IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Synthesis of nanoparticles with interesting physico-chemical properties using efficient as well as eco-friendly technology is one of the main objectives of nanotechnology. Biological systems have been reported to synthesize inorganic materials under certain circumstances. Exploiting the biosynthetic potential of different organisms, nanoparticles of varying morphologies and sizes have been synthesized. Among the nanomaterials, gold has received considerable attention owing to its varied applications in the fields of nano-medicine, catalysis, electronics, and optics. This review gives an account on the biosynthesis of gold nanoparticles from microorganisms, plants, and other biological sources, with particular emphasis on the probable mechanisms leading to the formation of gold nanoparticles and the extent of control over nanoparticle properties that has been achieved so far in the biosynthetic protocols. It has been speculated that enzymes and/or proteins secreted by the organisms are involved in the bio-reduction and stabilization of the nanoparticles. The biosynthetic procedures could compete with existing solvent-based chemical synthetic procedures in order to achieve stable and monodisperse gold nanoparticles in large scale. Copyright © 2011 American Scientific Publishers All rights reserved.

Department Of Chemical Engineering

Journal of Nanoscience and Nanotechnology

Biosynthesis of gold nanoparticles

Nano drug delivery system is the latest technology employed in various medicinal applications. This technology can be adapted to the conventional drug administration due to its site-specific targeting phenomena. The oral lipophilic drug administration has its drawbacks due to poor solubility and bioavailability. Lipid-based carrier systems are now widely popular due to improved efficiency, especially for lovastatin delivery. Lovastatin is an important drug which arrests the rate-limiting step of the cholesterol cascade. This drug has short half-lives, poor oral-administered bioavailability, poor solubility, and is rapidly metabolizable. Based on the composition, the drug delivery carriers are classified into solid lipid nanoparticles (SLNs), lipid emulsions (LEs), and nanostructured lipid carriers (NLCs). Among them, NLCs are a smarter generation of drug delivery carriers for lovastatin. The selection of various lipid systems and their formulation are discussed in this paper. Moreover, the characterization of these carrier systems to achieve the optimal characteristic features is discussed in a concise manner. © Seenivasan et al.

Fulltext

Open Biotechnology Journal

Lovastatin nanoparticle synthesis and characterization for better drug delivery

Studies on the various cholesterol-lowering agents is one of the important areas in clinical research. Identification and characterization of potential molecules from various sources have been carried out in the past and their relationship with the enzymes which are involved in the cholesterol cascade is gaining interest. In this review, we have highlighted various inhibitors involved in the cholesterol cascade as well as cholesterol-lowering agents, viz., tocotrienol, flavonoids, phytosterols, phytostanols, statins, DADS, and synthetic compounds. The mechanism of action and characterization of these hypocholesterolemic compounds are discussed in this communication. Major natural sources as well as synthetic and biological routes of synthesis of these compounds are reviewed in a concise manner. Especially, various HMG-CoA analogues including statins have been reviewed specifically. © Seenivasan et al.

Open Enzyme Inhibition Journal

Characterization, modes of synthesis, and pleiotropic effects of hypocholesterolemic compounds - a review

Various options in biotechnology have been exercised to produce industrially important metabolites from filamentous organisms. To select a suitable production strategy, the direct and indirect roles of morphological parameters in controlling bioprocess variables are observed. Some progress has been made in quantitation of morphology.Useful correlations have been reported in the literature in this avenue. Of course, some of the models, with proper modification, can be used to explain the morphological phenomena. This review is concerned with the application of morphological variables to correlate with bioprocess parameters for explaining optimal production strategy. © Panda and Rameshaiah; Licensee Bentham Open.

Application of actinobacterial and fungal morphology on the design of operating strategies in bioprocess development

A suitable simple model tested by experiments is required to address complex biological reaction like esterase synthesis by Saccharomyces cerevisiae. Such an approach might be the answer to a proper bioprocessing strategy. In this regard, a logistic model for esterase production from Saccharomyces cerevisiae has been developed, which predicts well the cell mass, the carbon source (glucose) consumption, and the esterase activity. The accuracy of the model has been statistically examined by using the Student's t-test. The parameter sensitivity analysis showed that all five parameters (μm, Ks, Xm, Yx/s, and Yp/x) have significant influence on the predicted values of esterase activity. © The Korean Society for Microbiology and Biotechnology.

Journal of Microbiology and Biotechnology

Modeling of esterase production from Saccharomyces cerevisiae

The generalized distance function approach is employed to obtain a suitable near optimal conditions of variables. The optimal values of variables (medium constituents, microbiological parameters, and process parameters) have been evaluated separately using single responses (either specific esterase activity or cell mass) as per central-composite-design and multi-responses following generalized distance function approach. The optimal conditions (medium composition (g l-1): dextrose, 13.43; peptone, 7.285; yeast extract, 2.55; and malt extract, 1.695; microbiological parameters: slant age, 39.9 h; inoculum age, 9.6 h; and number of cells, 1.49 × 108 numbers ml-1; process conditions: temperature, 29.9 °C; and pH, 6.2) obtained by generalized distance approach can be considered as a 'near optimal' solution of interactive multi-response systems of intracellular esterase synthesis by Saccharomyces cerevisiae. © 2007 Elsevier Ltd. All rights reserved.

Bioresource Technology

Critical analysis of application of generalized distance function for optimization of important variables for esterase synthesis by Saccharomyces cerevisiae

Models of single cells, cell populations, and cultures can be most useful in organizing information in a comprehensive system description, as well as in optimizing and controlling actual production operations. Models discussed in this article are of various degrees of biological structure and mathematical complexity. The models are developed based on the biomass formation, substrate consumption, and product formation. The potentials and the limitations of all the models have been reported. The parameter estimation by different methods has been discussed in this communication. These parameters will be helpful to explore the areas where future-modeling studies may be especially valuable. © 2006 Springer-Verlag.

Applied Microbiology and Biotechnology

Modeling of enzyme production kinetics

A modified mixing plane approach for steady state simulation of flow field in fully baffled biological reactor is presented and discussed. Without requiring any experimental input, this approach of dividing the vessel into suitable number of connected and disconnected zones; solving steady state equation separately in each zone and then transferring information between them, provides a computationally less intensive alternative for simulating the flow in the whole vessel. Impeller used is the standard Rushton Turbine positioned at mid-height of the reactor and simulations are carried out using standard k-ε turbulence model implemented in CFD code FLUENT. Meshing is done using tetrahedral elements such that mesh size gradually increases from the center to the periphery. Most of the previous simulation works present only a few aspects of the flow field with scant importance to the energy balance in the tank and near tip turbulence. In this work, complete model prediction for velocity field and turbulence parameters (near tip and in the bulk region) are validated by comparison with experimental data. As compared to previous simulation works, the results predicted by this "Differential circumferential averaging mixing plane approach" show a better qualitative and quantitative agreement with the published experimental data. A distribution of energy dissipation in various zones of vessel is presented. Also a qualitative picture of flow field and stagnant zones inside the reactor is presented and discussed. Comparison of flow characteristics for different number of baffles shows that for the present dimension of the vessel, five baffles gives maximum enhanced mixing. © 2006 Wiley Periodicals, Inc.

Department of Mechanical Engineering

Biotechnology and Bioengineering

Numerical simulation of a fully baffled biological reactor: The differential circumferential averaging mixing plane approach

A Simplified version of rate equations for enzyme-catalyzed reactions has been developed in which the rate equation is analyzed with two different mechanisms: ordered bi-ter and Ping-Pong bi-bi mechanisms. This procedure is able to develop the rate expressions accurately. Random sequential order mechanism can be effectively explained by this approach. © 2006 Springer Science+Business Media, Inc.

Biotechnology Letters

Simplified approach for developing the rate expressions for enzyme-catalyzed reactions

Esterase plays a major role in the degradation of natural materials and industrial pollutants, viz., cereal wastes, plastics, and other toxic chemicals. It is useful in the synthesis of optically pure compounds, perfumes, and antioxidants. The potential applications of esterase with reference to agriculture, food, and pharmaceutical industries, are discussed in this review. Promising applications in this avenue can be supported by appropriate production strategies. © Springer-Verlag 2005.

Production and applications of esterases

The synthesis of pectolytic enzymes appears to be considerably influenced by the glucose content of the cultivation medium containing mixed carbon sources in a predetermined optimal ratio. Glucose is an essential component in the fermentation, promoting cell growth while the synthesis of pectolytic enzymes was found to be induced by the second carbon source, corn, only when the glucose concentration in the medium was significantly low. Studies conducted to examine the effect of glucose showed that glucose severely reduced the synthesis of polygalacturonase and polymethylgalacturonase at concentrations above 5g/l while pectinlyase was unaffected. In vitro studies showed that the inhibition of the two pectin hydrolases was reversible and competitive in nature. The results of the study also indicate induction of pectolytic enzymes by corn in Aspergillus niger NCIM 548. © 2004 Elsevier Inc. All rights reserved.

GENERAL

Enzyme and Microbial Technology

Regulation of synthesis of the pectolytic enzymes of Aspergillus niger

The enzyme, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) controls the biosynthesis of cholesterol. Hypercholesterolemia and atherosclerosis are critical health risk factors. One way of controlling these risk factors is to manipulate regulation as well as degradation of HMGR. At present, a class of compounds called statins, which are HMGR inhibitors, are used for the treatment of hypercholesterolemia. However, statins suffer major setbacks as their use produces more adverse reactions than the desirable one of inhibiting the enzyme. Genetically engineered forms of HMGR are also studied in primitive life forms like bacteria, but detailed investigation of this enzyme in human systems is certainly required. Extensive studies have been made on the regulatory aspects of this enzyme, but no breakthrough is conspicuous in the clinical background to find an alternative treatment for hypercholesterolemia. The immediate need is to find an alternate way of regulating degradation of the enzyme. This review presents the importance of regulation and degradation of the HMGR enzyme in different systems to gain possible insight into alternative schemes for regulating this enzyme and, if these exist, the feasibility of extending them same to studies in mammalian systems. A high degree of similarity exists between mammalian and yeast HMGR. Detailed studies reported on the regulation and degradation of the yeast enzyme also throw more light on the mammalian system, leading to a better understanding of ways of controlling hypercholesterolemia. © Springer-Verlag 2004.

Regulation and degradation of HMGCo-A reductase

The critical parameters, such as slant age, mycelium age and contact time of mycelium with lytic enzymes which affects the formation of protoplast from the Penicillium griseofulvum mycelium were studied using a novel technique called response surface methodology. The design used to optimize these parameters was full factorial central composite design. The number of protoplasts, viability of protoplasts and griseofulvin yield are the three responses studied in this communication. The individual optimum values of slant age, inoculum age and contact time obtained are 187.1, 30.81, 21.4 h, respectively, for number of protoplast/ml 68.92, 33.01, 9.88 h, respectively, for percentage viability of protoplasts and 230.2, 73.6, 31.2 h, respectively, for griseofulvin. In order to obtain a single optimum value for all the three responses, a multi-response analysis was carried out using a generalized distance approach. The simultaneous optimum values of slant age, inoculum age and contact time are 133.78, 37.1 and 15.97 h, respectively, for all the three responses. © 2003 Elsevier Science B.V. All rights reserved.

Department Of Biotechnology

Biochemical Engineering Journal

Statistical analysis on some critical parameters affecting the formation of protoplasts from the mycelium of Penicillium griseofulvum

Pectolytic enzymes, viz., polymethylgalacturonase (PMG), polygalacturonase (PG), and pectinlyase (PL) were deactivated at various combinations of pH and temperature. The deactivation process was modelled as first-order kinetics and the deactivation rate constant was found to be minimum at pH 2.2 and 23 °C, respectively for PMG, 4.8 and 28 °C, respectively for PG and 3.9 and 29 °C, respectively for PL. Thermodynamic parameters like ΔG*, ΔH*, ΔS*, and activation energies were evaluated for crude and partially purified enzymes. It was found that entropy values are negative for all the three enzymes. The partially purified enzymes were found to be less stable than the crude enzymes. Hence, the interaction effect among the enzymes and also the effect of protein (BSA) on deactivation were studied. The addition of protein doubled the half-life times of partially purified PMG, PG I and PG II. The interaction effect of pectolytic enzymes on deactivation was found to be significant. © 2003 Elsevier Science B.V. All rights reserved.

Studies on pH and thermal deactivation of pectolytic enzymes from Aspergillus niger

Taguchi's method was applied to evaluate the significant parameters for griseofulvin production by Penicillium griseofulvum MTCC 1898 in a batch bioreactor. Physical parameter, viz., controlled pH, agitation and aeration had a significant influence on griseofulvin production when compared with chemical parameters and were considered as significant ones. © 2002 Published by Elsevier Science Ltd.

Process Biochemistry

Determination of significant parameters for improved griseofulvin production in a batch bioreactor by Taguchi's method

Pectinases are a complex group of enzymes that degrade various pectic substances present in plant tissues. Pectinases have potential applications in fruit, paper and textile industries. Apart from these industrial applications, these enzymes possess biological importance in protoplast fusion technology and plant pathology. Since applications of pectinases in various fields are widening, it is important to understand the nature and properties of these enzymes for efficient and effective usage. For the past few years, vigorous research has been carried out on isolation and characterization of pectinases. New affinity matrices with improved characteristics and affinity-precipitation techniques have been developed for purification of pectinases. Recently much attention has been focused on chemical modification of pectinases and their catalytic performance by various researchers. These studies are helpful in determining key amino acid residues responsible for substrate binding, catalytic action, and physico-chemical environmental conditions for maximum hydrolysis. This short review highlights progress on purification and understanding the biochemical aspects of microbial pectinases. © 2002 Elsevier Science Ltd. All rights reserved.

Purification and biochemical properties of microbial pectinases - A review

Stability studies and kinetics of β-1,3-glucanase from Trichoderma harzianum NCIM 1185 are reported. The critical parameters, pH and temperature, affecting the stability of β-1,3-glucanase were optimized using response surface methodology. The optimal combination of pH and temperature were 3.6 and 41 °C, respectively. The stability of β-1,3-glucanase was studied at various conditions of pH and temperature above the optimal conditions. Since the final activity was not zero, a non-first order deactivation model was used to explain the experimental data. Enzyme kinetic studies were carried out with and without inhibitors. Cu2+ behaved as a noncompetitive- uncompetitive mixed inhibitor, whereas EDTA and NH4+ behaved as competitive-noncompetitive type mixed inhibitors during the hydrolysis of β-1,3-glucan. © 2002 Elsevier Ltd. All rights reserved.

Stability and kinetics of β-1,3-glucanse from Trichoderma harzianum

Enzyme kinetics data play a vital role in the design of reactors and control of processes. In the present study, kinetic studies on pectinases were carried out. Partially purified polymethylgalacturonase (PMG) and polygalacturonase (PG) were the two pectinases studied. The plot of initial rate vs. initial substrate concentration did not follow the conventional Michaelis-Menten kinetics, but substrate inhibition was observed. For PMG, maximum rate was attained at an initial pectin concentration of 3 g/l, whereas maximum rate was attained when the initial substrate concentration of 2.5 g/l of polygalacturonic acid for PG I and PG II. The kinetic data were fitted to five different kinetic models to explain the substrate inhibition effect. Among the five models tested, the combined mechanism of protective diffusion limitation of both high and inhibitory substrate concentrations (semi-empirical model) explained the inhibition data with 96-99% confidence interval.

Analysis of kinetic data of pectinases with substrate inhibition

The Plackett-Burman experimental design was employed to evaluate the relative importance of medium constituents of each medium for enhanced griseofulvin production by Penicillium griseofulvum MTCC 1898 and Penicillium griseofulvum MTCC 2004. It was found that the medium constituents, sucrose, K2HPO4, NaNO3, and FeSO4.7H2O, significantly influenced the griseofulvin production by Penicillium griseofulvum MTCC 1898. In the case of Penicillium griseofulvum MTCC 2004, lactose, glucose, and MnSO4·H2O significantly influenced the griseofulvin production.

Development of medium for griseofulvin production: Part I. Screening of medium constituents using the Plackett-Burman experimental design

Central composite experimental design was employed to determine the optimal concentration of medium constituents for griseofulvin production by Penicillium griseofulvum MTCC 1898 and Penicillium griseofulvum MTCC 2004. The optimal concentration of sucrose, K2HPO4, NaNO3, and FeSO4.7H2O were found to be 48.08 g/l, 1.228 g/l, 2.7 g/l, and 0.011 g/l, respectively, for Penicillium griseofulvum MTCC 1898, and for Penicillium griseofulvum MTCC 2004, 23.52 g/l, 43.67 g/l, and 0.0434 g/l of glucose, lactose, and MnSO4·H2O, respectively. The yield of griseofulvin under optimal composition of medium constituents increased by 1.26 and 1.38 times than prior to optimization, for Penicillium griseofulvum MTCC 1898 and Penicillium griseofulvum MTCC 2004, respectively.