Farklı Unlardan Üretilen Ekşi Hamurlardan İzole Edilen Lactobacillus Brevis ve Lactobacillus Plantarum’un Antimikrobiyel Etkilerinin İncelenmesi

Abstract

This study aimed to investigate the antimicrobial effect of lactic acid bacteria against some foodborne pathogens. Within the scope of Dr. Gizem KEZER's thesis as "Isolation and identification of lactic acid bacteria from natural sourdoughs and determination of some probiotic characteristics," 1of Lactobacillus brevis (Levilactobacillus brevis) (Gc3) and 3 of Lactobacillus plantarum (Lactiplantibacillus plantarum) (İz1, Hp2, Wz3) were investigated on foodborne pathogens Escherichia coli O104:H4, Yersinia enterocolitica, Bacillus cereus, and Methicillin-resistant Staphylococcus aureus (MRSA). Agar spot method, agar well diffusion method, and broth microdilution method were used to determine the antimicrobial activities of pathogenic bacteria with known counts (~107 cfu/mL) after incubation with lactic acid bacteria for 24 hours at 37°C. In the agar spot method, the most effective LAB (lactic acid bacteria) against Bacillus cereus with a 1.6 cm zone, the most effective LABs against L. plantarum (Hp2), Escherichia coli O104:H4 and MRSA were 1.075 cm and 1.125 cm, respectively. L. plantarum (Wz3) was determined as LAB by zone measurement. No zone formation was observed in the agar spot method against Y. enterocolitica. In the agar, well diffusion method, the zone measurements formed by the bacterial supernatants most effective against MRSA and Y. enterocolitica belong to L. plantarum (Hp2) LAB with 0.525 cm and 0.8625 cm, respectively. The zone formed by the LAB supernatant that was most effective against E. coli 0104:H4 was determined as 0.375 cm, with L. plantarum (Iz1) and L. plantarum (Wz3) LAB with 0.625 cm, the zone formed by the most effective LAB supernatant against Bacillus cereus. According to the data obtained from the broth microdilution method, the most effective supernatant against Bacillus cereus was L. plantarum (Iz1) LAB, and the average inhibition percentages of all concentrations was determined as 81%. The most effective supernatant against E. coli O104:H4 belonged to L. plantarum (Hp2) LAB, and the average inhibition percentages of all concentrations were determined as 80%. The most effective supernatant against MRSA belonged to L. plantarum (Iz1) LAB, and the average inhibition percentages of all concentrations was determined as 85%. The most effective supernatant against Y. enterocolitica belonged to L. plantarum (Hp2) LAB, and the average inhibition percentages of all concentrations was determined as 77%. Since the results obtained from agar spot, agar well diffusion, and broth microdilution methods of L. brevis (Gc3) were lower than the results obtained from other lactic acid bacteria, and it was concluded that the antimicrobial effect was more minor. As a result, it is thought that all LAB isolates examined are effective against foodborne pathogenic bacteria (Yersinia enterocolitica, MRSA, Bacillus cereus, and Escherichia coli O104:H4) and may have potential commercial use in this sense.