Nitish Kumar

Potential Role of Arsenic Resistant Bacteria in Bioremediation: CurrentStatus and Future Prospects

Arsenic is known as a toxic metalloid, which primarily exists in inorganic form (AsIII and AsV). The industrialization and anthropogenic activities are the source of arsenic in the environment. Some microorganisms under heavy metal stress, developed resistance against them and evolved various strategies to resist against the metal stress. Detoxification of arsenic includes uptake of AsV in the form of phosphate by phosphate transporters, uptake of AsIII in the form of arsenite by aquaglyceroporins, reduction of AsV to AsIII by arsenate reductase, oxidation and methylation of AsIII by arsenate oxidase and methyltransferase respectively and finally extrusion or sequestration of AsIII. Many bacteria have been reported having redox potential for arsenic. Some genetically modified or engineered bacteria, C. Glutamicum, have been developed which show increased efficiency for arsenic transformation and could be used as biocontainers for bioaccumulation of arsenic.

Arsenic trioxide induces apoptosis and inhibits the growth of human liver cancer cells

Aims: As a fifth most common cancer type, Hepatocellularcarcinoma (HCC) ranked third leading cause of cancer deaths worldwide. Arsenic trioxide (As2O3) is known as chemotherapeutic agent against few cancer including Acute promyelocyticleukemia and solid tumors. But its effect and possible associated mechanism in HCC is meager. Present study aimed to assess As2O3 modulatory effect on liver cancer by assessing cell growth and viability. Methods: Liver normal (Chang liver) and cancerous cells (Hep3B) were exposed to different concentrations (0, 1, 5, 10 & 15 &mgr;M) of As2O3 at different intervals (24, 48 & 72 h). Cell growth was assessed microscopically, and Cytotoxicity assays were done through 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) and Water‐soluble tetrazolium salt (WST) growth inhibition assays. Cell viability was studied by trypan blue staining. Apoptosis was analyzed by Annexin V/PI assay, and expression of genes (Notch and anti‐apoptotic) were determined through western blotting and Q‐PCR method. Key findings: A significant reduction in cell growth and viability was reported in liver cancerous cells as compare to normal cells at 5 &mgr;M As2O3. Consistently, As2O3 induced apoptosis along with down‐regulation of anti‐apoptotic protein Bcl‐xL, and up regulates expression of Notch that leads towards apoptosis. Significance: Results clearly suggest that As2O3 restricted growth and induces apoptosis more in liver cancer cells as compared to normal cells. This finding suggests that it could be a promising potential therapeutic agent against liver cancer which need further testing by in‐vivo investigations.

TDZ-Induced Plant Regeneration in Jatropha curcas : A Promising Biofuel Plant

In recent years, Jatropha curcas has pronounced attention due to its capacity of production of biodiesel. Uniform large-scale propagation of J. curcas is one of the significant keys that will eventually decide victory. Direct regeneration is one of the methods which help in the production of uniform and homogenous plant, and TDZ plays an important role in the production of plantlets by direct organogenesis in several number of plant species including J. curcas. Measuring the economical importance of J. curcas and the role of TDZ in shoot regeneration, the present book chapter briefly reviews the impact of TDZ on shoot bud induction from various explants of J. curcas.

Possible bioremediation of arsenic toxicity by isolating indigenous bacteria from the middle Gangetic plain of Bihar, India

Highlights • In middle Gangetic plains, high arsenic concentration is present in water, which causes a significant health risk.• Two bacterial isolates, AK1 (KY569423) and AK9 (KY569424) were isolated and characterised for Arsenic detoxification.• aoxR, aoxB and aoxC genes were also observed in the isolated starin which help in arsenic detoxification by oxidation method.

Conventional and Biotechnological Approaches to Enhance Steviol Glycosides (SGs) in Stevia rebaudiana Bertoni

Stevia rebaudiana Bertoni (Asteraceae) is a perennial herb with many secondary metabolites present mainly in the leaf and other plant parts. Major secondary metabolites, for which the plant is consumed, are steviol glycosides (SGs) containing diterpene steviol, attached to which are one to four molecules of glucose by glycosidic bond(s). They impart very less calorie in consumer’s diet, thus widely used as a sweetener in food and beverage industries. The amount of SGs in the plant varies from 8 to 10%, enhancement of which is always in demand. Both conventional and biotechnological approaches are being made till date to increase the level of SGs in the plant. In the present chapter, we discussed various ways to enhance the level of these sweeteners with the prime focus on conventional and biotechnological approaches.

In Vitro Culture and Production of Secondary Metabolites in Centella asiatica

Plants are ever a valuable source of secondary metabolite which is used for curing various diseases whether it is mild or chronic. Due to huge medicinal importance of plants, studies on plants have been focused worldwide. Centella asiatica is an important medicinal plant, used as brain tonic all over the world. In a broad spectrum application of Centella asiatica, it has been listed in threatened species. The rapid depletion and high demands of their bioactive molecules feel the necessity for their conservation. In vitro culture and micropropagation are basic tools for conserving this medicinal plant and for production of secondary metabolites. In the present book chapter, we focused on conservation of C. asiatica through in vitro culture, production of secondary metabolites and strategies employed for the enhancement of secondary metabolites through manipulation in culture media, effect of growth regulators and elicitation.

Hairy Root Culture for In Vitro Production of Secondary Metabolites: A Promising Biotechnological Approach

Hairy root culture (HRC)-based in vitro production system has become a promising biotechnological approach in recent years. The hairy root formation is the result of Agrobacterium rhizogenes-induced pathogenesis in plants, characterized by high growth rate, growth in hormone-free media besides genetic stability. These roots can imitate intact plants in the production of secondary metabolites and also amenable to upscaling in the bioreactor. HRCs are being harnessed as one of the methods of choice in tissue culture for high yield of valuable secondary metabolites of medicinal and other commercial importance. Many secondary metabolites, which were earlier extracted from wild plants from their natural habitat, are now being produced using plant cell cultures including HRCs. This book chapter is focussed mainly on the development of hairy root culture in different medicinal plants and its application, challenges, and prospects in the production of valuable secondary metabolites.

TDZ-Induced Regeneration in Stevia rebaudiana Bertoni: An Important Natural Sweetener

A substituted phenylurea, thidiazuron (TDZ), plays a vital role as cytokinins in the regeneration of large number of plant species including stevia. There are several reports that are available on regeneration of stevia using TDZ. Apart from inducing regeneration with very high frequency, TDZ is also proved to be non-mutagenic. Stevia is of great importance due to its steviol glycosides (SGs) which are natural sweeteners used by the food industry as well as having medicinal purposes. This chapter is reviewed focusing on the impact of TDZ on shoot regeneration of stevia.

SSR-Based DNA Fingerprinting and Diversity Assessment Among Indian Germplasm of Euryale ferox : an Aquatic Underutilized and Neglected Food Crop

Euryale ferox is native to Southeast Asia and China, and it is one of the important aquatic food crops propagated mostly in eastern part of India. The aim of the present study was to characterize and evaluate the genetic diversity of ex situ collections of E. ferox germplasm from different geographical states of India using microsatellite (simple sequence repeats (SSRs)) markers. Ten SSR markers were analyzed to assess DNA fingerprinting and genetic diversity of 16 cultivated germplasm of E. ferox. Total 37 polymorphic alleles were recorded with an average of 3.7 allele frequency per primer. The polymorphic information content value varied from 0.204 to 0.735 with mean of 0.448. A high range of heterozygosity (Ho 0.228; He 0.512) was detected in the present study. The neighbor-joining (N-J) tree and the principle coordinate analysis showed that the germplasm divided in to three main clusters. The results of the present investigation comply that SSR markers are effective for computing genetic assessment of genetic diversity and similarity with classifying cultivated varieties of E. ferox. Evaluation of genetic diversity among Indian E. ferox germplasm could provide useful information for genetic improvement.

Evaluation of Clonal Fidelity of Micropropagated Date Palm by Random Amplified Polymorphic DNA (RAPD)

Date palm is a fruit-bearing tree commonly found in arid and semiarid regions. It is a dioecious plant, producing fruit on female plants and a limited number of basal offshoots for propagation. To produce large numbers of uniform plantlets, tissue culture techniques are required. It is highly advisable to detect genetic variation that may occur through micropropagation techniques as it may lead to phenotypic alterations. Random amplified polymorphic DNA (RAPD) is a simple and PCR-based molecular marker technique which can be employed to check the somaclonal variation. Screening of markers requires repeated confirmation of the pattern obtained in individual samples.