Abstract. Irawati W, Pinontoan R, Mouretta B, Yuwono T. 2021. The potential of copper-resistant bacteria Acinetobacter sp. strain CN5 in decolorizing dyes. Biodiversitas 23: 680-686. Bacteria with multi-resistance to copper and dyes may be employed in bioremediation of copper and dye waste more effectively than physical or chemical remediation. This study aims at determining the effect of the addition of various textile dyes and copper on the growth of Acinetobacter sp. CN5 and its ability to decolorize dyes. The dye resistance test was carried out by inoculating bacterial isolates into Luria Bertani media containing 50, 100, 150, 200, 250, 300, 350, 400, 450, and 500 ppm dyes. The twelve dyes used in the test were methylene blue, malachite green, congo red, mordant orange, reactive black, direct yellow, basic fuchsine, reactive orange, dispersion orange, remazol red, wantex yellow, and wantex red. The decolorization activity was analyzed by spectrophotometry at a 300-900 nm wavelength. The study results demonstrated that bacteria thrived in media containing 50 ppm of all dyes, except malachite green dye. Acinetobacter sp. CN5 was found to be resistant to up to 500 ppm methylene blue, basic fuchsine, and wantex red and resistant to congo red at 450 ppm. Acinetobacter sp. CN5 was also able to decolorize methylene blue, congo red, basic fuchsine, and red wantex by 57.64%, 53.17%, 91.37%, and 67.50%, respectively. The addition of 5 mM CuSO4 to the medium increased the ability of Acinetobacter sp. CN5 to decolorize the congo red from 57.64% to 82.58%.

Dyes and copper are dangerous contaminants because they are toxic. Bioremediation using indigenous bacteria is the best solution to overcome water pollution. Copper resistant bacteria usually have resistance to dyes thereby helping the bioremediation of dye and copper wastes. This study aims to examine the ability of indigenous bacteria isolated from the Cisadane River, namely Klebsiella grimontii IrCis3, Shigella flexneri IrCis5, Enterobacter cloacae IrCis6, and Enterobacter cloacae IrCis9 in terms of resistance and ability to decolorize 12 textile dyes namely methylene blue, malachite green, congo red, mordant orange, reactive black, direct yellow, basic fuchsin, reactive orange, dispersed orange, remasol red, wantex yellow and wantex red. The results showed that Shigella flexneri IrCis5, Enterobacter cloacae IrCis6, and Enterobacter cloacae IrCis9 were resistant to all dye concentrations of 200 and 500 ppm except Klebsiella grimontii IrCis3 did not grow on malachite green and basic fuchsin at concentrations of 200 ppm and methylene blue, malachite green and basic fuchsin concentration of 500 ppm. Only Shigella flexneri IrCis5 has the ability to decolorize 200 ppm basic fuchsin up to 87.23% after 3 days of incubation. The addition of 3 mM CuSO4 reduced the ability to decolorize Shigella flexneri IrCis5 to 0.57%.