Molecular detection of nisin producing lactococcus from fermented food in Alnajaf

الملخص EN

Nisin is a small post-translationally modified lanthionine-containing peptide (lantibiotic) produced by certain strains which has a high antimicrobial activity against several pathogenic Grampositive bacteria.

Fifty four isolates from fermented food in Alnajaf were analyzed by conventional PCR to rapid molecular screening of nisin coding genes.

12 (22 %) isolates produced PCR fragments with specific primers.

Fragment of 608 bp indicate to presence of nisin gene.

Agar well diffusion method was used to show the antibacterial activity of nisin producing lactic acid bacteria against Staphylococcus aureus as indicator strain.

The supernatant of the strains gave inhibition zones (11-18mm) onto the indicator pathogenic strain.

Among LAB isolates, strain L9 nisin producer the most effective antibacterial compounds against Staphylococcus aureus.

(18 mm as diameter of inhibition).

Using an initial screening of lactic acid bacteria, the results of the 54 selected strains as belonging to lactic acid bacteria.

The selected isolates were 12 (22 %) Lactococcus lactis.