Production of polyhydroxyalkanoates by Azotobacter vinelandii UWD in beet molasses culture

Page, William

doi:10.1016/0378-1097(92)90304-7

Cited by 19 publications

(32 citation statements)

References 18 publications

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“…The strains were routinely grown in Burk's buffer salts (Page & Sadoff, 1976), supplemented with ferric citrate to bring the total iron concentration to 50 µM, 2 % (w\v) glucose and 15 mM ammonium acetate (Burk's medium). The medium for optimal PHB production was Burk's buffer salts, 50 µM ferric citrate, 3 % (w\v) glucose and 0n1% (w\v) fish peptone (Page, 1992). Cultures were incubated at high or low aeration (50 ml or 100 ml per 500 ml Erlenmeyer flask, respectively) with shaking at 225 r.p.m.…”

Section: Methodsmentioning

confidence: 99%

“…Azotobacter vinelandii strain UWD has been studied intensively as a candidate for the commercial production of polyhydroxyalkanoates (PHAs), which can be used as natural, biodegradable plastics (Chen & Page, 1997 ;Page, 1992 ;Page et al, 1992). A mutation in strain UWD limits the respiratory oxidation of NADH, which results in a constitutive PHA hyperproduction phenotype as the synthesis of poly-β-hydroxybutyrate (PHB) is used as an alternative electron sink to consume excess …”

Section: Introductionmentioning

confidence: 99%

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Alginate formation in Azotobacter vinelandii UWD during stationary phase and the turnover of poly-β-hydroxybutyrate

et al. 2001

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Azotobacter vinelandii UWD is a mutant of strain UW that is defective in the respiratory oxidation of NADH. This mutation causes an overproduction of polyhydroxyalkanoates (PHAs), as polyester synthesis is used as an alternative electron sink. Since PHAs have potential for use as natural, biodegradable plastics, studies of physiology related to their production are of interest.Alginate production by this strain is limited to T 11 µg (mg cell protein) N1 , which permits high efficiency conversion of carbon source into PHA. However, Z 400 µg (mg cell protein) N1 was formed when UWD cells were oxygen-limited and in the stationary phase of growth. Alginate formation was fuelled by PHA turnover, which was coincident with the synthesis of alkyl resorcinols, under conditions of exogenous glucose limitation. However, alginate production was a phenotypic and reversible change. Alginate production was stopped by interruption of algD with Tn5lacZ. LacZ activity in UWD was shown to increase in stationary phase, while LacZ activity in a similarly constructed mutant of strain UW did not. Transcription of algD in strain UWD started from a previously identified RpoD promoter and not from the AlgU (RpoE) promoter. This is because strain UWD has a natural insertion element in algU. Differences between strain UW and UWD may reside in the defective respiratory oxidation of NADH, where the NADH surplus in strain UWD may act as a signal of stationary phase. Indeed, a backcross of UW DNA into UWD generated NADHoxidase-proficient cells that failed to form alginate in stationary phase. Evidence is also presented to show that the RpoD promoter may be recognized by the stationary phase sigma factor (RpoS), which may mediate alginate production in strain UWD.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Alginate formation in Azotobacter vinelandii UWD during stationary phase and the turnover of poly-β-hydroxybutyrate

et al. 2001

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“…However, this alkyl side chain is not necessarily saturated: aromatic, unsaturated, halogenated, epoxidized and branched monomers have been reported as well (51)(52)(53)(54)(55). The majority of PHAs are composed of R(-)-3-hydroxyalkanoic acid monomers ranging from C 3 to C 14 carbon atoms with a variety of saturated or unsaturated and straight or branched chain containing aliphatic or aromatic side groups (27,56). Approximately 150 different hydroxyalkanoic acids are now known to occur as constituents of PHAs (57) and this number continues to increase with the introduction of new types of PHA through the chemical or physical modification of naturally occurring PHA, or through the creation of genetically modified organisms to produce PHA with specialized functional groups (58).…”

Section: Chemical Structurementioning

confidence: 99%

“…Once PHAs are extracted from bacterial cells, these polymers show crystalline, flexible, elastic and thermoplastic properties (22)(23)(24)(25). Further, they are synthesized from renewable carbon resources, based on agriculture or even on industrial wastes or fermentation feedstocks (25)(26)(27) so do not lead to the depletion of finite resources (28). Bacterial PHAs gained particular interest since they are completely biodegradable, non-toxic, biocompatible and also sources for commercially useful pool of chiral monomers (29)(30)(31)(32)(33).…”

Section: Introductionmentioning

confidence: 99%

Bacterial polyhydroxyalkanoates-eco-friendly next generation plastic: Production, biocompatibility, biodegradation, physical properties and applications

Muhammadi

Shabina

Afzal

et al. 2015

Green Chemistry Letters and Reviews

274

139

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Polyhydroxyalkanoates (PHAs) are intracellular aliphatic polyesters synthesized as energy reserves, in the form of water-insoluble, nano-sized discrete and optically dense granules in cytoplasm by a diverse bacteria and some archae under conditions of limiting nutrients in the presence of excess carbon source. Bacteria synthesize different PHAs from coenzyme A thioesters of respective hydroxyalkanoic acid, and degrade intracellularly for reuse and extracellularly in natural environments by other microorganisms. In vivo, PHAs exist as amorphous mobile liquid and water-insoluble inclusions but in vitro, exhibit material and mechanical properties, ranging from stiff and brittle crystalline to elastomeric and molding, similar to petrochemical thermoplastics. Further, they are hydrophobic, isotactic, biocompatible and exhibit piezoelectric properties. But as commodity plastics their applications are limited by high production cost, low yield, in vivo degradation, complexity of technology and difficulty of extraction. Therefore, to replace the conventional plastic with PHAs, it is prerequisite to standardize the PHA production systems.

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“…The microorganisms can utilise various carbon sources ranging from simple carbohydrates to inexpensive, complex waste effluents like beet/cane molasses 45,46 to alkanes 47 , plant oils 48 and fatty acids of plant oils 49,50,51 for production of PHA. On the basis of the types of monomer integrated into PHA, different metabolic pathways are involved in the generation of these monomers.…”

Section: Role Of R Eutropha and Metabolic Pathways For Pha Biosynthementioning

confidence: 99%

Polyhydroxyalkanoates: Role of Ralstonia eutropha

Priyadarshi¹,

Shukla²,

Borse³

2014

Int J of Biomed & Adv Res

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Polyhydroxyalkanoates (PHAs) are biopolymers, which can be used as a substitute for petrochemical plastics in diverse applications. However, these bioplastics are presently more costly than petrochemical plastics. Various researchers had investigated to exploit the use of economical waste streams derivative substrates. Waste frying oil is an ample cheap substrate which can be used without filtration in PHA production. Ralstonia eutropha is a handy organism for the production of PHA. Due to its similar physical properties to synthetic plastics, Polyhydroxyalkanoate (PHA) a biologically-synthesized plastic is attracting major interests in green material industries. Bioplastics are synthesized from renewable resources and they are degraded by aerobic microorganism to CO2 and H2O when disposed-off. For the commercialization of PHA; some important aspects like inexpensive carbon sources, selection of suitable bacterial strains, efficient fermentation and recovery processes should be taken into consideration.

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Production of polyhydroxyalkanoates by Azotobacter vinelandii UWD in beet molasses culture

Cited by 19 publications

References 18 publications

Alginate formation in Azotobacter vinelandii UWD during stationary phase and the turnover of poly-β-hydroxybutyrate

Alginate formation in Azotobacter vinelandii UWD during stationary phase and the turnover of poly-β-hydroxybutyrate

Bacterial polyhydroxyalkanoates-eco-friendly next generation plastic: Production, biocompatibility, biodegradation, physical properties and applications

Polyhydroxyalkanoates: Role of Ralstonia eutropha

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