Isolation and identification of soil-borne bacteria with the effect of Fusarium oxysporum ioinhibition in tomato plants

Plant growth-promoting rhizobacteria (PGPR) is an alternative to chemical pesticides against harmful microorganisms especially soil-borne diseases. Fusarium oxysporum is one of the important pathogenic fungi of tomato wilt that causes serious damage to agricultural products.

The purpose of this research is to investigate the inhibition of the growth of Fusarium oxysporum with bacteria isolated from soil in laboratory conditions.

In order to isolate biological inhibitors, isolates were screened based on the ability to auxin and phosphorus solubilization, siderophore production and fungal growth inhibition. Molecular identification of selected isolates was done by 16SrDNA gene amplification. Investigating the ability of bacteria to control the pathogen Fusarium oxysporum. It was done under greenhouse conditions.In this study, to screen successful bacterial isolates, the inhibition of pathogen growth was evaluated in-vitro.

Moreover,. Among the 80 isolates studied, seven isolates had the ability to produce auxin, ten isolates had the ability to P solubility, six isolates had the ability to produce siderophore, and seven isolates had the ability to inhibition pathogen growth. Among the isolates 56 and 83 had the highest amount of auxin production and the P solubility and the fungal growth inhibition. Multiple alignment of the 16SrDNA sequence of two selected bacteria with other 16SrDNA sequences in the NCBI gene bank showed that isolates 56 and 83 with 98 and 99.9 percent similarity belong to Bacillus amyloliquefaciens and Bacillus atrophaeus, respectively.

Among the isolates, seven isolates in vitro conditions showed a good ability to inhibit the growth of F. oxysporum. In greenhouse experiments, all 5 isolates as significantly (P<0.05) they controlled the disease, and the most control was related to isolate 56.