The antifungal effect of metabolites produced by a new strain of Lactiplantibacillus (Lpb.)
plantarum LPP703, isolated from naturally fermented yak yogurt, was investigated. The results
showed that Lpb. plantarum LPP703 significantly inhibited four fungal species, including Penicillium
sp., Rhizopus delemar, Aspergillus flavus, and Aspergillus niger. The metabolites produced after 20 h
of Lpb. plantarum LPP703 fermentation showed the highest antifungal activity against Penicillium sp.
Compared with the control group, the Lpb. plantarum LPP703 metabolites-treated Penicillium sp.
spores were stained red by propidium iodide, indicating that the cell membrane of the fungal
spores was damaged. Moreover, the antifungal effect of the Lpb. plantarum LPP703 metabolites on
Penicillium sp. was not changed after heating or treatment with various proteases, but showed a sharp
decrease when the pH value was regulated to 5.0 or above. The oleamide, trans-cinnamic acid, and
citric acid were the three most abundant in the Lpb. plantarum LPP703 metabolites. Molecular docking
predicated that the oleamide interacted with the active site of lanosterol 14-alpha-demethylase (CYP51,
a crucial enzyme for fungal membrane integrity) through hydrogen bonds and had the lowest docking
score, representing the strongest binding affinity to CYP51. Taken together, the metabolites from a
new strain of Lpb. plantarum, LPP703, had potent antifungal activity against Penicillium sp., which
might be associated with the damage of the active ingredient to fungal membrane integrity. This
study indicated that Lpb. plantarum LPP703 and its metabolites might act as biological control agents
to prevent fungal growth in the food industry.