Isolation and Identification of Bacterial Soft-Rot-Causing Isolates from Cassava, Homa-Bay County, Kenya

Abstract

Cassava bacterial soft rot is of great importance to economically valuable crop varieties. Commonly, bacterial soft rot strains cause destructive vegetable and potato diseases worldwide. The strain act similar to other species of the family Enterobacteriaceae that cause soft rot in plants. However, the disease has spread in a wide range of environment with its prevalence and causative strains less known to most agroecological zones of Kenya. Generally, aim of this study was to isolate, characterize and identify bacterial soft rot causative strains in cassava, Homa-Bay County. At the Sub County level, 104 farms were identified through a simple random method and symptomatic cassava plants sampled along laid transect in each farm. Rotten cassava tubers were then randomly sampled, packed and taken to the laboratory for pathogen identification. The bacterial strains were isolated in Nutrient Agar at 37˚c for 24 hours to obtain pure cultures. Identification was done using morphological, biochemical and 16S rRNA analysis method. The study identified: two Pectobacterium carotovorum, three Bacillus species: Bacillus amyloliquefaciens, Bacillus subtilis, and Bacillus tropicus, and three Achromobacter species: Achromobacter marplatensis, Verticiella sediminum, and Achromobacter xylosoxidans, pathogenic strains causing cassava bacterial soft rot. In this study, characterization and identification of cassava bacterial soft rot in Homa Bay County was done for the first time. The results can not only be used in the characterization enzymes produced by cassava bacterial soft rot strains but also in the development of effective control strategy.