Madhuri Girdhar

Comparative assessment for hyperaccumulatory and phytoremediation capability of three wild weeds

Abstract The composition and the organization of soil are changing rapidly by the diverged mankind activities, leading to the contamination of environment. Several methods are employed to clean up the environment from these kinds of contaminants, but most of them are costly and ineffective to yield optimum results. Phytoremediation is a natural green technology, which is eco-friendly for the removal of toxic metals from the polluted environment. Phytoremediation is a cost-effective technique through which the cleanup of contaminated soil laced with heavy metals is performed by wild weeds and small herbal plants. The phytoremediation technique provides a promising tool for hyperaccumulation of heavy metals; arsenic, lead, mercury, copper, chromium, and nickel, etc., by the wild weeds and that has been discussed here in detail in case of Cannabissativa, Solanum nigrum and Rorippa globosa. In general, weeds that have the intrinsic capacity to accumulate metals into their shoots and roots, have the ability to form phytochelates and formation of stable compound with ions. This behavior of accumulation along with chelate and stable compound formation is utilized as a tool for phytoremediation activity.

Metal Accumulation Capability of Weeds and Their Utilization in Phytoremediation Technology

A wide range of anthropogenic activities cause physiochemical changes in the nature of soil. This leads to the contamination of environment. There are many methods employed to clean up environment from these contaminants, but most of them are costly and ineffective to provide proper results. Chemical methods employed act with complicated mechanism and lots of cost input. Phytoremediation is a technology that acts with deployment of green plants, for removal of toxic metals from the polluted environment. Phytoremediation is a cost-effective technique through which clean-up of contaminated soil loaded with high heavy metals is performed by weeds and small herbal plants. Phytoremediation has become a successful technology for hyperaccumulation of heavy metals; arsenic, lead, mercury, copper, chromium, nickel etc., by weeds. Weeds have intrinsic capacity to accumulate metals into their shoots and root and further to form phytochelates and stabilize ions. This accumulation activity of these weeds along with stable compound formation acts as a boon for phytoremediation technology.

Inulinase: An Important Microbial Enzyme in Food Industry

Inulinases are industrial food enzymes which have earned vast attention recently. Inulin and inulin-containing materials are sustainable, economical polymeric carbohydrates which can be easily hydrolysed by microbial inulinases into fructose, glucose and inulooligosaccharides. The inulinase gene can also be cloned and can be used in the production of bioethanol, single-cell oil, and single-cell protein utilizing inulin as the substrate in many species of yeast. The utilization of inulin is immense for the production of monomeric fructose units, and it has replaced starch in many food industries with multiple applications. Plants like agave, asparagus, coffee, chicory, dahlia, dandelion, garlic, Jerusalem artichoke, etc. are richest source of inulin. Inulin showed encouraging biorefinery approach in which inulin-containing waste, produced with the help of microorganisms has been used to yield biofuels including renewable gas, renewable diesel and further for the production of electricity.

Current Technical Perspective and Application of Aquatic Weeds in Phytoremediation

Anthropogenic pollution inputs are a cause of great concern. Continuous inputs of polluting material such as heavy metals, pesticides, fertilizer and other organic, inorganic material are burdening the environment, specially the aquatic bodies. Water bodies when overloaded with polluting material causes high level of stress and becomes depleted with dissolved oxygen, life sustaining factors. These stressful conditions can be resisted by certain aquatic weeds. Some of them even thrive in such conditions and accumulate large amount of heavy metals and other xenobiotic compounds. These stress sustaining and thriving species could prove to be useful for wastewater treatment strategies collectively referred as phytoremediation and bioremediation strategies. The current chapter mainly deals with discussion regarding these technologies in aquatic environments utilizing such aquatic plants. Plants taken in consideration for discussion include water hyacinth and duckweed. It has been reported that these plants are efficient enough to reduce water pollution of textile industries, as they are good bioaccumulator and accumulate contaminants into their tissues. Water hyacinth has high capacity of absorbing various toxic organic substances from the contaminated water. It has been reported that duckweed is very efficient for reducing the biochemical oxygen demand, percentage of heavy metals, chemical oxygen demand, orthophosphate, nitrate, and ammonia during its exposure to wastewater. The current review chapter focuses enough on these specific capabilities of plants.

Evaluating Different Weeds for Phytoremediation Potential Available in Tannery Polluted Area by Conducting Pot and Hydroponic Experiments

The pot experiments were conducted to determine and compare the toxic effects of Chromium, Copper, Cadmium, Nickel and Lead on different parameters like shoot length, number of branches and area of leaf on different wild weedCannabis sativa, Solanumnigrum and Chenopodium album. The investigated amounts of metal were in the range of 7 different concentrations i.e. 5ppm, 10ppm,50ppm,100ppm,200ppm,300ppm and 350ppm.The average toxicity increases with increase in the concentration of metals but in certain cases variations were observed in toxicity parameters. The morphological response in Cannabis sativa showed that most of the changes on the morphological characteristics were observed at 100 ppm. The shoot length, leaf area and number of branches decrease at 100 ppm and above. The maximum variations as compared to other metals were shown in copper stress condition. In Chenopodium album all the metals except lead show morphological variation with increase in metal concentration. The morphological toxicity increases with increase in metal concentration. The overall pollen fertility analysis shows that metal exposure leads to the development of sterile pollens. This shows the relative toxic effect of metals on the pollen fertility. In the hydroponic experiments, the Chromium metal exposure on the weed Cannabis sativa(C) and (P) for 15 days shows decrease in the amount of Chromium in the medium detected throughdiphenylcarbazide method, which shows the hyper accumulation of chromium by these weeds.