Tetracycline, a widely used group of antibiotics, has been extensively employed for disease treatment in aquaculture practices in Bangladesh. Arsenic contamination in ground water is very high in southern and upper southern parts of Bangladesh. In this study, a large-scale screening of bioavailable tetracycline (TC) and arsenic (As) was carried out using Whole-Cell biosensor bacteria from the pond surface waters of selected prawn farms in the south-west coastal Bangladesh. Bioavailability of Tetracyclines and Arsenic was detected using biosensor bacteria E. coli K12 pTetLux1 and E. coli DH5R (pJAMA-arsR), respectively. Among the sampled ponds, 42 were found to contain tetracycline concentrations within the detection limit. The measured tetracycline concentrations ranged from 15.2 to 31.1 µg/l, indicating the presence of bioavailable tetracycline in the aquaculture environment of the south-west coastal Bangladesh . The average age of the experimental ponds was 11.47 years and average depth was 1.2 meters. The tetracycline concentration was highest (31.1 µg/l) in the oldest pond (20 years), while the lowest concentration (15.2 µg/l) was observed in a pond with the age of 14 years. Interestingly, an increase in tetracycline concentration was observed with increasing pond age, indicating a potential accumulation of tetracycline over time within the ponds. Bioavailable As were detected in only 3 .7% of all analyzed samples. Detectable As samples were higher in number among the collected samples at Satkhira and higher in percentage at Sathkhira (2 0%) followed by Khulna (15 %), and Bagerhat (10 .2%). Though the concentrations of arsenic in groundwater (tube well water) were high in all studied regions, the concentrations of arsenic in pond water were low in every region. The concentration of As in the experimental ponds was neither very high nor in the danger limit. Use of fertilizers, drugs, pesticides, and herbicides possessed with as during fish culture might be the source of as contamination. However, extensive use of antibiotics results in the emergence and spread of antibiotic resistance in the aquatic environment.
Keywords: biosensor, bioavailability, tetracyclines, arsenic, prawn aquaculture, Bangladesh