Characterization of Metal Tolerant Serratia spp. Isolates from Sediments of Uranium Ore Deposit of Domiasiat in Northeast India

Abstract

Three metal tolerant Serratia spp. isolates from sediments of pre-mined uranium ore deposit of Domiasiat, Meghalaya, India were characterized using morphological, biochemical and molecular methods. 16S rRNA gene analysis of the isolates identified one of the isolates (DB-10) as Serratia nematodiphila with 99.33 % pairwise similarity whereas remaining two isolates (DB-11 and DB-15) showed similarity with Serratia marcescens subsp. sakuensis with similarity of 98.78 and 99.54 % respectively. Randomly amplified polymorphic DNA (RAPD) and enterobacterial repetitive intergenic consensus sequence-based PCR (ERIC-PCR) studies of the isolates revealed genetic diversity among them. The isolates were found to tolerate all the five tested metals namely, uranium, cadmium, copper, zinc and lead and also could resist nine commonly used antibiotics namely, ampicillin, kanamycin, chloramphenicol, erythromycin, gentamicin, aztreonam, tetracycline, imipenem and ciprofloxin. All the three isolates were found to be superior in tolerance and resistance to the reference strain S. marcescens ATCC13880. The isolates showed high efficiency of uranium (VI) removal ranging from 90 to 92 % (21.4–21.9 mg/L) and from 65 to 70 % (309.4–333.2 mg/L) when challenged with 100 μM (23.8 mg/L) and 2 mM (476 mg/L) uranyl nitrate solutions respectively within 1 h of incubation.