Isolation and Characterization of Nickel Tolerant Bacterial Strains from Electroplating Effluent Sediments

In this wake of industrialization, consequent urbanization and over increasing population, the basic amenities of life viz, air, water and land are being polluted continuously. Industrial complexes have become the focus of environmental pollution (Shukla et al., 2007). Water, the most vital resource of all kinds of life on this planet and it is adversely affected both qualitatively and quantitatively by all kinds of human activities (Reddy et al., 2001). 

Disposal of industrial and urban wastes to soil and water bodies has led to disastrous consequences in the ecosystem (Smith, 1974). Industrial operations such as electroplating, steel manufacturing, leather tanning, wood preservation, ceramics, glass manufacturing, and chemical processing and fertilizer applications release alarmingly higher amounts of metals into the natural environment (Zoubolis et al., 2004). 

The increase in industrial activity during recent years is greatly contributing to the increase of heavy metals in the environment, mainly in the aquatic systems (Marques et al., 2000). Water pollution due to heavy metals is an issue of great environmental concern (Vasudevan et al., 2003). 

Various sources of pollutants industrial effluents containing heavy metals pose a threat to ecosystem. There metals present in the wastewater of different industries such as metal cleaning, plating baths, refineries, mining, electroplating, paper and pulp, paint, textile and tanneries (Mistry et al., 2010). 

Release of heavy metals without proper treatment poses a significant threat to public health because of its persistence, biomagnifications and accumulation in food chain (Rajendran et al., 2003).

 Electroplating is the most commonly adopted metal finishing process, these result in the generation of heavy metal pollutants, which are toxic and non biodegradable. Heavy metals are generally deposited in liver, muscles, kidneys, spleen, skin, bone and soft tissues of human beings. Heavy metals pollution is one of great environmental concerns, because the heavy metals are non degradable and persistent in water. Heavy metals in the environment may also change plant diversity (Zafar et al., 2007).

 Heavy metals may disrupt the normal function of the central nervous system and cause changes in the blood content, and adversely affect the function of lungs, kidneys, liver and other organs. The long-term action of heavy metals may cause the  development of cancer, allergy, dystrophy, physical and neurological degenerative processes, Alzheimer's and Parkinson's diseases. However, in small amounts, heavy metals are indispensable for many organisms, but their enhanced doses induce acute or chronic poisoning (Kvesitadze et al., 2006).

 Nickel is generated from batteries, wire and electrical parts. Steady ingestion (exposure to nickel) can lead to cancer especially of the lungs and nasal sinus (Hauser and Hauser, 2008). Nickel (Ni) is the 24th most abundant element in the ealih crust and has been detected in different media in all parts of the biosphere. Ni is classified as the borderline metal ion because it has both soft and hard metal properties and can bind to sulfur, nitrogen and oxygen groups. Ni has been implicated as an embryotoxin and teratogen (Weber and Digiano, 1996).

 Conventional techniques for removing heavy metals from industrial effluents include chemical precipitation, chemical reduction, adsorption; ion exchange, evaporation and membrane processes. Compared with conventional methods for the removal of toxic metals from wastewater, the biosorption process offers potential advantages such as low operating cost, minimization of chemical or biological sludge, high efficiency of heavy metal removal from diluted solutions, regeneration of biosorbents, possibility of metal recovery and environmental friendly (Ahluwalia and Goyal, 2007). 

Most of the industrial techniques are ineffective and excessively expensive at the metal concentration less than l mg/ml (Alloway, 1995). Microbial metal bioremediation is an efficient strategy due to its low cost, high efficiency and ecofriendly nature (Rajendran et al., 2003). 

In recent years, the biotechnology applied to control and remove metal pollution has received much attention, and gradually, becomes a hot topic in the field of metal pollution control because of its potential application. For heavy metal removal, an alternative process is biosorption, which utilizes certain natural materials of biological origin, including bacteria, fungi, yeast, and algae (Alloway, 1995). With a view of this, the present study is focused an isolation and characterization of nickel tolerant bacterial strains from the electroplating effluent contaminated soil.