EVALUATION OF KANG‐FUNG‐SOL MEDIUM FOR SELECTIVITY OF LACTIC ACID BACTERIA FROM LABORATORY MEDIUM AND GROUND BEEF1

Abstract

deMan Rogosa Sharpe (MRS) medium has usually been used for the recovery of lactic acid bacteria (LAB) from various food products. However, it also allows non‐LAB to grow due to its nutritive ingredients. Three kinds of agar media, MRS, Kang‐Fung (KF), and Kang‐Fung‐Sol (KFS), were evaluated for selective growth of LAB from mixed cultures. All bacteria tested grew well on MRS medium. KF medium was effective for the inhibition of gram‐negative bacteria, but not for some gram‐positive bacteria. KFS medium completely inhibited the growth of all non‐LAB tested. Furthermore, the growth of LAB tested on KFS medium was not significantly different from that on MRS or KF medium. Microbial counts from inoculated ground beef of Pediococcus pentosaceus, Escherichia coli O157:H7, Pseudomonas aeruginosa, and Salmonella arizonae did not show a significant difference between MRS and KF medium. However, no non‐LAB were recovered from ground beef using KFS medium. The recovery of Pediococcus pentosaceus was not significantly different on all three media tested. This research shows that KFS medium can be used to isolate and enumerate LAB in liquid medium or ground beef in the presence of other microorganisms.