Thermal assisted alkaline pretreatment of rice husk for enhanced biomass deconstruction and enzymatic saccharification: Physico-chemical and structural characterization.

Thermal assisted alkaline pretreatment (TAAP) of rice husk (RH) was investigated to facilitate enzymatic saccharification by enhancing the enzyme accessibility to cellulosic components. Statistically guided experiments based on the Box-Behnken design involving four factors viz. biomass loading, particle size, NaOH loading and reaction time was considered for optimization. The maximum sugar yield of 371 mg g-1 biomass was obtained at optimized pretreatment condition [biomass loading (10% w/w), particle size (0.25-0.625 mm), NaOH loading (2% w/w), and reaction time (40 min)]. The TAAP of RH resulted in the efficient removal of lignin (14.9-54% (w/w)) with low hemicellulose solubilization [10.7-33.1% (w/w)] and with a simultaneous increase in cellulose concentration [32.65-51.65% (w/w)]. The SEM analysis indicated increased porosity and biomass disruption during TAAP. The FTIR analysis showed progressive removal of noncellulosic constituents, and XRD analysis revealed an increase in cellulose crystallinity post-TAAP indicating the effectiveness of pretreatment.

Optimization of enzymatic clarification of sapodilla juice: a statistical perspective.

Response surface methodology (RSM) was employed to establish optimum conditions for enzymatic clarification of sapodilla juice. Polygalacturonase obtained from Streptomyces lydicus had been purified to homogeneity and was used for the treatment. The independent variables were temperature (30-45 degrees C), enzyme concentration (0.5-1.5 U), and treatment time (30-90 min), whose effects on viscosity and clarity of the juice were evaluated using a Box-Behnken design. Significant regression models describing the changes of viscosity and clarity with respect to the independent variables were obtained, with the coefficient of determination, R (2) , greater than 0.8. Based on response surfaces and contour plots, the optimum conditions for clarifying sapodilla juice were enzyme concentration 1.15 U, incubation temperature 34 degrees C, and incubation time 70 min.

Evaluation of alpha-galactosidase biosynthesis by Streptomyces griseoloalbus in solid-state fermentation using response surface methodology.

AIM: The present study was aimed at evaluating the effects of the three crucial factors, galactose concentration, inoculum size and moisture content, on alpha-galactosidase production by the filamentous actinobacterium Streptomyces griseoloalbus in solid-state fermentation. METHODS AND RESULTS: Central Composite design was adopted to derive a statistical model for the optimization of fermentation conditions. Maximum alpha-galactosidase yield (117 U g(-1) of dry fermented substrate) was obtained when soya bean flour supplemented with 1.5% galactose and with initial moisture content of 40% was inoculated with 1.9 x 10(6) CFU g(-1) initial dry substrate. CONCLUSIONS: The model was valid and could result in considerably enhanced enzyme yield. SIGNIFICANCE AND IMPACT OF THE STUDY: The results indicated a cost effective method for the production of alpha-galactosidase using soya bean flour. This is the first report on exploitation of the potential of filamentous bacterium for the production of alpha-galactosidase, an enzyme having versatile applications.

Evaluation of fungal culture filtrate containing chitinase as a biocontrol agent against Helicoverpa armigera.

AIMS: To evaluate the biocontrol efficacy of culture filtrate containing chitinase from Trichoderma harzianum against Heliothis. METHODS AND RESULTS: T. harzianum was cultured by submerged fermentation using colloidal chitin as sole carbon source. The ability of the culture filtrate to hydrolyse colloidal chitin indicated the presence of chitinase as one of its components. Biocontrol assay on Heliothis showed that the culture filtrate is a potent antifeedant as it reduced the feeding rate and body weight of the larvae. It reduced the successful pupation and increased larval and pupal mortality in a dosage-dependent manner when applied topically. The highest mortalities (70%) were recorded for groups treated with 2000 U ml(-1) chitinase activity. The percentage of adult emergence was zero for the highest chitinase concentration (2000 U ml(-1)) tried. CONCLUSIONS: The studies showed that the culture filtrate containing chitinase from T. harzianum is capable of negatively affecting the growth and metamorphosis of Heliothis larvae. SIGNIFICANCE AND IMPACT OF THE STUDY: In view of the need for safer and environmentally friendly pest management tools, the present study could help in the development of enzyme-based biopesticides against Heliothis.