Enrichment of bacterial communities for the bioremediation of soil contaminated with BTEX and CAH

Environmental pollution by volatile organic compounds (VOC) poses serious risks to the integrity of the environment. When ecosystems are compromised by pollution, they lose their ability to provide ecosystem services, creating cascading effects that affect the availability of resources and the ability to regulate chemical cycles and physical phenomena. This is why the degradation of the environment can undermine the stability of human society. This thesis focuses on the enrichment of microbial cultures that are capable of degrading BTEX and chlorinated solvents (PCE, TCA, TCE), to be used for in-situ bioremediation of an industrial site that presents these types of pollutants. The process involved the use of the contaminated environmental matrix (soil and groundwater) as a source of bacterial species, within the initial pool of species have been selected the ones capable of degrading the pollutants using the presence of the target compound as selective pressure. The enrichment of the cultures involved multiple generations of enrichments that progressively became more able to use the pollutants as carbon and energy sources. The final purpose of the enrichments is to be released back into the contaminated environment to degrade the target pollutants. These experiments are conceived within the European research project NYMPHE, which aims at cleaning up contaminated land with the use of biological solutions to restore a functioning ecosystem and gain back the services that it can provide. The results showed the ability of the native bacterial population to degrade BTEX compounds in aerobic conditions. Three generations were developed for ethylbenzene and toluene, and one generation was created for benzene and xylene. The biodegradation rates calculated from the cultures are 64 mgl-1day-1 for benzene, 118 mgl-1day-1 for toluene, 69 mgl-1day-1 for ethylbenzene and 19 mgl-1day-1 for xylene. The biodegradation rates resulting can be considered promising.