Soil bioremediation through flagellated bacteria: unravelling the mechanisms for enhancing bacterial tactic response

Bacterial dispersal is a key driver of pollutant turnover in contaminated soils.

Flagellated bacteria able to degrade organic pollutants hold tactic responses to a variety of stimuli and reach pollutant hotspots, enhancing the access to poorly bioavailable carbon sources by steepening pollutant concentration gradients at interfaces.

However, bacterial motility in porous media is often restricted due to high cell deposition rates and adhesion to soil particles, and in this sense, the modulating role of biological and chemical effectors is decisive.

The aim of BIOTAC is the study of the mechanisms operating with flagellated bacteria for bioavailability enhancements and, therefore, a faster turnover of persistent organic pollutants in soils, including polycyclic aromatic hydrocarbons and a pesticide, lindane.

We will study, at the microorganism scale, the role of bacterial taxis in chemical gradients (chemotaxis), as well as other tactic responses (repellence, surface taxis) in pollutant bioavailability, modelling and integrating them with other microbial adaptations (i.e. biofilm formation and the production of biosurfactants).

We will develop strategies to improve bacterial transport to pollutant sources, using carefully selected biological and chemical effectors (respectively including, mycelial networks and organic compounds -root exudates, humic acids, and fertilizers), that favour flagella-mediated taxis, and co-mobilization of immotile degrading strains.

The originality and innovation of the project lies on the macroscale projection of the microscale mechanisms underlying the access of self-propelled bacteria to limitedly available contaminants through an enhanced dispersal.

Through experimental and modelling approaches, aiming at balancing biosorption and colloidal transport of the pollutants against biodegradation rates, the project will perform a risk and benefit analysis of the new bioremediation technology.