Effect of growth conditions on the molecular weight of poly-3-hydroxybutyrate produced by Azotobacter chroococcum 7B

Мышкина, В. Л.; Nikolaeva, D. A.; Махина, Т. К.; Бонарцев, А. П.; Бонарцева, Г. А.

doi:10.1134/s0003683808050050

Cited by 45 publications

(56 citation statements)

References 8 publications

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“…The M w of 4.1 9 10 3 and 5.9 9 10 2 kDa was obtained with Azotobacter vinelandii UWD and A. chroococcum 7B on 5 and 2 % w/v molasses which further decreased on increasing molasses or acetate concentration in the feed. In contrast, M w in the range 1.2 9 10 3 -1.6 9 10 3 kDa was achieved on pure C-source (glucose, sucrose, starch or FAs) [69,70].…”

Section: Substrate and Feeding Regimementioning

confidence: 88%

Challenges and Opportunities for Customizing Polyhydroxyalkanoates

et al. 2015

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Polyhydroxyalkanoates (PHAs) as an alternative to synthetic plastics have been gaining increasing attention. Being natural in their origin, PHAs are completely biodegradable and eco-friendly. However, consistent efforts to exploit this biopolymer over the last few decades have not been able to pull PHAs out of their nascent stage, inspite of being the favorite of the commercial world. The major limitations are: (1) the high production cost, which is due to the high cost of the feed and (2) poor thermal and mechanical properties of polyhydroxybutyrate (PHB), the most commonly produced PHAs. PHAs have the physicochemical properties which are quite comparable to petroleum based plastics, but PHB being homopolymers are quite brittle, less elastic and have thermal properties which are not suitable for processing them into sturdy products. These properties, including melting point (T m ), glass transition temperature (T g ), elastic modulus, tensile strength, elongation etc. can be improved by varying the monomeric composition and molecular weight. These enhanced characteristics can be achieved by modifications in the types of substrates, feeding strategies, culture conditions and/or genetic manipulations.

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Section: Substrate and Feeding Regimementioning

confidence: 88%

Challenges and Opportunities for Customizing Polyhydroxyalkanoates

et al. 2015

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“…A PHA producer A. chroococcum strain 7B, a non-symbiotic nitrogen-fixing bacterium able to overproduce PHB (to 80% of cell dry weight) was used [26-29]. The strain was isolated from the wheat rhizosphere (sod-podzolic soil) and maintained on Ashby’s medium, containing 0.2 g/l K 2 HPO 4 × 3H 2 O, 0.2 g/l МgSO 4 × 7H 2 O, 0.2 g/l NaCl, 0.006 g/l Na 2 MoO 4 × 2H 2 O, 5.0 g/l CaCO 3 , 20 g/l sucrose, and 20 g/l agar.…”

Section: Methodsmentioning

confidence: 99%

Cell attachment on poly(3-hydroxybutyrate)-poly(ethylene glycol) copolymer produced by Azotobacter chroococcum 7B

et al. 2013

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BackgroundThe improvement of biomedical properties, e.g. biocompatibility, of poly(3-hydroxyalkanoates) (PHAs) by copolymerization is a promising trend in bioengineering. We used strain Azotobacter chroococcum 7B, an effective producer of PHAs, for biosynthesis of not only poly(3-hydroxybutyrate) (PHB) and its main copolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-HV), but also alternative copolymer, poly(3-hydroxybutyrate)-poly(ethylene glycol) (PHB-PEG).ResultsIn biosynthesis we used sucrose as the primary carbon source and valeric acid or poly(ethylene glycol) 300 (PEG 300) as additional carbon sources. The chemical structure of PHB-PEG and PHB-HV was confirmed by 1H nuclear-magnetic resonance (1H NMR) analysis. The physico-chemical properties (molecular weight, crystallinity, hydrophilicity, surface energy) and surface morphology of films from PHB copolymers were studied. To study copolymers biocompatibility in vitro the protein adsorption and COS-1 fibroblasts growth on biopolymer films by XTT assay were analyzed. Both copolymers had changed physico-chemical properties compared to PHB homopolymer: PHB-HV and PHB-PEG had less crystallinity than PHB; PHB-HV was more hydrophobic than PHB in contrast to PHB-PEG appeared to have greater hydrophilicity than PHB; whereas the morphology of polymer films did not differ significantly. The protein adsorption to PHB-PEG was greater and more uniform than to PHB and PHB-PEG copolymer promoted better growth of COS-1 fibroblasts compared with PHB homopolymer.ConclusionsThus, despite low EG-monomers content in bacterial origin PHB-PEG copolymer, this polymer demonstrated significant improvement in biocompatibility in contrast to PHB and PHB-HV copolymers, which may be coupled with increased protein adsorption and hydrophilicity of PEG-containing copolymer.

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“…Similarly, temperature is another critical parameter that affects quantity and quality of PHA/PHB accumulation (Myshkina et al, 2008, reported for Azotobacter sp.). Increasing temperatures (from 20 to 37 • C) improved PHA/PHB yields (from 1 to 5.8 g L −1 ) and their MW (from 897 to 1600 kDa) significantly (Myshkina et al, 2008). In general, the solubility of gases, such as O 2 and CH 4 decreased to one-third when temperature was increased from 20 to 60 • C in natural waters of low ionic strength (<100 mM) (Tsubota et al, 2005), but no studies reported the effect of various temperatures and PHA/PHB accumulation potential selectively in methanotrophs.…”

Section: Effect Of Ph and Temperaturementioning

confidence: 97%

Review of Sustainable Methane Mitigation and Biopolymer Production

Karthikeyan

Chidambarampadmavathy

Cirés

et al. 2014

Critical Reviews in Environmental Science and Technology

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Biological methane (CH 4 ) mitigation combined with biopolymer (PHA-polyhydroxyalkaonate/PHB-polyhydroxybutyrate) production is a viable option in this fossil fuel-constrained era.Methantrophs are bacteria that can re-route CH 4 into PHA/PHB under nutrient-starved conditions. However, most studies (up to 90%) investigated pure cultures to demonstrate capacity for PHA/PHB accumulation, which on an industrial scale is unlikely to be serviceable. Furthermore, commercialization is handicapped as there are still a number of unresolved issues which affect productivities, such as optimized process variables, characterization of robust consortia, and optimized reactor design. This review will summarize existing knowledge and highlight research needs to fast track methanotrophic PHA/PHB production from CH 4 .

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Effect of growth conditions on the molecular weight of poly-3-hydroxybutyrate produced by Azotobacter chroococcum 7B

Cited by 45 publications

References 8 publications

Challenges and Opportunities for Customizing Polyhydroxyalkanoates

Challenges and Opportunities for Customizing Polyhydroxyalkanoates

Cell attachment on poly(3-hydroxybutyrate)-poly(ethylene glycol) copolymer produced by Azotobacter chroococcum 7B

Review of Sustainable Methane Mitigation and Biopolymer Production

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