Shweta Narayana Murthy

Bio: Shweta Narayana Murthy is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Medicine & Biology. The author has an hindex of 3, co-authored 4 publications receiving 47 citations. Previous affiliations of Shweta Narayana Murthy include North Carolina State University.

Production of ethanol and arabitol by Debaryomyces nepalensis : influence of process parameters

Abstract: Debaryomyces nepalensis, osmotolerant yeast isolated from rotten apple, is known to utilize both hexoses and pentoses and produce industrially important metabolites like ethanol, xylitol and arabitol. In the present study, the effect of different growth substrates, trace elements, nitrogen concentration and initial pH on growth and formation of ethanol and arabitol were examined. Optimum conditions for maximizing the product yields were established: glucose as carbon source, an initial pH of 6.0, 6 g/L of ammonium sulphate and addition of micronutrients. Under these best suited conditions, a concentration of 11g/L of arabitol and 19 g/L of ethanol was obtained in shake flask fermentations. The fermentation was scaled up to 2.5 L bioreactor and the influence of aeration, agitation and initial substrate concentration was also determined. Under optimal conditions (150 g/L glucose, 400 rpm and 0.5 vvm) ethanol concentration reached 52 g/L, which corresponds to a yield of 0.34 g/g and volumetric productivity of 0.28 g/L/h, whereas arabitol production reached a maximum of 14 g/L with a yield and volumetric productivity of 0.1 g/g and 0.07 g/L/h respectively.

A Statistical Approach to Optimize Xylitol Production by Debaryomyces nepalensis NCYC 3413 in Vitro

Abstract: Debaryomyces nepalensis NCYC 3413, halotolerant yeast isolated from rotten apple, was capable of utilizing components of hemicellulose hydrolysate such as glucose, galactose, mannose, xylose and arabinose. The organism utilizes xylose as a sole carbon source and produces xylitol. The Plackett-Burman design was applied to determine the specific medium components affecting xylitol production and found that xylose, K2HPO4, and ZnSO4 were critical in augmenting xylitol production. These significant parameters were further optimized using response surface methodology. The optimum concentrations of xylose, K2HPO4, and ZnSO4 were found to be 100 g/l, 10.6 g/l and 8.9 mg/l respectively. Under these optimal conditions the xylitol production increased from 27 g/l to 36 g/l with a yield of 0.44 g/g (57% increase in total yield). In addition, formation of the by product (glycerol) was decreased under optimal conditions.

Identification and characterization of the novel nuclease activity of human phospholipid scramblase 1

Abstract: Background Human phospholipid scramblase 1 (hPLSCR1) was initially identified as a Ca2+ dependent phospholipid translocator involved in disrupting membrane asymmetry. Recent reports revealed that hPLSCR1 acts as a multifunctional signaling molecule rather than functioning as scramblase. hPLSCR1 is overexpressed in a variety of tumor cells and is known to interact with a number of protein molecules implying diverse functions.

Antibiotic Resistance and Molecular Profiling of the Clinical Isolates of Staphylococcus aureus Causing Bovine Mastitis from India

Abstract: Staphylococcus aureus is an opportunistic bacterium known to cause severe infections in humans and animals. It is one of the major bacteria causing subclinical and clinical mastitis, leading to significant economic losses in livestock industry. In this study, we have isolated and characterized 80 S. aureus clinical isolates from mastitis-infected animals. The analysis of antimicrobial susceptibility, molecular typing, biofilm production and genetic determinants was performed to understand molecular and phenotypic features of the prevalent pathogen. Our antibiotic susceptibility assays showed the majority (57.5%) of isolates to be multidrug-resistant (MDR), 38.75% resistant and 3.75% sensitive. We found 25% isolates to be methicillin-resistant S. aureus (MRSA) based on oxacillin susceptibility assays. In the MRSA group, maximum isolates (95%) were MDR compared to 45% in MSSA. Multilocus sequence typing (MLST) revealed 15 different STs; ST-97 was the most common ST, followed by ST-2459, ST-1, ST-9 and ST-72. The agr typing showed agr-I as the most common type, followed by type II and III. Most isolates developed biofilms, which ranged in intensity from strong to weak. The presence or absence of lukS, a virulence-related gene, was found to have a substantial relationship with the biofilm phenotype. However, no significant association was found between biofilm formation and antimicrobial resistance or other virulence genes. We also found four MRSA isolates that were mecA negative based on molecular assays. Our findings reveal the prevalence of multidrug-resistant S. aureus clinical isolates in India that are biofilm positive and have critical genetic factors for disease pathogenesis causing bovine mastitis. This study emphasizes the need for the comprehensive surveillance of S. aureus and other mastitis-causing pathogens to control the disease effectively.

Do prices vary with purchase volumes in healthcare contracts

Abstract: Hospitals are facing severe increases in the cost of clinical supplies, and a common strategy is to drive economies of scale achieved by hospital consolidation. The supply strategy of “volume lever...

Production of arabitol by yeasts: current status and future prospects

Abstract: Arabitol belongs to the pentitol family and is used in the food industry as a sweetener and in the production of human therapeutics as an anticariogenic agent and an adipose tissue reducer. It can also be utilized as a substrate for chemical products such as arabinoic and xylonic acids, propylene, ethylene glycol, xylitol and others. It is included on the list of 12 building block C3-C6 compounds, designated for further biotechnological research. This polyol can be produced by yeasts in the processes of bioconversion or biotransformation of waste materials from agriculture, the forest industry (l-arabinose, glucose) and the biodiesel industry (glycerol). The present review discusses research on native yeasts from the genera Candida, Pichia, Debaryomyces and Zygosaccharomyces as well as genetically modified strains of Saccharomyces cerevisiae which are able to utilize biomass hydrolysates to effectively produce L- or D-arabitol. The metabolic pathways of these yeasts leading from sugars and glycerol to arabitol are presented. Although the number of reports concerning microbial production of arabitol is rather limited, the research on this topic has been growing for the last several years, with researchers looking for new micro-organisms, substrates and technologies.

Production of ethanol and arabitol by Debaryomyces nepalensis : influence of process parameters

Abstract: Debaryomyces nepalensis, osmotolerant yeast isolated from rotten apple, is known to utilize both hexoses and pentoses and produce industrially important metabolites like ethanol, xylitol and arabitol. In the present study, the effect of different growth substrates, trace elements, nitrogen concentration and initial pH on growth and formation of ethanol and arabitol were examined. Optimum conditions for maximizing the product yields were established: glucose as carbon source, an initial pH of 6.0, 6 g/L of ammonium sulphate and addition of micronutrients. Under these best suited conditions, a concentration of 11g/L of arabitol and 19 g/L of ethanol was obtained in shake flask fermentations. The fermentation was scaled up to 2.5 L bioreactor and the influence of aeration, agitation and initial substrate concentration was also determined. Under optimal conditions (150 g/L glucose, 400 rpm and 0.5 vvm) ethanol concentration reached 52 g/L, which corresponds to a yield of 0.34 g/g and volumetric productivity of 0.28 g/L/h, whereas arabitol production reached a maximum of 14 g/L with a yield and volumetric productivity of 0.1 g/g and 0.07 g/L/h respectively.

Isolation, identification and screening of yeasts towards their ability to assimilate biodiesel-derived crude glycerol: microbial production of polyols, endopolysaccharides and lipid.

Abstract: Aims To assess the ability of various newly isolated or belonging in official collections yeast strains to convert biodiesel-derived glycerol (Gly) into added-value compounds. Methods and results Ten newly isolated yeast strains belonging to Debaryomyces sp., Naganishia uzbekistanensis, Rhodotorula sp. and Yarrowia lipolytica, isolated from fishes, metabolized Gly under nitrogen limitation. The aim of the study was to identify potential newly isolated microbial candidates that could produce single-cell oil (SCO), endopolysaccharides and polyols when these micro-organisms were grown on biodiesel-derived Gly. As controls producing SCO and endopolysaccharides were the strains Rhodotorula glutinis NRRL YB-252 and Cryptococcus curvatus NRRL Y-1511. At initial Gly (Gly0 ) ≈40 g l-1 , most strains presented remarkable dry cell weight (DCW) production, whereas Y. lipolytica and Debaryomyces sp. produced non-negligible quantities of mannitol and arabitol (Ara). Five strains were further cultivated at increasing Gly0 concentrations. Rhodotorula glutinis NRRL YB-252 produced 7·2 g l-1 of lipid (lipid in DCW value ≈38% w/w), whereas Debaryomyces sp. FMCC Y69 in batch-bioreactor experiment with Gly0 ≈80 g l-1 , produced 30-33 g l-1 of DCW and ~30 g l-1 of Ara. At shake-flasks with Gly0 ≈125 g l-1 , Ara of ~48 g l-1 (conversion yield of polyol on Gly consumed ≈0·62 g g-1 ) was achieved. Cellular lipids of all yeasts contained in variable concentrations oleic, palmitic, stearic and linoleic acids. Conclusions Newly isolated, food-derived and non-previously studied yeast isolates converted biodiesel-derived Gly into several added-value metabolites. Significance and impact of the study Alternative ways of crude Gly valorization through yeast fermentations were provided and added-value compounds were synthesized.