Microbial diversity analysis of wood degrading microbiome and screening of natural consortia for bioalcohol production

Abstract

Current research on bioalcohol production focuses mainly on the utilization of lignocellulosic biomass such as agricultural wastes. Biological degradation of lignocellulosic biomass requires investigation of microorganisms that can efficiently degrade all the components including lignin, cellulose and hemicellulose for biofuel applications. Hence a natural consortium capable of producing multiple enzymes for effective degradation of lignocellulosic biomass without pre-treatment is preferred over individual microbes. In the current study, natural consortia from the degraded wood sample were chosen to analyse the microbial community using Metagenomics Rapid Annotation using Subsystem Technology. The cellulolytic and solventogenic properties of the consortia were analysed. Enzyme assays confirmed the endoglucanase, xylanase, beta-glucosidase activities of the consortia. Fermentation experiments with glucose, CMC and cellulose produced acetone, ethanol, butanol and isopropanol with a total solvent concentration of 5.15 g L−1, 0.40 g L−1 and 0.41 g L−1, respectively. Total solvent production increased between 0.505 g L−1 and 0.541 g L−1 when the initial pH of the media was adjusted to 6.0 with CMC and cellulose, respectively. However, media supplemented with 5 g L−1 glucose and 20 g L−1 cellulose produced 3.92 g L−1 total solvent. 16S rRNA sequence analysis showed the presence of Clostridium beijerinckii, Clostridium butyricum, Bacillus subtilis and Bacillus humi in consortia isolated from the degraded wood sample.