Design of experiments for enhanced production of bioactive exopolysaccharides from indigenous probiotic lactic acid bacteria

539-551Exopolysaccharides (EPS) produced by several bacteria including the probiotic lactic acid bacteria (LAB) not only help them to execute certain vital life functions, but offers huge potential for applications in sectors like medical/pharmaceutical, food, agriculture, and environmental health. However, low yield of EPS from probiotic LAB has always been a challenge. Previously we have reported that EPS from two LAB probiotic strains i.e. Enterococcus faecium K1 (isolate from kalarei), and Lactobacillus paracasei M7 (isolate from human breast milk) possessed several bioactive functional attributes like hypocholesterolemic activity, antioxidant potential, antibiofilm activity, antimicrobial activity, emulsification ability, and desirable physiochemical properties. However, the EPS yield was low. Current study reports optimization of process variables by Design of Experiments (DoE) to enhance EPS yield from these bacteria. The most effective process variables for EPS production were earmarked for E. faecium K1 (lactose, ammonium citrate, incubation time and pH), and for L. paracasei M7 (glucose, incubation time and pH), by Plackett–Burman design, and the same were optimized using central composite design (CCD) of response surface methodology (RSM). The EPS yield from E. faecium K1 was enhanced by 101.40% at optimal level of variables (lactose 10.07 g/L, ammonium citrate 2.49 g/L, incubation time 94.05 h and pH 5.4). Similarly, EPS yield was enhanced by 79.6% from L. paracasei M7 using optimal level of variables (glucose 10 g/L, incubation time 48 h and pH 7.6). Thus, DoE represents a powerful approach for optimization of process variables

Cellulase Production from Bacillus subtilis SV1 and Its Application Potential for Saccharification of Ionic Liquid Pretreated Pine Needle Biomass under One Pot Consolidated Bioprocess

Pretreatment is the requisite step for the bioconversion of lignocellulosics. Since most of the pretreatment strategies are cost/energy intensive and environmentally hazardous, there is a need for the development of an environment-friendly pretreatment process. An ionic liquid (IL) based pretreatment approach has recently emerged as the most appropriate one as it can be accomplished under ambient process conditions. However, IL-pretreated biomass needs extensive washing prior to enzymatic saccharification as the enzymes may be inhibited by the residual IL. This necessitated the exploration of IL-stable saccharification enzymes (cellulases). Current study aims at optimizing the bioprocess variables viz. carbon/nitrogen sources, medium pH and fermentation time, by using a Design of Experiments approach for achieving enhanced production of ionic liquid tolerant cellulase from a bacterial isolate Bacillus subtilis SV1. The cellulase production was increased by 1.41-fold as compared to that under unoptimized conditions. IL-stable cellulase was employed for saccharification of IL (1-ethyl-3-methylimidazolium methanesulfonate) pretreated pine needle biomass in a newly designed bioprocess named as “one pot consolidated bioprocess” (OPCB), and a saccharification efficiency of 65.9% was obtained. Consolidated bioprocesses, i.e., OPCB, offer numerous techno-economic advantages over conventional multistep processes, and may potentially pave the way for successful biorefining of biomass to biofuel, and other commercial products