Copper-stress induced alterations in protein profile and antioxidant enzymes activities in the in vitro grown Withania somnifera L.

Withania somnifera L. seedlings were grown in half-strength MS (Murashige and Skoog) basal medium for 4 weeks and then transferred to full-strength MS liquid medium for 3 weeks. The sustainable plants were subcultured in the same medium but with different concentrations (0, 25, 50, 100 and 200 µM) of Cu for 7 and 14 days. The growth parameters (root length, shoot length, leaf length and total number of leaves per plant) showed a declining trend in the treated plants in a concentration dependant manner. Roots and leaves were analyzed for protein profiling and antioxidant enzymes [catalase (CAT, EC 1.11.1.6), superoxide dismutase (SOD, EC 1.15.1.1) and guaiacol peroxidase (GPX, EC 1.11.1.7)]. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of crude protein extracts showed the appearance of some new proteins due to Cu treatment. In plant samples grown with 25 and 50 µM of Cu, a rapid increase in antioxidant activities were noticed but at higher concentration (100 and 200 µM) the activities declined. Isoforms of CAT, SOD and GPX were separated using non-denaturing polyacrylamide gel electrophoresis and concentration specific new isoforms were noticed during the study. Isoforms of the antioxidant enzymes synthesized due to Cu stress may be used as biomarkers for other species grown under metal stress.

Physico-chemical assessment of paper mill effluent and its heavy metal remediation using aquatic macrophytes--a case study at JK Paper mill, Rayagada, India.

The present investigation aims to assess the phytoremediation potential of six aquatic macrophytes, viz. Eichhornia crassipes, Hydrilla verticillata, Jussiaea repens, Lemna minor, Pistia stratiotes and Trapa natans grown in paper mill effluent of JK Paper mill of Rayagada, Orissa, for remediation of heavy metals. The experiment was designed in pot culture experiments. Assessment of physico-chemical parameters of paper mill effluent showed significant decrease in pH, conductivity, total dissolved solids, total suspended solids, chlorine, sulphur, biological and chemical oxygen demand after growth of macrophytes for 20 days. Phytoremediation ability of these aquatic macrophytic species for copper (Cu) and mercury (Hg) was indicated by assessing the decrease in the levels of heavy metals from effluent water. Maximum reduction (66.5 %) in Hg content of untreated paper mill effluent was observed using L. minor followed by T. natans (64.8 %). L. minor showed highest reduction (71.4 %) of Cu content from effluent water followed by E. crassipes (63.6 %). Phytoextraction potential of L. minor was remarkable for Hg and Cu, and bioaccumulation was evident from bioconcentration factor values, i.e. 0.59 and 0.70, respectively. The present phytoremediation approach was considered more effective than conventional chemical treatment method for removing toxic contaminants from paper mill effluent.