The paper reports the populations of B. thuringiensis on wine grapes harvested at various stages during cultivation, the potential for its growth and survival in grape juice and wine, and its antagonistic activity towards a range of grape fungi, wine yeasts and malolactic bacteria. Commercial preparations of B. thuringiensis were sprayed onto grapes as a biological insecticide. Grapes samples were collected at several phenological stages of development in order to isolate and identify B. thuringiensis strains. Isolation of B. thuringiensis from wines and grape juices at a commercial winery were performed too. Growth and survival of B. thuringiensis on grape musts and wine and its interactions with other microorganisms such as S. cerevisiae, O. oeni, B. cinerea and other fungi were then investigated. Results pointed out that at the time of harvest, B. thuringiensis populations on grapes varied between 102 and 104 cfu/g, depending on vineyard. A small density of B. thuringiensis cells were isolated from musts at different stage of fermentation. The ability of B. thuringiensis to survive (but not to grow) both in grape juice and in wine was observed. Inhibition of some yeasts (Cryptococcus, Debaryomyces, Metschnikowia, Pichia, Rhodotorula and Sporobolomyces), bacteria (O. oeni, Lactobacillus brevis…) and fungi species (B. cinerea, Alternaria infectoria, Aspergillus aculeatus, A. carbonarius, and Cladosporium cladosporioides) was pointed out too. At the contrary S. cerevisiae was not affected by B. thuringiensis. Authors suggest B. thuringiensis does not adversely impact on wine quality or safety. We suggest you to read the entire article. Original title: Occurrence and significance of Bacillus thuringiensis on wine grapes