The Role of Heavy Metals-Resistant Bacteria Acinetobacter sp. in Copper Phytoremediation using Eichhornia crasippes [(Mart.) Solms]

Abstract

Phytoremediation is a bioremediation process using plants and microorganisms to extract, sequester, or detoxify heavy metals. Eichhornia crassipes [(Mart.) Solms] is a well-known phytoremediating plant that has the ability to remove heavy metals from water by accumulating them in their tissues. Acinetobacter sp. IrC1 and Acinetobacter sp. IrC2 are copper resistant bacteria isolated from industrial waste in Rungkut, Surabaya. The aim of this research was to study the effect of Acinetobacter sp. IrC1 and Acinetobacter sp. IrC2 inoculation in copper phytoremediation process using Eichhornia crassipes. Bacterial isolate with colony form unit of 10 8 was inoculated into the rhizosphere of Eichhornia crassipes in water containing 10 mL · L –1 and 20 mL · L –1 copper. Copper removal in contaminated water and copper accumulation in the plant roots was analyzed using atomic absorption spectrophotometer. The results showed that inoculation treatment enhanced the potency of the plant to reduce copper from  94 % concentration level in the medium without bacterial inoculation to 98.3 % and 97 % in medium inoculated with Acinetobacter sp. IrC1 and Acinetobacter sp. IrC2, respectively. Eichhornia crassipes inoculated with Acinetobacter sp. IrC1 accumulated up to six fold higher copper concentrations in roots compared with un-inoculated controls. The roots of Eichhornia crassipes accumulated 596 mg · kg –1 and 391 mg · kg –1 in medium containing 5 mL · L –1 and 10 mL · L –1 copper without inoculation, while, the upper part of the plants accumulated up to 353 2.5 mg · kg –1 and 194 1.5 mg · kg –1 in medium inoculated with Acinetobacter sp. IrC1, respectively. The findings of the study indicated that Acinetobacter sp. IrC1 and Acinetobacter sp. IrC2 can improve the phytoremediation potential of Eichhornia crassipes.