Role of bpfA in adhesion and biofilm formation of Shewanella putrefaciens CN32 under cold stress: a comprehensive transcriptomic analysis

As a specific spoilage organism of seafood under refrigerated temperature conditions, Shewanella spp. tend to form biofilms that exacerbate the occurrence of seafood spoilage. Biofilm-promoting factor A (BpfA) has been reported to promote the adhesion and biofilm formation of Shewanella spp., but its role in adhesion and biofilm formation of S. putrefaciens under cold stress needs to be further investigated. To better comprehend the effect of BpfA on adhesion and biofilm formation of S. putrefaciens under cold stress (4 ℃), bacterial adhesion and biofilm phenotype of S. putrefaciens CN32 WT and ΔbpfA at 4 ℃ were analyzed and performed transcriptomics. The results showed that the deletion of bpfA had almost no effect on the growth of S. putrefaciens CN32 at 4 ℃, but weakened the unicellular adhesion capacity of S. putrefaciens CN32 and destabilized the stability of the multicellular adhesion layer. In addition, the biomass of the mature biofilm formed by ΔbpfA was merely around 50% of that observed in the mature biofilm of S. putrefaciens CN32 WT, the average thickness and volume of the biofilm decreased by 18% and 27%, respectively, and the composition of the biofilm changed. Transcriptome analysis demonstrated that the deletion of bpfA led to differential expression of genes involved in metabolic pathways such as bacterial chemotaxis, two-component system, tyrosine metabolism, drug metabolism-other enzymes and biofilm formation-Vibrio cholerae, which in turn influenced bacterial adhesion and biofilm formation. Those results advance our acknowledgment of the character of BpfA on adhesion and biofilm formation of S. putrefaciens CN32, which contributes to understanding bacterial adhesion and the control of biofilm formation.