Investigation of the antifungal mechanism activity of Lactobacillus plantarum NCDN4 against Aspergillus niger and its application in brown rice gemination ☆

Germinated brown rice has a higher nutritional value than brown rice due to the germination process, which enhances nutrient content. However, this product is easily contaminated by mold during germination, leading to food safety concerns. The aims of this study were to evaluate the antifungal ability of Lactobacillus plantarum NCDN4 lactic acid bacteria against Aspergillus niger CBS 76997 during the germination of brown rice. The in vitro antifungal activity of L. plantarum NCDN4 was assessed in agar and liquid medium. The effect of the bacterial cell-free supernatant and/or biomass on the growth of A. niger was determined based on the mycelial growth diameter of fungi over time. The research results indicated that the mycelial diameter of A. niger treated with L. plantarum ranged from 15 - 30mm, lower than the control sample (85mm) after five days of incubation. L. plantarum also delayed the formation of fungi spores. The preliminary results showed that the antifungal mechanism of L. plantarum related to the lactic acid produced during bacteria metabolism, delayed and reduced spore formation, nutrient competition and damaged mycelium of A. niger. L. plantarum reduced the mould contamination rate during the germination of brown rice without affecting the germination of rice, with a germination ability of 94.7%. The mould contamination rates in the samples non-treated and treated with LAB were 100.0% and 15.7%, respectively. The results demonstrated the potential application of L. plantarum in food technology as a biocontrol agent in inhibiting fungi.