Novel endolysin LysMP for control of Limosilactobacillus fermentum contamination in small-scale corn mash fermentation

Biotechnology for Biofuels and Bioproducts

Research

Maulik H. Patel¹  Shao-Yeh Lu²  Christopher D. Skory²  Siqing Liu² 

[1] Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN, USA;USDA, Agricultural Research Service, National Center for Agricultural Utilization Research, Renewable Product Technology Research Unit, 1815 N. University St, 61604-3902, Peoria, IL, USA;

关键词: Endolysin;    Peptidoglycan hydrolase;    Bioethanol;    Lactobacillus;    Antimicrobial;    Biorefineries;    Corn mash fermentation;    Limosilactobacillus;   

DOI  :  10.1186/s13068-023-02400-5

 received in 2023-07-31, accepted in 2023-09-18,  发布年份 2023

来源: Springer

【 摘 要 】

BackgroundTraditional bioethanol fermentation industries are not operated under strict sterile conditions and are prone to microbial contamination. Lactic acid bacteria (LAB) are often pervasive in fermentation tanks, competing for nutrients and producing inhibitory acids that have a negative impact on ethanol-producing yeast, resulting in decreased yields and stuck fermentations. Antibiotics are frequently used to combat contamination, but antibiotic stewardship has resulted in a shift to alternative antimicrobials.ResultsWe demonstrate that endolysin LysMP, a bacteriophage-encoded peptidoglycan hydrolase, is an effective method for controlling growth of LAB. The LysMP gene was synthesized based on the prophage sequence in the genome of Limosilactobacillus fermentum KGL7. Analysis of the recombinant enzyme expressed in E. coli and purified by immobilized metal chelate affinity chromatography (IMAC) showed an optimal lysis activity against various LAB species at pH 6, with stability from pH 4 to 8 and from 20 to 40 °C up to 48 h. Moreover, it retains more than 80% of its activity at 10% ethanol (v/v) for up to 48 h. When LysMP was added at 250 µg/mL to yeast corn mash fermentations containing L. fermentum, it reduced bacterial load by at least 4-log fold compared to the untreated controls and prevented stuck fermentation. In comparison, untreated controls with contamination increased from an initial bacterial load of 1.50 × 107 CFU/mL to 2.25 × 109 CFU/mL and 1.89 × 109 CFU/mL after 24 h and 48 h, respectively. Glucose in the treated samples was fully utilized, while untreated controls with contamination had more than 4% (w/v) remaining at 48 h. Furthermore, there was at least a fivefold reduction in lactic acid (0.085 M untreated contamination controls compared to 0.016 M treated), and a fourfold reduction in acetic acid (0.027 M untreated contamination controls vs. 0.007 M treated), when LysMP was used to treat contaminated corn mash fermentations. Most importantly, final ethanol yields increased from 6.3% (w/v) in untreated contamination samples to 9.3% (w/v) in treated contamination samples, an approximate 50% increase to levels comparable to uncontaminated controls 9.3% (w/v).ConclusionLysMP could be a good alternative to replace antibiotics for mitigation of LAB contamination in biofuel refineries.

【 授权许可】

CC BY   
© BioMed Central Ltd., part of Springer Nature 2023

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