Labeling of Bacillus velezensis FZB42 by expressing superfolder GFP at the locus of the pseudogene xkdB

Abstract:

[Objective] We used a super-bright variant of GFP, superfolder GFP (SfGFP), to label the Bacillus velezensis FZB42 strain, so as to establish a universal GFP labeling method for B. velezensis. This helps to develop a viable technique to study the colonization mechanism of beneficial rhizobacteria. [Methods] A mutant strain was generated by integrating SfGFP into a neutral locus called xkdB in the genome of FZB42, and then the fluorescence intensities of the mutant strains carrying different GFPs were detected to evaluate the influence of xkdB knockout. [Results] In this study, a marker strain labeled with SfGFP for FZB42 was constructed, whose fluorescence intensity was more than 5 times that of the gfp+ variant marker strain. The knockout of xkdB did not affect the growth rate, carbon source utilization, motility or biofilm formation, which confirmed the feasibility of using xkdB as a neutral locus for exogenous gene expression. [Conclusion] In this study, we confirmed a new locus suitable for the expression of foreign genes in the FZB42 genome, and exogenously expressed SfGFP at this locus, thus labeling FZB42 with fluorescence. This study provides a reference for the labeling of similar strains.