Biocontrol potential of Lactobacillus kefiri probiotic strain against Aspergillus flavus and aflatoxin production in almonds

Aspergillus flavus is a major producer of aflatoxin in almonds, causing fungal decay and posing a significant threat to human health. Lactobacillus kefiri MH107106 was used to inhibit the growth of A. flavus 15UA005, an aflatoxin producing strain previously isolated from curcumin. The inhibition effect in vitro was tested in Malt Extract Agar (MEA), while in vivo effect was examined in almonds. Results showed that L. kefiri strain inhibited 51.67% of Aspergillus flavus growth in agar medium. The cell-free supernatants (CFS) from L. kefiri reduced 40.56 % of fungal growth, while, no inhibition was observed for A. flavus treated with the cell-free supernatants at pH7 (CFS-pH7). Additionally, the strain L. kefiri inhibited the production of AFB1 and AFB2 by 97.22% and 95.27%, respectively. In the other hand, the inoculation of L. kefiri in almonds artificially contaminated with A. flavus decrease 85.27% of AFB1 and 83.94% of AFB2 content after 7 days of incubation. This study reveals that L. kefiri could be a promising natural agent for an effective bio-control, non-toxic bio-preservative, and an eco-friendly alternative to synthetic additives against A. flavus in almonds.