Production of bioethanol in sugarcane bagasse hemicellulosic hydrolysate by Scheffersomyces parashehatae, Scheffersomyces illinoinensis and Spathaspora arborariae isolated from Brazilian ecosystems.

AIMS: This study aimed to evaluate new d-xylose-fermenting yeasts from Brazilian ecosystems for the production of second-generation ethanol. METHODS AND RESULTS: d-xylose-fermenting yeasts isolated from rotting wood and wood-boring insects were identified as the species Scheffersomyces parashehatae, Scheffersomyces illinoinensis, Spathaspora arborariae and Wickerhamomyces rabaulensis. Among the yeasts tested, those of Sc. parashehatae exhibited the highest ethanol production when cultivated on complex medium (Yp/set  = 0·437 g g-1 ). Sheffersomyces illinoinensis and Sp. arborariae showed similar ethanol production in this assay (Yp/set up to 0·295 g g-1 ). In contrast, in sugarcane bagasse hemicellulosic hydrolysate, Sc. parashehatae and Sc. illinoinensis exhibited similar ethanol production (Yp/set up to 0·254 g g-1 ), whereas Sp. arborariae showed the lowest results (peak Yp/set  = 0·160 g g-1 ). Wickerhamomyces rabaulensis exhibited a remarkable xylitol production (Yp/sxyl  = 0·681  g g-1 ), but producing low levels of ethanol (Yp/set  = 0·042 g g-1 ). CONCLUSIONS: The novel d-xylose-fermenting yeasts showed promising metabolic characteristics for use in fermentation processes for second-generation ethanol production, highlighting the importance of bioprospecting research of micro-organisms for biotechnological applications. SIGNIFICANCE AND IMPACT OF THE STUDY: This study widens the scope for future researches that may examine the native yeasts presented, as limited studies have investigated these species previously.

Biochemical conversion of sugarcane straw hemicellulosic hydrolyzate supplemented with co-substrates for xylitol production.

Biotechnological production of xylitol is an attractive route to add value to a sugarcane biorefinery, through utilization of the hemicellulosic fraction of sugarcane straw, whose availability is increasing in Brazil. Herein, supplementation of the sugarcane straw hemicellulosic hydrolyzate (xylose 57gL(-1)) with maltose, sucrose, cellobiose or glycerol was proposed, and their effect as co-substrates on xylitol production by Candida guilliermondii FTI 20037 was studied. Sucrose (10gL(-1)) and glycerol (0.7gL(-1)) supplementation led to significant increase of 8.88% and 6.86% on xylose uptake rate (1.11gL(-1)h(-1) and 1.09gL(-1)), respectively, but only with sucrose, significant increments of 12.88% and 8.69% on final xylitol concentration (36.11gL(-1)) and volumetric productivity (0.75gL(-1)h(-1)), respectively, were achieved. Based on these results, utilization of complex sources of sucrose, derived from agro-industries, as nutritional supplementation for xylitol production can be proposed as a strategy for improving the yeast performance and reducing the cost of this bioprocess by replacing more expensive nutrients.

Analysis of a reactive extraction process for biodiesel production using a lipase immobilized on magnetic nanostructures.

Magnetic nanoparticles were prepared by coprecipitating Fe(2+) and Fe(3+) ions in a sodium hydroxide solution and used as support for lipase. The lipase-coated particles were applied in a reactive extraction process that allowed separation of the products formed during transesterification. Kinetics data for triolein and ethanol consumption during biodiesel (ethyl oleate) synthesis together with a thermodynamic phase equilibrium model (liquid-liquid) were used for simulation of batch and continuous processes. The analysis demonstrated the possibility of applying this biocatalytic system in the reactive zone using external magnetic fields. This approach implies new advantages in efficient location and use of lipases in column reactors for producing biodiesel.