Study of the antimicrobial activity of bacteriocins produced by lactic bacteria isolated from camel milk in southern Algeria

Abstract

The objective of this work is the research of lactic bacteria producing antimicrobial substances against harmful germs, the purification of the bacteriocins produced by these bacteria and the determination of their activity spectra. After sampling camel milk in the regions of El Oued (southern Algeria), microbiological and biochemical methods are used to identify the bacteria with antimicrobial activity and the purification of the bacteriocin produced. Nine isolates of lactic acid bacteria have been identified. The dominant species belonging to the genus Lactococcus are: Lactococcus. lactis subsp. lactis, Lactococcus. Lactis subsp. Cremoris, Lactococcus sp, at the genus Pediococci are: Pediococcus acidilactici, at the genus Streptococci are: Streptococcus. Sp, Streptococcus. Thermophilus and the genus Lactobacilli are: Lactobacillus amylophilus. The search for the antagonist substance was performed according to the method of diffusion of the wells. The six lactic strains gave zones of inhibition against pathogenic bacteria. Extraction of the bioactive peptides by the ammonium sulphate precipitation method was carried out. The results obtained show an inhibitory effect of bacteriocin against certain human pathogens (seven bacteria). The greatest inhibition (8mm) was observed for bacteriocin of the Lac. lactis subsp. Cremoris against Staphylococcus aureus, then their bactericidal activity against Staphylococcus aureus was studied by the method of minimal inhibitory concentration (MIC). In conclusion, bacteriocin has not only the bactericidal activity, but also the dependent dose of different bacteria.