Sathyanarayana N. Gummadi

Bio: Sathyanarayana N. Gummadi is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Phospholipid scramblase & Caffeine. The author has an hindex of 25, co-authored 139 publications receiving 2332 citations. Previous affiliations of Sathyanarayana N. Gummadi include Indian Institutes of Technology & University of Wisconsin-Madison.

Identification and characterization of oxidoreductase component (NdmD) of methylxanthine oxygenase system in Pseudomonas sp. NCIM 5235

Abstract: Pseudomonas sp. NCIM 5235 is a caffeine-degrading bacterial strain that metabolizes caffeine by sequential demethylation using methylxanthine demethylases. These enzymes belong to the class of two-component Rieske oxygenases and require an oxidoreductase, NdmD, for efficient catalysis. NdmD in Pseudomonas sp. has a unique domain fusion in its N-terminal that is not observed in any other Rieske oxygenase reductases reported so far. In this report, a ~ 1.7 kb ndmD gene from the gDNA of Pseudomonas sp. has been isolated and has been cloned in a pET28a expression vector. Soluble NdmD was over-expressed in Escherichia coli BL21 cells and purified by Ni2+ NTA chromatography. Monomeric molecular mass of the protein was found to be ~ 65 kDa and optimal activity was observed at 35 °C and pH 8.0. It showed broad substrate specificity with highest Kcat/km of 490.8 ± 17.7 towards cytochrome c. To determine the role of N-terminal Rieske domain in its reductase activity, two deletion constructs Δ114NdmD and Δ250NdmD were made. Cytochrome c reductase (ccr) activity of the NdmD constructs and demethylase activity of NdmA in the presence of NdmD constructs showed that there is no significant difference in the catalytic activity of NdmD upon deletion of its N-terminal Rieske domain. However, there might be some functional and evolutionary significance for the fusion of Rieske domain to NdmD and we hypothesize that this domain fusion is an intermediate phase of evolution towards the development of a more efficient enzyme system for xenobiotic degradation.

Enhanced degradation of caffeine and caffeine demethylase production by Pseudomonas sp. in bioreactors under fed-batch mode.

Abstract: The growth of Pseudomonas sp was studied in fed-batch process with an aim to improve the caffeine degradation rate and caffeine demethylase activity The effects of varying initial caffeine concentrations in the batch mode, increase in the number of feeds, varying feed flow rates, and added nutrients to the feed on the fed-batch process were investigated A maximum caffeine degradation rate of 082 g/L h and maximum caffeine demethylase activity of 26 U/mg were achieved using manual intermittent pulse feeds of caffeine with substrate concentration as feedback parameter for the fed batch started with an initial caffeine concentration of 3 g/L A slight increase in the caffeine degradation rate (085 g/L h) and caffeine demethylase activity (34 U/mg) was observed when the additional nutrients were added along with caffeine in the feed This is the first report showing complete degradation of large magnitudes of caffeine amounting to 237 g in 75 h These results show that the fed-batch conditions achieved in this study using Pseudomonas sp facilitate the development of a sustainable bioprocess to degrade the high concentrations of caffeine in industrial effluents

Bacterial extracellular polysaccharides involved in biofilm formation.

Abstract: Extracellular polymeric substances (EPS) produced by microorganisms are a complex mixture of biopolymers primarily consisting of polysaccharides, as well as proteins, nucleic acids, lipids and humic substances. EPS make up the intercellular space of microbial aggregates and form the structure and architecture of the biofilm matrix. The key functions of EPS comprise the mediation of the initial attachment of cells to different substrata and protection against environmental stress and dehydration. The aim of this review is to present a summary of the current status of the research into the role of EPS in bacterial attachment followed by biofilm formation. The latter has a profound impact on an array of biomedical, biotechnology and industrial fields including pharmaceutical and surgical applications, food engineering, bioremediation and biohydrometallurgy. The diverse structural variations of EPS produced by bacteria of different taxonomic lineages, together with examples of biotechnological applications, are discussed. Finally, a range of novel techniques that can be used in studies involving biofilm-specific polysaccharides is discussed.

The distribution and function of phosphatidylserine in cellular membranes.

Abstract: Phosphatidylserine (PS) is the most abundant negatively charged phospholipid in eukaryotic membranes. PS directs the binding of proteins that bear C2 or gamma-carboxyglutamic domains and contributes to the electrostatic association of polycationic ligands with cellular membranes. Rather than being evenly distributed, PS is found preferentially in the inner leaflet of the plasma membrane and in endocytic membranes. The loss of PS asymmetry is an early indicator of apoptosis and serves as a signal to initiate blood clotting. This review discusses the determinants and functional implications of the subcellular distribution and membrane topology of PS.