Purification and characterization of a 1,3-β-d-glucanase from Streptomyces torulosus PCPOK-0324

A hydrolytic enzyme designated as a 1,3-β-d-glucanase having an antifungal activity was purified and characterized from Streptomyces torulosus PCPOK-0324. Fungal growth inhibitors in the culture filtrates from an antagonistic S. torulosus PCPOK-0324 exhibited higher antifungal activity against the hyphal growth of Phytophthora capsici and Rhizoctonia solani. The 1,3-β-d-glucanase was purified by four chromatographic steps from culture supernatant. The molecular weight of the purified enzyme was estimated to be 31.5 kDa. The optimal pH and temperature were 7.5 and 50 °C. Both the purified enzyme and the antibiotic extract inhibited R. solani and P. capsici with minimal inhibitory concentration values of 12.50 and 6.25 mU ml−1 and 3.95 and 1.94 μg ml−1, respectively. Our findings collectively show that the 1,3-β-d-glucanase in combination with the antibiotic extract have strong synergistic antifungal activity against the hyphal growth of both fungi causing root rot disease in pepper plants.