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Characterization and identification of cadmium-tolerant bacteria isolated from contaminated regions in Egypt

El-Meihy, Rasha M., Abou-Aly, Hamed E., Tewfike, Taha A., El-Alkshar, Eman A., Youssef, Ahmed M.
Biocatalysis and agricultural biotechnology 2019 v.21 pp. 101299
Alcaligenes faecalis, Bacillus cereus, agricultural soils, antioxidant activity, bacteria, biosorption, cadmium, copper, heavy metals, laboratory experimentation, lead, pH, ribosomal DNA, zinc, Egypt
This study was designed under laboratory conditions to isolate, identify and characterize some cadmium-tolerant bacteria from heavy metals-contaminated regions of Egypt. These regions included three sites along Al-Rahawy drain, Giza Governorate and two agricultural soils from Kaluybia Governorate, Egypt. Three of sixty-nine cadmium-tolerant bacterial isolates were evident as the most tolerant isolates for cadmium according to the MIC and MTC tests. Results proved that MR99, MR100, and MR108 were able to grow on medium supplemented with cadmium at 2000 mg/l and inhibited at 2500 mg/l. After that, their ability to tolerate other heavy metals (copper, zinc, and lead) was evaluated and resulted in two highest tolerant isolates namely MR99 and MR108 which able to tolerate all four tested heavy metals at different concentrations. These isolates were identified as Bacillus cereus MG257494.1 (MR99) and Alcaligenes faecalis MG966440.1 (MR108) according to the morphological, cultural, biochemical characteristics and 16S rDNA partial sequence. Then, their biosorption potentials under different pH values in media supplemented with four heavy metals at 1000 mg/l were examined in addition to their enzymatic and non-enzymatic antioxidant activities.