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Wongmoon C, Napathorn SC. Optimization for the efficient recovery of poly(3-hydroxybutyrate) using the green solvent 1,3-dioxolane. Front Bioeng Biotechnol 2022; 10:1086636. [PMID: 36561051 PMCID: PMC9763598 DOI: 10.3389/fbioe.2022.1086636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 11/17/2022] [Indexed: 12/12/2022] Open
Abstract
In this study, a simple non-toxic recovery process of biodegradable poly(3-hydroxybutyrate) (PHB) using the green solvent 1,3-dioxolane and water was successfully developed. The critical parameters were optimized, and the process platform was scaled up from 2 ml to 1,000 ml for the efficient recovery of PHB. The physical parameters including continuous shaking, ultrasonication, extraction using the Soxhlet extractor, diluted 1,3-dioxolane, reused 1,3-dioxolane, and cell rupture by steam explosion prior to solvent extraction were carefully investigated. The results showed that continuous shaking played a major role in increasing the recovery efficiency during the scale-up process. The PHB extraction at 2 ml from dried cells at 80°C with 100 rpm of shaking speed for 5 h resulted in a recovery yield of 96.6 ± 0.1% with purity up to 99.1 ± 0.6% and that from wet cells under the same condition resulted in a recovery yield of 94.6 ± 4.8% and purity of 97.0 ± 0.1%. It should be noted that the PHB extracted from wet cells at room temperature with 150 rpm of shaking speed for 36 h resulted in a recovery yield of 93.5 ± 0.7% and purity of 97.7 ± 1.3% and had an MW of 3.1×105, MN of 2.7×105, and polydispersity index of 1.1. The direct scale-up process at 1,000 ml showed comparable results in purity, recovery yield, molecular weight distribution, thermal properties, and mechanical properties. The PHB extraction from dried cells gave the highest purity of 99.3 ± 0.5% and recovery of 94.0 ± 0.3%, whereas the PHB extraction from wet cells gave a purity of 90.3 ± 1.5% and recovery of 92.6 ± 1.0%. The novel recovery process showed its feasibility to be applied on an industrial scale.
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Affiliation(s)
- Chanakarn Wongmoon
- Programme in Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - Suchada Chanprateep Napathorn
- Programme in Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand,Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand,*Correspondence: Suchada Chanprateep Napathorn,
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Samrot AV, Samanvitha SK, Shobana N, Renitta ER, Senthilkumar P, Kumar SS, Abirami S, Dhiva S, Bavanilatha M, Prakash P, Saigeetha S, Shree KS, Thirumurugan R. The Synthesis, Characterization and Applications of Polyhydroxyalkanoates (PHAs) and PHA-Based Nanoparticles. Polymers (Basel) 2021; 13:3302. [PMID: 34641118 PMCID: PMC8512352 DOI: 10.3390/polym13193302] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/31/2021] [Accepted: 08/31/2021] [Indexed: 12/22/2022] Open
Abstract
Polyhydroxyalkanoates (PHAs) are storage granules found in bacteria that are essentially hydroxy fatty acid polyesters. PHA molecules appear in variety of structures, and amongst all types of PHAs, polyhydroxybutyrate (PHB) is used in versatile fields as it is a biodegradable, biocompatible, and ecologically safe thermoplastic. The unique physicochemical characteristics of these PHAs have made them applicable in nanotechnology, tissue engineering, and other biomedical applications. In this review, the optimization, extraction, and characterization of PHAs are described. Their production and application in nanotechnology are also portrayed in this review, and the precise and various production methods of PHA-based nanoparticles, such as emulsion solvent diffusion, nanoprecipitation, and dialysis are discussed. The characterization techniques such as UV-Vis, FTIR, SEM, Zeta Potential, and XRD are also elaborated.
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Affiliation(s)
- Antony V. Samrot
- School of Bioscience, Faculty of Medicine, Bioscience and Nursing, MAHSA University, Jalan SP2, Bandar Saujana Putra, Jenjarom 42610, Selangor, Malaysia
| | - Sree K. Samanvitha
- Department of Biotechnology, Shanmugha Arts, Science, Technology & Research Academy, Thanjavur 613401, Tamil Nadu, India;
| | - N. Shobana
- Department of Biotechnology, School of Bio and Chemical Engineering, Sathyabama Institute of Science and Technology, Chennai 600119, Tamil Nadu, India; (N.S.); (M.B.); (P.P.); (S.S.); (K.S.S.)
| | - Emilin R. Renitta
- Department of Food Processing Technology, School of Agriculture and Biosciences, Karunya Institute of Science and Technology, Karunya Nagar, Coimbatore, 641114, Tamil Nadu, India;
| | - P. Senthilkumar
- Department of Chemical Engineering, School of Bio and Chemical Engineering, Sathyabama Institute of Science and Technology, Chennai 600119, Tamil Nadu, India;
| | - Suresh S. Kumar
- Centre for Materials Engineering and Regenerative Medicine, Bharath Institute of Higher Education and Research, Chennai 600126, Tamil Nadu, India
| | - S. Abirami
- Department of Microbiology, Kamaraj College, Thoothukudi 628003, Tamil Nadu, India;
| | - S. Dhiva
- Department of Microbiology, Sree Narayana College, Alathur, Palakkad 678682, Kerala, India;
| | - M. Bavanilatha
- Department of Biotechnology, School of Bio and Chemical Engineering, Sathyabama Institute of Science and Technology, Chennai 600119, Tamil Nadu, India; (N.S.); (M.B.); (P.P.); (S.S.); (K.S.S.)
| | - P. Prakash
- Department of Biotechnology, School of Bio and Chemical Engineering, Sathyabama Institute of Science and Technology, Chennai 600119, Tamil Nadu, India; (N.S.); (M.B.); (P.P.); (S.S.); (K.S.S.)
| | - S. Saigeetha
- Department of Biotechnology, School of Bio and Chemical Engineering, Sathyabama Institute of Science and Technology, Chennai 600119, Tamil Nadu, India; (N.S.); (M.B.); (P.P.); (S.S.); (K.S.S.)
| | - Krithika S. Shree
- Department of Biotechnology, School of Bio and Chemical Engineering, Sathyabama Institute of Science and Technology, Chennai 600119, Tamil Nadu, India; (N.S.); (M.B.); (P.P.); (S.S.); (K.S.S.)
| | - R. Thirumurugan
- Department of Transfusion Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry 605006, India;
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Bedade DK, Edson CB, Gross RA. Emergent Approaches to Efficient and Sustainable Polyhydroxyalkanoate Production. Molecules 2021; 26:3463. [PMID: 34200447 PMCID: PMC8201374 DOI: 10.3390/molecules26113463] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 05/25/2021] [Accepted: 05/27/2021] [Indexed: 11/16/2022] Open
Abstract
Petroleum-derived plastics dominate currently used plastic materials. These plastics are derived from finite fossil carbon sources and were not designed for recycling or biodegradation. With the ever-increasing quantities of plastic wastes entering landfills and polluting our environment, there is an urgent need for fundamental change. One component to that change is developing cost-effective plastics derived from readily renewable resources that offer chemical or biological recycling and can be designed to have properties that not only allow the replacement of current plastics but also offer new application opportunities. Polyhydroxyalkanoates (PHAs) remain a promising candidate for commodity bioplastic production, despite the many decades of efforts by academicians and industrial scientists that have not yet achieved that goal. This article focuses on defining obstacles and solutions to overcome cost-performance metrics that are not sufficiently competitive with current commodity thermoplastics. To that end, this review describes various process innovations that build on fed-batch and semi-continuous modes of operation as well as methods that lead to high cell density cultivations. Also, we discuss work to move from costly to lower cost substrates such as lignocellulose-derived hydrolysates, metabolic engineering of organisms that provide higher substrate conversion rates, the potential of halophiles to provide low-cost platforms in non-sterile environments for PHA formation, and work that uses mixed culture strategies to overcome obstacles of using waste substrates. We also describe historical problems and potential solutions to downstream processing for PHA isolation that, along with feedstock costs, have been an Achilles heel towards the realization of cost-efficient processes. Finally, future directions for efficient PHA production and relevant structural variations are discussed.
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Affiliation(s)
- Dattatray K. Bedade
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA;
| | - Cody B. Edson
- New York State Center for Polymer Synthesis, Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA;
| | - Richard A. Gross
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA;
- New York State Center for Polymer Synthesis, Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA;
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Comparative analysis of various extraction processes based on economy, eco-friendly, purity and recovery of polyhydroxyalkanoate: A review. Int J Biol Macromol 2021; 183:1881-1890. [PMID: 34090850 DOI: 10.1016/j.ijbiomac.2021.06.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 05/31/2021] [Accepted: 06/01/2021] [Indexed: 01/06/2023]
Abstract
Bioplastics have been an interesting area of research and development in the last few decades. Normal plastics are made out of petroleum products, which is a non-renewable resource. Apart from that, its non-biodegradable nature makes it a serious threat to the environment, and hence a better alternative is needed. Bioplastics are synthesized by microorganisms and are biodegradable; this property makes them a promising alternative to normal plastic. However, the major drawback related to bioplastic is the high cost of its production. Polyhydroxyalkanoate (PHA) is a very popular biopolymer produced by different types of microbes. The review focuses on the different methods of extraction of PHA based on the percentage of purity, recovery, eco-friendly, and cost-effectiveness. There is a wide array of extraction methods reported to date, wherein there is the involvement of different types of solvents (like halogenated, non-halogenated, and green solvents) or mechanical or enzymatic methods. Each extraction process has its advantages and disadvantages. In this study, we have attempted to present a structured comparison of these different methods and highlight the factors that can be addressed for better extraction of PHA thereby making it a feasible alternative to commercial synthetic plastic.
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Silva JB, Pereira JR, Marreiros BC, Reis MA, Freitas F. Microbial production of medium-chain length polyhydroxyalkanoates. Process Biochem 2021. [DOI: 10.1016/j.procbio.2021.01.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Pagliano G, Galletti P, Samorì C, Zaghini A, Torri C. Recovery of Polyhydroxyalkanoates From Single and Mixed Microbial Cultures: A Review. Front Bioeng Biotechnol 2021; 9:624021. [PMID: 33644018 PMCID: PMC7902716 DOI: 10.3389/fbioe.2021.624021] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/18/2021] [Indexed: 01/08/2023] Open
Abstract
An overview of the main polyhydroxyalkanoates (PHA) recovery methods is here reported, by considering the kind of PHA-producing bacteria (single bacterial strains or mixed microbial cultures) and the chemico-physical characteristics of the extracted polymer (molecular weight and polydispersity index). Several recovery approaches are presented and categorized in two main strategies: PHA recovery with solvents (halogenated solvents, alkanes, alcohols, esters, carbonates and ketones) and PHA recovery by cellular lysis (with oxidants, acid and alkaline compounds, surfactants and enzymes). Comparative evaluations based on the recovery, purity and molecular weight of the recovered polymers as well as on the potential sustainability of the different approaches are here presented.
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Affiliation(s)
- Giorgia Pagliano
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, Ravenna, Italy
| | - Paola Galletti
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, Ravenna, Italy
- CIRI-Fonti Rinnovabili, Ambiente, Mare ed Energia, Ravenna, Italy
| | - Chiara Samorì
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, Ravenna, Italy
- CIRI-Fonti Rinnovabili, Ambiente, Mare ed Energia, Ravenna, Italy
| | - Agnese Zaghini
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, Ravenna, Italy
| | - Cristian Torri
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, Ravenna, Italy
- CIRI-Fonti Rinnovabili, Ambiente, Mare ed Energia, Ravenna, Italy
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Established and advanced approaches for recovery of microbial polyhydroxyalkanoate (PHA) biopolyesters from surrounding microbial biomass. EUROBIOTECH JOURNAL 2020. [DOI: 10.2478/ebtj-2020-0013] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Abstract
Downstream processing for recovery of microbial polyhydroxyalkanoate (PHA) biopolyesters from biomass constitutes an integral part of the entire PHA production chain; beside the feedstocks used for cultivation of PHA-production strains, this process is currently considered the major cost factor for PHA production.
Besides economic aspects, PHA recovery techniques need to be sustainable by avoiding excessive use of (often precarious!) solvents, other hazardous chemicals, non-recyclable compounds, and energy. Moreover, the applied PHA recovery method is decisive for the molecular mass and purity of the obtained product, and the achievable recovery yield. In addition to the applied method, also the PHA content in biomass is decisive for the feasibility of a selected technique. Further, not all investigated recovery techniques are applicable for all types of PHA (crystalline versus amorphous PHA) and all PHA-producing microorganisms (robust versus fragile cell structures).
The present review shines a light on benefits and shortcomings of established solvent-based, chemical, enzymatic, and mechanical methods for PHA recovery. Focus is dedicated on innovative, novel recovery strategies, encompassing the use of “green” solvents, application of classical “PHA anti-solvents” under pressurized conditions, ionic liquids, supercritical solvents, hypotonic cell disintegration for release of PHA granules, switchable anionic surfactants, and even digestion of non-PHA biomass by animals.
The different established and novel techniques are compared in terms of PHA recovery yield, product purity, impact on PHA molar mass, scalability to industrial plants, and demand for chemicals, energy, and time.
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Mannina G, Presti D, Montiel-Jarillo G, Carrera J, Suárez-Ojeda ME. Recovery of polyhydroxyalkanoates (PHAs) from wastewater: A review. BIORESOURCE TECHNOLOGY 2020; 297:122478. [PMID: 31810735 DOI: 10.1016/j.biortech.2019.122478] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/19/2019] [Accepted: 11/21/2019] [Indexed: 06/10/2023]
Abstract
Polyhydroxyalkanoates (PHAs) are biopolyesters accumulated as carbon and energy storage materials under unbalanced growth conditions by various microorganisms. They are one of the most promising potential substitutes for conventional non-biodegradable plastics due to their similar physicochemical properties, but most important, its biodegradability. Production cost of PHAs is still a great barrier to extend its application at industrial scale. In order to reduce that cost, research is focusing on the use of several wastes as feedstock (such as agro-industrial and municipal organic waste and wastewater) in a platform based on mixed microbial cultures. This review provides a critical illustration of the state of the art of the most likely-to-be-scale-up PHA production processes using mixed microbial cultures platform and waste streams as feedstock, with a particular focus on both, upstream and downstream processes. Current pilot scale studies, future prospects, challenges and developments in the field are also highlighted.
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Affiliation(s)
- Giorgio Mannina
- Engineering Department, Palermo University, Viale delle Scienze, Ed.8, 90128 Palermo, Italy.
| | - Dario Presti
- Departament d'Enginyeria Química, Biològica i Ambiental, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellatera (Barcelona), Spain
| | - Gabriela Montiel-Jarillo
- Departament d'Enginyeria Química, Biològica i Ambiental, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellatera (Barcelona), Spain
| | - Julián Carrera
- Departament d'Enginyeria Química, Biològica i Ambiental, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellatera (Barcelona), Spain
| | - María Eugenia Suárez-Ojeda
- Departament d'Enginyeria Química, Biològica i Ambiental, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellatera (Barcelona), Spain
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A sustainable approach for the downstream processing of bacterial polyhydroxyalkanoates: State-of-the-art and latest developments. Biochem Eng J 2019. [DOI: 10.1016/j.bej.2019.107283] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Demirdöğen RE, Emen FM, Ocakoglu K, Murugan P, Sudesh K, Avşar G. Green Nanotechnology for Synthesis and characterization of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) nanoparticles for sustained bortezomib release using supercritical CO2 assisted particle formation combined with electrodeposition. Int J Biol Macromol 2018; 107:436-445. [DOI: 10.1016/j.ijbiomac.2017.09.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Revised: 08/13/2017] [Accepted: 09/05/2017] [Indexed: 11/16/2022]
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Koller M, Niebelschütz H, Braunegg G. Strategies for recovery and purification of poly[(R)-3-hydroxyalkanoates] (PHA) biopolyesters from surrounding biomass. Eng Life Sci 2013. [DOI: 10.1002/elsc.201300021] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Affiliation(s)
- Martin Koller
- Institute of Biotechnology and Biochemical Engineering; Graz University of Technology; Graz Austria
- ARENA Arbeitsgemeinschaft für Ressourcenschonende & Nachhaltige Technologien; Graz Austria
| | | | - Gerhart Braunegg
- ARENA Arbeitsgemeinschaft für Ressourcenschonende & Nachhaltige Technologien; Graz Austria
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Khosravi-Darani K. Research Activities on Supercritical Fluid Science in Food Biotechnology. Crit Rev Food Sci Nutr 2010; 50:479-88. [DOI: 10.1080/10408390802248759] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Khosravi-Darani K, Vasheghani-Farahani E. Application of Supercritical Fluid Extraction in Biotechnology. Crit Rev Biotechnol 2008; 25:231-42. [PMID: 16419619 DOI: 10.1080/07388550500354841] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
In the present paper recent investigations on the applications of supercritical fluid extraction (SCE) from post fermentation biomass or in situ extraction of inhibitory fermentation products as a promising method for increasing the yield of extraction have been reviewed. Although supercritical CO2 (SC-CO2) is unfriendly, or even toxic, for some living cells and precludes direct fermentation in dense CO2, it does not rule out other useful applications for in situ extraction of inhibitory fermentation products and fractional extraction of biomass constituents. This technique is a highly desirable method for fractional extraction of biomass constituents, and intracellular metabolites due to the potential of system modification by physical parameters and addition of co-solvents to selectively extract compounds of different polarity, volatility and hydrophilicity without any contamination.
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Affiliation(s)
- K Khosravi-Darani
- Department of Chemical Engineering, Tarbiat Modarres University, Tehran, IR Iran
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Abstract
AIMS To investigate the regulation of de novo pyrimidine biosynthesis in the bacterium Pseudomonas resinovorans ATCC 14235. METHODS AND RESULTS The pyrimidine biosynthetic pathway enzymes were measured in cell extracts from P. resinovorans ATCC 14235 and from an auxotroph lacking orotate phosphoribosyltransferase activity. Pyrimidine biosynthetic pathway enzyme activities in ATCC 14235 were affected by the addition of pyrimidine bases to the culture medium. The de novo enzyme activities of the phosphoribosyltransferase mutant strain increased after pyrimidine starvation indicating possible repression of the pathway by a pyrimidine-related compound. Aspartate transcarbamoylase activity in ATCC 14235 was inhibited in vitro by ATP, UTP and pyrophosphate. CONCLUSIONS Pyrimidine biosynthesis in P. resinovorans was regulated at the level of enzyme synthesis and at the level of activity for aspartate transcarbamoylase. Its regulation of enzyme synthesis seemed to be similar to what has been observed in the taxonomically related species Pseudomonas oleovorans. SIGNIFICANCE AND IMPACT OF THE STUDY This study found that pyrimidine biosynthesis is regulated in P. resinovorans. This could prove helpful to future studies investigating polyhydroxyalkanoate production by the bacterium.
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Affiliation(s)
- T P West
- Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD, USA.
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Ashby RD, Solaiman DK, Foglia TA, Liu CK. Glucose/lipid mixed substrates as a means of controlling the properties of medium chain length poly(hydroxyalkanoates). Biomacromolecules 2002; 2:211-6. [PMID: 11749175 DOI: 10.1021/bm000098+] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Glucose-triacylglycerol (TAG) mixed substrates were used to modulate the physical and mechanical properties of medium-chain-length poly(hydroxyalkanoates) (mcl-PHAs). Pseudomonas resinovorans NRRL B-2649 grew and produced mcl-PHAs on glucose and TAGs (coconut oil, C; soybean oil, S) after 24 h in a shake flask culture. However, with the exception of coconut oil, maximum cell productivity was not reached in any of the cultures until 72 h post-inoculation. Here, 50:50 mixtures of glucose and coconut oil (glc/C) or glucose and soybean oil (glc/S) resulted in intermediate cell productivities with a maximum of 57% and 48% of the CDW at 72 h, respectively. In addition, mixed substrates resulted in mcl-PHAs with compositions that varied slightly over time. PHA-glc/C and PHA-glc/S were composed of 7 mol % and 8 mol % 3-hydroxydodecenoic acid (C(12:1)), respectively at 72 h. These concentrations were intermediate to the C(12:1) concentration of PHA-glc and respective PHA-TAG. Also, significant amounts of 3-hydroxytetradecanoic acid (C(14:0)), 3-hydroxytetradecenoic acid (C(14:1)), and 3-hydroxytetradecadienoic acid (C(14:2)) were present in PHA-glc/C and PHA-glc/S, which were derived from the respective TAG, as glucose resulted in almost no C(14:)(X) monomers. The molar masses of each of the polymers remained relatively constant between 24 and 96 h. At 72 h, the number-average molar masses (M(n)) of PHA-glc/C and PHA-glc/S were 178,000 and 163,000 g/mol, respectively, which were also intermediate to the M(n) of PHA-glc (225,000 g/mol) and the respective PHA-TAG (PHA-C = 153,000 g/mol; PHA-S = 75,000 g/mol). These physical differences caused variations in the mechanical properties of mcl-PHA films, thus providing a new and effective method of modifying their properties.
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Affiliation(s)
- R D Ashby
- United States Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
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