Isolation and screening of bacteria from radionuclide containing soil for bioremediation of contaminated sites

Abstract

Radionuclides are present in minute concentrations in soils, especially around atomic power stations. Several microorganisms have been reported to grow in presence of radionuclides and even extreme gamma-radiation. Deinococcus radiodurans serves as the model radioresistant bacterium owing to its tolerance to extreme levels of gamma-radiation. In the present study, the soil sample was randomly collected from the area around Kakrapar Atomic Power Station, Surat (India) and was characterized physico-chemically. Based on the inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis, the soil was found to be rich in iron, titanium and magnesium. The nutrient medium was used for the cultivation and isolation of indigenous bacterial flora which were then characterized for their biochemical and metabolic potential. Twenty-five isolates were isolated which were sequentially screened to five. Furthermore, the five screened-in isolates exhibited the ability to produce exopolysaccharide (EPS) and biofilm, serving as one of the criteria for secondary screening of two isolates. The two screened bacteria were then identified as Providencia vermicola AM3 and Ochrobactrum sp. AM7 by 16S partial rRNA sequencing and their nucleotide sequences have been submitted to GenBank (NCBI). Additional optimization of medium components supporting the growth as well as facilitating the production of EPS by isolates P. vermicola AM3 and Ochrobactrum sp. AM7 is required for their potential application in bioremediation of radionuclide containing waste.