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Addition of a surfactant to tryptic soy broth allows growth of a Lactic Acid Bacteria food antimicrobial, Escherichia coli O157:H7, and Salmonella enterica

Cálix‐Lara, T.F., Duong, T., Taylor, T.M.
Letters in applied microbiology 2012 v.54 no.5 pp. 392-397
Escherichia coli O157, Salmonella enterica subsp. enterica, food pathogens, food safety, foods, lactic acid bacteria
Aims: This study aimed to determine the survival and growth of Escherichia coli O157:H7 and Salmonella enterica subsp. enterica in a medium supporting the growth of a Lactic Acid Bacteria (LAB) food antimicrobial culture. Methods and Results: Foodborne pathogens and LAB were cultured individually in tryptic soy broth (TSB), tryptic soy broth supplemented with one g l−1 Tween 80® (TSB‐T80), and de Man, Rogosa and Sharpe (MRS) broth. Growth of E. coli O157:H7 and Salmonella was similar in TSB and TSB‐T80 but was significantly less in MRS. Conversely, LAB growth was similar in MRS and TSB‐T80 but was significantly less in TSB. Conclusions: Supplementation of TSB with Tween 80® allows growth of LAB to levels similar to that observed with MRS but does not inhibit the growth of E. coli O157:H7 and Salmonella. We present the formulation of a medium useful in studies useful for evaluating competitive inhibition of foodborne pathogens by LAB in vitro. Significance and Impact of the Study: This study reports the utility of TSB‐T80 for the completion of in vitro competitive inhibition assays incorporating a Lactic Acid Bacteria food safety culture.