Optimization of ethanol production from co-substrate of waste glycerol and acetic acid by Enterobacter aerogenes

This research study aims to optimize the addition of acetic acid concentration to a waste glycerol-based, thereby leading to the maximum production of ethanol from Enterobacter aerogenes. The co-substrate (waste glycerol and acetic acid) was used in varied chemical oxygen demand (COD) ratios of 1:1, 10:1, and 100:1 for the ethanol fermentation. The maximum ethanol production was obtained from 100:1 ratio (Gly: HAc), EtOH was 272.64 ± 3.30 mM in 24 h. The productivity and yield of EtOH were 0.52 ± 0.01 g L−1 h− 1 and 1.08 ± 0.20 mol EtOH mol−1 Gly, respectively. The results of this study indicated that the co-substrate of waste glycerol and acetic acid can improve the productivity of ethanol production. The addition of acetic acid may concern to increase the regulation of the transcription level of genes involved in the fermentation process. Furthermore, the high level of initial acetic acid concentration in the medium results in the inhibition effects to the glycerol utilization and ethanol production.