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Functional Structure of Microbial Communities – Mechanism for Management of Biotransformation Processes in the Sediments
Abstract
A key factor for realization of the self-purification potential in the hydroecosystems is the functioning of microbial communities. Their flexible metabolism is in the base of the biotransformation processes of the organics and nutrients. The functional diversity can play the role of an indicative mechanism and its adequate elucidation presents an effective mechanism for management of the biotransformation processes in the sediments.
In nowdays an important ecological problem in the middle part of Iskar River are the accumulated sediments in the reservoirs at the functioning of small hydroelectric power plants (HEPP) Lakatnik and Svrazhen. This part of Iskar River is located in the heavily urbanized area. There are not wastewater treatment plants of the villages in the region and a lot of industrial and municipal pollutants have been accumulated in the river sediments. After the building and functioning of the HEPP the essential part of the pollutants has been concentrated in the bottom sediments of the HEPP reservoir and they became “hot ecological points”.
The present work is focused on the investigation of the functional structure of the microbial communities and their role in the biotransformation processes as well as on the possible correlative connection between microbiological, enzymological or chemical indicators. In the experiments the key functional and taxonomic bacterial groups – g. Pseudomonas, g. Acinetobacter, Endo-bacteria, sulfate-reducing bacteria have been studied.
It has been approved that in the anoxic and anaerobic conditions in the sediments the processes of denitrification, ammonification and sulfate reduction have been realized. These processes are a natural, highly effective mechanism in the base of self-purificaion ability of the sediments water ecosystem.
... Therefore, an understanding of the functional structure of the microbial community would contribute to the better understanding of this potential. The study of the groups of microorganisms that are present, through separation that is based on a specific physiological process, would contribute to the study of the details of the bio-transformation processes [10,11]. An example in which the self-purification biotransformation processes that occur in river sediments can be studied in detail is the case of the cascade "Middle Iskar", which includes five small hydro power plants (SHPPs) on the middle stream of the Iskar River in the region of the villages Rebrovo and Gabrovnitsa in Bulgaria. ...
The pollution of aquatic ecosystems is a big problem that has its impact on river sediments. In recent decades, an effective solution to this problem has been the application of bioremediation technologies. Nanoremediation is an innovative part of these technologies. We still know little about the efficiency of nanoparticles, especially nanodiamonds, in modelled conditions. The aim of the present study is to investigate the effect of nanodiamonds on the key parameters of modelled bioremediation of river sediments that are polluted with phenol, as well their effect on the structures and functions of microbial communities. An important indicative mechanism that was used is the application of fluorescent in situ hybridization for sediment microbial communities. The results of this study revealed the positive role of nanodiamonds that is associated with their intoxication with high concentrations of phenol. Readaptation was also found, in which the xenobiotic biodegradation potential evolved by increasing the relative proportions of non-culturable bacteria, namely Acinetobacter (at the 144th hour) and Pseudomonas (at the 214th hour). The results can help to find an effective solution to the question of how information from such precise molecular methods and the application of nanodiamonds can be translated into the accessible language of management and bioremediation technologies.
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