Flagellar Motility Is Critical for Salmonella enterica Serovar Typhimurium Biofilm Development

Abstract

The food-borne pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) causes self-limiting gastroenteritis in humans and is not easily eradicated because it often attaches to suitable surfaces to form biofilms that have high resistance to disinfectants and antimicrobials. To develop an alternative strategy for the treatment of biofilms, it is necessary to further explore the effects of flagellar motility on the development process of Salmonella biofilms. Here, we constructed flagella mutants (flgE and fliC) to systematically study this process. By comparing them with wild-type strains, we found that these mutants lacking flagellar motility form fewer biofilms in the early stage, and the formed mature biofilms contain more cells and extracellular polymeric substances (EPS). In addition, fewer mutant cells adhered to glass plates compared with wild-type cells even after 6 h of incubation, suggesting that flagellar motility plays a significant role in preliminary cell-surface interactions. More importantly, the motility of wild-type strain was greatly decreased when they were treated with carbonyl cyanide m-chlorophenylhydrazone, which inhibited flagellar motility and reduced biofilm formation, as in the case of the flgE mutant. Overall, these findings suggest that flagellar motility plays an important role in Salmonella biofilm initiation and maturation, which can help us to counteract the mechanisms involved in biofilm formation and to develop more rational control strategies.

Massively parallel transposon mutagenesis identifies temporally essential genes for biofilm formation in Escherichia coli

“…The relationship between motility and biofilm formation is complex. Although it is widely understood that motility is crucial for initial adhesion [55, 56], there is also an inverse relationship between motility and expression of matrix components; when biofilm matrix production is induced, motility is repressed in a motile-to-sessile lifestyle transition [66, 70, 71]. We found that insertional inactivation of negative motility regulators lrhA and hdfR improved biofilm fitness according to the TraDIS- Xpress data.…”

“…No mutants in flgD and fliE , encoding flagellar filament proteins, were identified at 24 and 48 h, respectively. It has previously been shown that motility is important for initial biofilm formation [55, 56], but this may not relate to biomass formation where no differences were seen for Δ flhD , Δ flhC , Δ fliE and Δ flgD mutants.…”

Massively parallel transposon mutagenesis identifies temporally essential genes for biofilm formation inEscherichia coli

“…The relationship between motility and biofilm formation is complex. Although it is widely understood that motility is crucial for biofilm formation 52,53 , it is also true that motility and curli production have an inverse relationship, where biofilm matrix production is induced and motility is repressed for a motile-to-sessile lifestyle transition 67,77,80 . We found that although insertional inactivation of negative motility regulators lrhA and hdfR improved biofilm fitness according to the TraDIS- Xpress data, a Δ hdfR deletion mutant had reduced biofilm biomass, and deletion of either lrhA or hdfR impaired cell aggregation.…”

“…The relationship between motility and biofilm formation is complex. Although it is widely understood that motility is crucial for biofilm formation 47,48 , it is also true that motility and curli production have an inverse relationship, where csgD directly represses fliE 69 and induces c-di-GMP synthesis through adrA, which reduces motility through ycgR [70][71][72] . This is often referred to as a lifestyle 'switch', where biofilm matrix production represses motility for a motile-to-sessile lifestyle transition 73 .…”

“…Curli biosynthesis became important by the 24 hour time point as no insertions mapped to csgC, encoding a curli subunit chaperone 46 identified at 24 and 48 hours, respectively. It has previously been shown that motility is important for initial biofilm formation 48,49 , but this may not relate to biomass formation where no differences were seen for ΔflhD, ΔflhC, ΔfliE and ΔflgD mutants.…”