Identification, Safety Assessment, and Antimicrobial Characteristics of Cocci Lactic Acid Bacteria Isolated from Traditional Egyptian Dairy Products

Abstract

The main objective of this study is to isolate and identify lactic acid bacteria (LAB) from various Egyptian dairy products, examine their antibacterial and hemolysis potential, and ensure their safety when used as starter cultures in different dairy industries. Egyptian dairy products are often made without the use of commercial starter cultures, using raw milk and artisanal methods. The most popular traditional dairy products are Laban Rayeb and Zabady, as well as the cheese varieties of Ras, Domiati, and Karish. The microbial communities used for fermentation and the diversity of lactic acid bacteria are the most important factors that can affect the quality of these products. In order to investigate the diversity of cocci lactic acid bacteria in Egyptian dairy products, 70 samples of raw or fermented milk and cheeses were collected from traditional cheese-making factories, local markets, and farmhouses located in the Delta area of Egypt. Following this, the LAB were isolated from the samples. One hundred fifty-seven isolates of Gram-positive, catalase-negative, and cocci bacterial species were identified via rep-PCR, and some isolates were confirmed using pheS and 16S rRNA gene sequencing, as follows: <i>Streptococcus infantarius</i> subsp. <i>infantarius</i> (three isolates), <i>Enterococcus hirae</i> (three isolates), <i>Enterococcus faecium</i> (ninety-six isolates), <i>Enterococcus faecalis</i> (forty isolates), <i>Enterococcus durans</i> (six isolates), <i>Lactococcus garvieae</i> (one isolate), <i>Pediococcus acidilactici</i> (seven isolates), and <i>Lactococcus lactis</i> subsp. <i>Lactis</i> (one isolate). These findings validate that five strains have strong antibacterial activity against <i>Escherichia coli, Salmonella typhimurium</i>, and <i>Listeria monocytogenes</i>, and one hundred thirty-four strains were safe for hemolysis. The five strains were selected as protective cultures, including <i>Pediococcus acidilactici</i>, <i>Lactococcus lactis</i> subsp. <i>lactis</i>, <i>E. faecalis</i>, and <i>E. faecium</i>.