Characterization and evaluation of a natural derived bacterial consortium for efficient lignocellulosic biomass valorization

A concerted enzymatic de-structuring of lignocellulosic materials using a compost-derived microbial consortia favoring the consolidated pretreatment and bio-saccharification

The robustness of microbial consortia isolated from compost habitat encompasses the complementary metabolism that aids in consolidated bioprocessing (CBP) of lignocellulosic biomass (LCB) by division of labor across the symbionts. Composting of organic waste is deemed to be an efficient way of carbon recycling, where the syntrophic microbial population exerts a concerted action of lignin and polysaccharide (hemicellulose and cellulose) component of plant biomass. The potential of this interrelated microorganism could be enhanced through adaptive laboratory evolution (ALE) with LCB for its desired functional capabilities. Therefore, in this study, microbial symbionts derived from organic compost was enriched on saw dust (SD) (woody biomass), aloe vera leaf rind (AVLR) (agro-industrial waste) and commercial filter paper (FP) (pure cellulose) through ALE under different conditions. Later, the efficacy of enriched consortium (EC) on consolidated pretreatment and bio-saccharification was determined based on substrate degradation, endo-enzymes profiling and fermentable sugar yield. Among the treatment sets, AVLR biomass treated with EC-5 has resulted in the higher degradation rate of lignin (47.01 ± 0.66%, w/w) and polysaccharides (45.87 ± 1.82%, w/w) with a total sugar yield of about 60.01 ± 4.24 mg/g. In addition, the extent of structural disintegration of substrate after EC-treatment was clearly deciphered by FTIR and XRD analysis. And the factors of Pearson correlation matrix reinforces the potency of EC-5 by exhibiting a strong positive correlation between AVLR degradation and the sugar release. Thus, a consortium based CBP could promote the feasibility of establishing a sustainable second generation biorefinery framework.

Developing rumen mimicry process for biological ammonia synthesis

The ruminant rumen houses hyper-ammonia-producing bacteria (HAB) that produce ammonia with minimal energy use. Here we developed a mimicry process to produce bio-ammonia, a solution of ammonia and ammonium. The rumen microbes were used to ferment soybean (SYB), soybean protein isolate (SPI), and pepsin-hydrolysate (HP) for bio-ammonia production. The maximum bio-ammonia produced from SYB, SPI, and HP were 0.65, 1.2_, and 1.1 g/L, respectively. The presence of non-protein in SYB hindered bio-ammonia production and the processing of SYB to SPI and HP significantly (p < 0.05) increased bio-ammonia production. HP was converted to bio-ammonia quicker than SPI suggesting that enzymatic hydrolysis increases bioprocessing efficiency. Metagenomic analysis of a sample culture revealed that the HAB population is predominantly Klebsiella quasivariicola (73%), Escherichia coli (6%), and Enterobacter cloacae (6%). The bioprocessing steps developed would enable industrial ammonia production to achieve a low CO₂ footprint.