Document Type : Research Paper
Authors
1
Tashkent State Technical University, Tashkent, Republic of Uzbekistan
2
Tashkent State University of Economics, Tashkent, Republic of Uzbekistan
3
Gulistan State University, Republic of Uzbekistan
4
Department of Finance, Termez State University, Uzbekistan
5
Teacher of the Department of Fruits and Vegetables At the Urganch State University, Uzbekistan
6
Tashkent Institute of Irrigation and Agricultural Mechanization Engineers National Research University, Tashkent, Uzbekistan, & University of Tashkent for Applied Sciences, Str. Gavhar 1, Tashkent 100149, Uzbekistan & Western Caspian University, Scientific Researcher, Baku, Azerbaijan
7
International School of Finance and Technology, Tashkent region, Kibrai district, University street2, Tashkent, 111200, Uzbekistan
8
Associate Professor of Alfraganus University, Uzbekistan
9
Associate Professor of the Department of Electrical Technology and Operation of Electrical Equipment, PhD, Associate Professor, Tashkent Institute of Irrigation and Agricultural Mechanization Engineers National Research University, Uzbekistan
10.22124/cjes.2024.8062
Abstract
The Caspian Sea, Earth's largest enclosed inland water body, faces significant environmental challenges due to anthropogenic pollution. This study aimed to assess pollution levels in Caspian Sea sediments and evaluate the potential for microbial bioremediation. Sediment samples were collected from 15 sites along the Caspian coastline. Polycyclic aromatic hydrocarbons (PAHs) and heavy metals (lead and cadmium) were quantified using GC-MS and AAS, respectively. Microbial community analysis was performed through 16S rRNA gene sequencing. Native bacterial strains were isolated, characterized for their pollutant degradation capabilities, and tested in laboratory-scale bioremediation experiments. Total PAH concentrations ranged from 119.5 to 2032.7 μg/kg dry weight, while mean concentrations of lead and cadmium were 67.9 and 2.15 mg/kg, respectively. Microbial analysis revealed diverse communities dominated by Proteobacteria, with genera known for hydrocarbon degradation (e.g., Pseudomonas, Alcanivorax) showing strong positive correlations with contaminant levels. Isolated bacterial strains demonstrated remarkable PAH degradation (up to 87% for naphthalene) and heavy metal removal capabilities. In microcosm experiments, bacterial consortia achieved up to 89.7% PAH removal and 61.4% lead removal after 30 days. This study provides comprehensive insights into pollution status and microbial ecology in Caspian Sea sediments, revealing both significant contamination and remarkable potential for intrinsic bioremediation. The identified native bacterial strains and consortia offer promising avenues for developing tailored bioremediation strategies, although further field-scale trials are necessary to validate their effectiveness under real-world conditions.
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