Investigation of Microbes in the Rhizosphere of Selected Grasses for Rhizoremediation of Hydrocarbon-Contaminated Soils

Molecular tools to understand the bioremediation effect of plants and earthworms on contaminated marine sediments

“…This finding should not be surprising since GP bacteria have a stronger cell envelope than do GN bacteria, have a low maintenance-energy requirement, and make use of some tools to augment the PAH bioavailability such as biosurfactant secretion or biofilm formation directly on hydrocarbons, enabling them to thrive and adapt better to harsh conditions and resourcelimited situations [40].In this study, both the total and metabolically active PAH GP degraders' population increased with time, especially in the treatment where plants and earthworms were applied together.When plants were used alone, an increase of PAH GP metabolically active degraders was also found, in concordance with the resultsof other authors, who found that some plants as P.vaginatumincreased PAH GP bacterial gene abundance in rhizosphere and favoured the maintenance of a larger proportion of GP bacteria capable of PAH degradation in aged contaminated soils [33,41].…”

“…After one year of treatment,the combination of green compost and P.vaginatumreducedby half the heavy-metals (except for Ni)and hydrocarbons content.It is known that hydrocarbon-degrading microorganisms associatedwiththe rhizosphere of P.vaginatum are effective in degrading organic compounds [33], and it is has also been proven that the use of compost may enhance the degradation of the bioavailable fraction of organic pollutants by introducing new degrading microorganisms [34].However, no additional degradation was detected when sediments were left untreated forone moreyear, suggesting that the available compounds had already been depleted andsome additional stimulus was necessary to reactivate the bioremediation. To test this hypothesis two different plant species and plantsplus earthworms were applied,resulting in further hydrocarbon degradation in both cases.…”

Influence of Arbuscular Mycorrhiza andRhizobiumon Phytoremediation by Alfalfa of an Agricultural Soil Contaminated with Weathered PCBs: A Field Study

“…Certain lower-molecular-weight organic compounds may be translocated by plants, stored in cell walls or lignin and lost by transpiration from the vegetative plant parts (Aitchison et al, 2000) or may be degraded within the plant tissues (Newman et al, 1997). Microbial consortia including indigenous and introduced microorganisms in the rhizosphere can work in tandem to effectively enhance the breakdown of organic pollutants in the environment (Macek et al, 2000;Chaudhry et al, 2005;Kuiper et al, 2004;Yateem et al, 2007).…”

Influence of Rhizobium meliloti on phytoremediation of polycyclic aromatic hydrocarbons by alfalfa in an aged contaminated soil

“…The efficiency of phytoremediation relies on the establishment of active plants with sufficient biomass growth, active root proliferation and/or root activities that can support a flourishing microbial consortium assisting phytoremediation in the rhizosphere [3,40,41]. Legumes, including alfalfa, have been identified as strong candidates for remediation of contaminated sites [22,23,42,43].…”