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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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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: 74] [Impact Index Per Article: 18.5] [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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Da Costa Basto RM, Casals MP, Mudde RF, van der Wielen LA, Cuellar MC. A mechanistic model for oil recovery in a region of high oil droplet concentration from multiphasic fermentations. CHEMICAL ENGINEERING SCIENCE: X 2019. [DOI: 10.1016/j.cesx.2019.100033] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Israni N, Thapa S, Shivakumar S. Biolytic extraction of poly(3-hydroxybutyrate) from Bacillus megaterium Ti3 using the lytic enzyme of Streptomyces albus Tia1. J Genet Eng Biotechnol 2018; 16:265-271. [PMID: 30733734 PMCID: PMC6354000 DOI: 10.1016/j.jgeb.2018.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 07/02/2018] [Accepted: 07/16/2018] [Indexed: 11/21/2022]
Abstract
The applicability of Streptomyces sp. cell lytic enzymes for devising a simple and competent biological polyhydroxyalkanoate (PHA) recovery approach from Bacillus megaterium cells was investigated. B. megaterium strain Ti3 produced 50% (w/w) PHA using glucose as carbon source. The intracellular PHA was recovered employing a non-PHA accumulating actinomycetes (Tia1) identified as Streptomyces albus, having potent lytic activity against living and heat inactivated B. megaterium. Interestingly, maximum biomass (2.53 ± 0.6 g/L by 24 h) of the lytic actinomycete was obtained in PHA production medium itself thus circumventing the prior actinomycete acclimatization just by co-inoculation with B. megaterium as an inducer. Maximum lytic activity was observed at pH 6.0, 40 °C, 220 mg of biomass and 33.3 mL of concentrated culture filtrate in a 100 mL reaction mixture. Preliminary biochemical investigations confirmed the proteolytic and caseinolytic nature of the lytic enzyme. PHA yield of 0.55 g/g by co-inoculation extraction approach was comparable with the conventional sodium hypochlorite based extraction method. Interestingly, S. albus also demonstrated a broad spectrum lytic potential against varied Gram-negative and Gram-positive PHA producers highlighting the extensive applicability of this biolytic PHA recovery approach. The lytic enzyme retained almost 100% relative activity on storage at -20 °C upto two months. 1H Nuclear magnetic resonance analysis of the extracted polymer confirmed it as a homopolymer composed of 3-hydroxybutyrate monomeric units. This is the first report on Streptomyces sp. based biological and eco-friendly, intracellular PHA recovery from Bacillus spp.
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Affiliation(s)
| | | | - Srividya Shivakumar
- Department of Microbiology, School of Sciences, Jain University, Bangalore 560011, India
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6
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Bayat AE, Rajaei K, Junin R. Assessing the effects of nanoparticle type and concentration on the stability of CO 2 foams and the performance in enhanced oil recovery. Colloids Surf A Physicochem Eng Asp 2016. [DOI: 10.1016/j.colsurfa.2016.09.083] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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7
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Madkour MH, Heinrich D, Alghamdi MA, Shabbaj II, Steinbüchel A. PHA Recovery from Biomass. Biomacromolecules 2013; 14:2963-72. [DOI: 10.1021/bm4010244] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mohamed H. Madkour
- Institut
für Molekulare Mikrobiologie und Biotechnologie, Westfälische
Wilhelms-Universität Münster, and ‡Environmental Sciences Department,
Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah, 21589,
Saudi-Arabia
| | - Daniel Heinrich
- Institut
für Molekulare Mikrobiologie und Biotechnologie, Westfälische
Wilhelms-Universität Münster, and ‡Environmental Sciences Department,
Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah, 21589,
Saudi-Arabia
| | - Mansour A. Alghamdi
- Institut
für Molekulare Mikrobiologie und Biotechnologie, Westfälische
Wilhelms-Universität Münster, and ‡Environmental Sciences Department,
Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah, 21589,
Saudi-Arabia
| | - Ibraheem I. Shabbaj
- Institut
für Molekulare Mikrobiologie und Biotechnologie, Westfälische
Wilhelms-Universität Münster, and ‡Environmental Sciences Department,
Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah, 21589,
Saudi-Arabia
| | - Alexander Steinbüchel
- Institut
für Molekulare Mikrobiologie und Biotechnologie, Westfälische
Wilhelms-Universität Münster, and ‡Environmental Sciences Department,
Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah, 21589,
Saudi-Arabia
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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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9
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Cuellar MC, Heijnen JJ, van der Wielen LAM. Large-scale production of diesel-like biofuels - process design as an inherent part of microorganism development. Biotechnol J 2013; 8:682-9. [DOI: 10.1002/biot.201200319] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 02/21/2013] [Accepted: 03/27/2013] [Indexed: 01/17/2023]
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Enhanced Recovery and Purification of P(3HB-co-3HHx) from Recombinant Cupriavidus necator Using Alkaline Digestion Method. Appl Biochem Biotechnol 2012; 167:524-35. [DOI: 10.1007/s12010-012-9677-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Accepted: 04/10/2012] [Indexed: 11/24/2022]
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Anis SNS, Iqbal NM, Kumar S, Al-Ashraf A. Increased recovery and improved purity of PHA from recombinant Cupriavidus necator. Bioengineered 2012; 4:115-8. [PMID: 23018620 DOI: 10.4161/bioe.22350] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
A simple procedure for recovering biodegradable polymer from bacterial cells has been developed using economical and environmentally friendly solvent or chemicals. Recombinant bacterium, Cupriavidus necator harboring pBBR1MCS-C2 plasmid polyhydroxyalkanoate (PHA) synthase gene was used for the production of copolymer P(3HB-co-3HHx) from crude palm kernel oil (CPKO). NaOH was chosen in this study as it could give high purity and recovery yield. Increase of NaOH concentration had resulted in an increase of the PHA purity, but the recovery yield had decreased. The greater improvement of PHA purity and recovery were achieved by incubating the freeze-dried cells (10-30 g/L) in NaOH (0.1 M) for 1-3 h at 30°C and polishing using 20% (v/v) of ethanol. The treatment caused negligible degradation of the molecular weight of PHA recovered from the bacterial cells. The present review also highlights other extraction methods to provide greater insights into economical and sustainable recovery of PHA from bacterial cells.
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12
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Foam mitigation and exploitation in biosurfactant production. Biotechnol Lett 2011; 34:187-95. [PMID: 22038550 DOI: 10.1007/s10529-011-0782-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 10/13/2011] [Indexed: 10/16/2022]
Abstract
Biosurfactants could potentially outperform traditional surfactants in many applications whilst being more sustainable to source, manufacture, use and dispose of. However, currently available fermentation production methods are too inefficient to manufacture biosurfactants for these high volume markets. Foaming in an inherent issue with biosurfactant production and adds significantly to the cost of production using traditional unit operations. This review illustrates how the application of process engineering has enabled nuisance foaming to be transformed into a cost saving feature of the production system. The scope of biosurfactants and their application is discussed and the fundamentals of foam generation and control are reviewed. The range of specific phenomena associated with the interaction of foams with bioproducts is assessed. Finally, recent work which has aimed at taking advantage of some of these phenomena in order to intensify the biosurfactant production process is discussed in detail.
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Martínez V, García P, García JL, Prieto MA. Controlled autolysis facilitates the polyhydroxyalkanoate recovery in Pseudomonas putida KT2440. Microb Biotechnol 2011; 4:533-47. [PMID: 21418544 PMCID: PMC3815265 DOI: 10.1111/j.1751-7915.2011.00257.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The development of efficient recovery processes is essential to reduce the cost of polyhydroxyalkanoates (PHAs) production. In this work, a programmed self‐disruptive Pseudomonas putida BXHL strain, derived from the prototype medium‐chain‐length PHA producer bacterium P. putida KT2440, was constructed as a proof of concept for exploring the possibility to control and facilitate the release of PHA granules to the extracellular medium. The new autolytic cell disruption system is based on two simultaneous strategies: the coordinated action of two proteins from the pneumococcal bacteriophage EJ‐1, an endolysin (Ejl) and a holin (Ejh), and the mutation of the tolB gene, which exhibits alterations in outer membrane integrity that induce lysis hypersensitivity. The ejl and ejh coding genes were expressed under a XylS/Pm monocopy expression system inserted into the chromosome of the tolB mutant strain, in the presence of 3‐methylbenzoate as inducer molecule. Our results demonstrate that the intracellular presence of PHA granules confers resistance to cell envelope. Conditions to control the cell autolysis in P. putida BXHL in terms of optimal fermentation, PHA content and PHA recovery have been set up by exploring the sensitivity to detergents, chelating agents and wet biomass solubility in organic solvents such as ethyl acetate.
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Affiliation(s)
- Virginia Martínez
- Environmental Biology Department, Centro de Investigaciones Biológicas, Madrid, Spain
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14
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Rayat ACME, Micheletti M, Lye GJ. Evaluation of cell disruption effects on primary recovery of antibody fragments using microscale bioprocessing techniques. Biotechnol Prog 2011; 26:1312-21. [PMID: 20945488 DOI: 10.1002/btpr.450] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Intracellular antibody Fab' fragments periplasmically expressed in Escherichia coli require the release of Fab' from the cells before initial product recovery. This work demonstrates the utility of microscale bioprocessing techniques to evaluate the influence of different cell disruption operations on subsequent solid-liquid separation and product recovery. Initially, the industrial method of Fab' release by thermochemical extraction was established experimentally at the microwell scale and was observed to yield Fab' release consistent with the larger scale process. The influence of two further cell disruption operations, homogenization and sonication, on subsequent Fab' recovery by microfiltration was also examined. The results showed that the heat-extracted cells give better dead-end microfiltration performance in terms of permeate flux and specific cake resistance. In contrast, the cell suspensions prepared by homogenization and sonication showed more efficient product release but with lower product purity and poorer microfiltration performance. Having established the various microscale methods the linked sequence was automated on the deck of a laboratory robotic platform and used to show how different conditions during thermochemical extraction impacted on the optimal performance of the linked unit operations. The results illustrate the power of microscale techniques to evaluate crucial unit operation interactions in a bioprocess sequence using only microliter volumes of feed.
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Affiliation(s)
- Andrea C M E Rayat
- Dept. of Biochemical Engineering, The Advanced Centre for Biochemical Engineering, University College London, Torrington Place, London WC1E7JE, UK
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Mumtaz T, Yahaya NA, Abd-Aziz S, Abdul Rahman N, Yee PL, Shirai Y, Hassan MA. Turning waste to wealth-biodegradable plastics polyhydroxyalkanoates from palm oil mill effluent – a Malaysian perspective. JOURNAL OF CLEANER PRODUCTION 2010; 18:1393-1402. [DOI: 10.1016/j.jclepro.2010.05.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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16
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McChalicher CWJ, Srienc F, Rouse DP. Solubility and degradation of polyhydroxyalkanoate biopolymers in propylene carbonate. AIChE J 2009. [DOI: 10.1002/aic.12087] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Christopher W. J. McChalicher
- Dept. of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455
- Biotechnology Institute, University of Minnesota, St. Paul, MN 55108
| | - Friedrich Srienc
- Dept. of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455
- Biotechnology Institute, University of Minnesota, St. Paul, MN 55108
| | - Daniel P. Rouse
- Biotechnology Institute, University of Minnesota, St. Paul, MN 55108
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Ibrahim MHA, Steinbüchel A. Poly(3-hydroxybutyrate) production from glycerol by Zobellella denitrificans MW1 via high-cell-density fed-batch fermentation and simplified solvent extraction. Appl Environ Microbiol 2009; 75:6222-31. [PMID: 19666728 PMCID: PMC2753068 DOI: 10.1128/aem.01162-09] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Accepted: 07/28/2009] [Indexed: 11/20/2022] Open
Abstract
Industrial production of biodegradable polyesters such as polyhydroxyalkanoates is hampered by high production costs, among which the costs for substrates and for downstream processing represent the main obstacles. Inexpensive fermentable raw materials such as crude glycerol, an abundant by-product of the biodiesel industry, have emerged to be promising carbon sources for industrial fermentations. In this study, Zobellella denitrificans MW1, a recently isolated bacterium, was used for the production of poly(3-hydroxybutyrate) (PHB) from glycerol as the sole carbon source. Pilot-scale fermentations (42-liter scale) were conducted to scale up the high PHB accumulation capability of this strain. By fed-batch cultivation, at first a relatively high cell density (29.9 +/- 1.3 g/liter) was obtained during only a short fermentation period (24 h). However, the PHB content was relatively low (31.0% +/- 4.2% [wt/wt]). Afterwards, much higher concentrations of PHB (up to 54.3 +/- 7.9 g/liter) and higher cell densities (up to 81.2 +/- 2.5 g/liter) were obtained by further fed-batch optimization in the presence of 20 g/liter NaCl, with optimized feeding of glycerol and ammonia to support both cell growth and polymer accumulation over a period of 50 h. A high specific growth rate (0.422/h) and a short doubling time (1.64 h) were attained. The maximum PHB content obtained was 66.9% +/- 7.6% of cell dry weight, and the maximum polymer productivity and substrate yield coefficient were 1.09 +/- 0.16 g/liter/h and 0.25 +/- 0.04 g PHB/g glycerol, respectively. Furthermore, a simple organic solvent extraction process was employed for PHB recovery during downstream processing: self-flotation of cell debris after extraction of PHB with chloroform allowed a convenient separation of a clear PHB-solvent solution from the cells. Maximum PHB recovery (85.0% +/- 0.10% [wt/wt]) was reached after 72 h of extraction with chloroform at 30 degrees C, with a polymer purity of 98.3% +/- 1.3%.
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Affiliation(s)
- Mohammad H A Ibrahim
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany
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Elbahloul Y, Steinbüchel A. Large-scale production of poly(3-hydroxyoctanoic acid) by Pseudomonas putida GPo1 and a simplified downstream process. Appl Environ Microbiol 2009; 75:643-51. [PMID: 19047387 PMCID: PMC2632139 DOI: 10.1128/aem.01869-08] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 11/21/2008] [Indexed: 11/20/2022] Open
Abstract
The suitability of Pseudomonas putida GPo1 for large-scale cultivation and production of poly(3-hydroxyoctanoate) (PHO) was investigated in this study. Three fed-batch cultivations of P. putida GPo1 at the 350- or 400-liter scale in a bioreactor with a capacity of 650 liters were done in mineral salts medium containing initially 20 mM sodium octanoate as the carbon source. The feeding solution included ammonium octanoate, which was fed at a relatively low concentration to promote PHO accumulation under nitrogen-limited conditions. During cultivation, the pH was regulated by addition of NaOH, NH(4)OH, or octanoic acid, which was used as an additional carbon source. Partial O(2) pressure (pO(2)) was adjusted to 20 to 40% by controlling the airflow and stirrer speed. Under the optimized conditions, P. putida GPo1 was able to grow to cell densities as high as 18, 37, and 53 g cells (dry mass) (CDM) per liter containing 49, 55, and 60% (wt/wt) of PHO, respectively. The resulting 40 kg CDM from these three cultivations was used directly for extraction of PHO. Three different methods of extraction of PHO were applied. From these, only acetone extraction showed better performance and resulted in 94% recovery of the PHO contents of cells. A novel mixture of precipitation solvents composed of 70% (vol/vol) methanol and 70% (vol/vol) ethanol was identified in this study. The ratio of PHO concentrate to the mixture was 0.2:1 (vol/vol) and allowed complete precipitation of PHO as white flakes. However, at a ratio of 1:1 (vol/vol) of the solvent mixture to PHO concentrate, a highly purified PHO was obtained. Precipitation yielded a dough-like polymeric material which was cast into thin layers and then shredded into small strips to allow evaporation of the remaining solvents. Gas chromatographic analysis revealed a purity of about 99% +/- 0.2% (wt/wt) of the polymer, which consisted mainly of 3-hydroxyoctanoic acid (96 mol%).
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Affiliation(s)
- Yasser Elbahloul
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Germany
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Verlinden RAJ, Hill DJ, Kenward MA, Williams CD, Radecka I. Bacterial synthesis of biodegradable polyhydroxyalkanoates. J Appl Microbiol 2007; 102:1437-49. [PMID: 17578408 DOI: 10.1111/j.1365-2672.2007.03335.x] [Citation(s) in RCA: 372] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Various bacterial species accumulate intracellular polyhydroxyalkanoates (PHAs) granules as energy and carbon reserves inside their cells. PHAs are biodegradable, environmentally friendly and biocompatible thermoplastics. Varying in toughness and flexibility, depending on their formulation, they can be used in various ways similar to many nonbiodegradable petrochemical plastics currently in use. They can be used either in pure form or as additives to oil-derived plastics such as polyethylene. However, these bioplastics are currently far more expensive than petrochemically based plastics and are therefore used mostly in applications that conventional plastics cannot perform, such as medical applications. PHAs are immunologically inert and are only slowly degraded in human tissue, which means they can be used as devices inside the body. Recent research has focused on the use of alternative substrates, novel extraction methods, genetically enhanced species and mixed cultures with a view to make PHAs more commercially attractive.
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Affiliation(s)
- R A J Verlinden
- School of Applied Sciences, University of Wolverhampton, Wolverhampton, UK
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Sun Z, Ramsay JA, Guay M, Ramsay BA. Fermentation process development for the production of medium-chain-length poly-3-hyroxyalkanoates. Appl Microbiol Biotechnol 2007; 75:475-85. [PMID: 17453197 DOI: 10.1007/s00253-007-0857-4] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Revised: 01/19/2007] [Accepted: 01/22/2007] [Indexed: 10/23/2022]
Abstract
This paper presents a review of the existing fermentation processes for the production of medium-chain-length poly-3-hydroxyalkanoates (MCL-PHAs). These biodegradable polymers are usually produced most efficiently from structurally related carbon sources such as alkanes and alkanoic acids. Unlike alkanoic acids, alkanes exhibit little toxicity but their low aqueous solubility limits their use in high density culture. Alkanoic acids pose little mass transfer difficulty, but their toxicity requires that their concentration be well controlled. Using presently available technology, large-scale production of MCL-PHA from octane has been reported to cost from US $5 to 10 per kilogram, with expenditures almost evenly divided between carbon source, fermentation process, and the separation process. However, MCL-PHAs, even some with functional groups in their subunits, can also be produced from cheaper unrelated carbon sources, such as glucose. Metabolic engineering and other approaches should also allow increased PHA cellular content to be achieved. These approaches, as well as a better understanding of fermentation kinetics, will likely result in increased productivity and lower production costs.
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Affiliation(s)
- Zhiyong Sun
- Department of Chemical Engineering, Queen's University, Kingston, ON, K7L 3N6, Canada
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