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.
The concept of one-health recognizes the interconnection between people, animals, plants, and their shared environment. The term medical geobiology covers the interactions between life and sedimentary systems and their implications for life and health of humans, organisms, ecosystems and our planet.
I have made my way in this field studying a broad range of scientific disciplines and using a multi-scale experimental approaches. Here I provide a visual context of how molecule-mineral interactions are important for a wide range of medical health aspects
Mineralization inside cells
implications for:
Cell health and stability
Minerals are essential for life, but how do single celled organism create intricate mineral structures beyond human capabilities? Our studies using a 60 Ma extracted polysaccharide show pH, cations and ionic strength are important tools.
Influence of life on the rock record.
implications for:
Drug delivery and fouling
Origin of life had a large impact on the geologic world. Our studies provides a mechanistic understanding for the changed rock record and how biopolymers influence mineralsation.
Biomimicry
implications for
Intracellular mineralisation
Organisms manage to create functional hard part at very low temperatures and using a very limited range of building blocks. We have much to learn from their sustainable approaches
Origin of life
implications for:
Assembly and drug delivery
Mineral surfaces hold the capability of up concentrating building blocks for life. We studied free energy of binding and show the how mineralogy play a large role for polymer binding.
Biofilm formation and propagation of antibiotic resistance
implications for:
Fouling and mitigation
The interfacial geochemistry between different minerals and bacteria play a large role for which surfaces enhance biofilm formation and also how fast genes can propagate in the biofilm
Preserving life
implications for:
interpretations of ecosystem health
DNA and proteins can be preserved across time and space on mineral surfaces. We show that the preferential interactions between the components of the molecules and different mineral surface influence preservation and their recovery.
Evolution of life
implications for
Evolutionary pathways
DNA preserved on mineral surfaces provide an unrecognized pathway for the evolution of life. We show that past genes can be reoccur and get incorporated into bacteria.
Resistance of Cancer and antibiotics
implications for:
Cancer treatment and ARg mitigation
Extracellular DNA poses an unrecognized pathway for evolution of antibiotic resistance genes and of cancer resistance. We are addressing how stored DNA can reoccur in contemporary cells