Nickel Promotes Biofilm Formation by Escherichia coli K-12 Strains That Produce Curli

Abstract

The survival of bacteria exposed to toxic compounds is a multifactorial phenomenon, involving well-known molecular mechanisms of resistance but also less-well-understood mechanisms of tolerance that need to be clarified. In particular, the contribution of biofilm formation to survival in the presence of toxic compounds, such as nickel, was investigated in this study. We found that a subinhibitory concentration of nickel leads Escherichia coli bacteria to change their lifestyle, developing biofilm structures rather than growing as freefloating cells. Interestingly, whereas nickel and magnesium both alter the global cell surface charge, only nickel promotes biofilm formation in our system. Genetic evidence indicates that biofilm formation induced by nickel is mediated by the transcriptional induction of the adhesive curli-encoding genes. Biofilm formation induced by nickel does not rely on efflux mechanisms using the RcnA pump, as these require a higher concentration of nickel to be activated. Our results demonstrate that the nickel-induced biofilm formation in E. coli is an adaptational process, occurring through a transcriptional effect on genes coding for adherence structures. The biofilm lifestyle is obviously a selective advantage in the presence of nickel, but the means by which it improves bacterial survival needs to be investigated.

Effects of Subinhibitory Concentrations of Menthol on Adaptation, Morphological, and Gene Expression Changes in Enterohemorrhagic Escherichia coli

“…The regulation of curli gene expression is extremely complex (14), and little attention has been given to the effect of adaptation to SI stress on curli production. An increase in curli formation has been reported in adaptation of Salmonella enterica serovar Typhimurium (10) and exposure to SI conditions of the E. coli K-12 strain (33). In contrast to those results, we found that adaptation to menthol reduces curli production.…”

Nickel, molybdenum, and tungsten nanoparticle-dispersed alkylalkoxysilane polymer for biomaterial coating: evaluation of effects on bacterial biofilm formation and biosafety

“…On the other hand, Ni NPs exist on the surface or in the free volume of AAS polymer that can permeate water [5], and therefore, more Ni ions will be leaked from the polymer compared with organic Ni compounds conjugated to the AAS polymer. Perrin et al reported that at a moderate concentration (100 µM), Ni enhanced biofilm formation of E. coli K-12, and at a high Ni concentration (>200 µM), cell growth was inhibited [18]. These results indicate that Ni concentration influences bacterial proliferation and biofilm formation.…”

Engineering Adherent Bacteria by Creating a Single Synthetic Curli Operon

“…Determine biofilm thickness by the analysis of the average z value along statistical longitudinal sections. Quantification of biofilm biovolumes can be extracted from confocal z-stacks as described elsewhere 22 . …”

“…Bacterial attachment to abiotic surfaces such as polystyrene and glass depends on the ionic strength or osmolarity of the medium. Best results are usually obtained in minimal medium or diluted LB 22,24 .…”