Ensiling pretreatment with two novel microbial consortia enhances bioethanol production in sterile rice straw

Abstract

The present study extracts and enriches cellulolytic microbial consortia from yak (Bos grunniens) and evaluates their effects on the fermentation profile and bioethanol yield in rice straw silage. Two microbial consortia (CF and PY) with high cellulolytic activity were isolated and observed to be prone to utilize natural carbon sources. Two consortia were introduced with and without combined lactic acid bacteria (CLAB) to rice straw for up to 60 days of ensiling, and their application notably decreased the levels of structural carbohydrates and pH values of rice straw silages. Treatments that combining microbial consortia and CLAB resulted in the highest levels of lactic acid, water soluble carbohydrates, mono- and disaccharides, and lignocellulose degradation, with PY + CLAB group yielding the highest bioethanol production. The microbial consortia identified herein exhibit great potential for degrading fibrous substrates, and their combination with CLAB provides a feasible way to efficiently use rice straw for bioethanol production.