The Transcription Factor CsgD Contributes to Engineered Resistance by Regulating Biofilm Formation and Stress Responses.

The high cell density, immobilization and stability of biofilms are ideal characteristics for bacteria in resisting antibiotic therapy. CsgD is a transcription activating factor that regulates the synthesis of curly fimbriae and cellulose in , thereby enhancing bacterial adhesion and promoting biofilm formation. To investigate the role of CsgD in biofilm formation and stress resistance in bacteria, the D deletion mutant ΔD was successfully constructed from the engineered strain BL21(DE3) using the CRISPR/Cas9 gene-editing system. The results demonstrated that the biofilm of ΔD decreased by 70.07% ( < 0.05). Additionally, the mobility and adhesion of ΔD were inhibited due to the decrease in curly fimbriae and extracellular polymeric substances. Furthermore, ΔD exhibited a significantly decreased resistance to acid, alkali and osmotic stress conditions ( < 0.05). RNA-Seq results revealed 491 differentially expressed genes between the parent strain and ΔD, with enrichment primarily observed in metabolism-related processes as well as cell membrane structure and catalytic activity categories. Moreover, CsgD influenced the expression of biofilm and stress response genes A, B, A, C, P, A, C, E and B, indicating that the CsgD participated in the resistance of by regulating the expression of biofilm and stress response. In brief, the transcription factor CsgD plays a key role in the stress resistance of , and is a potential target for treating and controlling biofilm.