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.
Anchoring of bacteria to substrates and subsequent formation of biofilms has a vital role to play for survival of the bacteria. In addition the bacteria can influences the chemistry of their near surroundings, they can facilitate recrystalization/dissolution of minerals through electron transfer or pH gradients, serve as mineral nucleation sites for mineral growth and they have a large impact on element cycling in our environments.
In collaboration with the Jauffred lab (Biocomplexity and Biophysics, NBI), the Posth lab, (Section of Geology, IGN) and and the Burmølle lab, (Section of Microbiology, KU) we are exploring the binding strength between different strands of bacteria and mineral surfaces as well as microplastics.
Bacterial colony formation.
By Lisselotte Jauffred (NBI collaborator)
SEM image of bacterial colony formation on an iron oxides aggregate
We are combining microbiological top down techniques with bond and bulk level bottom up approaches
Stay tuned for progress
(Check the SUBPROJECT below).
I am looking for students with knowledge of
geology, chemistry or microbiology
to look into different aspects of mineral-DNA-microbial binding.
You will be trained in atomic force spectroscopy and how to handle DNA and taught how to study interactions and dynamics at mineral surfaces.
Send an informal email for for more info: email@example.com