Submitted to: Society of Industrial Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/27/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Zymomonas mobilis is a Gram-negative ethanologenic bacterium recognized for its high ethanol fermentation efficiency via the Entner-Doudoroff pathway. However, it is often less competitive than brewer’s yeast (Saccharomyces cerevisiae) for industrial application in bioethanol production because of intolerance to organic acids, such as acetic acid, produced by bacterial contaminants. Recent advancements in genetic engineering have improved acid tolerance in Z. mobilis for the production of sorbitol, gluconic acid, 2,3-butanediol, and isobutanol. Nevertheless, bacterial contamination from lactic acid bacteria (LAB) remains a major challenge that is typically mitigated through extensive cleaning protocols, chemical treatments, and/or antibiotics. These approaches each have limitations, such as limited efficacy, extended downtime during cleaning, or antibiotic resistance concerns. To address this challenge, we evaluated the efficacy of recombinant bacteriophage endolysin LysKB317 for LAB control in Z. mobilis corn mash fermentation. Exogenous addition of 1 µM purified LysKB317 successfully reduced LAB contamination to undetectable levels (<1 log CFU/mL). Contaminated corn mash fermentations treated with endolysin exhibited significant improvements in glucose utilization and ethanol production (p< 0.0001), alongside a marked reduction in acetic and lactic acid accumulation (p<0.0001). To our knowledge, this study represents the first successful utilization of endolysin for bacterial contamination control in Z. mobilis corn mash fermentation, offering a promising alternative to conventional antimicrobial strategies.