SAMAGACI Lamine^1,, OUATTARA Hadja¹, KOSSONOU Silver¹, KADET Victoria¹, LEMAIRE Marc², NIAMKE Sebastien¹

The yeasts involved in cocoa fermentation play an important role in obtaining good cocoa beans’ quality. Apart from cocoa fermentation, these yeasts could have a good inhibitory action against the growth of any phytopathogenic microorganism notably Dickeya dqdantii and Dickeya solani. This study is the first to evaluate the inhibitory action of yeasts involved in cocoa fermentation on the rot potato phytopathogen. For this purpose, the yeasts isolated from Côte d’Ivoire were confronted with the sensitive strain of Saccharomyces cerevisiae (W303). Moreover, the yeast killers were used to evaluate their inhibitory action on Dickeya solani and Dickeya dadantii. Finally, the physicochemical parameters (temperature, pH and salt concentration) capable to influence the inhibitory action of killer yeasts on Dickeya solani and Dickeya were evaluated. Thirty-three (33) yeasts out of the yeasts isolates tested were capable to produce toxic substances against the sensitive strain of Saccharomyces cerevisiae (W303). Among these yeasts, 14 are capable to inhibit the growth of Dickeya solani at temperature of 25 °C and 30 °C as well as pH of 4.5 and 6. Four (4) of these yeasts (C1P8, E10P10, D12P12 and E10P19) exert an inhibiting action on the growth of Dickeya dadantii in the same condition as before. These four yeasts isolates can be used in the biological fight against these two phytopathogens responsible for potato rot.

Cocoa yeast, Dickeya dadantii, Dickeya solani inhibition activity