Screening of Antibacterial Active Substance-producing Strains and Determination of Antibacterial Mechanism
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Abstract:
A total of nine strains of lactic acid bacteria and five yeast strains isolated from koumiss from Xilin Gol League, Inner Mongolia, and strains with higher antibacterial capacity were screened, and antibacterial mechanism of their fermentation broth was studied. Staphylococcus aureus, Salmonella enterica subsp. Enteric, and Pseudomonas fluorescens were used as indicators, while co-fermentation of Lactobacillus D6 and E13 with yeast J10A1 was performed using oxford cup agar diffusion method. The antibacterial effects of Lactobacillus D6 and E13 exceeded that of lactic acid bacteria by 2.48 mm and 1.45 mm, respectively. The antibacterial substances produced by strains D6 and E13 affected Salmonella to a large extent. The lag phase of Salmonella growth curve was delayed and its logarithmic phase was shortened with logarithmic peak being reduced. Intracellular total soluble sugars and electrolytes were purged, leading to an increase in liquid conductivity and content of total soluble sugars in the Salmonella suspension. Sugar absorption capacity was decreased and phosphorus metabolism was reduced to a constant value. Antibacterial substances produced by E13 showed a stronger inhibitory action. The results showed that the antibacterial substances produced by lactic acid bacteria not only destroy the cell wall and cell membrane, but also affect the metabolism of bacteria, exerting an inhibitory effect by inhibiting normal growth and reproduction of the bacteria.
