Bioremediation via Nanoparticles: An Innovative Microbial Approach

Introduction

Increment in the population density, necessity of up gradation in agriculture productivity, industrialization and urbanization of human societies are accountable for environmental contamination (Figure 1). The extensive use of anthropogenic materials contaminates the natural ecosystem which degrades the environment in long term by several means such as loss in biodiversity, introducing heavy metals and other organic recalcitrant compounds. On this regard decontamination of these hazardous wastes via eco friendly approaches is an enigma. In the diverse biological species present in nature, many are blessed with the ability to tolerate heavy metals. Progress in science and technology facilitate us to concern the ability of biological diversity for depletion of pollution which is termed as bioremediation. This is promising efficient novel technology for dealing with extensive range of contaminants. This technology mediates phytoremediation (plants), rhizoremediation (plant and microbe interaction) and remediation via biosynthesis of nanoparticles (nanoparticles synthesized by microbes).

Figure 1.

Effect of nanoparticles on contaminate sites and their possible mechanism to reduce the contaminants

Currently maintaining ecosystem and biodiversity has become an increasingly important field of research, as well as a resource management goal. Various industrial chemicals are released daily which are hazardous to the environment and cause harmful effects to the biodiversity by entering the food chain. These chemicals include petroleum hydrocarbon, heavy metals, phenolic compounds, metalloids, radionuclide, effluents and halogenated solvents from industrial sources, explosives, agricultural chemicals. Common contaminants and their health hazards: Polyaromatic Hydrocarbon: Carcinogen, mutagen, single ring compound does not have carcinogen property but after fusion they become carcinogen. Chlorinated hydrocarbon: Easily dissolved in water, mainly affects the respiratory tract, non carcinogenic, causes irritation in eyes.

• Phenols: Irritating and corrosive effect on skin and become chronic by affecting central nervous system and kidneys.

• Heavy Metal: Cadmium exposure: renal tubular damage, effect on bone and fracture

• Arsenic Exposure: Hyperkeratosis, lung cancer

• Lead Exposure: Toxic blood, neurotoxic effect of lead at lower levels.

• Chromium Exposure: Epigastric pain, nausea, diarrhea, chronic ulcer.

Major part of biosphere which is contaminated with anthropogenic substances is soil and water. Soil, the most important land constituent is contaminated with chlorinated compounds, polycyclic aromatic hydrocarbon, heavy metals and radionuclides (Acevedo et al., 2010). These contaminants sequestered in saturated and unsaturated layer of the soil which underlying between the ground surface and groundwater level. Consequently, sites can have a high concentration of organic contaminants in soil layers in addition to possible groundwater contamination. They can cause detrimental effect on the flora and fauna of affected habitats through uptake and accumulation in food chains, and in some instances, pose serious health problems and or genetic defects in humans.

Water is mainly contaminated by chlorinated hydrocarbon, heavy metals, chlorine compound like Trichloroethene (TCE) and Polychlorinated biphenyls or mixtures of anthropogenic organic chlorinated compounds (He, F) which is highly reactive and water soluble(Arjoon, Olaniran, & Pillay, 2013). These compounds are carcinogenic and naturally non degradable, so it persists in water and soil for long time and become a challenge to remediate these compounds (Figure 2).

Figure 2.

Emission of different contaminants in different natural resources