Potential application of lactic acid bacteria in the biopreservation of red grape from mycotoxigenic fungi

BACKGROUND: Filamentous fungi are the main contamination agent in the viticultural sector. Use of synthetic fungicides is theregular answer to these contaminations. Nevertheless, because of several problems associated with the use of synthetic com-pounds, the industry demands new and safer methods. In the present work, the biopreservation potential of four lactic acidbacteria (LAB) strains was studied against the principal grape contaminant fungi.RESULTS: Agar diffusion test evidenced that all four culture-free supernatant (CFS) had antifungal properties against all testedfungi. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) test values evidenced thatmedia fermented by theLactobacillus plantarumE3 andLactobacillus plantarumE4 strains showed the highest antifungal activ-ity, resulting in an MFC from 6.3 to 100 g L−1. Analysis of CFS evidenced the presence of different antifungal compounds, suchas lactic acid, phenyllactic acid and pyrazines. In tests on red grapes, an average reduction of 1.32 log10of the spores per gramof fruit was achieved by all CFS in grapes inoculated withAspergillus ochraceusand by 0.94 log10forL. plantarumE3 CFS againstBotrytis cinerea.CONCLUSION: The antifungal activity of the fermented CFS byL. plantarumE3 reduced the growth ofB. cinereaandA. ochraceusin grapes, which are the main contaminant and main producer of ochratoxin A in these crops, respectively. Therefore, based onthe results obtained in this work, use of the strainL. plantarumE3 could be an interesting option for the biopreservation ofgrapes.