title: Overexpression of the key virulence proteases Bace16 and Bae16 in Bacillus nematocida B16 to improve its nematocidal activity.
abstract: Proteases Bace16 and Bae16, an alkaline serine protease and a neutral protease, respectively, in the nematocidal bacterium Bacillus nematocida B16, have been identified as two key virulence factors and shown to have remarkable nematotoxic activities against the free-living nematode Panagrellus redivius and the plant parasite nematode Bursaphelenchus xylophilus. To facilitate the successful biological control application of this organism in the field, we genetically altered the strain B. nematocida B16 and optimized its growth condition to overexpress these two pathogenic proteases. The recombinant integration vectors of pAX01-Bace16 and pAX01-Bae16 for overexpressing the two proteases were constructed and successfully transformed into competent cells of the bacterium B. nematocida B16. The optimal induction condition for overexpressing Bace16 is 2% xylose at 37°C for 48 h. Our analyses showed that the proteolytic activity and nematocidal activity of the strain overexpressing Bace16 increased by about 62 and 80%, respectively, over the wild-type strain. However, our tested induction conditions could not significantly improve either the proteolytic activity or the nematocidal activity of the Bae16 overexpression mutant.
authors.affiliation: Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China.
authors.forename: Qiuhong
authors.initials: Q
authors.lastname: Niu
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Tian
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.forename: Xiao'e
authors.initials: X
authors.lastname: Xu
authors.forename: Xuemei
authors.initials: X
authors.lastname: Niu
authors.forename: Zhenyuan
authors.initials: Z
authors.lastname: Xia
authors.forename: Liping
authors.initials: L
authors.lastname: Lei
authors.forename: Ke-Qin
authors.initials: KQ
authors.lastname: Zhang
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Huang
mesh_terms: D000818:Animals; D001407:Bacillus / Q000235:genetics* / Q000472:pathogenicity*; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D030781:Organisms, Genetically Modified; D010447:Peptide Hydrolases / Q000096:biosynthesis* / Q000235:genetics; D017168:Rhabditida / Q000382:microbiology* / Q000502:physiology*; D016019:Survival Analysis; D014774:Virulence; D037521:Virulence Factors / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D037521:Virulence Factors; D010447:Peptide Hydrolases