Som Dutt

Bio: Som Dutt is an academic researcher from Indian Council of Agricultural Research. The author has contributed to research in topics: Picrorhiza & Resistant starch. The author has an hindex of 16, co-authored 51 publications receiving 1316 citations. Previous affiliations of Som Dutt include Council of Scientific and Industrial Research & Academy of Scientific and Innovative Research.

A rapid and easy method for the detection of microbial cellulases on agar plates using gram's iodine

Abstract: Screening for cellulase-producing microorganisms is routinely done on carboxymethylcellulose (CMC) plates. The culture plates are flooded either with 1% hexadecyltrimethyl ammonium bromide or with 0.1% Congo red followed by 1 M NaCl. In both cases, it takes a minimum of 30 to 40 minutes to obtain the zone of hydrolysis after flooding, and the hydrolyzed area is not sharply discernible. An improved method is reported herein for the detection of extracellular cellulase production by microorganisms by way of plate assay. In this method, CMC plates were flooded with Gram’s iodine instead of the reagents just mentioned. Gram’s iodine formed a bluish-black complex with cellulose but not with hydrolyzed cellulose, giving a sharp and distinct zone around the cellulase-producing microbial colonies within 3 to 5 minutes. The new method is rapid and efficient; therefore, it can be easily performed for screening large numbers of microbial cultures of both bacteria and fungi. This is the first report on the use of Gram’s iodine for the detection of cellulase production by microorganisms using plate assay.

Recent updates on bioaccessibility of phytonutrients

Abstract: Background Fruits and vegetables are rich source of phytonutrients. These phytonutrients are present in high concentrations in raw form, and decrease to some extent after processing. The major phytonutrients present in fruits and vegetables are vitamins, carotenoids, polyphenols, curcuminoids, polyunsaturated fatty acids, proteins, peptides, dietary fibers, oligosaccharides, and minerals that exhibit multiple beneficial effects on human health. Lots of research work has been carried out on assessing these phytonutrients in various fruits and vegetables however very limited knowledge is available on assessment of how much of these phytonutrients are available to exert their biological function in the human body. Scope and approach In this review we attempted to provide updated information regarding the methods used for assessing bioaccessibility, extent of bioaccessibile phytonutrients from different food matrix and effect of different processing (boiling, microwaving, frying) and preservation techniques (dehydration and freezing) on bioaccessibility of phytonutrients. Key Finding and Conclusions Food matrix, processing and preservation methods have major influence on the bioaccessibility of phytonutrients. Cooking, frying and pasteurization increased the bioaccessibility of polyphenols and carotenoids in fruits and vegetables. Dehydration can be a good technique to enhance the bioaccessibility of carotenoids. Freezing showed contradictory response on bioaccessibility as it increased bioaccessibility of phytonutrients in some fruits and decreased in others. To achieve maximum bioaccessibility of carotenoids, thermal treatment along with addition of oil is the best; to enhance ascorbic acid and polyphenols bioaccessibility thermal treatment is the best and for enhanced bioaccessibility of mineral and tocopherols high pressure-processing is most suitable.

Light and temperature regulated terpene biosynthesis: hepatoprotective monoterpene picroside accumulation in Picrorhiza kurrooa

Abstract: Picrorhiza (Picrorhiza kurrooa) is an endangered medicinal plant with well-known hepatoprotective activity attributed to monoterpenoid picrosides. The present article details on regulatory genes of terpenoid metabolism, 3-hydroxy-3-methylglutaryl coenzyme A reductase (pkhmgr) and 1-deoxy-D-xylulose-5-phosphate synthase (pkdxs) from picrorhiza. Since no molecular information was available, these genes were cloned to full-length by degenerate primers and rapid amplification of cDNA ends, followed by cloning of the upstream sequences that showed the presence of core sequences for light and temperature responsiveness. Electrophoretic mobility shift assay confirmed binding of protein to these motifs. Expression of pkhmgr and pkdxs was up-regulated at 15°C as compared to at 25°C as well as under light as compared to dark conditions. Picrosides content exhibited the trend similar to gene expression. To rule out the possible limitation of carbon pool under dark condition, plantlets of picrorhiza were raised in vitro in Murashige and Skoog medium supplemented with 3% sucrose. Results showed similar up-regulation of both the genes and the higher picrosides content in in vitro raised plantlets in the presence of light. Data suggested the important roles played by light and temperature in regulating pkhmgr and pkdxs, and the picrosides level in picrorhiza.

The basic and applied aspects of superoxide dismutase

Abstract: Superoxide dismutase (SOD) is among the most potent antioxidants known in nature and is an important constituent of cellular defence against oxidative stress. The enzyme shows several interesting properties like very high catalytic rate of reaction and high stability to physico-chemical stress. It has also attracted widespread interest due to its therapeutic potential. Oxidative stress is known to be involved in pathophysiology of several diseases and SOD supplementation has been shown to be beneficial in treatment or prevention of such diseases. However, it is yet to be developed into effective, reliable and safe antioxidant therapy. Current review focuses on the physiological importance of SOD, and developments and obstacles in its therapeutic applications for treatment of various disorders. The review also summarizes SOD-based products and patents, its potentiation to improve efficacy, and major clinical trials of SOD in human subjects. Besides, latest literature on phylogeny and biochemistry of the enzyme is also reviewed.

Engineering a thermo-stable superoxide dismutase functional at sub-zero to >50°C, which also tolerates autoclaving

Abstract: Superoxide dismutase (SOD) is a critical enzyme associated with controlling oxygen toxicity arising out of oxidative stress in any living system. A hyper-thermostable SOD isolated from a polyextremophile higher plant Potentilla atrosanguinea Lodd. var. argyrophylla (Wall. ex Lehm.) was engineered by mutation of a single amino acid that enhanced the thermostability of the enzyme to twofold. The engineered enzyme was functional from sub-zero temperature to >50°C, tolerated autoclaving (heating at 121°C, at a pressure of 1.1 kg per square cm for 20 min) and was resistant to proteolysis. The present work is the first example to enhance the thermostability of a hyper-thermostable protein and has potential to application to other proteins for enhancing thermostability.

Response of Phenylpropanoid Pathway and the Role of Polyphenols in Plants under Abiotic Stress.

Abstract: Phenolic compounds are an important class of plant secondary metabolites which play crucial physiological roles throughout the plant life cycle. Phenolics are produced under optimal and suboptimal conditions in plants and play key roles in developmental processes like cell division, hormonal regulation, photosynthetic activity, nutrient mineralization, and reproduction. Plants exhibit increased synthesis of polyphenols such as phenolic acids and flavonoids under abiotic stress conditions, which help the plant to cope with environmental constraints. Phenylpropanoid biosynthetic pathway is activated under abiotic stress conditions (drought, heavy metal, salinity, high/low temperature, and ultraviolet radiations) resulting in accumulation of various phenolic compounds which, among other roles, have the potential to scavenge harmful reactive oxygen species. Deepening the research focuses on the phenolic responses to abiotic stress is of great interest for the scientific community. In the present article, we discuss the biochemical and molecular mechanisms related to the activation of phenylpropanoid metabolism and we describe phenolic-mediated stress tolerance in plants. An attempt has been made to provide updated and brand-new information about the response of phenolics under a challenging environment.

The prospects of cellulase-producing bacteria for the bioconversion of lignocellulosic biomass.

Abstract: Lignocellulosic biomass is a renewable and abundant resource with great potential for bioconversion to value-added bioproducts. However, the biorefining process remains economically unfeasible due to a lack of biocatalysts that can overcome costly hurdles such as cooling from high temperature, pumping of oxygen/stirring, and, neutralization from acidic or basic pH. The extreme environmental resistance of bacteria permits screening and isolation of novel cellulases to help overcome these challenges. Rapid, efficient cellulase screening techniques, using cellulase assays and metagenomic libraries, are a must. Rare cellulases with activities on soluble and crystalline cellulose have been isolated from strains of Paenibacillus and Bacillus and shown to have high thermostability and/or activity over a wide pH spectrum. While novel cellulases from strains like Cellulomonas flavigena and Terendinibacter turnerae, produce multifunctional cellulases with broader substrate utilization. These enzymes offer a framework for enhancement of cellulases including: specific activity, thermalstability, or end-product inhibition. In addition, anaerobic bacteria like the clostridia offer potential due to species capable of producing compound multienzyme complexes called cellulosomes. Cellulosomes provide synergy and close proximity of enzymes to substrate, increasing activity towards crystalline cellulose. This has lead to the construction of designer cellulosomes enhanced for specific substrate activity. Furthermore, cellulosome-producing Clostridium thermocellum and its ability to ferment sugars to ethanol; its amenability to co-culture and, recent advances in genetic engineering, offer a promising future in biofuels. The exploitation of bacteria in the search for improved enzymes or strategies provides a means to upgrade feasibility for lignocellulosic biomass conversion, ultimately providing means to a 'greener' technology.

Conservation and Diversity of Seed Associated Endophytes in Zea across Boundaries of Evolution, Ethnography and Ecology

Abstract: Endophytes are non-pathogenic microbes living inside plants. We asked whether endophytic species were conserved in the agriculturally important plant genus Zea as it became domesticated from its wild ancestors (teosinte) to modern maize (corn) and moved from Mexico to Canada. Kernels from populations of four different teosintes and 10 different maize varieties were screened for endophytic bacteria by culturing, cloning and DNA fingerprinting using terminal restriction fragment length polymorphism (TRFLP) of 16S rDNA. Principle component analysis of TRFLP data showed that seed endophyte community composition varied in relation to plant host phylogeny. However, there was a core microbiota of endophytes that was conserved in Zea seeds across boundaries of evolution, ethnography and ecology. The majority of seed endophytes in the wild ancestor persist today in domesticated maize, though ancient selection against the hard fruitcase surrounding seeds may have altered the abundance of endophytes. Four TRFLP signals including two predicted to represent Clostridium and Paenibacillus species were conserved across all Zea genotypes, while culturing showed that Enterobacter, Methylobacteria, Pantoea and Pseudomonas species were widespread, with γ-proteobacteria being the prevalent class. Twenty-six different genera were cultured, and these were evaluated for their ability to stimulate plant growth, grow on nitrogen-free media, solubilize phosphate, sequester iron, secrete RNAse, antagonize pathogens, catabolize the precursor of ethylene, produce auxin and acetoin/butanediol. Of these traits, phosphate solubilization and production of acetoin/butanediol were the most commonly observed. An isolate from the giant Mexican landrace Mixteco, with 100% identity to Burkholderia phytofirmans, significantly promoted shoot potato biomass. GFP tagging and maize stem injection confirmed that several seed endophytes could spread systemically through the plant. One seed isolate, Enterobacter asburiae, was able to exit the root and colonize the rhizosphere. Conservation and diversity in Zea-microbe relationships are discussed in the context of ecology, crop domestication, selection and migration.