Reena Gupta

Bio: Reena Gupta is an academic researcher from Himachal Pradesh University. The author has contributed to research in topics: Lipase & Immobilized enzyme. The author has an hindex of 21, co-authored 95 publications receiving 2446 citations.

Microbial pectinolytic enzymes: A review

Abstract: Pectinases or petinolytic enzymes, hydrolyze pectic substances. They have a share of 25% in the global sales of food enzymes. Pectinases are one of the most widely distributed enzymes in bacteria, fungi and plants. Protopectinases, polygalacturonases, lyases and pectin esterases are among the extensively studied pectinolytic enzymes. Protopectinases catalyze the solubilization of protopectin. Polygalacturonases hydrolyze the polygalacturonic acid chain by addition of water and are the most abundant among all the pectinolytic enzymes. Lyases catalyze the trans-eliminative cleavage of the galacturonic acid polymer. Pectinesterases liberate pectins and methanol by de-esterifying the methyl ester linkages of the pectin backbone. Pectinolytic enzymes are of significant importance in the current biotechnological era with their all-embracing applications in fruit juice extraction and its clarification, scouring of cotton, degumming of plant fibers, waste water treatment, vegetable oil extraction, tea and coffee fermentations, bleaching of paper, in poultry feed additives and in the alcoholic beverages and food industries. The present review mainly contemplates on the types and structure of pectic substances, the classification of pectinolytic enzymes, their assay methods, physicochemical and biological properties and a bird's eye view of their industrial applications.

Production, purification, and characterization of lipase from thermophilic and alkaliphilic Bacillus coagulans BTS-3.

Abstract: A thermophilic isolate Bacillus coagulans BTS-3 produced an extracellular alkaline lipase, the production of which was substantially enhanced when the type of carbon source, nitrogen source, and the initial pH of culture medium were consecutively optimized. Lipase activity 1.16 U/ml of culture medium was obtained in 48 h at 55 °C and pH 8.5 with refined mustard oil as carbon source and a combination of peptone and yeast extract (1:1) as nitrogen sources. The enzyme was purified 40-fold to homogeneity by ammonium sulfate precipitation and DEAE–Sepharose column chromatography. Its molecular weight was 31 kDa on SDS–PAGE. The enzyme showed maximum activity at 55 °C and pH 8.5, and was stable between pH 8.0 and 10.5 and at temperatures upto 70 °C. The enzyme was found to be inhibited by Al 3+ , Co 2+ , Mn 2+ , and Zn 2+ ions while K + , Fe 3+ , Hg 2+ , and Mg 2+ ions enhanced the enzyme activity; Na + ions have no effect on enzyme activity. The purified lipase showed a variable specificity/hydrolytic activity towards various 4-nitrophenyl esters.

Glutaraldehyde activation of polymer Nylon-6 for lipase immobilization: Enzyme characteristics and stability

Abstract: An extracellular alkaline lipase of a thermo tolerant Bacillus coagulans BTS-3 was immobilized onto glutaraldehyde activated Nylon-6 by covalent binding. Under optimum conditions, the immobilization yielded a protein loading of 228 μg/g of Nylon-6. Immobilized enzyme showed maximum activity at a temperature of 55 °C and pH 7.5. The enzyme was stable between pH 7.5–9.5. It retained 88% of its original activity at 55 °C for 2 h and also retained 85% of its original activity after eight cycles of hydrolysis of p -NPP. Kinetic parameters K m and V max were found to be 4 mM and 10 μmol/min/ml, respectively. The influence of organic solvents on the catalytic activity of immobilized enzyme was also evaluated. The bound lipase showed enhanced activity when exposed to n -heptane. The substrate specificity of immobilized enzyme revealed more efficient hydrolysis of higher carbon length (C-16) ester than other ones.

Polyhydroxyalkanoate (PHA): Properties and Modifications

Abstract: There are a wide range of biopolymers produced by a number of different microorganisms. Polyhydroxyalkanoates are also a diverse group among these biopolymers. In recent times, PHA is gaining a lot of attraction due to its properties like biodegradability, biocompatibility, hydrophobicity, etc. but on the other hand, these biopolymers also possess some disadvantages which limit their competition with synthetic polymers. Therefore, to overcome these limitations, PHAs are being modified to improve their properties for their potential applications in different fields. This review comprises different PHA modification methods which include physical bending using natural and synthetic polymers, different approaches of chemical modification and some biological modification methods. The aim of this review is to represent new approaches and ideas to improve the degradable properties of PHAs and to present them as one of the valuable and eco-friendly biopolymer, so that, they can contribute their potentials in various fields.

Biodiesel production by transesterification using immobilized lipase

Abstract: Biodiesel can be produced by transesterification of vegetable or waste oil catalysed by lipases. Biodiesel is an alternative energy source to conventional fuel. It combines environmental friendliness with biodegradability, low toxicity and renewability. Biodiesel transesterification reactions can be broadly classified into two categories: chemical and enzymatic. The production of biodiesel using the enzymatic route eliminates the reactions catalysed under acid or alkali conditions by yielding product of very high purity. The modification of lipases can improve their stability, activity and tolerance to alcohol. The cost of lipases and the relatively slower reaction rate remain the major obstacles for enzymatic production of biodiesel. However, this problem can be solved by immobilizing the enzyme on a suitable matrix or support, which increases the chances of re-usability. The main factors affecting biodiesel production are composition of fatty acids, catalyst, solvents, molar ratio of alcohol and oil, temperature, water content, type of alcohol and reactor configuration. Optimization of these parameters is necessary to reduce the cost of biodiesel production.

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

Industrial applications of microbial lipases

Abstract: Lipases are a class of enzymes which catalyse the hydrolysis of long chain triglycerides. Microbial lipases are currently receiving much attention with the rapid development of enzyme technology. Lipases constitute the most important group of biocatalysts for biotechnological applications. This review describes various industrial applications of microbial lipases in the detergent, food, flavour industry, biocatalytic resolution of pharmaceuticals, esters and amino acid derivatives, making of fine chemicals, agrochemicals, use as biosensor, bioremediation and cosmetics and perfumery.

Bioconversion of lignocellulosic biomass: biochemical and molecular perspectives

Abstract: In view of rising prices of crude oil due to increasing fuel demands, the need for alternative sources of bioenergy is expected to increase sharply in the coming years. Among potential alternative bioenergy resources, lignocellulosics have been identified as the prime source of biofuels and other value-added products. Lignocelluloses as agricultural, industrial and forest residuals account for the majority of the total biomass present in the world. To initiate the production of industrially important products from cellulosic biomass, bioconversion of the cellulosic components into fermentable sugars is necessary. A variety of microorganisms including bacteria and fungi may have the ability to degrade the cellulosic biomass to glucose monomers. Bacterial cellulases exist as discrete multi-enzyme complexes, called cellulosomes that consist of multiple subunits. Cellulolytic enzyme systems from the filamentous fungi, especially Trichoderma reesei, contain two exoglucanases or cellobiohydrolases (CBH1 and CBH2), at least four endoglucanases (EG1, EG2, EG3, EG5), and one β-glucosidase. These enzymes act synergistically to catalyse the hydrolysis of cellulose. Different physical parameters such as pH, temperature, adsorption, chemical factors like nitrogen, phosphorus, presence of phenolic compounds and other inhibitors can critically influence the bioconversion of lignocellulose. The production of cellulases by microbial cells is governed by genetic and biochemical controls including induction, catabolite repression, or end product inhibition. Several efforts have been made to increase the production of cellulases through strain improvement by mutagenesis. Various physical and chemical methods have been used to develop bacterial and fungal strains producing higher amounts of cellulase, all with limited success. Cellulosic bioconversion is a complex process and requires the synergistic action of the three enzymatic components consisting of endoglucanases, exoglucanases and β-glucosidases. The co-cultivation of microbes in fermentation can increase the quantity of the desirable components of the cellulase complex. An understanding of the molecular mechanism leading to biodegradation of lignocelluloses and the development of the bioprocessing potential of cellulolytic microorganisms might effectively be accomplished with recombinant DNA technology. For instance, cloning and sequencing of the various cellulolytic genes could economize the cellulase production process. Apart from that, metabolic engineering and genomics approaches have great potential for enhancing our understanding of the molecular mechanism of bioconversion of lignocelluloses to value added economically significant products in the future.

Polymeric materials with antimicrobial activity

Abstract: This article describes the state of the art in the field of antimicrobial polymeric systems during the last decade. Keeping in mind the multitude of existing systems, a classification of the different materials is carried out dividing basically those synthetic polymers that: (a) exhibit antimicrobial activity by themselves; (b) those whose biocidal activity is conferred through their chemical modification; (c) those that incorporate antimicrobial organic compounds with either low or high molecular weight; and (d) those that involve the addition of active inorganic systems. This classification is not absolutely unique and in occasions some described polymeric systems could belong to more than one section. However, the purpose of this review is to provide a handy overall vision of the antimicrobial synthetic polymers world.

Enzyme immobilization: an overview on techniques and support materials.

Abstract: The current demands of the world’s biotechnological industries are enhancement in enzyme productivity and development of novel techniques for increasing their shelf life. These requirements are inevitable to facilitate large-scale and economic formulation. Enzyme immobilization provides an excellent base for increasing availability of enzyme to the substrate with greater turnover over a considerable period of time. Several natural and synthetic supports have been assessed for their efficiency for enzyme immobilization. Nowadays, immobilized enzymes are preferred over their free counterpart due to their prolonged availability that curtails redundant downstream and purification processes. Future investigations should endeavor at adopting logistic and sensible entrapment techniques along with innovatively modified supports to improve the state of enzyme immobilization and provide new perspectives to the industrial sector.