Introduction heavy metal pollution

CONCLUSIONS
Since the plant-associated microbes possess the capability of plant growth promotion and/or metal mobilization/immobilization. There has been increasing interest in the possibility of manipulating plant microbe interactions in contaminated soils (Aafi et al., 2012; Azcón et al., 2010; Braud et al., 2009b; Dimkpa et al., 2008, 2009a,b; Hrynkiewicz et al., 2012; Kuffner et al., 2010; Luo et al., 2011; Luo et al., 2012; Maria et al., 2011; Mastretta et al., 2009; Orłowska et al., 2011; Sheng et al., 2008a,b). Bioremediation is cost effective, faster than natural attenuation, high public acceptance and generates less secondary wastes and emerged as an integrated tool for environmental cleanup as well as ecosystem service provider. (Dickinson et al. 2009). The potential role of plants and associated rhizomicrobial population in facilitating microbial degradation for in situ bioremediation of surface soils contaminated with hazardous organic compounds is substantial. Support for this concept comes from the fundamental microbial ecology of the rhizosphere, documented acceleration of microbial degradation of agricultural chemicals and mobilization/immobilization of metals in the root zone.

Further understanding of the critical factors influencing the plant-microbe-toxicant interaction in soils will permit more rapid realization of this new approach to in situ bioremediation (Dubey and Fulekar, 2013). To effectively restore an ecosystem or ecological community, it is often critical to consider multiple species, multiple functions, and their interactions. Furthermore, the restoration of self-maintaining systems is increasingly requiring the consideration of human-induced local- to global-scale environmental changes. Studies on plant–soil interactions vis-à-vis plant microbe interaction provide an important foundation for eco-restoration. In order to help managers with the challenge of designing successful restoration techniques at a specific site, we need to embrace the variability of ecological studies and develop frameworks to understand this variability (Bever, 2002; Eviner and Hawkes, 2008). Bioremediation is not a Panacea to restore all the contaminated environmental sites, however, in comparison to other remediation processes i.e. incineration, thermal disposition, land farming etc. it has a better future in development of technology for removal of contaminants from actual site and restoration of degraded lands (Singh, 2008). With a global political shift towards sustainable and green technologies, the use of plant-associated microorganisms to degrade toxic synthetic organic and inorganic pollutants in environmental soil may provide an efficient, economic, and sustainable green remediation technology for future environment (Bhatiya and Malik, 2011).