Genetic Bioaugmentation-Mediated Bioremediation of Terephthalate in Soil Microcosms Using an Engineered Environmental Plasmid.

Harnessing in situ microbial communities to clean-up polluted natural environments is a potentially efficient means of bioremediation, but often the necessary genes to breakdown pollutants are missing. Genetic bioaugmentation, whereby the required genes are delivered to resident bacteria via horizontal gene transfer, offers a promising solution to this problem. Here, we engineered a conjugative plasmid previously isolated from soil, pQBR57, to carry a synthetic set of genes allowing bacteria to consume terephthalate, a chemical component of plastics commonly released during their manufacture and breakdown.

Global genomic diversity of Pseudomonas aeruginosa in bronchiectasis.

Objectives: Pseudomonas aeruginosa is the most common pathogen in the bronchiectasis lung, associated with worsened outcomes. P. aeruginosa genomic studies in this context have been limited to single-country, European studies.

Ecological and evolutionary mechanisms driving within-patient emergence of antimicrobial resistance.

The ecological and evolutionary mechanisms of antimicrobial resistance (AMR) emergence within patients and how these vary across bacterial infections are poorly understood. Increasingly widespread use of pathogen genome sequencing in the clinic enables a deeper understanding of these processes. In this Review, we explore the clinical evidence to support four major mechanisms of within-patient AMR emergence in bacteria: spontaneous resistance mutations; in situ horizontal gene transfer of resistance genes; selection of pre-existing resistance; and immigration of resistant lineages.

The dilution effect limits plasmid horizontal transmission in multispecies bacterial communities.

By transferring ecologically important traits between species, plasmids drive genomic divergence and evolutionary innovation in their bacterial hosts. Bacterial communities are often diverse and contain multiple coexisting plasmids, but the dynamics of plasmids in multi-species communities are poorly understood. Here, we show, using experimental multi-species communities containing two plasmids, that bacterial diversity limits the horizontal transmission of plasmids due to the 'dilution effect'; this is an epidemiological phenomenon whereby living alongside less proficient host species reduces the expected infection risk for a focal host species.

Positive Selection Inhibits Plasmid Coexistence in Bacterial Genomes.

Plasmids play an important role in bacterial evolution by transferring niche-adaptive functional genes between lineages, thus driving genomic diversification. Bacterial genomes commonly contain multiple, coexisting plasmid replicons, which could fuel adaptation by increasing the range of gene functions available to selection and allowing their recombination. However, plasmid coexistence is difficult to explain because the acquisition of plasmids typically incurs high fitness costs for the host cell.