 and 0.51 in synthetic medium simulating the sugar composition of RHH and in RHH, respectively, with both glucose and xylose being completely depleted, while pure cultures of C. shehatae produced slightly lower ethanol yields (0.40). Experiments were scaled-up to bioreactors, in which anaerobiosis and oxygen limitation conditions were tested. Bioreactor co-cultures produced similar ethanol yields in both conditions (0.50-0.51) in synthetic medium, while in RHH, yields of 0.48 and 0.44 were obtained, respectively. The results showed near-theoretical yields of ethanol. Results suggest the feasibility of co-cultures of C. shehatae, a newly isolated strain, and S. cerevisiae in RHH as substrate for second-generation ethanol production.

The objective of this work was to isolate bacteria from soil historically exposed to tebuconazole and to evaluate the biodegradation of this fungicide by them. Tebuconazole is a commonly used systemic fungicide of the triazol group, which inhibits the sterol C-14 alpha-demethylation of 24-methylenedihydrolanosterol, a precursor of ergosterol, a cell membrane component in fungi. Microorganisms were isolated by different methods of soil sampling and the screening of degrading bacteria was performed in bioreactors cultivations, with some isolates showing the ability to degrade up to 42.76 mg L(- 1) of tebuconazole (51% of the initial concentration). These strains were identified by standard biochemical procedures as being Enterobacter sakazakii and Serratia sp. These bacteria present some important characteristics for potential uses on environmental bioremediation, considering that tebucanozale is an extremely recalcitrant chemical.