ARS | Publication request: ANTIMICROBIAL SUSCEPTIBILITY OF BACTERIAL CONTAMINANTS FROM A WET-MILL ETHANOL PLANT

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 25, 2005
Publication Date: August 25, 2005
Citation: Bischoff, K.M., Skinner-Nemec, K., Leathers, T.D., Hughes, S.R. 2005. Antimicrobial susceptibility of bacterial contaminants from a wet-mill ethanol plant [abstract]. Society for Industrial Microbiology. Poster P42.

Technical Abstract: Contamination of commercial fermentation cultures is a recurring problem in the fuel ethanol industry. Although some facilities use antimicrobials to control contamination, there are little data available to assess the value of such treatments. As part of a broader study to determine the efficacy of antimicrobial treatments, the present work examines the antimicrobial susceptibility of bacterial species isolated from a commercial wet-mill ethanol plant that does not use antibiotics. Fifty-seven bacterial isolates were identified using Biolog and API tests, and susceptibility to the following antimicrobial agents was determined using broth microdilution or agar dilution methods: ampicillin, chloramphenicol, gentamicin, penicillin G, synercid, tetracycline, vancomycin, and virginiamycin. The majority of the isolates were species of Lactobacillus (37/57), followed by Propionibacterium (6/57), Bacteroides (4/57), Bifidobacterium (3/57), Leuconostoc (3/57), Clostridium (2/57), and Pediococcus (2/57). Thirty-eight isolates had an MIC of >/= 16 ug/ml for vancomycin, thirteen isolates had an MIC of >/= 16 ug/ml for tetracycline, and seven had an MIC of >/= to 500 ug/ml for gentamicin. The MIC90 for penicillin G and virginiamycin was 2 ug/ml and 0.25 ug/ml, respectively. Thus, bacterial contaminants from a fuel ethanol facility that does not use antibiotics are susceptible to penicillin G and virginiamycin, the two most common antimicrobials used to control bacterial contamination.