Indigenous copper and dye resistant bacteria: Enterobacter cloacae Suk1 and Serratia nematodiphila Suk13 isolated from Sukolilo River, Surabaya Province, Indonesia

Abstract

Bioremediation using indigenous copper-resistant bacteria has been successfully used in reducing copper concentrations. However, little information is available concerning the resistance of bacteria to copper and dyes. This study, therefore, was aimed at 1) isolating and characterizing multi-resistant bacteria, 2) measuring the copper biosorption and accumulation ability, and 3) measuring the growth and decolorization ability of various dyes. Dye-multi-resistant bacteria were isolated from Sukolilo River, Indonesia. Copper resistance was determined by measuring the Minimum Inhibitory Concentration (MIC). The biosorption and accumulation abilities were measured using an atomic absorption spectrophotometer. 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 wavelength of 300-900 nm. The results showed that nine isolates of copper-resistant bacteria demonstrated MIC of 3-9 mM CuSO4. Enterobacter cloacae Suk1 and Serratia nematodiphila Suk13 have been demonstrated to possess multi-resistance to CuSO4, and the twelve dyes, except Enterobacter cloacae Suk1 which did not grow on malachite green and basic fuchsine. Enterobacter cloacae Suk1 was able to decolorize 89.42% of methylene blue and 83.61% of congo red in a medium supplemented with 500 ppm of each dye. Enterobacter cloacae Suk1 and Serratia nematodiphila Suk13 also accumulated copper of up to 2.61 mg and 2.48 mg/g dry weight of cell, respectively, and removed copper of up to 94.64% and 90.52% in a medium containing 5 mM CuSO4, respectively.