The consistent differential expression of genetic pathways following exposure of an industrial Pseudomonas aeruginosa strain to preservatives and a laundry detergent formulation.

Angharad E Green,Matthew J Bull,Thomas R Connor,Eshwar Mahenthiralingam,Alejandro Amézquita,Yvan Le Marc

doi:10.1093/femsle/fny062

Abstract

Pseudomonas aeruginosa is a common contaminant associated with product recalls in the home and personal care industry. Preservation systems are used to prevent spoilage and protect consumers, but greater knowledge is needed of preservative resistance mechanisms used by P. aeruginosa contaminants. We aimed to identify genetic pathways associated with preservative exposure by using an industrial P. aeruginosa strain and implementing RNA-Seq to understand gene expression changes in response to industry relevant conditions. The consistent differential expression of five genetic pathways during exposure to multiple industrial growth conditions associated with benzisothiazolone (BIT) and phenoxyethanol (POE) preservatives, and a laundry detergent (LD) formulation, was observed. A MexPQ-OpmE Resistance Nodulation Division efflux pump system was commonly upregulated in response to POE, a combination of BIT and POE, and LD together with BIT. In response to all industry conditions, a putative sialic acid transporter and isoprenoid biosynthesis gnyRDBHAL operon demonstrated consistent upregulation. Two operons phnBA and pqsEDCBA involved in Pseudomonas quinolone signaling production and quorum-sensing were also consistently downregulated during exposure to all the industry conditions. The ability to identify consistently differentially expressed genetic pathways in P. aeruginosa can inform the development of future targeted preservation systems that maintain product safety and minimise resistance development.

Highlights

The opportunistic pathogen Pseudomonas aeruginosa demonstrates pro ciency at surviving in environments with minimal nutritional levels (Favero et al 1971), exhibits multiple metabolic capabilities (Stanier, Palleroni and Doudoroff 1966) and has a genome size range of ∼5.2–7.0 Mbp (Stover et al 2000)
There is an incomplete understanding of strains isolated from the natural environment and much less is known about isolates that are successful contaminants of non-sterile cosmetic and household products (Jimenez 2007)
P. aeruginosa has been found in cosmetics (Tan, Tuysuz and Otuk 2013), shampoo products (Neza and Centini 2016), contact lens solutions and eye cosmetic products, where it has been reported to cause a number of infections of the eye and surrounding tissues (Reid and Wood 1979; Blumenfeld et al 2005)

Summary

Introduction

The opportunistic pathogen Pseudomonas aeruginosa demonstrates pro ciency at surviving in environments with minimal nutritional levels (Favero et al 1971), exhibits multiple metabolic capabilities (Stanier, Palleroni and Doudoroff 1966) and has a genome size range of ∼5.2–7.0 Mbp (Stover et al 2000) These key attributes allow the microorganism to grow and proliferate within a variety of environments. P. aeruginosa has been found in cosmetics (Tan, Tuysuz and Otuk 2013), shampoo products (Neza and Centini 2016), contact lens solutions and eye cosmetic products, where it has been reported to cause a number of infections of the eye and surrounding tissues (Reid and Wood 1979; Blumenfeld et al 2005) This highlights the requirement to minimise the occurrence of HPC product contamination with this pathogen through the improvement of manufacturing practices, and with enhanced product preservation systems. The proposed mechanism of action of POE is the disruption of bacterial cell membranes, cell lysis and leakage of cellular protein material (Gilbert, Beveridge and Crone 1977; Fitzgerald, Davies and Russell 1992)

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