IRAWATI W., KUSUMAWATI L. AND SOPIAH R.N.
Abstract
Microorganisms have developed several mechanisms to tolerate high concentration of heavy metals. One of these mechanisms dependent upon metabolic energy of microorganisms is the bioaccumulation of heavy metals. Acinetobacter sp. IrC2 is a copper-resistant bacteria isolated from activated sludge in an Industrial Wastewater Treatment Plant in Rungkut-Surabaya, Indonesia. The purpose of this research was to study the potency of Acinetobacter sp. IrC2 as a bioremediation agent for copper, cadmium, lead, and zinc. Resistance of Acinetobacter sp. IrC2 to heavy metals were determined by measuring the minimum inhibitory concentration (MIC). Accumulation of copper, cadmium, lead, and zinc were determined by Atomic Absorption Spectrophotometer. Acinetobacter sp. IrC2 showed multiple resistance to heavy metals. The MICs of Acinetobacter sp. IrC2 to copper, cadmium, lead, and zinc were 10 mM, 4 mM, 13 mM, and 9 mM, respectively. Acinetobacter sp. IrC2 has capabillity to accumulate copper, cadmium, zinc,and lead up to 138,96 mg, 37,17 mg, 151,96, 307,15 mg per gram dry weight of cells, respectively. The bacteria also demonstrated growth in the medium containing the mixture of 1 mM copper, cadmium, lead, zinc and accumulated those heavy metals up to 1.50 mg/g, 54.57 mg/g, 22.29 mg/g and 13.57 mg/g dry weight of cells, respectively.