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Soil pollution caused by toxic and hazardous chemical contaminants is in high enough concentrations to be of risk to plants, wildlife, humans and certainly for soil to itself. Pot experiments were conducted to investigate the phytoextraction capacity of an ornamental plant Sansevieria roxburghiana cultivated in soil artificially contaminated with 200, 400, and 600 mg kg-1 of zinc (Zn) treatments including control for 6 weeks. The soil was amended with garlic and cilantro extracts as the natural irrigation solutions (metal chelants). Garlic application significantly enhanced the Zn accumulation and was found to be the most efficient chelating amendment, increasing concentrations of Zn in roots from 65 mg kg-1 to 423 mg kg-1 dry weight (DW) soil. The phytochemical screening of acetone and ether extracts of S. roxburghiana plant samples revealed the presence of biologically active phytochemicals. Thin layer chromatography (TLC) of plant extracts revealed antibacterial efficacy against pathogenic bacterial strain. The plant samples were also characterized by thermogravimetric analysis and differential scanning calorimetric technique. The use of ornamental plant and varied irrigation solutions in our present study revealed positive effects on growth and phytoextraction together with an improvement of the soil quality.

Chlorpropham [isopropyl N-(3-chlorophenyl) carbamate] (CIPC), an important phenyl carbamate herbicide, has been used as a plant growth regulator and potato sprout suppressant (Solanum tuberosum L) during long-term storage. A bacterium capable of utilizing the residual herbicide CIPC as a sole source of carbon and energy was isolated from herbicide-contaminated soil samples employing selective enrichment method. The isolated bacterial strain was identified as Bacillus licheniformis NKC-1 on the basis of its morphological, cultural, biochemical characteristics and also by phylogenetic analysis based on 16S rRNA gene sequences. The organism degraded CIPC through its initial hydrolysis by CIPC hydrolase enzyme to yield 3-chloroaniline (3-CA) as a major metabolic product. An inducible 3-CA dioxygenase not only catalyzes the incorporation of molecular oxygen but also removes the amino group by the deamination yielding a monochlorinated catechol. Further, degradation of 4-chlorocatechol proceeded via ortho- ring cleavage through the maleylacetate process. 3-Chloroaniline and 4-chlorocatechol are the intermediates in the CIPC degradation which suggested that dechlorination had occurred after the aromatic ring cleavage. The presence of these metabolites has been confirmed by using ultra-violet (UV), high-performance liquid chromatography (HPLC), thin layer chromatography (TLC), Fourier transmission-infrared (FT-IR), proton nuclear magnetic resonance (1H NMR) and gas chromatography-mass (GC-MS) spectral analysis. Enzyme activities of CIPC hydrolase, 3-CA dioxygenase and chlorocatechol 1, 2-dioxygenase were detected in the cell-free-extract of the CIPC culture and are induced by cells of NKC-1 strain. These results demonstrate the biodegradation pathways of herbicide CIPC and promote the potential use of NKC-1 strain to bioremediate CIPC-contaminated environment with subsequent release of ammonia, chloride ions and carbon dioxide.