Isolation of coagulase negative Enterococcous sp. strains from non-broiler chicken producing bacteriocin active against Staphylococcus aureus

Abstract

Lactic acid bacteria (LAB) were isolated from the bile, gizzard, intestine and caecum of the Malaysian domestic non-broiler chicken. Of the 56 isolates grown on MRS agar plates, 7 - namely, B3L3, B4L4, G5L5, B5L6, B10L7, I1L8, and C4L10 - showed inhibition against the methicillin resistant Staphylococcus aureus (MRSA). These isolates were all Gram positive cocci, non-spore forming, and catalase negative. The purified fraction from the three phase partitioning (TPP) method, employing t-butanol and ammonium sulfate, produced inhibitory zones of 8 to 18 mm in diameter on the indicator organism, Staphylococcus aureus (MRSA). The TPP purified fraction contained heat stable proteins of about 10 kDa in size and was inactivated by trypsin. Based on the partial rDNA sequences (>89% similarity), isolates B4L4 and G5L5 belonged to Enterococcus hirae; isolate B3L3 belonged to Enterococcus faecium; isolates B5L6, B10L7, I1L8 to Enterococcus faecalis; and isolate C4L10 to Enterococcus mundtii. These probiotic strains, exclusively isolated from the Malaysian non-broiler chicken, produced an antimicrobial protein or bacteriocin which was active against a pathogenic strain of methicillin resistant Staphylococcus aureus (MRSA).