Synchronous production of bioethanol and short-chain fatty acids associated with microbial mechanisms via the short-term cultivation of waste molasses inoculated with Aspergillus oryzae

Abstract

This study proposes a novel approach for the concurrent production of short-chain fatty acids (SCFAs) and bioethanol, during a 96 h cultivation of waste molasses (with direct air exposure) inoculated with Aspergillus oryzae using vermiculite as a carrier. Results showed that fungal-bacterial symbiotes were formed by enriching acidogens for the bioconversion of SCFAs, such as Enterococcus, Bacillus and Pseudomonas and bioethanol producers, like Klebsiella, Candida tropicalis, Aspergillus oryzae and Barnettozyma californica. The Aspergillus oryzae was found to play various diverse roles during the short-term cultivation process, secreting hydrolase (i.e. α-amylase) for the hydrolysis of waste molasses and contributing to the formation of fungal-bacterial symbiotes. Furthermore, the mechanisms of fungal-bacterial interaction related to simultaneous generation of SCFAs and bioethanol were investigated. Consequently, the cultivation liquid obtained could feasibly be used as a low-cost carbon source for enhancing total nitrogen (TN) removal in the process of low C/N ratio wastewater treatment.