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Investigating the genetic basis of preservative resistance in an industrial Pseudomonas aeruginosa strain

Green, Angharad 2017. Investigating the genetic basis of preservative resistance in an industrial Pseudomonas aeruginosa strain. PhD Thesis, Cardiff University.
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Pseudomonas aeruginosa is a common industrial contaminant associated with costly recalls of home and personal care(HPC) products. Preservation systems are used to prevent bacterial contamination and protect consumers, but little is known about the mechanisms of preservative resistance in P. aeruginosa. The aim of this research was to map genetic and metabolic pathways associated with preservative resistance and bacterial growth in HPC products. The genome of the industrial strain P. aeruginosa RW109 was sequenced, functionally annotated, and compared to other strains of the species. This revealed the first complete genome of a P. aeruginosa isolate from the HPC industry. Comparative analysis with 102 P. aeruginosa strains from various sources, showed industrial strains’ genomes to be significantly larger than clinical and environmental strains and RW109’s genome was the largest of the species (7.8 Mbp) and included two plasmids. Identification of differentially expressed genes by RNA-Seq (more informative than mini-Tn5-luxCDABE mutagenesis), revealed complex genetic networks utilised by RW109 when exposed to benzisothiazolone(BIT), phenoxyethanol (POE) and a laundry detergent formulation. Differential expression of five sets of genes was consistently observed in response to these industry relevant conditions - MexPQ-OpmE efflux pump, sialic acid transporter and isoprenoid biosynthesis (gnyRDBHAL) genes were frequently upregulated; whereas phnBA and pqsEDCBA genes encoding PQS production and quorum-sensing, respectively, were consistently down-regulated. Genome-scale metabolic network reconstruction of RW109, the first with a P. aeruginosa industrial strain, along with integration of transcriptomic data, predicted essential pathways for RW109’s preservative resistance (e.g. cell membrane phospholipid biosynthesis as a key pathway for POE resistance). This study highlights the utility of integrating genomic, transcriptomic and metabolic modelling approaches to uncover the basis of industrial bacterial resistance to preservative and product formulations. The ability to predict the metabolic basis of P. aeruginosa preservative resistance will inform the development of targeted industrial preservation systems, enhancing product safety and minimising future resistance development.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Biosciences
Subjects: Q Science > QR Microbiology
Uncontrolled Keywords: Pseudomonas aeruginosa; Preservatives; Industry; Antimicrobial Resistance; RNA-Seq; Whole genome Sequencing; RNA-Seq; Metabolic Modelling
Funders: Biotechnology and Biological Sciences Research Council (BBSRC), Unilever Safety and Environment Assurance Centre (SEAC)
Date of First Compliant Deposit: 16 January 2018
Date of Acceptance: 7 December 2017
Last Modified: 28 Jun 2019 03:21

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