DISTRIBUTION OF ANTIBIOTIC RESISTANCE GENES IN THE ENVIRONMENT:
THE ROLE OF MINERAL FACILITATED HORIZONTAL GENE TRANSFER
Combining recent research across disciplines, I see evidence that minerals hold a high and unrecognized potential for enhancing the distribution of the ARg in the environment. Adsorption of ARg to minerals significantly increases the ARg’s lifetime and facilitates their distribution by sedimentary transport processes. In addition, minerals also serve as a) sites for horizontal gene transfer (HGT), b) platforms for microbial growth and, hence 3) act as hot spots for propagation of adsorbed ARg to other microbes. However, some minerals and ARg are bound more strongly than others and various bacteria have different affinities toward various minerals. Those variations in affinity are poorly quantified but vital for predicting the distribution of ARg in the environment.
Bacterial colony formation.
Image by Lisselotte Jauffred (collaborator from NBI)
The spread of antibiotic resistance genes (ARg) is a worldwide health risk1 and is no longer only a clinical issue. Vast reservoirs of ARg are found in natural environments2–4 such as soils, sediments and oceans. The emergence and release of ARg to the environment is in particular caused by extended use of antibiotics in farming, e.g. where the genes dissipate from the manure.5 Once in the environment, the ARg are surprisingly rapidly propagated. It is well known that the ARg are distributed to neighbour bacteria through processes of both cell sharing or through horizontal gene transfer (HGT) where one species acquirer resistance from another.6,7 Most HGT responsible for the spread of ARg are assumed to be through direct microbe-microbe contact. However, I find that the outcome of non-contact transfer is grossly underestimated. In the HGT mechanism called “Transformation”, free ARg in suspension or adsorbed to a mineral can be picked up and incorporated into non-related organisms. Considering that free DNA only can survive for a few weeks in sea- and freshwater environments,8–10 any HGT from free DNA can rightly be assumed to be local, but if the DNA gets adsorbed to a mineral, it can survive for several hundred thousands of years.11–14 If this also holds for ARg, then minerals offer a potent mechanism for distributing ARg through our environments my means of sedimentary processes.
RESISTANCE GENES
Issue
The propagation of antibiotic resistance genes (ARg) in our environment and resistant cancer clones in our bodies is a threat to human health. Even if current research and mitigation strategies apply evolutionary principles, we are still unable to decipher the mechanisms driving the fitness of resistant clones
View from across the disciplines of evolutionary geobiology
Horizontal gene transfer (HGT) of extracellular DNA preserved on surfaces have an unappreciated potential to influence evolution of prokaryotes and eukaryotes. The transfer of extrinsic DNA stored on surfaces remains poorly understood. We claim this understudied evolutionary pathway represents a missing link to understanding evolutionary processes at the root of modern challenges. We find that a strong understanding of how surface-facilitated HGT1 contributes to heritable variation, both in nature and within the body will advance our insight to how both bacterial and cancer therapy resistance arise and may be managed.
Line-up
We are addressing these questions using a synergy melding our perspectives, approaches, and individual expertise of the evolutionary geobiology consortium:
Importance of extracellular DNA for evolution, a missing link
The project is fonded by Novo Nordisk Fonden through their Exploratory Interdisciplinary Synergy Programme.
We will kick off in May 2024
Funding
Funding
