DegQ regulates the production of fengycins and biofilm formation of the biocontrol agent Bacillus subtilis NCD-2

Abstract

Bacillus subtilis NCD-2 is an excellent biocontrol agent for tomato gray mold and cotton soil-borne diseases. The fengycin lipopeptides serve as a major role in its biocontrol ability. A previous study revealed that insertion of degQ with the mini-Tn10 transposon decreased the antifungal activity of strain NCD-2 against the growth of Botrytis cinerea. To clarify the regulation of degQ on the production of fengycin, we deleted degQ by in-frame mutagenesis. Compared with the wild-type strain NCD-2, the degQ-null mutant had decreased extracellular protease and cellulase activities as well as antifungal ability against the growth of B. cinerea in vitro. The lipopeptides from the degQ-null mutant also had significantly decreased antifungal activity against B. cinerea in vitro and in vivo. This result was confirmed by the decreased fengycin production in the degQ-null mutant that was detected by fast protein liquid chromatography analysis. Quantitative reverse transcription PCR further demonstrated that degQ positively regulated the expression of the fengycin synthetase gene. In addition, the degQ-null mutant also had a flatter colony phenotype and significantly decreased biofilm formation ability relative to the wild-type strain. All of those characteristics from degQ-null mutant could be restored to the strain NCD-2 wild-type level by complementation of intact degQ in the mutant. Therefore, DegQ may be an important regulator of fengycin production and biofilm formation in B. subtilis NCD-2.

Effect of fructose on promoting fengycin biosynthesis inBacillus amyloliquefaciensfmb-60

“…Previous studies have suggested that DegQ can enhance the production of fengycin (Wang et al . ). Moreover, the expression of degQ is regulated by ComA and DegU, and upstream from promoter regions of degQ are two target sites for ComA and DegU (Msadek et al .…”

Stimulation of Fengycin-Type Antifungal Lipopeptides in Bacillus amyloliquefaciens in the Presence of the Maize Fungal Pathogen Rhizomucor variabilis

“…This is to our knowledge the first report on fengycin inhibitory activity toward that particular pathogen with a quite low MIC in the μM range. Fengycins were already described for their inhibitory effect on a range of phytopathogenic fungi such as Podosphaera fusca (Romero et al, 2007), Botrytis cinerea (Touré et al, 2004) and various Fusarium species (Hanene et al, 2012; Wang et al, 2015). Fengycins thus acts at low concentrations against several fungi but the molecular mechanisms explaining this antifungal activity are still unclear and may vary according to the pathogen target.…”

Fungal-bacterial interaction selects for quorum sensing mutants and a metabolic shift towards the production of natural antifungal compounds

“…But, how could mutations in comQXPA genes explain the reduction in the production of plipastatin also observed in the post-ST variants? ComQXPA system has also been described to be involved in the transcription of the pleiotropic regulator DegQ, which controls the production of degradative enzymes and is necessary for plipastatin production (21, 48, 49). Thus, we hypothesize that the reduction in plipastatin might represent an indirect effect of the mutations in comA and comP genes through alteration in degQ expression.…”