Abstract
Pseudomonas aeruginosa is a ubiquitous gram-negative bacterium capable of forming a biofilm on living and non-living surfaces, which frequently leads to undesirable consequences. We found that lauroyl arginate ethyl (LAE), a synthetic non-oxidizing biocide, inhibited biofilm formation by P. aeruginosa at a sub-growth inhibitory concentration under both static and flow conditions. A global transcriptome analysis was conducted using a gene chip microarray to identify the genes targeted by LAE. In response to LAE treatment, P. aeruginosa cells up-regulated iron acquisition and signaling genes and down-regulated iron storage genes. LAE demonstrated the capacity to chelate iron in an experiment in which free LAE molecules were measured by increasing the ratio of iron to LAE. Furthermore, compared to untreated cells, P. aeruginosa cells treated with LAE exhibited enhanced twitching motility, a phenotype that is usually evident when the cells are starved for iron. Taken together, these results imply that LAE generated iron-limiting conditions, and in turn, blocked iron signals necessary for P. aeruginosa biofilm development. As destroying or blocking signals leading to biofilm development would be an efficient way to mitigate problematic biofilms, our findings suggest that LAE can aid in reducing P. aeruginosa biofilms for therapeutic and industrial purposes.
Highlights
Pseudomonas aeruginosa is an opportunistic pathogen of various plants and animals (Stover et al, 2000; He et al, 2004)
P. aeruginosa biofilm formation was investigated in borosilicate bottles under static conditions under the sub-growth inhibitory conditions at lauroyl arginate ethyl (LAE) (10, 50, and 100 μM)
Excess ferrous iron is bound to a Fur protein and regulates the genes involved in iron acquisition, biofilm formation, synthesis of small RNAs, etc., directly or via extracytoplasmic sigma factors (ECF σ factors) or other regulators (Cornelis et al, 2009)
Summary
Pseudomonas aeruginosa is an opportunistic pathogen of various plants and animals (Stover et al, 2000; He et al, 2004). P. aeruginosa can contaminate medical devices such as catheters and joint. LAE Inhibits Biofilm Development prostheses, which can lead to serious medical complications (Weinstein and Darouiche, 2001). It is difficult to appropriately treat these infections or contamination by P. aeruginosa (Percival et al, 2015), mainly because P. aeruginosa can form a biofilm on both inert and living surfaces (Costerton et al, 1999). A biofilm is a surface-attached microbial community embedded in a self-produced hydrated polymeric matrix. Because the diffusion of antibiotics or biocides into cells across the polymeric matrix is retarded by a biofilm and biofilm cells grow slowly, biofilm cells are more resistant to antimicrobial agents than the corresponding planktonic cells (Costerton et al, 1999)
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