Molecular Identification of Four Antifungal Bacteria from Potato (Solanum tuberosum) and Strawberry (Fragaria x ananassa) Plants and their Rhizosphere Soils

Rhizosphere bacteria enhance plant growth and protection by producing active compounds.These bacteria remain the means of attraction to substitute for chemical pesticides, fertilizers,and other additives. Several studies are examining the biological control potential of antifungalbacteria, whose identity is currently unknown. The present study was conducted to isolate,identify, and characterize four bacteria with antifungal properties from potato and strawberryplants and their rhizosphere soils. Bacteria were isolated from potato and strawberry plants, andtheir respective rhizosphere soils. The bacterial isolates were subjected to antifungal activitytesting. Twenty-four of the isolates with antifungal activity were further subjected to anantifungal activity assay against Botrytis cinerea, Alternaria alternata, and Fusariumoxysporum. These bacterial isolates were identified using microscopic, phenotypic, andbiochemical tests. The identity of the four bacteria with strong antifungal activity was confirmedwith 16S rRNA gene sequencing. A total of 374 strains of bacteria were isolated, with 24 havingantagonistic activity. The results of the tests classified the isolates into three categories withvarying percentages; 25, 17, and 58% of the bacterial isolates were of the genera Bacillus,Acinetobacter, and Pseudomonas. Four of these bacterial isolates (Fr43, F31, B6, and B29) hadstrong antifungal activity. The molecular analysis revealed their identities as Bacillusamyloliquefaciens DMB3, Acinetobacter lwoffii strain HATC14, Pseudomonas brassicacearumsubsp. neoaurantiaca strain IHBB13645, and Bacillus amyloliquefaciens strain CD2901,respectively. The present study found four distinct bacterial strains with strong antagonisticpotential, probably belonging to new species, based on 16S rRNA gene sequence analysis.