Lateral gene transfer, bacterial genome evolution, and the Anthropocene

Abstract

Lateral gene transfer (LGT) has significantly influenced bacterial evolution since the origins of life. It helped bacteria generate flexible, mosaic genomes and enables individual cells to rapidly acquire adaptive phenotypes. In turn, this allowed bacteria to mount strong defenses against human attempts to control their growth. The widespread dissemination of genes conferring resistance to antimicrobial agents has precipitated a crisis for modern medicine. Our actions can promote increased rates of LGT and also provide selective forces to fix such events in bacterial populations. For instance, the use of selective agents induces the bacterial SOS response, which stimulates LGT. We create hotspots for lateral transfer, such as wastewater systems, hospitals, and animal production facilities. Conduits of gene transfer between humans and animals ensure rapid dissemination of recent transfer events, as does modern transport and globalization. As resistance to antibacterial compounds becomes universal, there is likely to be increasing selection pressure for phenotypes with adverse consequences for human welfare, such as enhanced virulence, pathogenicity, and transmission. Improved understanding of the ecology of LGT could help us devise strategies to control this fundamental evolutionary process.

Horizontal gene transfer to a defensive symbiont with a reduced genome amongst a multipartite beetle microbiome

“…Most genes appear to have been obtained from gammaproteobacteria and alphaproteobacteria, with a small number from firmicutes, cyanobacteria and phages (see Dataset S1H). The distribution is consistent with the notion that horizontal transfer occurs most frequently between closely-related species (Gillings, 2017). In particular, Burkholderiaceae was the most frequent apparent donor amongst gammaproteobacterial proteins.…”

Antimicrobial Resistance on Farms: A Review Including Biosecurity and the Potential Role of Disinfectants in Resistance Selection

“…Spread of resistance. One effect of antimicrobial drug use on farms may be the increased spread of mobile AMR genes by mechanisms (probably including global stress responses) that enhance the frequency of conjugative transfer between bacteria (Gillings, 2016). Such effects differ between antimicrobial drugs, and also occur with sublethal exposure to certain disinfectants (Jutkina, Marathe, Flach, & Larsson, 2018).…”

Potential impacts of horizontal gene transfer on human health and physiology and how anthropogenic activity can affect it

“…In addition, recycled water used for irrigation carries free naked DNA that can also be a source of antibiotic resistant genes available for the resident microbial community. For these reasons, the potential threat in relation to human health of HGT in these and other human affected environments, such as soils in the neighborhood of pollutant industries or clinical waste systems, is just beginning to be considered .…”

“…in the neighborhood of pollutant industries or clinical waste systems, is just beginning to be considered [54,55]. In managed environments, HGT can be affected by anthropogenic activities in three ways [55]: (a) by the creation of new ecological niches such as biofilms where gene transfers between different organisms can be favored; (b) by the introduction of selective pressures (antibiotic abuse) that allow the maintenance of transferred genes; and (c) by acting over HGT mechanisms through compounds such as pollutants that could modulate the frequency of transfers via the host SOS response, being the last one the most sensitive to an experimental approach.…”