title: Alternative antimicrobial compounds to control potential Lactobacillus contamination in bioethanol fermentations.
abstract: Antibiotics are commonly used to control microbial contaminants in yeast-based bioethanol fermentation. Given the increase in antibiotic-resistant bacteria, alternative natural antimicrobials were evaluated against the potential contaminant, Lactobacillus. The effects of nisin, ϵ-polylysine, chitosan (CS) and lysozyme were screened against 5 Lactobacillus strains. A standard broth- microdilution method was used in 96-well plates to assess the minimal inhibitory concentration (MIC). L. delbrueckii subsp lactis ATCC479 exhibited maximal MICs with CS, ϵ-polylysine and nisin (1.87, 0.3125 and 0.05 mg/mL, respectively). Nisin reduced most Lactobacillus strains by 6 log CFU/mL after 48 hours with the exception of L. casei. Synergism occurred when ethylenediaminetetraacetic acid (EDTA) was added with nisin. An MIC of 0.4 mg/mL of nisin combined with the EDTA at an MIC of 1 mg/ml markedly suppressed L .casei by 6 log CFU/mL. In conclusion, alternative antimicrobials proved to be a potential candidate for controlling bacterial contamination in the fermentation process. Synergistic effect of nisin with EDTA successfully inhibited the nisin-resistant contaminant, L. casei.
authors: Center for Food Safety and Department of Food Science, University of Arkansas, Fayetteville, Arkansas, USA.
authors: Alya
authors: A
authors: Limayem
authors: Irene B
authors: IB
authors: Hanning
authors: Arunachalam
authors: A
authors: Muthaiyan
authors: Koen
authors: K
authors: Illeghems
authors: Jin-Woo
authors: JW
authors: Kim
authors: Philip G
authors: PG
authors: Crandall
authors: Corliss A
authors: CA
authors: O'Bryan
authors: Steven C
authors: SC
authors: Ricke
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D048271:Chitosan / Q000494:pharmacology; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation / Q000187:drug effects*; D007778:Lactobacillus / Q000187:drug effects*; D009561:Nisin / Q000494:pharmacology; D011107:Polylysine / Q000494:pharmacology; D015003:Yeasts / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D009561:Nisin; D011107:Polylysine; D000431:Ethanol; D048271:Chitosan