Isolation and Identification of Bacteria Found in Raw Ground Beef that Inhibit the Growth of Eschericia coli O157:H7

<p>The natural microflora of ground beef appears to exhibit a bacteriostatic effect on the growth of E. coli O157:H7. This project took raw ground beef and screened it for naturally occurring organisms that possess the ability to inhibit the growth of E. coli O157:H7. After isolating approximately 500 Gram-negative organisms, individual organisms were tested for their effectiveness in inhibiting E. coli O157:H7. Several Gram-negative organisms (13 total) had inhibitory properties with 11 identified as Pseudomonas aeruginosa and two isolates identified as Serratia liquefaciens. The majority (90%) of the isolated lactic acid bacteria (LAB) showed inhibitory effects against E. coli O157:H7. By controlling the pH of the growth agar, it was determined that the inhibitory effect from LAB was due to acid production and not some other bacteriocin or antimicrobial substance.</p>