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Lipopeptides from Bacillus subtilis have potential application in the winemaking process: inhibiting fungal and ochratoxin A contamination and enhancing esters and acids biosynthesis

Jiang, C., Chen, X., Lei, S., Zhao, H., Liu, Y., Shi, J.
Australian journal of grape and wine research 2017 v.23 no.3 pp. 350-358
Aspergillus carbonarius, Bacillus subtilis, acids, biosynthesis, esters, fermentation, flavor, grapes, lipopeptides, microbial contamination, microbial growth, ochratoxin A, sulfur dioxide, winemaking, wines, yeasts
BACKGROUND AND AIMS: Aspergillus carbonarius is considered the major cause of ochratoxin A (OTA) contamination in grape products, especially wine. The lipopeptides produced by Bacillus subtilis have been found to inhibit A. carbonarius contamination and OTA production in grapes. In order to assess the potential application of these lipopeptides during the winemaking process, they were tested alone or in combination with SO₂ to evaluate their effect on fungal growth and OTA contamination. METHODS AND RESULTS: Lipopeptides at 200 and 400 mg/L were added alone or in combination with SO₂ during the winemaking process using naturally contaminated grapes. Aspergillus carbonarius was also manually inoculated before fermentation to simulate grapes with a high fungal contamination and to investigate the inhibitory effect of lipopeptides on OTA‐producing fungi. The lipopeptides inhibited significantly fungal contamination and OTA production, much stronger than SO₂ against OTA‐producing A. carbonarius, at an optimum level of 200 mg/L. Yeast growth and biosynthesis of esters and acids were also promoted by lipopeptides during winemaking, which led to an improvement of wine flavour. CONCLUSIONS: Lipopeptides isolated from B. subtilis had a more potent inhibitory effect on fungal contamination and OTA accumulation than that of SO₂ during winemaking. Moreover, lipopeptides had no negative effect on fermentation, wine composition and sensory attributes. SIGNIFICANCE OF THE STUDY: These findings highlight the interesting possibility for the application of lipopeptides to replace or reduce the amount of SO₂ added during winemaking, especially when the inhibition of fungal contamination and OTA accumulation is considered.