Bacillus sp.

The study was carried out to determine the antagonistic activity of Trichoderma viride and Bacillus sp. against microorganisms responsible for disease or spoilage of potato. Diseased/spoilt potato tubers were obtained from open markets in Benin City. Standard microbiological techniques were employed for isolation of bacteria and fungi from diseased/spoilt potato tubers. Bacteria and fungi were enumerated using pour plate method. Cultural, morphological and biochemical characteristics were employed for identification of the isolates. Pathogenicity tests were used to evaluate the involvement of the isolates in the spoilage or disease of potato tubers. Biocontrol or antagonistic activity was carried out for the spoilage-causing microbes which were Trichoderma viride and Bacillus sp. using Potato dextrose agar and Mueller Hinton agar. The results revealed that the heterotrophic bacterial counts for spoilt/diseased potato ranged from log10 3.65±0.41 cfu/g (Uselu market) to log10 4.02±0.25 cfu/g (Aduwawa Market), while the fungal counts ranged from log10 3.57±0.30 cfu/g (Aduwawa market) to log10 3.85±0.10 cfu/g (Uselu market). The cultural morphological and biochemical characteristics of bacterial isolates from spoilt potato revealed their identity as; Erwinia sp, Pseudomonas aeruginosa, Bacillus sp. and Staphylococcus aureus while the fungal isolates from spoilt potato were Aspergillus sp., Rhizopus sp. and Penicillium sp.. The pathogenicity or spoilage test of isolated microorganisms from spoilt to healthy potato tubers showed that only Erwinia sp. and Aspergillus sp. were found to induce disease or spoilage condition in potato tubers. The in vitro antagonism (percentage inhibition) of Bacillus sp. and Trichoderma viridia on growth of Aspergillus sp. and Erwinia sp. showed that Trichoderma viridia had more biocontrol effect on growth of Aspergillus (50%) and Erwinia (47%) after 5 days of culture on growth media. In conclusion, Trichoderma viride and Bacillus sp. exhibited significant antagonistic activity against potato soft rot pathogens. The study identifies Erwinia sp. and Aspergillus sp. as key contributors to potato spoilage. Trichoderma viride demonstrates a notable biocontrol effect, inhibiting the growth of Aspergillus sp. and Erwinia sp.. These findings reveals the potential of Trichoderma viride and Bacillus sp. as promising biocontrol agents for mitigating potato soft rot, offering sustainable and environmentally friendly alternatives for potato cultivation and storage.