Surabhi Chaudhuri

Extracellular alkaline protease from Bacillus licheniformis NCIM‐2042: Improving enzyme activity assay and characterization

Optimization of enzyme assay conditions for alkaline protease from Bacillus licheniformis NCIM‐2042 was carried out by a statistical approach. Four key determinants such as pH, temperature, buffer concentration, and incubation time were optimized by response surface methodology using rotatable central composite design. Maximum enzyme activity was found to be at pH 9.0, temperature 75°C in phosphate buffer (50 mM) when incubated for 10 min. Protease was stable over a broad range of pH 6.0–12.0 and it was stable at 50°C for 1 h. The protease was completely inhibited by PMSF (5 mM), suggesting that the enzyme is a serine alkaline protease. This enzyme had good stability in the presence of H2O2, SDS, Triton X‐100, and retained more than 88% of its initial activity after preincubation for 30 min at room temperature in the presence of 25% v/v DMSO, methanol, ethanol, ACN, and 2‐propanol.

Statistical Optimization of Media Components for Production of Fibrinolytic Alkaline Metalloproteases from Xenorhabdus indica KB-3

Xenorhabdus indica KB-3, a well-known protease producer, was isolated from its entomopathogenic nematode symbiont Steinernema thermophilum. Since medium constituents are critical to the protease production, the chemical components of the selected medium (soya casein digest broth) were optimized by rotatable central composite design (RCCD) using response surface methodology (RSM). The effects of all five chemical components (considered as independent variables), namely tryptone, soya peptone, dextrose, NaCl, and dipotassium phosphate, on protease production (dependent variable) were studied, and it was found that tryptone and dextrose had maximum influence on protease production. The protease production was increased significantly by 66.31% under optimal medium conditions (tryptone—5.71, soya peptone—4.9, dextrose—1.45, NaCl—6.08, and dipotassium phosphate—0.47 in g/L). To best of knowledge, there are no reports on optimization of medium component for protease production by X. indica KB-3 using RSM and their application in fibrinolysis. This study will be useful for industrial processes for production of protease enzyme from X. indica KB-3 for its application in the field of agriculture and medicine.

Characterization and Antioxidant Potential of a Carotenoid from a Newly Isolated Yeast

A newly isolated yeast strain was identified and explored for characteristic growth and pigment production in batch cultures. Based on nucleotide homology and phylogenetic analysis, the strain was identified as Sporidiobolus pararoseus DAGIII (Accession ID-KF724150). Pigment production was carried out using 1% (v/v) of an inoculum at 25ºC and 120 rpm after incubation for 5 days. By HPLC, Elemental, and FTIR analysis, the produced pigment was identified as β-carotene. The antiradical activity was measured and the half maximal inhibitory concentration (IC50) value was 449.11 μg/mL. Optimization of β-carotene production was achieved using a Plackett-Burman design and response surface methodology. A maximum concentration of 15.2614 mg/L of β-carotene was obtained for cultures in a medium containing 21.77 gm/L of dextrose, 20 gm/L of peptone, and 10 gm/L of yeast extract with incubation at 26ºC, an initial pH of 5.3, a shaker speed of 120 rpm, and a percentage inoculum=1.5%.

A sensitivity analysis study of enzyme inhibition kinetics through Cellular Automata

Biochemical reactions are the basis of life, allowing processes move with a time scale. Enzymes are proteins that catalyze the biochemical reactions. These enzyme‐catalyzed reactions are controlled in a number of ways. Among them, inhibitors play a major role. A simulation model helps to monitor the parameters of the reactions at each and every time step, otherwise difficult to analyze experimentally. Cell‐based models, such as Cellular Automata (CA) provide an understanding of the organizational principles of interacting cellular systems, to link the individual cell (microscopic) dynamics with a particular collective (macroscopic) phenomenon. The dynamics are governed only through local rules to produce a global effect from the local changes. In this study, CA model for competitive enzyme‐inhibition reactions have been formulated. The rule framework described in this study is probabilistic. It is found that cellular automata can capture the essential features of a discrete real system without making comp...

Moisture absorption and swelling kinetics in bean seeds: A Generalized Maxwell‐Stefan approach

The swelling kinetics of bean seeds have been modeled according to General Maxwell Stefan (GMS) model to allow for the integration of the swelling behavior on moisture absorption. The set of differential equations are solved using Linear Driving Force (LDF) approach and Homogenous Driving Force (HDF) approach. The simulation results are compared with experimental data. The parameters dependant on properties of bean seed and bean seed‐water together are optimized. HDF approach has shown the intraparticle nature during swelling. The results of the simulation showing the change in effective diffusion coefficient with time indicates that it is better to use Ogston model with LDF, and Hydrodynamic model with HDF.