Identification of cadmium resistant bacteria and evaluation of their resistance spectrum during quarterly monitoring on the Kor River

Kor River is a valuable ecologic area and source of water for the Bakhtegan Lake in Fars province, Iran. This river has been contaminated with various waste pollutants including agricultural, industrial, urban and rural. Cadmium is one of the common hazardous heavy metals entering the natural environments. This study mainly aimed at isolation and identification of the cadmium resistant bacteria, determining the resistance spectrum and investing the growth of opted bacteria against Cd. Additionally, physic-chemical and biological factors have been monitored quarterly. Samples were taken from five different stations at Dorudzan dam downstream to the mouth of the river to the Bakhtegan Lake since these areas are believed to contain more contaminants. Two sets of water and sediments samples were taken simultaneously to measure physic-chemical and biological factors and detection of cadmium resistant bacteria. More resistant bacteria were screening through MIC and MBC. Tow opted (G+ and G-) bacteria were studied in batch culture at three different containing harsh conditions by growth kinetic curve. The presence of cadmium was found to be more dominant in sediments than the water. Serratia marcescens MT015 and Pseudomonas aeruginosa ET017 showed maximum cadmium resistance up to six mille molar. P.aeruginosa ET017 and Bacillus OA017 represented proper growth in the harsh conditions. Discussion and The Kor River is a significant ecological area in Fars province, Iran where annual monitoring seems essential. Some indigenous bacteria in this river have represented high ability of cadmium resistance which enabling them to be exploited as valuable agents for bio-remediation in bio-filters and "in-situ" form for cadmium contaminated environments. No need of genetically manipulation and wide spectrum of study upon physicochemical, biological and bacterial assessing are advantages of our research. In compare to recent researches, our presented strains demonstrated more resistance to cadmium.