ARS | Publication request: Antimicrobial peptides against contaminating bacteria in fuel ethanol production

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 2, 2012
Publication Date: February 2, 2012
Citation: Manitchotpisit, P., Bischoff, K.M., Price, N.P., Leathers, T.D. 2012. Antimicrobial peptides against contaminating bacteria in fuel ethanol production. Proceedings of Thai Society for Biotechnology. p. 27-28.

Technical Abstract: Lactic acid bacteria (LAB) are commonly found as contaminants of fuel ethanol production, resulting in reduced ethanol yields (1). Recent reports suggest that LAB can develop resistance to antibiotics such as virginiamycin and penicillin that are commonly used to control bacterial contamination (2). As an alternative approach, new microorganisms that inhibit LAB were isolated from various environmental sources in different parts of Thailand. Four different strains, ALT3A, ALT3B, ALT17, and MR1 were determined to have inhibitory effects on LAB growth. These strains were identified as Bacillus spp. using 16 s rRNA sequence analysis. Cell mass from colonies and agar samples from inhibition zones were analyzed by mass spectrometry. The chromatograms of the ALT strains showed some patterns similar to fusaricidin, a depsipeptide antibiotic, while those of MR1 appeared to show a new unknown small molecule. Protein extracts from ALT3A and MR1 were separated on SDS-PAGE which was then overlaid with LAB to produce a zymogram. Both strains produced inhibitory proteins of approximately 10 kD, possibly representing bacteriocins. Interestingly, the antimicrobial agent from MR1 appears to be an intracellular peptide, while that from ALT3A is extracellular or membrane bound. Characterization of these small peptides and their coding genes will be very useful for further studies to develop novel inhibitors of bacterial contamination in fuel ethanol fermentation.