Accelerated bioconversion and value addition of rice straw on inoculation with microbial consortium

Abstract Rice straw is one of the most abundant yet underutilized agricultural residues, largely due to its recalcitrant lignocellulosic structure. A total of 10 bacterial strains were isolated from diverse lignin‐rich sources and screened for alkali lignin and rice straw lignin degradation, along with their lignocellulolytic enzyme secretion. Integrated analysis of enzymatic and degradation parameters, identified four efficient isolates, namely Lysinibacillus boronitolerans strain CP–2, Bacillus sp. strain D–6, Pseudomonas sp. strain S–4, and Priestia megaterium strain T–3. These isolates were combined to formulate two compatible microbial consortia, namely, consortium 1 ( Pseudomonas sp. strain S–4 + Priestia megaterium strain T–3 + Lysinibacillus boronitolerans strain CP–2) and consortium 2 ( Pseudomonas sp. strain S–4 + Priestia megaterium strain T–3 + Bacillus sp. strain D–6). Highest reduction in lignin and cellulose content of rice straw was observed on treatment with consortia 2 with 19.9% and 37.5% for lignin and cellulose respectively over the control. Scanning electron micrographs of degraded material with consortia 2 further confirmed extensive microstructural disintegration. GC–MS profiling of degraded rice straw using consortium 2 also resulted in reduction in phytotoxic volatile compounds and the presence of unique metabolites on degradation. Degraded material was used as potting mixture and growth and yield attributes of cowpea were assessed. There was an increase of 78.5% in number of pods and 81% increase in pod weight from consortia 2 derived potting mixture compared to control. Application of bacterial consortium 2 could be a sustainable and eco‐friendly strategy for rice straw management and generation of value‐added organic amendment.