L.N. Gumilyov Eurasian National University, a dissertation defense for the degree of Doctor of Philosophy (PhD) by Bakeshova Zhumabike on the topic «Effect of xenobiotics in water on the cleaning capacity of bacterioplankton» to the educational program «8D05208 – Ecology and nature management».
The dissertation was carried out at the «Management and Engineering in environmental protection education department» of L.N. Gumilyov Eurasian National University.
The language of defense is kazakh
Official reviewers:
Shorabayev Yeryk Zharylkasynovich – Candidate of Biological Sciences (PhD), Director of LLP «Industrial Microbiology» (Almaty, Republic of Kazakhstan);
Shamshedenova Samal Salamatovna – Doctor of Philosophy (PhD), Acting Associate Professor, Department of Ecology, Kh. Dosmukhamedov Atyrau University (Atyrau, Republic of Kazakhstan).
Temporary members of the Dissertation Council:
Bakhov Zhumabek Kubeevich – Doctor of Technical Sciences, Professor of the Department of Ecology, S. Seifullin Kazakh Agrotechnical University (Astana, Republic of Kazakhstan);
Zayadan Bolatkhan Kazykhanuly – Doctor of Biological Sciences, Professor of the Department of Biotechnology, Al-Farabi Kazakh National University (Almaty, Republic of Kazakhstan);
Popkova Anna Vladimirovna – Candidate of Biological Sciences, Associate Professor, Patris Lumumba Peoples' Friendship University of Russia (Moscow, Russian Federation).
Scientific consultants:
Akbayeva Lyailya Khamidullaevna – Candidate of Biological Sciences, acting Professor of the department «Management and Engineering in the Sphere of Environmental Protection» ENU named after L.N. Gumilyov (Astana, Republic of Kazakhstan);
Kuzmetov Abdulakhmet – doctor of biological sciences, professor, Kokand State University (Kokand, Republic of Uzbekistan).
The defense will take place on September 23, 2025, at 03:00 PM in the Dissertation Council for the training direction «8D052 – Environment» in the educational program «8D05208 – Ecology and nature management» of L.N. Gumilyov Eurasian National University. Conducting a meeting of the dissertation council in a mixed (offline and online) format.
Link: https://gclnk.com/fPxGBBQB
Address: Astana, st. Kazhymukhan, 13, Educational building No. 3, room. No. 333.
Abstract (English): Description of the research. The dissertation is devoted to identifying the distribution of substances toxic to aquatic microorganisms in water bodies subjected to anthropogenic pressure, as well as assessing the self-purification capacity of polluted reservoirs. Relevance of the dissertation research. In the areas surrounding industrial centers, large cities, and agricultural complexes, various pollutants accumulate in the environment under the influence of anthropogenic factors, notably heavy metals and pharmaceutical contaminants. Given the multi-component nature of these pollutants, comprehensive studies of their effects and the development of effective detection methods should be regarded as priority directions in environmental protection. Xenobiotics possess high ecotoxicological hazards and exert continuous long-term impacts on aquatic ecosystems due to their prolonged persistence in the natural environment. The majority of chemical pollutants degrade water quality, cause the death of aquatic organisms, and reduce the self-purification capacity of water bodies. Primarily, these include xenobiotics that affect microorganisms in aquatic ecosystems. Water bodies undergo eutrophication, and changes occur in the species composition of aquatic organisms. Such changes create favorable conditions for the excessive growth of pathogenic microflora in reservoirs. The self-purification of surface waters is a complex process involving many components of the aquatic ecosystem, among which bacterioplankton plays a key role. The main function of bacterioplankton is to detoxify pollutants entering the water body through their primary oxidation or reduction. Xenobiotics most harmful to water microorganisms include pharmaceutical compounds. Their presence in natural waters is insufficiently studied. Chemical-analytical methods for detecting pharmaceutical compounds cannot fully reflect the extent of microbiocenosis disruption in surface waters. Therefore, conducting large-scale monitoring of xenobiotics, including previously little-studied pharmaceutical compounds in water bodies, has become an urgent task. This requires not only determining the extent of their distribution but also a comprehensive assessment of their impact on aquatic biota, especially on the ecosystem’s self-purification potential. Such studies are a crucial component of ensuring ecological safety and effective management of water resources. Purpose of the study: Determination of the distribution of several substances toxic to aquatic microorganisms in water bodies subjected to anthropogenic pressure, as well as assessing the self-purification capacity of polluted reservoirs. Research objectives: 1.Study the impact of overall chemical pollution in natural water bodies on their self-purification capacity through microorganisms. 2.Conduct biotesting for the presence of antibiotics in several water bodies of the Akmola region located in zones potentially exposed to antimicrobial agents. 3.Characterize the sanitary-microbiological status of lakes subjected to high anthropogenic pressure (Zhaltyrkol and Big Taldykol lakes). 4.Identify the species of bacterioplankton involved in the self-purification of the water body. 5.Analyze the risks associated with the entry of antibiotics into aquatic ecosystems and their effects on biodiversity and ecological processes. 6.Propose strategies and technologies to reduce surface water contamination by xenobiotics. Objects of the research. 1. Water samples from the Ishim River and Big Taldykol Lake were used to determine the mass concentration of dissolved oxygen and biological oxygen demand (BOD). 2. For monitoring water bodies and detecting microorganism resistance to antibiotics, the experimental group included lakes located within the Akmola region near settlements, poultry farms, and intensive agriculture: Small Chebache, Big Shabakty, Kopa, Zhaltyrkol, Small Saryoba, Koygeldy, Zhalanash, Big Taldykol, Kumkol. The control group consisted of the following lakes: Big Saryoba, Zhangula, Esei, Kokay, Sultankeldy 3. Water samples from Big Taldykol and Zhaltyrkol lakes were used to assess microbiological and parasitological indicators. 4. Water samples from Big Taldykol Lake were used to identify species of microorganisms involved in the self-purification of water bodies. Research methods. 1. Method of hydrochemical analysis of natural waters. 2. Determination of biological oxygen demand (BOD) and mass concentration of dissolved oxygen. 3. Modified disk-diffusion method for determining microorganism resistance to antibiotics. 4. Methods for assessing sanitary-microbiological and parasitological water quality indicators. 5. Identification of bacterial species involved in the self-purification process of surface waters. The scientific novelty of the research. In a number of lakes in the Akmola region, antibiotic monitoring was conducted for the first time by determining the resistance of microorganisms to antibiotics using a modified version of the disk-diffusion method. For the first time, the impact of xenobiotics such as A-92 gasoline, the detergent “Fairy” containing surfactants, and the antibiotic “Ospamox 250 mg” on the self-purification capacity of water bodies was assessed based on the relationship between oxygen indicators — dissolved oxygen content and biological oxygen demand (BOD). A comprehensive analysis of ecotoxicological processes caused by antibiotic exposure was carried out for the first time, considering these processes as a system of interdependent biogeochemical connections within aquatic ecosystems. Also, for the first time, the use of the mineral colemanite as a sorbent for removing antibiotics from wastewater at treatment facilities was proposed. Practical significance of the research. The conducted study holds significant methodological value: the modified disk-diffusion method for determining microorganism resistance to antibiotics, applied in this work, can be used in the future to monitor antibiotic resistance of microorganisms in water bodies. The research results — scientific conclusions and practical recommendations — can be utilized in the ecological certification of water bodies in the Akmola region, as well as in decision-making related to the use and protection of water resources. The obtained data may be of interest to authorized agencies responsible for water resource management, healthcare, agriculture, environmental protection, and environmental engineering. Research principles recommended for defense: 1. In a comparative study of the degree of suppression of heterotrophic degradation in lake and river water, the most aggressive effect was observed from the antibiotic Ospamox 250 mg; moderate suppression of self-purification was noted under the influence of the detergent Fairy; gasoline was able to suppress self-purification only at relatively high concentrations: 1:9 ratio with water. 2. The following features can be distinguished in the distribution of microorganism resistance to antibiotics in the studied lakes of the Akmola region: Antibiotics for which no microbial resistance was found in the lakes include: enronit, furagin, cefuroxime, cefoperazone, and amikacin. Resistance is most frequently detected against antibiotics used simultaneously for humans and animals or only for animals. The level of microorganism resistance to antibiotics in natural waters can be classified into nine groups in descending order. 3. Although microorganism resistance to a range of antibiotics was detected in lakes Zhaltyrkol and Big Taldykol, the sanitary-epidemiological condition of Zhaltyrkol lake is assessed as satisfactory, while in Taldykol lake organoleptic indicators are mainly impaired. However, the presence of sulfite-reducing clostridia, a large number of ciliates (Ciliophora), rotifers (Rotatoria), gastrotrichs (Gastrotricha), and the dominance of diatom algae (Diatomeae) indicate eutrophication of the water body, a high risk of water blooming, and that allochthonous organic substances predominate in the organic pollution composition. 4. Representatives of heterotrophic microflora were isolated from water samples taken from Big Taldykol Lake. Forty-one bacterial isolates were obtained. The isolates were Gram-stained and underwent microscopic examination, allowing preliminary morphological and Gram-differential classification of microorganisms. Morphological analysis showed that the majority of isolated bacteria were Gram-negative forms typical of rod-shaped cells. To determine the taxonomic affiliation of bacterial isolates from Lake Big Taldykol, molecular genetic identification based on 16S rRNA gene sequence analysis was performed. According to the analysis, at the genus level, the predominant bacterial isolates were Serratia sp. — 13.2%; Pantoea sp. — 5.4%; Aeromonas sp. — 40%; Bacillus sp. — 18.4%; Shewanella sp. — 10.5%. 5. The hazards associated with antibiotics entering natural water bodies include: suppression of photosynthetic activity of microalgae, reduction in productivity of water bodies, weakening of zooplankton and benthic organisms, disruption of the endocrine system in fish and other hydrobionts, weakening of immune systems and physiological functions in waterfowl and mammals, destabilization of biogeochemical cycles, eutrophication, and deterioration of water quality indicators, among others. Moreover, the increase in microorganism resistance to antibiotics in natural waters poses both ecological and medical problems, since antibiotics from aquatic environments can enter terrestrial ecosystems, posing a threat to human health. 6. Based on the analysis of scientific and technical literature, strategies have been developed to reduce the risk of antibiotic pollution in natural waters and to combat the spread of microorganism resistance to antibiotics. These strategies include the following measures: monitoring the condition of natural waters, improving wastewater treatment technologies, regulating antibiotic use, developing alternative treatment methods, creating biodegradable antibiotics, controlling the use of antibiotics in medicine and veterinary medicine, educating the public, and legislative regulation. Authors' contribution. The analysis of literary data related to the problem under study, determination of the goals and objectives of the work, conducting field - practical research, processing and analysis of the results, writing the dissertation and registration of the signature were carried out with the personal participation of the author. Approbation of results of the research. The results of the research and the main provisions of the dissertation are presented and published in international and republican journals. 1. Journal of Ecological Engineering.–2024,–Vol. 25, Issue 6. –P. 99–108. 2. Eurasian Journal of Ecology–2024. -№2 (79). –P . 32–41. 3. Geography and water resources. –2025. –№1. –P. 78–87. 4. BULLETIN of the L.N. Gumilyov Eurasian National University. Chemistry. Geography. Ecology Series. –2025. –№2. –P. 211–236. Structure and scope of the dissertation: The dissertation consists of an introduction, definitions, designations and abbreviations, a review of the literature, materials and methods, the results of the author's own research, a conclusion, and an appendix. The volume of the dissertation is confirmed by 97 written pages, and 9 tables, 14 figures. The dissertation uses 175 references.
Conclusion of the Research Ethics Committee
Defense of the dissertation: https://www.youtube.com/watch?v=9yfE07uaQZg
