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10 a.m. Video conference
Doctoral thesis defense
Title: “Analysis and impact of antibiotics in marine organisms. Laboratory experiments and field studies”
In charge of: Albert Serra Compte
Directors Prof. Damià Barceló, Dr. Sara Rodriguez-Mozaz, Dr. Diana Alvarez
Day and time: 26/03/2021 at 10:00 AM
Summary:
Antibiotic residues have been detected in the aquatic environment worldwide including rivers, lakes, groundwater and seawater. The accumulation of antibiotics in aquatic organisms has also been reported in several studies, which may provoke ecotoxicological effects to these organisms and alter the functioning of the ecosystems. Besides, antibiotics bioaccumulation can be of concern for human health when accumulating in animals used for human consumption, such as seafood. Furthermore, antibiotic pollution can contribute to the development and spread of antibiotic resistance in the environment, an issue of high concern due to the risk for human health.
The main aim of this thesis was to investigate the fate and environmental impact of antibiotic residues in the environment with a special emphasis on the marine ecosystem. Antibiotic bioaccumulation in marine organisms was assessed under both, controlled conditions, and through the analysis of aquatic organisms from aquaculture and natural environments. Exposure experiments were also used to characterize the ecotoxicological effects of antibiotics and to evaluate their contribution to the spread of antibiotic resistance genes.
The first part is dedicated to the development of analytical methodologies to determine the occurrence of antibiotic residues in marine organisms and water samples. Two different methodologies were explored in this part. On one hand, an analytical method based on QuEChERS extraction followed by Liquid Chromatography coupled to Mass Spectrometry (LC-MS/MS) analysis was developed for the identification and quantification of 23 antibiotics in fish, mussel and clam samples. On the other hand, a methodology based on microbial growth inhibition was optimized for the screening of four antibiotic families in organism’s biofluids and water samples. Both methodologies were applied for the determination of antibiotic residues in organisms and water samples from a monitoring campaign.
The second part evaluates the environmental impact of antibiotic pollution on marine organisms. Three different sets of exposure experiments were performed in order to assess antibiotic bioaccumulation, ecotoxicological effects and spread of antibiotic resistance in marine mussels. The first study assessed alterations on antibiotics bioaccumulation due to climate change expected conditions to the marine environment such as water warming and acidification. The second study comprehensively evaluated the ecotoxicological effects of sulfamethoxazole antibiotic exposure to marine mussels through the characterization of enzymatic activities, and observation of metabolism changes applying a non-targeted metabolomics approach. Finally, the third study determined the effects of antibiotic water pollution on the abundance of antibiotic resistance genes occurring in the bacteria located in the mussel’s gastrointestinal tract.
