Title: Bacillus spp. produce antibacterial activities against lactic acid bacteria that contaminate fuel ethanol plants Authors
Submitted to: Current Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 8, 2012
Publication Date: May 15, 2013
Citation: Manitchotpisit, P., Bischoff, K.M., Price, N.P., Leathers, T.D. 2013. Bacillus spp. produce antibacterial activities against lactic acid bacteria that contaminate fuel ethanol plants. Current Microbiology. 66(5):443-449. Interpretive Summary: In this research we discovered four strains of bacteria that produce an antibacterial compound. Antibiotics may be used to control bacterial contamination of fuel ethanol fermentations, but the emergence of resistant bacteria may limit their effectiveness and there is a need for new antibacterial agents. Four strains of bacteria called Bacillus were found to produce an antibacterial compound with strong activity against several species of lactic acid bacteria that were isolated as contaminants at commercial ethanol facilities. This research will be used by scientists and ethanol producers to develop effective intervention strategies to control bacterial contamination in commercial fermentation cultures.
Technical Abstract: Lactic acid bacteria (LAB) frequently contaminate commercial fuel ethanol fermentations, reducing yields and decreasing profitability of biofuel production. Microorganisms from environmental sources in different geographic regions of Thailand were tested for antibacterial activity against LAB. Four bacterial strains, designated as ALT3A, ALT3B, ALT17, and MR1, produced inhibitory effects on growth of LAB. Sequencing of rRNA identified these strains as species of Bacillus subtilis (ALT3A, and ALT3B) and B. cereus (ALT17 and MR1). Cell mass from colonies and agar samples from inhibition zones were analyzed by MALDI-TOF mass spectrometry. The spectra of ALT3A and ALT3B showed a strong signal at 1060 m/z, similar in mass of the surfactin family of antimicrobial lipopeptides. ALT3A and ALT3B were analyzed by zymogram analysis using SDS-PAGE gels placed on agar plates inoculated with LAB. Cell lysates possessed an inhibitory protein of less than 10 kDa, consistent with the production of an antibacterial lipopeptide. Mass spectra of ALT17 and MR1 had notable signals at 908 and 930 m/z in the whole cell extracts and at 687 m/z in agar, but these masses do not correlate with those of previously reported antibacterial lipopeptides, and no antibacterial activity was detected by zymogram. Thus, ALT17 and MR1 may produce a new class of antibacterials. The antibacterial activities produced by these strains may have application in the fuel ethanol industry as an alternative to antibiotics for prevention and control of bacterial contamination.