HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Fernandes, C. F. Articles by Amer, M. A. Search for Related Content PubMed Articles by Fernandes, C. F. Articles by Amer, M. A.

Effect of Nutrient Media and Bile Salts on Growth and Antimicrobial Activity of Lactobacillus acidophilus¹

Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln 68583-0919

M. A. (Vic) Amer

Department of Food Science and Agricultural Chemistry, MacDonald College of McGill University, St. Anne de Bellevue, Quebec, Canada

ABSTRACT

The Lactobacillus acidophilus strains produced variable quantities of antimicrobial substances in three different media: Elliker's, MRS (deMan, Rogosa, and Sharpe), and LBS (Lactobacillus selection) broths. The interaction between L. acidophilus strain and nutrient medium was statistically significant, indicating an influence of the nutrient medium on the level of antimicrobial activity produced. Also statistically significant different were levels of the antimicrobial activity of different strains and the pH of the medium at the end of the fermentation period. Bile salts were added to MRS broth to simulate concentrations in gastrointestinal tract of humans. Antimicrobial activity as well as growth decreased in the presence of high concentrations of bile salts. Sodium glycocholate was more inhibitory than sodium taurocholate at equimolar levels. Calcium hydroxide was added to MRS broth at hourly intervals for 8 h to adjust the pH of the fermentation medium to pH of 6.5, which resulted in a doubling of cell numbers. However, there were no differences in the levels of antimicrobial activity at the end of 24 h. Although there were no differences in pH of the fermentation medium at the end of 24 and 48 h, the antimicrobial activity increased after 24 h of fermentation.

¹ Published as Paper Number 8366, Journal Series, Agriculture Experiment Station, Lincoln. Research was conducted under the Nebraska Agriculture Experiment Station Project 16-032 and supported by grants from the Dairy Bureau of Canada.