Date of Award

12-20-2026

Document Type

Thesis

Divisions

Faculty of Engineering

Department

Department of Chemical Engineering

Institution

Universiti Malaya

Abstract

As a result of the damaging impacts of prolonged environmental contamination, heavy metal pollution represents a significant danger to all living organisms in the environment. Copper and zinc constitute the two heavy metals that are both necessary in a minimal amount but hazardous in excessive ones. Heavy metals, such as copper and zinc, are not biodegradable and persist in the aquatic environment and food chain for extended periods of time; therefore, they must be eliminated. Bioremediation with microorganisms has recently emerged as a prospective and alternative solution to the heavy metal problem, as microorganisms have a range of methods for degrading, breaking down, and transforming heavy metals into less hazardous or harmless forms. Therefore, this study aimed at determining the potency of Escherichia coli and Aeromonas hydrophila to remediate copper and zinc in water. This study consisted of three parts, i.e: (1) Identification and characterization of E. coli and A. hydrophila, (2) In-vitro resistivity test of E. coli and A. hydrophila against copper and zinc, and (3) In-vivo test on the ability of E. coli and A. hydrophila bacteria in bioremediation of copper and zinc level by tissue analysis on Oreochromis mossambicus. The selected bacteria were isolated from water of Panteriek pond, Banda Aceh (Indonesia) followed by purification and characterization of the bacteria using Gram staining test, colony morphological studies, and biochemical tests. The bacteria were then tested for their resistivity against CuSO4 and ZnCl2 in vitro by evaluation of the minimum inhibitory concentration (MIC) value followed by heavy metal degradability test and viability detection test. The in-vivo tests of both bacteria against copper and zinc were performed using Oreochromis mossambicus (tilapia) fish as one of the freshwater fish. A total of 126 O. mossambicus fish were alloted into various conditions (K1 negative control group; K2, K3, and K4 were exposed to CuSO4 1-5 mg.L-1; K5, K6, and K7 were exposed to ZnCl2 2.5-7.5 mg.L-1), respectively. Each treatment group consisted of 6 analysis namely: (1) atomic absorption spectrophotometry (AAS) test before bioremediation, (2&3) AAS test after bioremediation by E. coli and A. hydrophila, (4) histopathological tests of liver and gills of fish before bioremediation followed by (5&6) after bioremediation by E. coli and A. hydrophila. The results showed that E. coli and A. hydrophila were successfully isolated as indicated by the characterization test results. The MIC results revealed that E. coli was able to tolerate the greatest absorbed metal toxicity for CuSO4 (20 mg.L-1) and ZnCl2 (300 mg.L-1). While A. hydrophila was able to resist the highest taken CuSO4 200 mg.L-1 and 300 mg.L-1 of ZnCl2. Both bacteria were able to survive in distilled water dissolved in several concentrations of CuSO4 and ZnCl2 for more than 7 days without any nutrient sources. The best viability rate of E. coli against CuSO4 and ZnCl2 was at 20 mg.L-1 and 80 mg.L-1, while A. hydrophila against CuSO4 and ZnCl2 was 300 mg.L-1 and 5 mg.L-1, respectively. The AAS results demonstrated that both bacteria were able to decrease the copper and zinc level. Similarly, the histopathological test showed the ability of the bacteria in decreasing the severity level of liver and gills tissues damage due to copper and zinc exposure. In conclusion, E. coli and A. hydrophila have the potency to be developed as microbioremediation towards CuSO4 and ZnCl2.

Initial

khm

Additional Information

Thesis (PhD) - Faculty of Engineering, Universiti Malaya, 2026.

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