Isolation and characterization of a Pichia anomala strain: a promising candidate for bioethanol production

Biotechnological potential of yeast isolates from cachaça: the Brazilian spirit

This study identified phenotypic traits appropriate for biotechnological applications of 118 yeasts isolated from cachaça distilleries. Different properties were verified: capacity to use alternative carbon sources; ability to tolerate high concentrations of sucrose, ethanol, methanol, aluminum and zinc as well as different pH values and foam production. Pichia guilliermondii and Pichia anomala strains were identified as the most promising ones for application in the second-generation biofuel industry, showing ability to grow on high glycerol concentrations. Other isolates, identified as Saccharomyces cerevisiae, produced bioethanol comparable to the industrial strains, and were therefore ideal for use in the first-generation ethanol industry. Some of these strains also showed high resistance to aluminum, as observed in sugarcane juice, and to inter-cycle washings with diluted sulphuric acid, as performed in the industrial bioethanol production process. In summary, yeast isolates from cachaça distilleries displayed robustness and phenotypic plasticity, which makes them interesting for biotechnological applications.

Glucose(xylose) isomerase production by Streptomyces sp. CH7 grown on agricultural residues

Streptomyces sp. CH7 was found to efficiently produce glucose(xylose) isomerase when grown on either xylan or agricultural residues. This strain produced a glucose(xylose) isomerase activity of roughly 1.8 U/mg of protein when it was grown in medium containing 1% xylose as a carbon source. Maximal enzymatic activities of about 5 and 3 U/mg were obtained when 1% xylan and 2.5% corn husks were used, respectively. The enzyme was purified from a mycelial extract to 16-fold purity with only two consecutive column chromatography steps using Macro-prep DEAE and Sephacryl-300, respectively. The approximate molecular weight of the purified enzyme is 170 kDa, and it has four identical subunits of 43.6 kDa as estimated by SDS-PAGE. Its K m values for glucose and xylose were found to be 258.96 and 82.77 mM, respectively, and its V max values are 32.42 and 63.64 μM/min/mg, respectively. The purified enzyme is optimally active at 85°C and pH 7.0. It is stable at pH 5.5-8.5 and at temperatures up to 60°C after 30 min. These findings indicate that glucose(xylose) isomerase from Streptomyces sp. CH7 has the potential for industrial applications, especially for high-fructose syrup production and bioethanol fermentation from hemicellulosic hydrolysates by Saccharomyces cerevisiae.