Isolation of Lactic Acid Bacteria from Camel Milk and in vitro Assessment of Their Antagonism Against Selected Foodborne Pathogenic Bacteria

The use of lactic acid bacteria (LAB) as a protective culture offers a suitable alternative to chemical food pre-servatives. This study aimed to isolate LAB from raw and fermented camel milk and assess their antagonistic effects against selected bacterial pathogens (Staphylococcus aureus, Escherichia coli, and Salmonella Typhi). Twenty raw and 20 fermented camel milk samples were collected from Jigjiga, Ethiopia. Recommended microbiological protocols were followed to quantify, isolate, and identify represen-tative LAB from the samples. Moreover, the antagonistic effect of the LAB isolates was assessed using the agar-well diffusion method. A total of 112 LAB isolates were classified into three genera: Lactobacillus, Pediococcus, and Leuconostoc. Of the 112 isolates, 94 (83.9%) showed antagonism against one or more of the test pathogens, with a mean diameter of the inhibition zone (MDIZ) ranging between 16.3 and 23.5 mm. More than 21% of the LAB isolates (18 of 83) that were antagonistic to S. aureus had an MDIZ ≥22 mm. However, only four and three LAB showed an MDIZ of > 22 mm against E. coli and S. Typhi, respectively. This study allowed the isolation of LAB from camel milk, with potential biotechnological applications as a protective culture. Further taxonomic identity confirma-tion of the promising LAB isolates and their performance as in situ protective cultures for food items is envisaged.