Potential of marine chitinolytic Bacillus isolates as biocontrol agents of phytopathogenic fungi

Phytopathogenic fungi pose a serious problem around the world in the economically important plants. Chemical fungicides are widely used in current agriculture. However, excessive use of chemical fungicides has led to the deterioration of human health, environmental pollution, and development of pathogenic resistance to fungicides. A serious search is required to identify alternative methods for crop protection, which is less dependent on chemicals and more environmentally friendly. Microbial antagonists widely used for biocontrol of plant fungal disease. The success of biocontrol depends on the nature of antagonistic properties and mechanisms of action of the biocontrol agent against the phytopathogenic fungi. In the present study, 83 Bacillus isolates isolated from marine samples were screened on the colloidal chitin agar medium. Based on the chitinolytic activity and percentage inhibition against fungal phytopathogens by dual plate technique, isolate B26 is most potent as biocontrol agents. The Bacillus B26 inhibited the growth of Fusarium solani TISTR 3436 and Penicillium chrysogenum with percentage inhibition 69% and 46.6% respectively, while did not inhibit the growth of Aspergillus niger and Aspergillus flavus. Bacillus isolate B26 showed a positive result for the urease production, catalase test, starch hydrolysis, casein hydrolysis with most suitable growth condition at 37^°C, pH 7-8, and could grow at 0-5% NaCl concentration.