Biohydrogen production process optimization using anaerobic mixed consortia: a prelude study for use of agro-industrial material hydrolysate as substrate.

Efficient biohydrogen production from lignocellulosic hydrolysate assumes considerable practical and academic importance. The impact of glucose to xylose ratio, medium pH, inoculum size and age on biohydrogen production indicated that glucose to xylose ratio is the critical parameter for effective H(2) production compared to either pure glucose or xylose as carbon source. Inoculum size and its age contributed more than 70% to overall H(2) production and revealed significance at individual as well as interactive level. Maximum interaction of 39% and 32% was noticed with inoculum size and its age vs. glucose to xylose ratio (2:3), respectively. The H(2) production yield enhanced from 140 to 357 ml/g substrate upon statistical optimization revealing >240% improvement.

Mixture design as first step for improved glutaminase production in solid-state fermentation by isolated Bacillus.

AIM: Investigation of mixture-design impact on glutaminase production by isolated Bacillus sp. METHODS AND RESULTS: An augmented simplex centroid design was used to optimize a three (wheat bran, Bengal gram husk and palm seed fibre) component mixture for glutaminase production. Selected substrate materials showed impact on glutaminase production values at individual level by Bengal gram husk [2789 U gds(-1) (gram dry substrate] and in two-level combination with wheat bran and Bengal gram husk (maximum of 3300 U gds(-1)). CONCLUSION: Bengal gram husk is the most suitable substrate medium for glutaminase production by Bacillus sp. Maximum glutaminase production is achieved using solid-substrate mixture at two-level combinations in the ratio of 66 : 34 for Bengal gram husk and wheat bran, respectively. SIGNIFICANCE AND IMPACT OF THE STUDY: The present study has significance in large-scale production of glutaminase at commercial level with the use of multi-substrate rather than single-substrate/support material.