Assessment of probiotic and antifungal activity of Lactiplantibacillus plantarum MYSAGT3 isolated from locally available herbal juice against mycotoxigenic Aspergillus species

This study investigated the antifungal activities of probiotic bacteria isolated from traditional herbal juice, which was a blend of Tulsi, Mint, Bael and Indian borage leaves. About 20 isolates were obtained from the herbal juice sample; these isolates were initially screened against fungal pathogens such as Aspergillus parasiticus, Aspergillus flavus, Aspergillus ochraceus, Aspergillus carbonarius and Aspergillus fumigatus. Of the 20 isolates obtained, MYSAGT3 and MYSAGT4 exhibited potential antifungal activity against the tested fungal pathogens. Moreover, MYSAGT3 and MYSAGT4 was found to survive acidic pH and bile conditions, but were susceptible to tested antibiotics. Both the isolates exhibited 40-60% of autoaggregation ability, >90% of cell surface hydrophobicity and tolerance to 0.4-0.6% phenol. The 16S rRNA sequencing results identified the isolates MYSAGT3 and MYSAGT4 as Lactiplantibacillus plantarum. The MYSAGT3 exhibited potent antagonistic and probiotic activity compared to MYSAGT4; hence MYSAGT3 was further used for the control of Aspergillus ochraceus. Initial antifungal activity of MYSAGT3 inhibited about 76.67% growth of Aspergillus ochraceus comparatively higher than other Aspergillus sp. tested. Co-inoculation and microdilution assay revealed the high inhibitory activity of Lactiplantibacillus plantarum MYSAGT3. Further, cell free supernatant (CFS) of Lactiplantibacillus plantarum MYSAGT3 reduced the growth of fungal hyphae and conidial germination of Aspergillus ochraceus in conidial germination assay and bio preservative activity on peanuts. The CFS characterization and Liquid chromatography-mass spectroscopy (LCMS) results showed that, the antifungal activity was due to different organic acids present in the CFS of MYSAGT3. MYSAGT3 and its CFS also reduced the growth of Aspergillus ochraceus in Poultry feeds and about 21.80% of ochratoxin A (OTA) degradation was attained after 24 h of incubation with MYSAGT3. The isolated Lactic acid bacteria are able to inhibit Aspergillus ochraceus and degrade OTA in-vitro. Hence, the results suggest Lactiplantibacillus plantarum MYSAGT3 as an efficient probiotic organism and possess antifungal properties.

Automated summary

The study identified Lactiplantibacillus plantarum MYSAGT3 as a potent probiotic organism with antifungal properties, showing potential in controlling Aspergillus ochraceus, inhibiting fungal growth in poultry feed and peanuts, as well as degrading OTA.