Marine chitinase AfChi: green defense management against Colletotrichum gloeosporioides and anthracnose

Anthracnose disease, caused by the Colletotrichum gloeosporioides species, affects vegetables, fruits, pulses, and cereals, leading to significant economic losses worldwide. Although many synthetic fungicides are used to control this pathogen, eco-friendly biological alternatives are gaining popularity. This study focuses on isolating and purifying chitinase ( Af Chi)from a marine bacterium and testing its antifungal efficacy against C. gloeosporioides spore germination by targeting the chitin in the fungal cell wall. The chitinase was purified from a marine bacterium A. faecalis from the Arabian Sea and had a molecular mass of 45 kDa and a specific activity of 84.6 U/mg. Af Chi worked best at 50 °C and pH 7.0 in Tris HCl buffer. Na⁺ ion was the highest cofactor, highlighting the halophilic nature of this chitinase. K⁺, Ca²⁺, Cu²⁺, Mg²⁺, Mn²⁺, and EDTA also increased activity, while Fe³⁺, Zn²⁺, Co²⁺, and Pb²⁺ decreased it. The K_m and V_max values were 1.87 µg/mL and 17.45 U/mL, respectively. Purified Af Chi at 10 mg/mL completely inhibited spore germination within 8 h and reduced the size of the spores.