Pharmaceuticals in the environment: biodegradation and effects on natural microbial communities. A review

Environmental microorganisms play a key role in fundamental ecological processes such as biogeochemical cycling and organic contaminant degradation. Microorganisms comprise a large unexplored reservoir of genetic diversity and metabolic capability providing several ecosystem services, most importantly the maintenance of soil and water quality. Pharmaceutical occurrence in the environment can compromise microbial community structure and activities in different ways. The fate of a pharmaceutical in soil or water depends on numerous factors, including its inherent physic-chemical properties (e.g. water solubility, lipophilicity, vapour pressure), environmental factors and climate conditions (e.g. temperature, incident radiation, pH) and most importantly the presence and activity of microorganisms that possess the ability to biodegrade it. The presence of a natural microbial community is a necessary prerequisite for an effective response to the various chemicals that can contaminate an ecosystem. The recovery from contamination is only possible if toxicity does not hamper microbial activity. This review presents current knowledge on the effects on natural microbial communities of some pharmaceuticals and of some biocides commonly found as environmental microcontaminants.