Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2010
Publication Date: 1/4/2011
Publication URL: http://hdl.handle.net/10113/48062
Citation: Rich, J.O., Leathers, T.D., Nunnally, M.S., Bischoff, K.M. 2011. Rapid evaluation of the antibiotic susceptibility of fuel ethanol contaminant biofilms. Bioresource Technology. 102(2):1124-1130. Interpretive Summary: In this research, a rapid method was developed to evaluate the effect of antibiotic on the growth of fuel ethanol contaminants as biofilms. New methods are needed to control contaminants of fuel ethanol production, which reduce ethanol yields and can lead to stuck fermentations. Results showed that contaminants varied in their ability to form biofilms, and that growth as biofilms did not provide resistance to antibiotic. These results are important to researchers developing improved methods to control contamination of fuel ethanol production.
Technical Abstract: Bacterial contaminants from commercial fuel ethanol production facilities were previously shown to form biofilms as mixed cultures under laboratory conditions. In this study, a rapid assay was developed to simultaneously compare isolates for their ability to form biofilms as pure cultures. Ten strains were isolated from a dry-grind fuel ethanol plant that routinely doses with virginiamycin. These were identified by sequence analysis as six strains of Lactobacillus fermentum, two strains of L. johnsonii, and one strain each of L. mucosae and L. amylovorus. Isolates exhibited a range of susceptibility to virginiamycin in a planktonic assay, with MIC’s (minimum inhibitory concentrations) of <= 0.5 microg/ml to 16 microg/ml. Even though all strains were isolated from a mixed culture biofilm, they varied greatly in their ability to form biofilms as pure cultures. Surprisingly, growth as biofilms did not appear to provide resistance to virginiamycin, even if biofilms were grown for 144 h prior to antibiotic challenge.