Evaluation of Bacopa monnieri as a Suitable Hyperaccumulant for Copper Contaminated Soil Using in vitro Techniques

Various heavy metals like as, Cu, Zn, Pb, Hg etc. affect the environment by affecting soil properties, its fertility, biomass and crop yield and ultimately human health. Therefore, heavy metal pollution poses a great threat to the environment and mankind. In order to maintain good quality of soil and water and keep them free from contamination, continuous efforts have been made to develop technologies that are easy to use, sustainable and economically feasible. Phytoremediation as an emerging technology that employs the use of higher plants for the clean-up of contaminated environment has been reported using several plant species. Presently an attempt has been made to study the efficiency of in vitro regenerated multiple shoot cultures of Bacopa monnieri to accumulate copper from the plant medium. Copper sulphate (CuSO45H2O) was added to the shoot multiplication medium at varying concentrations of 0, 20, 40 and 80 mg/ltr media. The effect of copper on plant growth, chlorophyll content and production of pharmaceutically important bacosides from the regenerants was examined. It was observed that copper sulphate acted as an elicitor for plant growth at a concentration of 20 mg/l. Although, when the concentration was increased from 20 mg/l to 80 mg/l it resulted in suppression of plant growth. The efficiency of copper removal was highest in plants treated with 40 mg/l of copper sulphate and decreased upon increase in concentration to 80 mg/l. Bio-concentration factor (BCF) calculated for all the treatments was found to be maximum (3.03) at 40 mg/l followed by 20 mg/l (2.7) and 80 mg/l (1.91). Bacoside content measured by HPLC was found to be maximum in the cultures treated with copper at a concentration of 40 mg/l (12.405 mg/g DW) followed by 80 mg/l (8.091 mg/g DW), control (8.047 mg/g DW) and 20 mg/l (1.127 mg/g DW). The study suggests the practical application of B. monnieri plants which can act as hyperaccumulants for the removal of copper in industries where the metal is a major contaminant.