| dc.description.abstract | Lake Victoria in East Africa is an important source of fish for domestic, regional and global
market. Recently the lake has suffered massive pollution from industrial and wastewater
discharge. Microplastics, pharmaceutical, drugs, heavy metals, agrochemical and personal
care products are ubiquitous in Winam Gulf section of the lake located in Kisumu County in
Kenya. The pollutants are known to alter microbial assemblages in aquatic ecosystems with
calamitous consequences to human health. Some of the pollutants are reportedly associated
with human cancers and induce antibiotic resistance. There is paucity of data on the effects of
pollutants on microbial profiles of this important but heavily polluted aquatic ecosystem. The
objectives of this study were to identify heavy metals and pharmaceutical residues in the
aquatic ecosystems of Winam Gulf Kisumu, assess the impacts on microbial communities,
look into patterns of antibiotic resistance in bacterial populations, and explore genes and
pathways for possible pollutant bioremediation. The presence of pharmaceutical residues was
determined by the solid-phase extraction method, high-performance liquid chromatography
(mass spectrophotometry), and the HACH method spectrophotometer was used in the
identification of heavy metals in the samples. Total genomic DNA pooled from all samples
was extracted and analyzed by whole-genome shotgun metagenomics sequencing. The
analysis of antibiotic resistance genes and pathways were done using the shotgun
metagenomics method. Phenotypic antibiotic resistance was carried out by exposing bacteria
to discs containing common antibiotics. KEGG functional annotation was used to identify
the genes and pathways capable bioremediation of pollutants. This study revealed the
presence of pharmaceuticals such as Sulfamethoxazole, Caffeine, Trimethoprim,
Tetracycline, Amoxillin, Artemether and Neverapine in the sediment and water samples.
Further, the study reports the presence of Mercury, Nickel, lead, Aluminum, Copper,
Chromium and Cadmium pollutants. Metagenomics analysis revealed three major kingdoms;
Bacteria, Archaea and Eukaryotes belonging to 3 phyla, 13 classes, 14 families, 9 order, 14
genera and 10 species. Proteobacteria, Betaproteobacteria, Comamonadaceae,
Burkholdariales and Arcobacter were the dominated phyla, class, family, order, genera and
species respectively. KEGG analysis highest number of genes involved in metabolism. In
addition, carbohydrate active enzymes were the most abundant and included genes in
glycoside hydrolases. The study reported 9 ARGs from the 37 high-risk AMR gene families
previously reported by the WHO. Proteobacteria (53%) had the highest relative abundance
of antibiotic resistance, followed by Bacteriodes (4%), Verrumicrobia (2%), (Plantomycetes
Chlorflexi, Firmicutes) (2%), and other unclassified bacteria at (39%). Classification of genes
including genes that target protection, replacement, change, and antibiotic efflux were listed
in order of dominance. The dominant genes were antibiotic resistant efflux. KEGG pathway
analysis on antibiotic resistance to beta lactamase and vancomycin were observed.
Phenotypic resistance to vancomycin, tetracycline, and sulfamethoxazole, erythromycin,
trimethoprim tetracycline and penicillin was observed. Through the KEGG functional
annotation the following biodegradation pathways and genes were reported; Xylene, drug
and enzyme metabolism, Atrazine, Steroid and Nutrotolene. The study draws attention to the
possible health concerns to human and biodivesity associated with the presence of heavy
metal pollution, antibiotic-resistant genes, and pharmaceutical residues in Lake Victoria.
Furthermore, the results indicate that native microbial communities may be useful for
ecosystem bioremediation. | en_US |
