Marine Bacillus haynesii chitinase: Purification, characterization and antifungal potential for sustainable chitin bioconversion

The development of chitinase tailored for the bioconversion of chitin to chitin oligosaccharides has attracted significant attention due to its potential to alleviate environmental pollution associated with chemical conversion processes. In this present investigation, we purified extracellular chitinase derived from marine Bacillus haynesii to homogeneity and subsequently characterized it. The molecular weight of BhChi was approximately 35 kDa. BhChi displayed its peak catalytic activity at pH 6.0, with an optimal temperature of 37 °C. It exhibited stability across a pH range of 6.0–9.0. In addition, BhChi showed activation in the presence of Mn²⁺ with the improved activity of 105 U mL⁻¹. Ca²⁺ and Fe²⁺ metal ions did not have any significant impact on enzyme activity. Under the optimized enzymatic conditions, there was a notable enhancement in catalytic activity on colloidal chitin with K_m of 0.01 mg mL⁻¹ and V_max of 5.75 mmol min⁻¹. K_cat and catalytic efficiency were measured at 1.91 s⁻¹ and 191 mL mg⁻¹ s⁻¹, respectively. The product profiling of BhChi using thin layer chromatography and Mass spectrometric techniques hinted an exochitinase mode of action with chitobiose and N-Acetyl glucosamine as the products. This study represents the first report on an exochitinase from Bacillus haynesii. Furthermore, the chitinase showcased promising antifungal properties against key pathogens, Fusarium oxysporum and Penicillium chrysogenum, reinforcing its potential as a potent biocontrol agent.