Study on Heavy Metal Resistant Bacteria in Guheswori Sewage Treatment Plant

Abstract

Removal of heavy metals from wastewater needs advance chemical technology and is more expensive too. The cheaper alternative for this is the bioremediation using heavy metals resistant microorganisms. In this study, 10 heavy metal resistant bacteria were isolated from oxidation ditch of wastewater treatment plant of Bagmati Area Sewerage Project. These include chromium resistant Staphylococcus spp, Escherichia coli, Klebsiella spp; cadmium resistant Acinetobacter spp, Flavobacterium spp, Citrobacter spp; nickel resistant Staphylococcus spp, Bacillus spp; copper resistant Pseudomonas spp; and cobalt resistant Methylobacterium spp. All the isolates showed high resistance to heavy metals with Minimum Inhibitor Concentration (MIC) for heavy metals ranging from 150 mug/ml to 500 mug/ml. Six resistant isolates showed multiple tolerance to heavy metals. All the 10 isolates also showed antibiotic resistance of which 10% were resistant to single antibiotic and 90% were multi-antibiotic resistant. Heavy metal tolerance test showed maximum microbial tolerance to chromium and minimum tolerance to nickel in mixed liquor sample of oxidation ditch.Keywords: Heavy metal resistant bacteria, multiple tolerance, antibiotic resistance, Guheswori Sewage Treatment Plantdoi: 10.3126/on.v6i1.1655Our Nature (2008)6:52-57