In Vivo Characterization and Application of the PHA Synthase from Azotobacter vinelandii for the Biosynthesis of Polyhydroxyalkanoate Containing 4-Hydroxybutyrate

Abstract

Polyhydroxyalkanoate (PHA) is a biodegradable thermoplastic naturally synthesized by many microorganisms, and the PHA synthase (PhaC) is known to be the key enzyme involved in determining the material properties and monomer composition of the produced PHA. The ability to exploit widely distributed, commonly found soil microorganisms such as Azotobacter vinelandii to synthesize PHA containing the lipase-degradable 4-hydroxybutyrate (4HB) monomer will allow for convenient production of biocompatible and flexible PHA. Comparisons between the A. vinelandii wild type and mutant strains, with and without a surface layer (S-layer), respectively, in terms of gene or amino acid sequences, synthase activity, granule morphology, and PHA productivity, revealed that the S-layer is the sole factor affecting PHA biosynthesis by A. vinelandii. Based on PHA biosynthesis using different carbon sources, the PhaC of A. vinelandii showed specificity for short-chain-length PHA monomers, making it a member of the Class I PHA synthases. In addition, it was proven that the PhaC of A. vinelandii has the inherent ability to polymerize 4-hydroxybutyrate (4HB) and the mediated accumulation of PHA with 4HB fractions ranging from 10 mol% to as high as 22 mol%. The synthesis of biocompatible PHA containing tailorable amounts of 4HB with an expanded range of elasticity and lipase-degradability will enable a wider range of applications in the biomedical field.

oxigenic Profiling and Antibiotic Resistance of Baclllus cereus Strains Isolated from Food Consumed By School Children In Ilorin Metropolis

“…This finding was also supported by the report of [21]. Some authors [29,30] suggested that susceptible bacteria could acquire multi-drug resistance (MDR) plasmid during treatment with antibiotics that can induce and select for horizontal transfer and. It may be plausible to suggest that the possession of plasmid may have helped the strains to acquire their resistance through selective pressure from increased use and misuse of antibiotics [31,32] Two different enterotoxin protein complexes have been characterized in Bacillus cereus strains: emetic and diarrheal type (nhe and hbl) [21,32]; production of emetic toxin is reported to be restricted to a specific group of B. cereus.…”

Polihidroxialcanoatos (PHAs) en bacterias como alternativa ante el aumento de la contaminación ambiental: análisis metabólico y avances en la actualidad

“…han demostrado su potencial de eliminación de contaminantes de aguas residuales donde los PHA producidos alcanzan el 51% en el peso seco de sus células, asociado al consumo de ácidos grasos como medio metabólico principal [51]. Por su parte, Azotobacter vinelandii produjo hasta un 58% de PHA al utilizar aguas residuales porcinas como medio de crecimiento [53], donde sus fuentes de carbono son principalmente azúcares como la glucosa [54].…”

Toughness Enhancement of Poly(methyl methacrylate) (PMMA)/Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) Nanocomposites by Multiwall Carbon Nanotubes (MWNT)

“…Polyhydroxyalkanoates (PHA) are a biodegradable thermoplastic synthesized by bacterial fermentation of sugar and lipid [5]. PHBV is a kind of PHA, which is synthesized with starch as raw material and fermentation technology.…”