About this Research Topic
The intensive use of pesticides, antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs) and other chemicals, their disposal and consequent presence in various environments are of great concern regarding their ecotoxicological effect on the organisms of different trophic levels. Such widespread use results in an increased concentration of these compounds in water, sediments and soils. Organic pollutants undergo many different pathways once they enter the environment, including transformation/degradation, sorption-desorption, volatilization, uptake by plants, runoff into surface waters and transport into groundwater. Transformation or degradation is one of the key processes that governs the environmental fate and transport of organic pollutants, which also comprises different processes including abiotic degradation and biodegradation. During these processes, organic pollutants are transformed into the degradation products or are completely mineralized to a carbon field. Although abiotic degradation plays a role in many cases, the biodegradation of chemicals by microorganisms is usually the most important and dominant process.
The increasing awareness of the risks to humans related to organic pollutants has forced us to limit their application, to design new, more environmentally-friendly agricultural chemicals, and to develop effective strategies, including biological technologies to clean up environments contaminated with persistent organic pollutants. Among the biological approaches, which include attenuation, biostimulation and bioaugmentation, the last one seems to be the most promising for the removal of organic pollutants and their residues from environment. Bioaugmentation belongs to the green technologies that are used to remove organic contaminants from environments. It is the compelling method of engineered bioremediation, based on the inoculation of given environments (e.g. soil, activated sludge, sediments, water, etc.) with microorganisms characterized with desired catalytic capabilities. Bioaugmentation is mainly recommended for sites where the number of autochthonous microorganisms that enable contaminants to be degraded is insufficient and/or those in which native populations do not have the catabolic pathways necessary to metabolize pollutants. Bioaugmentation relies on the enhancement of the catabolic potential of soil microbial communities for the degradation of pollutants. This goal may be achieved by soil inoculation with selected single strains of bacteria and/or fungi or their consortia with desired catabolic capabilities. Moreover, genetically engineered microorganisms (GEMs), which exhibit an enhanced ability to degrade a wide range of toxic pollutants, also have the potential for bioaugmentation. The selection of the appropriate strains for bioaugmentation should take into consideration the following features of microorganisms: a high potential for contaminant degradation, fast growth, ease of cultivation, the ability to withstand high concentrations of pollutants and to survive in a wide range of environmental conditions. However, the behavior of inoculants as well as changes in the structure and activity of microbial communities during bioremediation processes are still little known. Molecular methods offer the possibility of monitoring the fate and abundance of inoculants as well as the expression of genes encoding enzymes involved in the degradation of toxic pollutants.
This Research Topic welcomes researchers all over the world to contribute with original articles, as well as reviews addressing the latest knowledge about subjects such as:
- the microorganisms degrading organic pollutants such as pesticides, antibiotics, NSAIDs, hydrocarbons etc.,
- the degradation pathways of pollutants,
- the enzymes that are involved in the cleavage of pollutant molecules,
- the pot and field experiments on bioremediation of contaminated sites by inoculating of degrading microorganisms,
- the factors/conditions that influence the rate of the removal of pollutants and survival of microorganisms,
- the ecological behavior of inoculated degrading microorganisms including their survival dynamics and the interaction with indigenous microorganisms (the impact on the structure and activity of microbial communities)
- the use of molecular tools for monitoring the changes in microbial communities during bioremediation processes
- the specific markers for studying the fate and activity of introduced microorganisms involved in the degradation of organic pollutants
- the use of the combination of detection techniques for monitoring the survivability of inoculants
- the use of biosurfactant-producing microorganisms in bioaugmentation processes and perspectives in bioremediation of contaminated environments.
Keywords: organic pollutants, environmental contamination, microbial degradation, degradation pathways of contaminants, bioremediation of environment, bioaugmentation, behavior of inoculated microorganisms, biotic and abiotic factors
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