Extraction of polyhydroxyalkanoates from mixed microbial cultures: Impact on polymer quality and recovery

Samorì, Chiara; Abbondanzi, Federica; Galletti, Paola; Giorgini, Loris; Mazzocchetti, Laura; Torri, Cristian; Tagliavini, Emilio

doi:10.1016/j.biortech.2015.03.062

Cited by 112 publications

(72 citation statements)

References 32 publications

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“…Thus, a sonication pre‐treatment was investigated as a strategy to enhance NH 3 digestion at lower temperatures. Sonication was chosen based on its reported efficiency in disaggregating the exopolysaccharide structures of microbial cultures, which have been suggested as the main reason behind the recalcitrance of MMC to PHA extraction . The results of these experiments are displayed in Fig.…”

Section: Resultsmentioning

confidence: 99%

Polyhydroxyalkanoate (PHA) purification through dilute aqueous ammonia digestion at elevated temperatures

Burniol-Figols

Skiadas

Daugaard

et al. 2020

J of Chemical Tech & Biotech

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BACKGROUND Purification of polyhydroxyalkanoates (PHA) is a challenging step, given the difficulty of achieving high PHA purity, while maintaining polymer integrity, in a sustainable and cost‐efficient manner. This study evaluated the potential of dilute ammonia digestion as a method to purify PHA from mixed microbial consortia. RESULTS Digestion temperatures were critical to the obtainable purity and the amount of recovered PHA. At temperatures below 75 °C (regardless of the incubation time and ammonia concentration), a low PHA recovery (down to 65%) and no increase in purity was observed. By increasing the temperature above 75 °C, a significantly higher PHA purity and higher recovery (above 90%) could be achieved. Temperatures maximizing the purity (140 °C) led to a detrimental reduction in the molar mass of the isolated PHA, but the use of a sonication pre‐treatment enabled to increase the purity at temperatures leading to limited molar mass loss (75–115 °C). The impurities still present in the recovered PHA did not compromise its thermal stability, and no significant degradation occurred during melting of PHA with 86% purity (comparably to pure chloroform‐extracted PHA). Conversely, PHA recovered through sulphuric acid (H2SO4) digestion underwent severe degradation during melting, despite presenting higher purity (98%). CONCLUSIONS High PHA purity, recovery and thermal stability can be obtained with dilute ammonia digestion. These observations, combined with the possibility of reusing ammonia within the process, make this method a promising approach for a more sustainable purification of PHA. © 2020 Society of Chemical Industry

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Section: Resultsmentioning

confidence: 99%

Polyhydroxyalkanoate (PHA) purification through dilute aqueous ammonia digestion at elevated temperatures

Burniol-Figols

Skiadas

Daugaard

et al. 2020

J of Chemical Tech & Biotech

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“…We have now found that lactones, such as GVL, γ‐butyrolactone and δ‐valerolactone, are able to dissolve up to 20 wt% of PHB in 1 min at temperatures above 100 °C, subsequently thickening to form a gel‐like material when the solution is cooled (seven‐membered ring lactones such as ϵ‐caprolactone did not dissolve PHB even under more severe conditions). This behavior was already described for other solvents such as chloroform, dimethylformamide, dimethyl sulfoxide (DMSO), dimethyl carbonate (DMC) and methyl isobutyl ketone . Since the addition of plasticizers can improve thermal and mechanical properties of the copolymer P(3HB‐3HV), TEC was used to enhance gel handling, increasing the overall greenness; TEC in fact, is a non‐toxic, bio‐based and biodegradable plasticizer, thus its use is highly advantageous respect to the health‐concerning phthalates …”

Section: Introductionmentioning

confidence: 85%

The Green Attitude in Art Conservation: Polyhydroxybutyrate–based Gels for the Cleaning of Oil Paintings

et al. 2016

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Fully biodegradable novel bio‐based organogels were developed for removing aged protective films from the surfaces of paintings, aiming at providing effective cleaning tools, easily controllable by reducing the solvent permeation into underlying paint layers and not dangerous for human health and the environment. The gels were based on poly‐3‐hydroxybutyrate (PHB) as gelling agent, γ‐valerolactone (GVL) as solvent and triethyl citrate (TEC) as plasticizer. PHB‐gels were able to completely remove protective varnishes on real oil paintings, without affecting the pictorial layer and leaving negligible residues after the application. Moreover, the gels showed good mechanical and handling properties, they were fully composed by non‐toxic ingredients and resulted readily biodegradable in water, therefore easily disposable after the use.

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“…Recovery of polymer from bacterial cell mass is the major factor contributing more than 50% of the PHA production cost (Samori et al 2015a, b). An ideal polymer extraction process should be simple, inexpensive, environmental friendly, yielding polymer of high purity and of higher recovery rate (Heinrich et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Enhanced production of poly(3-hydroxybutyrate) in recombinant Escherichia coli and EDTA–microwave-assisted cell lysis for polymer recovery

2018

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Poly(3-hydroxybutyrate) (PHB) is a bacterial polymer of great commercial importance due to its properties similar to polypropylene. With an aim to develop a recombinant system for economical polymer production, PHB biosynthesis genes from Bacillus aryabhattai PHB10 were cloned in E. coli. The recombinant cells accumulated a maximum level of 6.22 g/L biopolymer utilizing glycerol in shake flasks. The extracted polymer was confirmed as PHB by GC–MS and NMR analyses. The polymer showed melting point at 171 °C, thermal stability in a temperature range of 0–140 °C and no weight loss up to 200 °C. PHB extracted from sodium hypochlorite lysed cells had average molecular weight of 143.108 kDa, polydispersity index (PDI) 1.81, tensile strength of 14.2 MPa and an elongation at break of 7.65%. This is the first report on high level polymer accumulation in recombinant E. coli solely expressing PHB biosynthesis genes from a Bacillus sp. As an alternative to sodium hypochlorite cell lysis mediated polymer extraction, the effect of combined treatment with ethylenediaminetetraacetic acid and microwave was studied which attained 93.75% yield. The polymer recovered through this method was 97.21% pure, showed 2.9-fold improvement in molecular weight and better PDI. The procedure is simple, with minimum polymer damage and more eco-friendly than the sodium hypochlorite lysis method.

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Extraction of polyhydroxyalkanoates from mixed microbial cultures: Impact on polymer quality and recovery

Cited by 112 publications

References 32 publications

Polyhydroxyalkanoate (PHA) purification through dilute aqueous ammonia digestion at elevated temperatures

Polyhydroxyalkanoate (PHA) purification through dilute aqueous ammonia digestion at elevated temperatures

The Green Attitude in Art Conservation: Polyhydroxybutyrate–based Gels for the Cleaning of Oil Paintings

Enhanced production of poly(3-hydroxybutyrate) in recombinant Escherichia coli and EDTA–microwave-assisted cell lysis for polymer recovery

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