Isolation and Screening of Heavy Metal Absorbing Bacteria from the Industry Effluent Sites of the River Nagavali

The present study was designed to evaluate the heavy metal absorbing potential of bacteria isolated from industry effluent sites of river Nagavali, Srikakulam Andhra Pradesh. From the effluent waste water three bacteria were isolated and confirmed as Staphylococcus aureus and Staphylococcus epidermidis and Staphylococcus saprophyticus after performing various biochemical tests. The heavy metal tolerant efficiency was determined by analyzing the growth of the bacteria in presence of heavy metal (Cu, Hg, Co and Zn) solution and their optimum tolerance was determined by measuring the optical density at 600nm after 24hr and 48hr of incubation. Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus saprophyticus were found to grow in heavy metal solutions. INTRODUCTION: An effluent is a out flow of water discarded after industrial operations and manufacturing processes. Industrialization is vital to a Nation’s economy because it serves as vehicle for development but the associated problems needs to be addressed using relevant technologies to minimize toxicity and other possible environmental hazards. Industrial waste consists of both organic and inorganic compounds. Organic wastes include pesticide residues, solvents, cleaning fluids, dissolved fluids, lignin from pulp and paper. Effluents can also contain some in organic wastes such as brine salts and metals. Heavy metal pollution of fresh water bodies arises from various industries and causes various environmental concerns for aquatic life. These effluents even at the low concentrations adversely affect the composition, distribution and diversity of benthic organisms . Removal of toxic heavy metals from industrial waste water is essential from the environmental point of view to combat water pollution . Conventional methods for removing metals from industrial effluents include chemical precipitation, chemical oxidation or reduction, ion exchange, filtration, electrochemical treatment, reverse osmosis, membrane technologies and evaporation recovery . These processes may be ineffective or extremely expensive especially when the metals in solution are in the range of 1-100 mg/l . Therefore, it is important to develop an innovative, low cost and ecofriendly method for removal of toxic heavy metal ions from the wastewater. Wide varieties of microorganisms are capable of growing in the presence of heavy metal ions and tolerate high concentrations . Since heavy metals are ubiquitously present in the environment microorganisms have developed resistance to these heavy metals . MATERIAL AND METHODS: Waste water samples were collected in screw capped sterilized bottles. 100μl of the effluent water sample was spread on nutrient agar plates. Nutrient agar plates were prepared by dissolving 0.5g peptone, 0.3g beef extract and 0.5g