Isolation and Characterization of Zinc Tolerant Bacteria from Contaminated Sediments and Soils in Egypt

El-Meihy, Rasha M.

doi:10.21608/assjm.2018.214382

Isolation and Characterization of Zinc Tolerant Bacteria from Contaminated Sediments and Soils in Egypt

Document Type : Original Article

Author

Rasha M. El-Meihy

Agricultural Microbiology Department, Faculty of Agriculture, Benha University, Egypt.

10.21608/assjm.2018.214382

Abstract

A total of 71 zinc tolerant bacteria were ,isolated from Four heavy metals contaminatedsediments and soils in Egypt, three sediment samples (Upstream, midstream, downstream Al-Rahawy drain, Giza Governorate) and two agricultural soil samples (Al-Gabal Al-Asfar region and Kafr-Ilwan village, Qalubia Governorate). The minimum inhibitory concentration (MIC) and maximum tolerance concentration (MTC) under zinc (Zn⁺²) concentrations ranged between 500-4500 mg/l. The most zinc tolerant isolate UR45 with MIC 4500 mg/l and MTC 4000 mg/l was identified by partial sequence of 16S rRNA genes as Alcaligenes faecalis MG257493.1 (UR45). Tolerance of A. faecalisto cadmium (Cd²⁺), copper (Cu²⁺) and lead (Pb²⁺) under different concentrations (1000-4500 mg/l) was evaluated. Growth of the strain and its biosorption activities (metal uptake, metal residual, metal biosorption) at 1000 mg/l of Zn²⁺, Cd²⁺, Cu²⁺ and Pb²⁺ under different pH values (5-9) was studied. pH 8 was optimum for growth in media supplemented with Zn²⁺ or Cu²⁺. Whereas, the biosorption potentials were differed according to the examined metal. Finally, enzymatic (catalase, peroxidase, polyphenol oxidase) and non-enzymatic (inhibition 2,2-DiPhenyl-2-Picrylhydrazyl hydrate (DPPH)) antioxidant activities of the A. faecalis MG257493.1 in presence of four heavy metals individually or in mixture at 1000 and 1500 mg/l were estimated. The obtained data showed that most antioxidant activities of the strain was increased with the increasing of heavy metals concentrations up to 1500 mg/l.

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