Biomedical subjects

Bhabatarini Panda

Publications and source records attributed to Bhabatarini Panda.

4 recordsLinked to original sources

PubMed2006

Process optimization for poly-beta-hydroxybutyrate production in a nitrogen fixing cyanobacterium, Nostoc muscorum using response surface methodology.

A five-level-four-factor central composite rotary design was employed to find out the interactive effects of four variables, viz. concentrations of acetate, glucose and K2HPO4, and dark incubation period on poly-beta-hydroxybutyrate (PHB) production in a N2-fixing cyanobacterium, Nostoc muscorum. Acetate, glucose and dark incubation period exhibited positive impacts on PHB yield. Using response surface methodology (RSM), a second order polynomial equation was obtained by multiple regression analysis. A yield of 45.6% of dry cell weight (dcw) was achieved at reduced level of nutrients, i.e. 0.17% acetate, 0.16% glucose and 5 mg l(-1) K2HPO4 at a dark incubation period of 95 h as compared to 41.6% PHB yield in 0.4% acetate, 0.4% glucose and 40 mg l(-1) K2HPO4 at a dark incubation period of 168 h under single factor optimization strategy.

Acetates↗

PubMed2006

Studies on poly-beta-hydroxybutyrate synthase activity of Nostoc muscorum.

This study compares the PHB synthase activity of Nostoc muscorum, a N(2)-fixing cyanobacterium under control (grown in usual BG-11 medium), nitrogen (N) and phosphorus (P) deprivation and chemoheterotrophic conditions. Specific activity of PHB synthase did not depict significant variations in the latter three types of cultures, except for the control one, where a significantly lower activity was recorded. PHB synthase activity was detected only in the soluble fractions of both the control as well as cells incubated under chemoheterotrophic conditions. A K(m) of 80.2 microM DL-beta-hydroxybutyryl-CoA and V(max) of 197.5 nmol thiobenzoate (TNB) mg protein(-1)min(-1) were observed for the enzyme. PHB synthase remained insensitive to acetyl-CoA, ATP, NADP, NADPH supplementation under in vitro condition. Addition of acetyl phosphate was found to activate the enzyme and the level of activation was dependent on the concentration of acetyl phosphate supplementation. Inhibition of PHB synthase in 2,3-butanedione supplemented cultures and reactivation following acetyl phosphate addition proved the post-translational control of acetyl phosphate over PHB synthase.

Acyltransferases↗

PubMed2005

Optimization of cultural and nutritional conditions for accumulation of poly-beta-hydroxybutyrate in Synechocystis sp. PCC 6803.

Poly-beta-hydroxybutyrate (PHB) accumulation in the unicellular cyanobacterium, Synechocystis sp. PCC 6803, was studied under various cultural and nutritional conditions. Under controlled condition, cells harvested at the stationary phase of growth depicted maximum accumulation of PHB, i.e., 4.5% (w/w of dry cells) as compared to lag (1.8%) or logarithmic (2.9%) phases of cultures. A temperature range of 28-32 degrees C and pH between 7.5 and 8.5 were preferred for PHB accumulation. Cells cultivated under regular light-dark cycles accumulated more PHB (4.5%) than those grown under continuous illumination (2.4%). Nitrogen and phosphorus starvation stimulated PHB accumulation up to the tune of 9.5 and 11% (w/w of dry cells), respectively. Synechocystis cells pre-grown in glucose (0.1%)-supplemented BG-11 medium when subjected to P-deficiency in presence of acetate (0.4%), PHB accumulation was boosted up to 29% (w/w of dry cells), the value almost 6-fold higher with respect to photoautotrophic condition. Fishpond discharges were found as suitable media for PHB accumulation in the test cyanobacterium.

Aquaculture↗

PubMed2005

Poly-beta-hydroxybutyrate accumulation in Nostoc muscorum and Spirulina platensis under phosphate limitation.

Nostoc muscorum and Spirulina platensis were grown under phosphate deficiency in order to investigate the role of internal phosphate pool and activity of alkaline phosphatase on poly-beta-hydroxybutyrate (PHB) accumulation. PHB accumulation in N. muscorum increased to 22.7% of dry weight (dw) after 4 day of phosphate deficiency, while the internal phosphate pool reduced to the level of 0.02 microM mg dw(-1) at a maximum APase activity of 2.57nM PNP mg dw(-1) h(-1). In contrary, S. platensis depicted maxima of 1.39nM PNP mg dw(-1) h(-1) on day 30 of incubation, which was about 2 fold lower than the observed value of N. muscorum. PHB content in S. platensis remained low even after prolonged phosphate starvation, and a rise only up to 3.5% of dw was recorded on day 60 of phosphate deficiency. Supplementation of NADPH exogenously to S. platensis cultures grown under phosphate deficiency favoured PHB accumulation in 10, 20 and 30 days old cultures, but not in the cultures grown under phosphate deficiency for 60 days. The possible role of phosphate limitation on PHB accumulation is discussed.

Alkaline Phosphatase↗