degQ associated with the degS/degU two‐component system regulates biofilm formation, antimicrobial metabolite production, and biocontrol activity in Bacillus velezensis DMW1

Abstract

The gram‐positive bacterium Bacillus velezensis strain DMW1 produces a high level of antimicrobial metabolites that can suppress the growth of phytopathogens. We investigated the mechanism used by degQ and the degS/degU two‐component system to regulate the biocontrol characteristics of DMW1. When degQ and degU were deleted, the biofilm formation, cell motility, colonization activities, and antifungal abilities of ΔdegQ and ΔdegU were significantly reduced compared to wild‐type DMW1. The expression levels of biofilm‐related genes (epsA, epsB, epsC, and tasA) and swarming‐related genes (swrA and swrB) were all down‐regulated. We also evaluated the impact on secondary metabolites of these two genes. The degQ and degU genes reduced surfactin and macrolactin production and up‐regulated the production of fengycin, iturin, bacillaene, and difficidin metabolites. The reverse transcription‐quantitative PCR results were consistent with these observations. Electrophoretic mobility shift assay and microscale thermophoresis revealed that DegU can bind to the promoter regions of these six antimicrobial metabolite genes and regulate their synthesis. In conclusion, we provided systematic evidence to demonstrate that the degQ and degU genes are important regulators of multicellular behaviour and antimicrobial metabolic processes in B. velezensis DMW1 and suggested novel amenable strains to be used for the industrial production of antimicrobial metabolites.

Strategies for improving fengycin production: a review

“…DegQ, a 46-amino acid protein coding for a pleiotropic regulator, can directly stimulate the autophosphorylation of DegS. The activated DegS-P then transfers the phosphoryl group to DegU, and the phosphorylated DegU-P can regulate the expression of related genes [ 8 , 81 ]. The knockout of comA resulted in a significant down-regulation of the expression of degU [ 80 ], indicating that ComA positively regulates the DegS-DegU two-component regulatory system.…”

“…It is hypothesized that this regulatory effect may be mediated by DegQ, since ComP-ComA positively regulates the expression of degQ [ 95 , 99 ]. Additionally, previous studies have shown that the yield of fengycin significantly decreased in strains with degU knockout [ 80 , 81 ], and the expression level of fenA was also down-regulated [ 81 ]. Da-Eun et al [ 82 ] substituted the “A” at position 32 of degU with a “T”, resulting in an approximately 2-fold increase in both the transcript level of pps gene cluster and their promoter activity, as well as a similar increase in the production of fengycin.…”

“…Similarly, Lilge et al [ 8 ] reported that the expression of degQ in B. subtilis JABs24 resulted in a six-fold increase in fengycin production, while the deletion of degQ in B. subtilis DSM10 T resulted in a five-fold decrease. In addition, the positive regulatory effect of degQ on the expression of fengycin synthase genes has also been proved by quantitative reverse transcription PCR [ 81 , 101 ]. Surprisingly, the introduction of sfp and degQ from different sources may lead to different types of plipastatin [ 102 ].…”

Research advances in the identification of regulatory mechanisms of surfactin production by Bacillus: a review

“…DegU owning typical helix-turn-helix DNA sequence-binding structures, has an ability to regulate the gene transcription by binding to the promoter regions through phosphorylated DegU (DegU-P) or unphosphorylated DegU [ 81 ]. DegU regulates bacillomycin D biosynthesis positively, and surfactin biosynthesis negatively [ 45 – 48 ]. In 2016, Mathieu et al [ 46 ] reported that the DegU-DegS system differentially regulates the “K-state” which is a growth-arrested state of cells induced by ComK regulon [ 82 ] in undomesticated wild and laboratory domesticated B. subtilis model strains.…”

Regulation, Biosynthesis, and Extraction of Bacillus-Derived Lipopeptides and Its Implications in Biological Control of Phytopathogens

“…DegU: The response regulator DegU is part of a two-component regulatory system. Phosphorylated DegU activates the transcription of genes involved in iturin biosynthesis, enhancing their expression [79].…”