Microcosm studies to evaluate microbial potential to degrade pollutants in soil and water ecosystems

Soil andwater microorganisms play an important role in maintaining ecosystem environmental quality. In fact, the ability of soil and water to recover from chemical contamination is primarily dependent on the presence of a microbial community with the ability to remove it. In this way, the microbial community represents an important key to understanding the impacts of environmental and anthropogenic factors on ecosystems. The presence of an abundant and varied microbial community is a necessary prerequisite for an immediate and effective response to the various natural and anthropic disturbances that can affect an ecosystem. Soil and water microcosm studies enable the studying, under controlled conditions, of the effects of selective pressures, such as xenobiotic occurrence on natural microbial communities. In this paper the main data (in terms of chemical persistence and bacterial abundance) of several microcosm degradation studies performed using natural soil and water were collected and discussed. The biotic and abiotic degradation of several contaminants (including the parent compounds of pesticides and pharmaceuticals and their metabolites) was evaluated comparing microbiologically active microcosms treated with the chemical with others previously sterilized. Moreover, in some cases additional microcosms were also used for evaluating the effect of some amendments (such as urea or wood amendments) on microbial degradation. The disappearance timeof 50% of the compound applied (DT50)was evaluated for each chemical in the presence/ absence of the natural microbial community in 19 microcosm experiments, performed using 16 different chemicals considered environmental contaminants. The overall results presented here show the key role of microorganisms in the degradation of all the chemicals studied and establish the relationship between degradation and the role of microbial communities in chemical disappearance fromthe environment, thus demonstrating the suitability of the of themicrocosmapproach for reproducing more realistic environmental exposure scenarios in the laboratory.