Glycerol (G), polyglycerols (PGs), glycerol triacetate (GTA), and tributyrate (GTB) were studied as additives of poly(3-hydroxybutyrate) (PHB). The effect different concentrations (5–30%) these compounds on microstructure final properties PHB films evaluated. Microscopic studies revealed that samples with GTA GTB presented uniform microstructure, meanwhile those containing G PGs evidenced exuda...

A quantitatively repeatable protocol was developed for poly(3-hydroxybutyrate) (PHB) production by Escherichia coli XL1-Blue (pSYL107). Two constant-glucose fed-batch fermentations of duration 25 h were carried out in a 5-L bioreactor, with the measured oxygen volumetric mass-transfer coefficient (k(L)a) held constant at 1.1 min(-1). All major consumption and production rates were quantified. T...

The use of polymer blends and composites based on fossil-based bio-based polymers has become an important environmentally protective alternative for common disposable plastics applications such as packaging, bottles trays. disposal these more degradable products, however, may also harm the environment and, therefore, recycling systems becomes relevant. Recycling involves reprocessing which can ...

The archaeon Haloferax mediterranei was selected for production of PHA co- and terpolyesters using inexpensive crude glycerol phase (CGP) from biodiesel production as carbon source. CGP was assessed by comparison with the application of pure glycerol. Applying pure glycerol, a copolyester with a molar fraction of 3-hydroxybutyrate (3HB) of 0.90 mol/mol and 3-hydroxyvalerate (3HV) of 0.10 mol/mo...

A novel poly-beta-hydroxybutyrate (PHB) production system in which the expression and gene dosage of the Alcaligenes eutrophus pha biosynthetic operon were effectively regulated by cultivation temperature was constructed in Escherichia coli. The pha operon was fused to the negatively regulated tac promoter and cloned into a vector in which the copy number is temperature dependent. A two-phase p...

2 Dipartimento di Biotecnologie Agrarie, Universita di Padova, Via Gradenigo 6, 35131 Padova, Italy Genes encoding fiketothiolase (phaA), acetoacetyl-CoA reductase (phaB) and PHB-synthase (phaC) from R. meliloti 41, together with a fourth gene, referred to as ORF1, presumed to be involved in PHB biosynthesis, have been cloned and sequenced. phaA, phaB and ORFl were identified by heterologous hy...

The expression of phenotypic variability can enhance geometric mean fitness and act as a bet-hedging strategy in unpredictable environments. Metazoan bet hedging usually involves phenotypic diversification among an individual's offspring, such as differences in seed dormancy. Virtually all known microbial bet-hedging strategies, in contrast, rely on low-probability stochastic switching of a her...