Journal of Pure and Applied MicrobiologyVol. 7 No. 4

Isolation of Zinc Resistant Bacteria from Karun River in Iran and Evaluation of their Growth Kinetics

Farshid Kafilzadeh1*, Mojdeh Chittaei1 and Niloofar Mojoodi2

1Department of Biology, Jahrom Branch, Islamic Azad University, Jahrom, Iran. 2Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran.

Received on 30 December 2012 and accepted on 26 February 2013



Zinc is an essential metal ion but at elevated concentrations it can be toxic and has inhibitory effects on cell activities. There are many industries along Karun river?s bank (longest river in Iran) discharging their zinc containing effluents to this river. The objectives of the present study were isolation and identification of zinc resistant bacteria from water and sediments of Karun River and study their growth kinetics. Sampling were done from water and sediments of 4 stations in 3 seasons, summer, autumn and winter. Zinc content of samples was measured by atomic absorption spectrophotometer. Bacterial numbers were count in both medium containing and without zinc. Bacterial isolation was performed by primary enrichment and direct plating methods. Isolates were examined for their resistance and growth kinetics in presence of zinc. Bacterial number was obtained 4.278 in medium containing zinc that was higher than control medium without zinc. Pseudomonas sp., Escherichia coli, Salmonella sp., Citrobacter sp. were isolated as zinc resistant bacteria. Some of these bacteria were able to tolerate 1000 mg/l of zinc. The maximum zinc uptake was found to be about 68% by Pseudomonas sp. Results of this experiment showed that presence of zinc cause growth cease of many bacteria. Using primary enrichment method compared with direct plating caused better isolation of resistant bacteria. Isolated bacteria were able to remove zinc metal.

Keywords : Zinc resistant bacteria, Bioelimination, Heavy metals, Karun River.