CHARACTERIZATION OF SOME BIOFILMFORMING BACILLUS SUBTILIS STRAINS AND EVALUATION OF THEIR BIOCONTROL POTENTIAL AGAINST FUSARIUM CULMORUM
M. Khezri, M. Ahmadzadeh, Gh. Salehi Jouzani, K. Behboudi, A. Ahangaran, M. Mousivand, H. Rahimian
Thirty Iranian native Bacillus sp. strains collected from the rhizosphere of various hosts in different regions of the country were studied. 16S rRNA identification and phylogenetic analysis was carried out and secondary metabolites of volatile components, protease activity, biofilm formation and antagonistic activity against Fusarium culmorum in greenhouse were investigated for a thorough characterization of the strains. Correlation between biofilm formation and biocontrol capabilities under greenhouse conditions was also studied. PCR amplification and partial sequencing of 16S rRNA showed that all Iranian strains had more than 98% similarity with Bacillus sp. strain sequences from GeneBank. Phenotypical characterization allowed their classification as Bacillus subtilis. Phylogenetic analysis revealed that the strains clustered into two different phylogenic groups. Results of laboratory and greenhouse experiments showed that volatile and protease production as well as biofilm formation by some strains had a significantly positive correlation with their antagonistic ability. Finally, based on the results from laboratory and greenhouse experiments, the most powerful antagonist strains with high biofilm production were selected for future field experiments.