Food Microbiology

Statement of the Problem: Alternaria is one of the main pathogenic bacteria of fruit black spot in postharvest storage. The huge economic loss in Xinjiang province has been resulted by Alternaria. There were many fermented dairy stuffs in Xinjiang, China. We first tried to utilize the local lactic acid bacteria(LAB) strains from fermented dairy products to control the local pathogenic Alternaria.

 

Methodology & Theoretical Orientation: Two strains of A. tenuissima isolated from the pear and apple in south Xinjiang and A. tenuissima CGMCC3.3546 standard strain was used as pathogenic bacteria to detect the inhibitory activity of 110 local LAB strains’ cultures on the MRS agar, and in stationary and shaked MRS broth. The antifungal substances in the cultures of LAB strains with high inhibitory activity were detected by UPLC-Q-TOF.

 

Findings: Three Lactobacillus pentosus strains and one L. paracasei shown high inhibitory activity on A. tenuissima Ap1, A. tenuissima Am1 and A. tenuissima CGMCC3.3546. The shaked broth of three LAB strains had the higher inhibitory activity on the three Alternaria stains than cultures on MRS agar and in stationary broth. The main antifungal substances in shaked broth of the representative LAB 86 strain included organic acids, esters, N-heterocyclic compounds, alkaloids, and benzene derivatives, they had molecular less than 1000Da and synergistic effect of antifungal activities on Alternaria.

 

Conclusion & Significance: The shaked broth of three local LAB strains from Xinjiang dairy products could be used to control the black spot disease caused by Alternaria in the postharvest.