Abstract:In this study，well growing lactic acid bacteria from naturally fermented coconut water were used as the research test material，and drug-resistant pathogens from dead broilers were used as the indicator bacteria for primary screening of antibacterial activity and re-screening of tolerance.A superior strain A32，which was identified as Lactobacillus fermentum，was obtained.A32 could grow vigorously in coconut water from 1 to 4 days，and viable bacteria count was maintained at 8 lg cfu/mL-9 lg cfu/mL.Large amount of acid，with the lowest pH of 3.55 and the highest total acid of 17.09 g/L，was produced.Protease and high temperature treatments had little antibacterial effect，and antibacterial activity disappeared when pH value was raised to 5.0.There was a significant positive correlation between antibacterial activity and total acid content（p<0.05）.Therefore，it was inferred that the main antibacterial substances produced by A32 were organic acids，and they include malic acid，citric acid，and lactic acid，among which the proportion of malic acid was more than 64%.It was speculated that the high antibacterial activity of A32 in coconut water might be related to its low pH value，high total acid and malic acid contents.