Optimized Production of Xylanase by Penicillium purpurogenum and Ultrasound Impact on Enzyme Kinetics for the Production of Monomeric Sugars From Pretreated Corn Cobs.

Corn cob is an abundant organic source with significant potential in sustainable energy development. For the effective conversion of the feedstocks to valued commodities, effective biocatalysts are highly desired. The present study aims at optimizing the critical parameters required for xylanase production by Penicillium purpurogenum isolated from rotten wood sample using the Taguchi orthogonal array layout of L25 (5∧6). The optimized conditions like temperature 40°C, pH 3, size of inoculum 1.2 × 108 spores/ml, moisture 70%, peptone 0.8%, and 5 days of incubation resulted in 1,097 ± 6.76 U/gram dry substrate (gds) xylanase which was 65.72% more when compared to un-optimized production of xylanase. The xylanase thus produced, effectively carried out pretreated corn cob saccharification and the reaction was further improved with ultrasound assistance which has increased the saccharification yield to 12.02% along with significant reduction in reaction time. The saccharification efficiency of pretreated corn cob was found to be 80.29% more compared to the raw corn cob, reflecting its recalcitrance to digestion. Indeed, xylan being the second most abundant polymer in lignocellulosic biomass, considerable attention is being paid for its effective conversion to valued products.

Improved physicochemical pretreatment and enzymatic hydrolysis of rice straw for bioethanol production by yeast fermentation.

Lignocellulosic biomass such as agricultural and forest residues are considered as an alternative, inexpensive, renewable, and abundant source for fuel ethanol production. In the present study, three different pretreatment methods for rice straw were carried out to investigate the maximum lignin removal for subsequent bioethanol fermentation. The chemical pretreatments of rice straw were optimized under different pretreatment severity conditions in the range of 1.79-2.26. Steam explosion of rice straw at 170 °C for 10 min, sequentially treated with 2% (w/v) KOH (SEKOH) in autoclave at 121 °C for 30 min, resulted in 85 ± 2% delignification with minimum sugar loss. Combined pretreatment of steam explosion and KOH at severity factor (SF 3.10) showed improved cellulose fraction of biomass. Furthermore, enzymatic hydrolysis at 30 FPU/g enzyme loading resulted in 664.0 ± 5.39 mg/g sugar yield with 82.60 ± 1.7% saccharification efficiency. Consequently, the hydrolysate of SEKOH with 58.70 ± 1.52 g/L sugars when fermented with Saccharomyces cerevisiae OBC14 showed 26.12 ± 1.24 g/L ethanol, 0.44 g/g ethanol yield with 87.03 ± 1.6% fermentation efficiency.

Plausible exploitation of Jatropha de-oiled seed cake for lipase and phytase production and simultaneous detoxification by Candida parapsilosis isolated from poultry garbage.

Jatropha de-oiled seed cake was explored to utilize as a basic nutrient source for Candida parapsilosis, isolated from poultry garbage and selected based on the production of lipase and phytase enzymes under submerged fermentation. At optimized parameters under solid-state fermentation, lipase and phytase activities were recorded as 1056.66±2.92 and 833±2.5U/g of substrate (U/g), respectively. Besides enzyme production, complete elimination of phorbol esters and significant phytate reduction from 6.51±0.01 to 0.43±0.01g/100g of seed cake were noted after 3days incubation. Curcin and trypsin inhibition activity were reduced significantly from 26.33±0.43 to 0.56±0.02mg/100g and 229.33±2.02 to 11.66±0.28U/g, respectively after 5days incubation. Saponins were reduced from 5.56±0.19 to 1.95±0.01g/100g of seed cake after 7days incubation.