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At least 757 records · Page 42Linked to original sources
PubMed2005

Degradation of polyesters by a novel marine Nocardiopsis aegyptia sp. nov.: application of Plackett-Burman experimental design for the improvement of PHB depolymerase activity.

This is the first report on the degradation of poly(3-hydroxybutyrate) (PHB), and its copolymers poly(3-hydroxyvalerate) P(3HB-co-10-20% HV) by Nocardiopsis aegyptia, a new species isolated from marine seashore sediments. The strain excreted an extracellular PHB depolymerase and grew efficiently on PHB or its copolymers as the sole carbon sources. The degradation activity was detectable by the formation of a transparent clearing zone around the colony on an agar Petri plate after 25 days, or a clearing depth under the colony in test tubes within 3 weeks. The previous techniques proved that the bacterium was able to assimilate the monomeric components of the shorter alkyl groups of the polymers. Nocardiopsis aegyptia hydrolyzed copolymers 10-20% PHBV more rapidly than the homopolymer PHB. The bacterial degradation of the naturally occurring sheets of poly(3-hydroxybutyrate), and its copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) was observed by scanning electron microscopy (SEM). The samples were degraded at the surface and proceeded to the inner part of the materials. Clear morphological alterations of the polymers were noticed, indicating the degradative capability of the bacterium. Plackett-Burman statistical experimental design has been employed to optimize culture conditions for maximal enzyme activity. The main factors that had significant positive effects on PHB depolymerase activity of Nocardiopsis aegyptia were sodium gluconate, volume of medium/flask and age of inoculum. On the other hand, MgSO4.7H2O, KH2PO4, K2HPO4 and NH4NO3 exhibited negative effects. Under optimized culture conditions, the highest activity (0.664 U/mg protein) was achieved in a medium predicted to be near optimum containing (in g/L): PHB, 0.5; C6H11O7Na, 7.5; MgSO4.7H2O, 0.35; K2HPO4, 0.35; NH4NO3, 0.5; KH2PO4, 0.35; malt extract, 0.5 and prepared with 50% seawater. The medium was inoculated with 1% (v/v) spore suspension of 7 days old culture. Complete clarity of the medium was achieved after 3 days at 30 degrees C.

Actinomycetales↗
PubMed1997

Surface-modified polyester fabrics.

The plasma treatment of poly(ethylene terephthalate) fabric offers new opportunities for product designers. The technique enhances surface properties while maintaining the beneficial physical characteristics of the bulk material. This article compares the surface properties of treated and untreated materials and looks at the specific application of treated fabric in the rapidly growing field of tissue engineering.

Cells, Cultured↗
PubMed1999

The influence of new polyester block copolymer on morphology of hepatocytes of rats liver.

The liver is a complex organ with metabolic, excretory, and defence functions, so the effect of toxic polymers is often find in disorganisation of hepatic structure and may induce cell damage. In this study it is estimated the influence of recently synthesised multiblock copolymers based on poly/butylene terepthalate) and a dimerized fatty acid. The films of polymers were implanted intra-abdominally in 45 rats of Wistar breed covering the right lobe of liver. The specimens of liver were collected in 1, 3 and 6 day of experiment in order to be evaluated under microscope. The morphology of lobules, size and shape of hepatocytes, size and shape of nuclei's of hepatocytes, any infiltration of plasma cell were taken into account during examination. There have been no difference in morphology between specimens of liver from rats with implanted polymer and control group which could implicate their toxicity.

Abdomen↗