Antibacterial Activity of Lactic Acid Producing QZ1178 Against Pathogenic .

Lactic acid bacteria (LAB) convert carbohydrates into organic acids [mainly lactic acid (LA)], which reportedly have bactericidal activities. is a Gram-negative bacteria which infects birds, and causes significant economic losses. In this study, we investigated the antibacterial activity of the LA producing, QZ1178 from Qula (fermented food), against , using the Oxford cup method. Our data showed that QZ1178 inhibited isolates from different origins; however, QZ1178 antibacterial activity dropped dramatically at pH 5.5-pH 6. The LA concentration and pH of the liquid broth containing QZ1178 after 24 h culture was 29 mg/mL and 3.6, respectively. This concentration (29 mg/mL at pH 3.6) and the antibiotic, cefotaxime (minimum inhibitory concentration (MIC) 2.5 μg/mL) effectively inhibited (GAC026) growth as observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). treated with LA exhibited extensive cell surface collapse, increased cell damage, cell membrane disruption, and cytoplasmic leakage, indicative of cell lysis. We suggest QZ1178 exerts potential antibacterial effects against the poultry pathogen, via LA.