DEVELOPMENT OF A FORMULATION BASED ON EXTRACTS OF THE COCULTURE OF Trichoderma SPP P3 AND Streptomyces cameroonensis TO FIGHT AGAINST Ralstonia solanasearum AN AGENT OF POTATO WILT DISEASE

Abstract

Potato is a crucial staple crop in Africa, particularly in Cameroon, but its production is hindered by pests and diseases. One of the most devastating of these is bacterial wilt, caused by the bacterium Ralstonia solanacearum and for which there is no known chemical control method. Bioformulations from microorganisms could potentially control this disease. This study tested the potential of a formulation based on an extract from a Trichoderma sp. P3 and Streptomyces cameroonensis co-culture to control bacterial wilt. The compatibility of Trichoderma sp. P3 and Streptomyces cameroonensis against phytopathogens, including Ralstonia solanacearum, was assessed. Two formulations based on extracts of Trichoderma sp. P3 and of its coculture with Streptomyces cameroonensis were developed and their modes of action against Ralstonia solanacearum were explored. The results showed that Trichoderma sp. P3 and Streptomyces cameroonensis can grow together in dual culture; the latter accelerates the maturation of the former, despite inhibiting its growth. Extracts of Trichoderma sp. P3 and its coculture with Streptomyces cameroonensis exhibited different GC-MS profiles and greater inhibitory effects against phytopathogens than Streptomyces cameroonensis extract alone. The bioformulation developed using these two extracts had the same minimal inhibitory concentration, acting on Ralstonia solanacearum by hydrolysing its cell wall and reducing its ATPase-H⁺ pumps. Pre-treatment of potato leaves reduced disease severity similar to chemical treatment. This study suggests that Trichoderma sp. P3 and its coculture with Streptomyces cameroonensis have the same effect on pathogens, albeit via different modes of action. This could be further explored for controlling bacterial wilt.