Response Surface Methodology-Based Optimization of the Chitinolytic Activity of Strain 614 Exerting Biological Control against Phytopathogenic Fungi.

As part of the development of alternative and environmentally friendly control against phytopathogenic fungi, could be a useful species notably via the generation of hydrolytic enzymes like chitinases, which can act as a biological control agent. Here, a S614 strain exhibiting chitinase activity was isolated from a soil in southern Tunisia. Then, response surface methodology (RSM) with a central composite design (CCD) was used to assess the impact of five factors (colloidal chitin, magnesium sulfate, dipotassium phosphate, yeast extract, and ammonium sulfate) on chitinase activity. strain 614 growing in the optimized medium showed up to a 3-fold higher chitinase activity. This enzyme was identified as beta-N-acetylhexosaminidase (90.1 kDa) based on its peptide sequences, which showed high similarity to those of strain 383. Furthermore, this chitinase significantly inhibited the growth of two phytopathogenic fungi: M5 and Ph8. Interestingly, a crude enzyme from strain S614 was effective in reducing damage on detached leaves of . Overall, our data provide strong arguments for the agricultural and biotechnological potential of strain S614 in the context of developing biocontrol approaches.