Etude de l’activité antibactérienne de souches lactiques isolées du lait de vache

Abstract

This study consists in demonstrating the antagonistic effect of lactic acid bacteria isolated from cow's milk, against some pathogenic bacteria responsible of different diseases in humans.The phenotypic study confirmed the viability of nine lactic strains from a collection of lactic acid bacteria isolated from cow's milk:(LMBAFS01; LMBAFS02; LMBAFS03; LMBAFS04; LMBAFS05; LMBAFS06; LMBAFS07; LMBAFS08; LMBAFS09) ;(08) strains related to the Lactobacillus genus by their rod-shaped cell and (01) lactococci-related strains by their cocci cellular form. Otherwise, tests for antibacterial activity against:staphylococcus aureus ATCC 6538; staphylococcus aureus ATCC 25923 ;PseudomeunasaeroginosaATCC 27853; Eschérichia coli ATCC 10536; shiguelladysenteriaCECT 457, using the well-diffusion method, led to the appearance of clear halot around the tested lactic strains with variable inhibition zone diameters,in fact the strains LMBAFS[01 ;02 ;03 ;04 ;05]were the best performers against staphylococcus aureus ATCC 6538 ,PseudomeunasaeroginosaATCC 27853et shiguelladysenteriaCECT 457. The interaction of antagonism with the supernatant after neutralization with a solution of 1N NaOH and filtration by millipore filter (0.45 μm), revealed antibacterial activity only againstStaphylococcus aureusATCC 6538 for the strains LMBAFS[01; 02; 03;04; 05], thisMakes possible to say that there are other antibacterial substances produced by our bacteria and a more detailed characterization willallow to determine their nature (H202, Diacetyl or bacteriocins).