Abstract：
Previous studies have demonstrated the presence of chitinase in Bacillus velezensis through extensive genomic sequencing and experimental analyses. However, the detailed structure, functional roles, and antifungal activity of these chitinases remain poorly characterized. In this study, genomic screening identified three genes-chiA, chiB, and lpmo10-associated with chitinase degradation in B. velezensis S161. These genes encode chitinases ChiA and ChiB, and lytic polysaccharide monooxygenase LPMO10. Both ChiA and ChiB contain two CBM50 binding domains and one catalytic domain, whereas LPMO10 includes a signal peptide and a single catalytic domain. The chitinases ChiA, its truncated variant ChiA2, and ChiB were heterologously expressed in Escherichia coli. The purified enzymes efficiently degraded colloidal chitin and inhibited the spore germination of Penicillium digitatum. Notably, even after losing one CBM50 domain, the resultant enzyme, consisting of the remaining CBM50 domain and the catalytic domain, maintained its colloidal chitin hydrolysis and antifungal activity, indicating commendable stability. These results underscore the role of B. velezensis chitinases in suppressing plant pathogenic fungi and provide a solid foundation for developing and applying chitinase-based biocontrol strategies.
摘要：
先前的研究已经通过广泛的基因组测序和实验分析证明了几丁质酶在velezensis芽孢杆菌中的存在。然而,详细的结构，功能角色，这些几丁质酶的抗真菌活性仍然缺乏表征。在这项研究中,基因组筛选确定了三个基因-chiA，chiB,和lpmo10与维氏芽孢杆菌S161中几丁质酶降解相关。这些基因编码几丁质酶ChiA和ChiB，和裂解多糖单加氧酶LPM010。ChiA和ChiB都包含两个CBM50结合域和一个催化域，而LPM010包括信号肽和单个催化结构域。几丁质酶ChiA，其截短的变体ChiA2和ChiB在大肠杆菌中异源表达。纯化的酶能有效降解胶体几丁质，抑制指状青霉的孢子萌发。值得注意的是,即使失去了一个CBM50域名，产生的酶，由剩余的CBM50结构域和催化结构域组成，保持其胶体几丁质水解和抗真菌活性，表现出良好的稳定性。这些结果强调了维氏芽孢杆菌几丁质酶在抑制植物病原真菌中的作用，并为开发和应用基于几丁质酶的生物防治策略提供了坚实的基础。
