Effectiveness of Plant Growth-Promoting Rhizobacteria in Phytoremediation of Chromium Stressed Soils

Newly isolated Bacillus sp. PS-6 assisted phytoremediation of heavy metals using Phragmites communis: Potential application in wastewater treatment

This work aimed to study Bacillus sp. PS-6 assisted phytoremediation of metals from pulp and paper industry wastewater as a novel green technique for the removal of metals of wastewater. Results revealed that heavy metal (mg L^-1) contents in wastewater were reduced after in-situ phytoremediation for Fe, Cu, Zn, Cd, Mn, Ni, Pb, and As. Phragmites communis showed higher potential for the enrichment of Fe, Cu, Zn, Cd, Mn, Ni, Pb, and As in its rhizomes, roots, and shoots compared to leaves. The strain produced indole acetic acid, siderophores, and hydrolytic and ligninolytic enzymes, and resulted in nutrients solubilization. Results offer potential basis for the removal of metals from pulp and paper industry wastewater at large scale and prevention of pollution.

A Review on Occurrence of Pesticides in Environment and Current Technologies for Their Remediation and Management

Pesticides are the chemicals used to prevent plant diseases, weeds, pests and to enhance the quality of the food products. The uniqueness of their chemical structure, and/or their interactions with the environment characterize the nature of pesticides. In most scenarios, the end users such as farmers and consumers, who know the serious effects of pesticides cannot translate this awareness into their practice. The mobility, bioavailability of pesticides in soils (atmosphere, water bodies) is based upon their absorption and desorption mechanisms from soil particles. Pesticides have harmful effects in the soil ecosystem, and mankind (which affects biological molecules, tissues, and organs resulting in acute or chronic disorders). It affects humans of all ages including prenatal. These pollutants, when released into the water bodies affects the aquatic systems. The water molecules in the river are affected by the accumulation of these toxic contaminants with its alkaline pH and heavy metals which could adversely affect the health of flora and fauna. This article discusses the scientific literature on various remediation technologies available for the safer use of pesticides. The limitations and benefits of chemically polluted soil using microorganisms and other biological methods have been discussed. However, future development measures are still needed to ensure full implementation of these methods to save the environment.

Micro-remediation of chromium contaminated soils

Bacteria are tiny organisms which are ubiquitously found in the environment. These microscopic living bodies are responsible for the flow of nutrients in biogeochemical cycles and fertility imparted to the soil. Release of excessive chromium in agricultural soils due to rapid growth of industries may result in minimizing the fertility of soil in future, which will lead to reduction in crop production. Plant growth promoting bacteria (PGPB) are beneficial to the environment, some of which can tolerate chromium and protect plants against heavy metal stress. The current study aims to identify such chromium-tolerant auxin-producing rhizobacteria and to investigate their inoculation effects on the growth characteristics of Lens culinaris in chromium polluted soils by using two different chromium salts i.e., K₂Cr₂O₇ and K₂CrO₄ in varying concentrations (0, 50, 100, 200, 400 and 500 µgml⁻¹). The results revealed that Bacillus species are efficient in significantly reducing the deleterious effects of Cr. These effective bacterial strains were able to stimulate the growth of metal effected plants of Lens culinaris which were grown in chromium contaminated environment. Therefore, these plant growth promoting rhizobacteria PGPRs, having both auxin production potential and chromium-resistance ability, are considered as efficient micro-factories against chromium pollution.