β-1,3-1,4-glucanase gene from Bacillus velezensis ZJ20 exerts antifungal effect on plant pathogenic fungi.

Abstract

Bacillus velezensis is a known antifungal bacteria. To understand the role of β-1, 3-1, 4-glucanase played on B. velezensis about the mechanism which exerts effect on fungi, we isolated and cloned the β-1, 3-1, 4-glucanase gene (Bglu1) from B. velezensis ZJ20. The Bglu1 open reading frame was 732bp that encoded a protein with 243 amino acids and a calculated molecular weight of 27.3kDa. The same gene without the signal peptide, termed Bglu2, was also cloned and expressed in E. coli BL21. Among the two variants, only Bglu2 protein was expressed. Purified Bglu2 could be eluted with imidazole solution at concentrations ranging from 100 to 500mM although the highest expression was observed at 150 and 200mM and the purest was at 500mM. In addition, activity of the crude enzyme was 1527Uml(-1) and the highest activity of the purified enzyme was 1706Uml(-1). The purified β-1, 3-1, 4-glucanase had activity on a wide range of pH and temperatures and displayed optimal activity at pH 5.0 and 35°C. More importantly, the mycelial morphology of three pathogenic fungi was destroyed by the purified β-1, 3-1, 4-glucanase. In conclusion, β-1, 3-1, 4-glucanase from B. velezensis ZJ20 can be highly expressed in E. coli BL21 and the recombinant protein is pathogenic to fungi.