Pseudomonas fluorescens ompW: plasmid localization and requirement for naphthalene uptake

Area of Science:

• Microbiology
• Molecular Biology
• Environmental Science

Background:

• Pseudomonas fluorescens is a bacterium known for its metabolic versatility.
• Naphthalene and polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants that some microorganisms can degrade.
• Understanding the microbial mechanisms for hydrocarbon assimilation is crucial for bioremediation strategies.

Purpose of the Study:

• To identify genes differentially expressed in Pseudomonas fluorescens during growth on naphthalene.
• To investigate the role of specific genes, particularly those involved in transport, in naphthalene assimilation.
• To elucidate the genetic basis of naphthalene utilization in P. fluorescens.

Main Methods:

• Suppressive subtractive hybridization (SSH) was used to create a cDNA library of differentially expressed genes.
• Gene isolation, cloning, and sequencing were performed for candidate genes.
• Site-directed mutagenesis was employed to study gene function.

Main Results:

• The cDNA library was enriched in genes associated with cellular uptake and efflux systems, rather than known naphthalene catabolism genes.
• The OmpW gene, encoding a putative porin, was identified and localized to a catabolic plasmid.
• Mutation of the OmpW gene abolished the ability of P. fluorescens to grow on naphthalene and other PAHs.

Conclusions:

• The primary response of P. fluorescens to naphthalene involves upregulating cellular uptake and assimilation mechanisms.
• The OmpW porin plays a critical role in the transport of naphthalene and related compounds into the cell.
• Uptake systems, like OmpW, are essential for P. fluorescens to utilize naphthalene as a carbon source.