Isolation and Identification of Antimicrobial Producing Lactic Acid Bacteria from Local Egyptian Dairy Products

Abstract

The aime of the present work is to evaluate the antimicrobial characteristics of lactic acid bacteria (LAB) being utilized as starter cultures in cheese and fermented dairy products. Morphological, biochemical and physiological features of the selected isolates were performed in their identification. A total of 226 isolates were recovered from 40 yogurt samples (23.45%), 30 Ras chesse samples (19.47%), 48 Kariesh cheese samples (33.18%) and 32 samples of Laban Rayeb (23.9%) that were randomly collected from local markets in Dakahlia governorate. The distribution of LAB isolates by the genus was as follows: Lactobacillus (33.63%), Streptococcus (17.69%), Lactococcus (8.85%) and Enterococcus (39.82%). Among these isolates, E. faecalis (55 isolates, of 24,34%), S. thermophilus (40 isolates, of 17.69%), Lb.delbrueckii subsp. bulgaricus (30 isolates, of 13.27%) E. faecium (25 isolates, of 11.06%), Lb. helveticus (16 isolates, of 7.1%), Lb. salivarius (15 isolates, of 6.64%), Lc.lactis subsp. lactis (15 isolates, of 6.64%), Lb. acidophilus (10 isolates, of 4.42%), E. gallinarum (7 isolates, of 3.1%), Lc. Lactis subsp. cremoris (5 isolates, of 2.21%) and E. malodoratus (3 isolates, of 1.33%). These 226 isolates were further examined for their capability to produce antimicrobial compounds. Only 16 out of 226 LAB isolates could inhibit the growth of the examined indicator organisms. Among these isolates, 8 LAB isolates (3 isolates of Enterococcus fecalis, 2 isolate of each E.faecium, E. gallinarum and E. malodoratus ) were still capable to inhibit the indicator organisms by neutralization to pH 6.8. These isolates may produce bacteriocin like substances.