Efficient transformation and expression of the glucanase gene from Bacillus megaterium in the biocontrol strain Streptomyces lydicus A02

发布时间：2016年09月27日 14:18　　浏览次数：1151

Huiling Wu, Dan Dong, Jinjin Li, Weicheng Liu, Ting Liu, Taotao Zhang & Zhaofeng Tian

Biocontrol Science and Technology, 2014

Streptomyces have been used extensively as the biocontrol agents due to their

ability to produce various antimicrobial compounds, such as antibiotics and

hydrolytic enzymes. Streptomyces lydicus strain A02, which was isolated from the

soil of suburban forest field in Beijing (China), is capable of producing natamycin

and has proved to be a potential biocontrol agent to several plant fungal diseases,

including wilts caused by Fusarium oxysporum f. spp. However, hydrolytic

enzymes like glucanase have not been detected in S. lydicus A02 on CMC-Na

plates by congo red staining. Glucanase, a pathogenesis-related (PR) protein,

degrades fungal cell walls and has been widely used as antifungal agent in plant

protection. Therefore, a recombinant S. lydicus expressing a glucanase gene,

which was cloned from the biocontrol strain Bacillus megaterium L103 and driven

by the Streptomyces erythraea ermE* promoter, was constructed in this study.

The engineered S. lydicus AG02 shared a similar yield of natamycin with the wildtype

A02 strain. Compared to the wild-type strain A02, the engineered S. lydicus

AG02 had a remarkably higher glucanase activity, as well as antifungal activity to

F. oxysporum f. sp. conglutinans, F. oxysporum f. sp. niveum and Rhizoctonia

cerealis. This demonstrated the improved biocontrol effect of S. lydicus AG02

attributed to transforming the exogenous glucanase from B. megaterium, which

acted synergistically with natamycin to increase the antifungal activity of the

strain.