Antimicrobial activity of yeasts against some pathogenic bacteria.

Aim: This study was designed to isolate and identify yeast species from milk and meat products, and to test their antimicrobial activity against some bacterial species.

Materials And Methods: A total of 160 milk and meat products samples were collected from random sellers and super markets in New Damietta city, Damietta, Egypt. Samples were subjected to yeast isolation procedures and tested for its antimicrobial activity against , , and . In addition, all yeast species isolates were subjected to polymerase chain reaction (PCR) for detection of (kievitone hydratase) and (pectate degrading enzyme)genes.

Results: The recovery rate of yeasts from sausage was 20% (2/10) followed by kareish cheese, processed cheese, and butter 10% (1/10) each as well as raw milk 9% (9/100), and fruit yoghurt 30% (6/20). Different yeast species were recovered, namely, (5 isolates), (4 isolates), (3 isolates), (2 isolates), (2 isolates), and (1 isolate). gene was detected in all isolates, however, gene was not detected in all identified yeast species. Antimicrobial activity of recovered yeasts against the selected bacterial species showed high activity with against and , against , and against . Moderate activities were obtained with , , and against ; meanwhile, all the tested yeasts revealed a very low antimicrobial activity against .

Conclusion: The obtained results confirmed that some kinds of yeasts have the ability to produce antimicrobial compounds that could inhibit some pathogenic and spoilage bacteria and these antimicrobial activity of yeasts enables them to be one of the novel agents in controlling spoilage of food.