ISOLATION OF LACTIC ACID BACTERIA FROM TRADITIONAL MOROCCAN PRODUCTS AND EVALUATION OF THEIR ANTIFUNGAL ACTIVITY ON GROWTH AND OCHRATOXIN A PRODUCTION BY ASPERGILLUS CARBONARIUS AND A. NIGER

Different agricultural products, including grapes, are susceptible to contamination and damage by several microorganisms, one being fungi and their mycotoxins such as ochratoxin A. These alterations are a source of food waste and lead to significant economic losses. Thus, new alternatives have been sought in parallel with existing methods. In this work, after isolation, identification by 16S rDNA sequencing and differentiation by Pulsed-Field Gel Electrophoresis (PFGE) of four lactic acid bacteria from different traditional Moroccan food products, antifungal activity was studied against Aspergillus carbonarius and A. niger isolated from Moroccan grapes. Their effect on ochratoxin A production was also assessed. A strain of Lactoccocus lactis ssp. lactis (F) and three strains of Leuconostoc mesenteroides ssp. mesenteroides (I, C, and D) selected from 16 isolated strains were tested. Their antifungal activities against Aspergillus spp. were quite significant, with growth inhibition rates ranging from 28.69% to 53.31%. Likewise, ochratoxin A production by Aspergillus strains was significantly reduced. Indeed, in the presence of the Lactoccocus lactis ssp. lactis (F) strain, this reduction was about 63.90% and 65.12% for A. niger and A. carbonarius, respectively; however, an 89.38% reduction for A. niger and 19.35 % A. carbonarius was achieved for the Leuconostoc mesenteroides ssp. mesenteroides (I) strain. These results revealed strain-dependent antifungal activity. Our study indicates that the use of these lactic acid bacteria can be applied as a biocontrol of fungal growth and mycotoxins production.