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1.
Poly[(R)-3-hydroxybutyric acid] (PHB) was produced at 37 °C by a recombinant Escherichia coli harboring the Alcaligenes eutrophus biosynthesis phbCAB genes in Luria-Bertani media containing glucose at 10–30 g/l at different pH values and the time-dependent changes in the
molecular mass of PHB were studied. PHB polymers accumulated within cells while glucose was present in the medium. The number-average
molecular mass of PHB decreased with time during the course of PHB accumulation, and the values for PHB were markedly dependent
on the cultivation conditions of the E. coli, ranging from 0.5 MDa to 20 MDa. Under specific conditions (pH 6.0), E. coli produced PHB with an extremely high molecular mass (20 MDa). It has been suggested that a chain-transfer agent is generated
in E. coli cells during the accumulation of PHB.
Received: 18 July 1996 / Received revision: 4 November 1996 / Accepted: 4 November 1996 相似文献
2.
A linear relationship between total solid concentration (TSC), δ-endotoxin production [Cry = 0.2795(TSC)−0.2472, R2 = 0.8644] and poly-β-hydroxybutyrate (PHB) accumulation [PHB = 0.1327(TSC) + 0.3974, R2 = 0.9877] in Bacillus thuringiensis var. kurstaki HD-73 was observed. A similar correlation between δ-endotoxin and PHB accumulation [Cry = 2.1573(PHB)−1.1248, R2 = 0.9181] was found. A minimum PHB accumulation of 0.52 mg l−1 was required before the onset of δ-endotoxin production.
Revisions requested 28 September 2005 and 4 November 2005; Revisions received 28 October 2005 and 1 February 2006 相似文献
3.
Poly-(3-hydroxybutyrate) production from whey by high-density cultivation of recombinant Escherichia coli 总被引:2,自引:0,他引:2
Recombinant Escherichia coli strain GCSC 6576, harboring a high-copy-number plasmid containing the Ralstonia eutropha genes for polyhydroxyalkanoate (PHA) synthesis and the E. coli ftsZ gene, was employed to produce poly-(3-hydroxybutyrate) (PHB) from whey. pH-stat fed-batch fermentation, using whey powder
as the nutrient feed, produced cellular dry weight and PHB concentrations of 109 g l−1 and 50 g l−1 respectively in 47 h. When concentrated whey solution containing 210 g l−1 lactose was used as the nutrient feed, cellular dry weight and PHB concentrations of 87 g l−1 and 69 g l−1 respectively could be obtained in 49 h by pH-stat fed-batch culture. The PHB content was as high as 80% of the cellular dry
weight. These results suggest that cost-effective production of PHB is possible by fed-batch culture of recombinant E. coli using concentrated whey solution as a substrate.
Received: 19 December 1997 / Received revision: 17 March 1998 / Accepted: 20 March 1998 相似文献
4.
Kathryn L. Houmiel Steven Slater Debra Broyles Laura Casagrande Susan Colburn Kathleen Gonzalez Timothy A. Mitsky Steven E. Reiser Devang Shah Nancy B. Taylor Mintien Tran Henry E. Valentin Kenneth J. Gruys 《Planta》1999,209(4):547-550
Polyhydroxyalkanoates (PHAs) comprise a class of biodegradable polymers which offer an environmentally sustainable alternative
to petroleum-based plastics. Production of PHAs in plants is attractive since current fermentation technology is prohibitively
expensive. The PHA homopolymer poly(β-hydroxybutyrate) (PHB) has previously been produced in leaves of Arabidopsis thaliana (Nawrath et al., 1994, Proc Natl Acad Sci USA 91: 12760–12764). However, Brassica napus oilseed may provide a better system for PHB production because acetyl-CoA, the substrate required in the first step of PHB
biosynthesis, is prevalent during fatty acid biosynthesis. Three enzymatic activities are needed to synthesize PHB: a β-ketothiolase,
an acetoacetyl-CoA reductase and a PHB synthase. Genes from the bacterium Ralstonia eutropha encoding these enzymes were independently engineered behind the seed-specific Lesquerella fendleri oleate 12-hydroxylase promoter in a modular fashion. The gene cassettes were sequentially transferred into a single, multi-gene
vector which was used to transform B. napus. Poly(β-hydroxybutyrate) accumulated in leukoplasts to levels as high as 7.7% fresh seed weight of mature seeds. Electron-microscopy
analyses indicated that leukoplasts from these plants were distorted, yet intact, and appeared to expand in response to polymer
accumulation.
Received: 26 May 1999 / Accepted: 16 June 1999 相似文献
5.
Poly(hydroxybutyric acid) (PHB) was produced by a selectant of Azotobacter beijerinckii in media containing only organic nitrogen sources such as N substrates. The chosen compounds were casein peptone, yeast extract,
casamino acids and urea, each combined with carbon substrates glucose or sucrose. The PHB was synthesized under growth-associated
conditions. The concentrations amounted to more than 50% of cell dry mass on casein peptone/glucose as well as urea/glucose
medium within 45 h fermentation time. Corresponding to these yields, productivities of about 0.8 g PHB l−1 h−1 were discovered. The highest values increased to 1.06 g PHB l−1 h−1 on casein peptone/glucose medium and 1.1 g PHB l−1 h−1 on yeast extract/glucose medium after a period of 20 h. It was found that oxygen limitation was essential for successful
product formation, as demonstrated earlier. These data from basic research may support further investigations into the use
of technical proteins from renewable sources as substrates for PHB production by a strain of A. beijerinckii.
Received: 3 June 1997 / Received revision: 29 August 1997 / Accepted: 15 September 1997 相似文献
6.
F O Ayorinde K A Saeed E Price A Morrow W E Collins F McInnis S K Pollack B E Eribo 《Journal of industrial microbiology & biotechnology》1998,21(1-2):46-50
Saponified vernonia oil was converted exclusively to poly(β-hydroxybutyrate) (PHB) by Alcaligenes eutrophus in a single-stage batch culture. After harvesting, centrifugation followed by lyophilization, the resulting dried cells contained
up to 42.8 wt% PHB having a peak molecular mass of 381 863 Da, weight-average molecular mass of 308 390 Da, and a polydispersity
of 1.1. The PHB had a melting point (Tm) range of 163–174°C with a maximum at 172°C (lit. Tm, 175°C), and heat of fusion of 18.43 cal g−1. Fermentation performed under varying conditions of nitrogen limitation indicated that there was no significant effect of
nitrogen concentration on the molecular mass of PHB produced from vernonia oil by A. eutrophus.
Received 27 March 1998/ Accepted in revised form 17 July 1998 相似文献
7.
《Applied microbiology and biotechnology》2008,78(6):1089-1343
Poly(3-hydroxybutyrate) (PHB) synthesis was analyzed under microaerobic conditions in a recombinant Escherichia coli arcA mutant using glycerol as the main carbon source. The effect of several additives was assessed in a semi-synthetic medium
by the ‘one-factor-at-a-time’ technique. Casein amino acids (CAS) concentration was an important factor influencing both growth
and PHB accumulation. Three factors exerting a statistically significant influence on PHB synthesis were selected by using
a Plackett–Burman screening design [glycerol, CAS, and initial cell dry weight (CDW) concentrations] and then optimized through
a Box–Wilson design. Under such optimized conditions (22.02 g l−1 glycerol, 1.78 g l−1 CAS, and 1.83 g l−1 inoculum) microaerobic batch cultures gave rise to 8.37 g l−1 CDW and 3.52 g l−1 PHB in 48 h (PHB content of 42%) in a benchtop bioreactor. Further improvements in microaerobic PHB accumulation were obtained
in fed-batch cultures, in which glycerol was added to maintain its concentration above 5 g l−1. After 60 h, CDW and PHB concentration reached 21.17 and 10.81 g l−1, respectively, which results in a PHB content of 51%. Microaerobic fed-batch cultures allowed a 2.57-fold increase in volumetric
productivity when compared with batch cultures.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
An erratum to this article can be found at 相似文献
8.
Hoi-Ping Shi Chi-Mei Lee Wei-Hsien Ma 《World journal of microbiology & biotechnology》2007,23(5):625-632
Polyhydroxyalkanoates (PHAs), intracellular carbon and energy reserve compounds in many bacteria, have been used extensively
in biodegradable plastics. PHA formation is influenced by nutrient limitations and growth conditions. To characterize the
PHA accumulation in a new denitrifying phosphorus-removing bacterium Brachymonas sp. P12, batch experiments were conducted in which the electron acceptor (oxygen or nitrate) was varied and different concentrations
of carbon (acetate), nitrogen (NH4Cl), and phosphorus (KH2PO4) were used. Polyhydroxybutyrate (PHB) was the dominant product during PHA formation when acetate was the sole carbon source.
The PHB content of aerobically growing cells increased from 431 to 636 mg PHB g−1 biomass, but the PHB concentration of an anoxic culture decreased (−218 mg PHB g−1 biomass), when PHB was utilized simultaneously with acetate as an electron donor for anoxic denitrification. The specific
PHB production rate of the carbon-limited batch, 158.2 mg PHB g−1 biomass h−1, was much greater than that of batches with normal or excess carbon. The effects of phosphorus and nitrogen concentrations
on PHB accumulation were clearly less than the effect of carbon concentration. According to the correlation between the specific
PHB production rate and the specific cell growth rate, PHB accumulation by Brachymonas sp. P12 is enhanced by nutrient limitation, is growth-associated, and provides additional energy for the biosynthesis of
non-PHB cell constituents to increase the cell growth rate beyond the usual level. 相似文献
9.
The bacterial polyester poly-β-hydroxybutyrate (PHB) was quantified and characterized on an isolate␣of the nitrogen-fixing
bacteria Azotobacter chroococcum 6B on the basis of its average molecular mass, determined from the relative viscosity at different aeration rates and carbon/nitrogen
ratios during culture in fermentors. A higher value for the molecular mass (1100 kDa) was obtained with the lower aeration
rates investigated, which diminished, significantly at the highest aeration rate of 2.5 vvm (a 100-fold decrease). The yield
of PHB relative to the amount of glucose consumed increased with the C/N ratio (a maximum of 0.16 g PHB/g glucose consumed
with a carbon/nitrogen ratio of 137.7), but the molecular mass was lowered from 800 kDa to nearly 100 kDa. The maximum PHB
content was 63.5% (on a cellular dry-weight basis) after 47 h in fed-batch culture with an initial C/N ratio of 68.9 and aeration
at a rate of 0.5 vvm. Calorimetric measurements on the isolated PHB showed a melting point near 175 °C.
Received: 25 June 1997 / Accepted: 2 July 1997 相似文献
10.
Quillaguamán J Muñoz M Mattiasson B Hatti-Kaul R 《Applied microbiology and biotechnology》2007,74(5):981-986
Halomonas boliviensis LC1 is able to accumulate poly(β-hydroxybutyrate) (PHB) under conditions of excess carbon source and depletion of essential
nutrients. This study was aimed at an efficient production of PHB by growing H. boliviensis to high cell concentrations in batch cultures. The effect of ammonium, phosphate, and yeast extract concentrations on cell
concentration [cell dry weight (CDW)] and PHB content of H. boliviensis cultured in shake flasks was assayed using a factorial design. High concentrations of these nutrients led to increments in
cell growth but reduced the PHB content to some extent. Cultivations of H. boliviensis under controlled conditions in a fermentor using 1.5% (w/v) yeast extract as N source, and intermittent addition of sucrose
to provide excess C source, resulted in a polymer accumulation of 44 wt.% and 12 g l−1 CDW after 24 h of cultivation. Batch cultures in a fermentor with initial concentrations of 2.5% (w/v) sucrose and 1.5% (w/v)
yeast extract, and with induced oxygen limitation, resulted in an optimum PHB accumulation, PHB concentration and CDW of 54 wt.%,
7.7 g l−1 and 14 g l−1, respectively, after 19 h of cultivation. The addition of casaminoacids in the medium increased the CDW to 14.4 g l−1 in 17 h but reduced the PHB content in the cells to 52 wt.%. 相似文献
11.
Poly(3-hydroxybutyrate) (PHB) biosynthesis from soybean oil by Cupriavidus necator was studied using a bench scale bioreactor. The highest cell concentration (83 g l−1) was achieved using soybean oil at 40 g l−1 and a pulse of the same concentration. The PHB content was 81% (w/w), PHB productivity was 2.5 g l−1 h−1, and the calculated Yp/s value was 0.85 g g−1. Growth limitation and the onset of PHB biosynthesis took place due to exhaustion of P, and probably also Cu, Ca, and Fe. 相似文献
12.
Batch cultivation of Ralstonia eutropha NRRL B14690 attained 21 g biomass l−1 and 9.4 g poly(β-hydroxybutyrate) l−1 (0.45 g PHB g−1 dry wt−1) in 60 h. Repeated batch operation (empty-and-fill protocol) to remove 20% (v/v) of the culture broth and to supplement an
equal volume of fresh media resulted in 49 g biomass l−1 and 25 g PHB l−1 (0.51 g PHB g−1 dry wt−1) with an overall productivity of 0.42 g PHB l−1 h−1 in 67 h. In the two cycles of repeated batch fermentation there was a 3-fold increase in productivity as compared to batch. 相似文献
13.
Vecherskaya M Dijkema C Stams AJ 《Journal of industrial microbiology & biotechnology》2001,26(1-2):15-21
Poly-β-hydroxybutyrate (PHB) formation under aerobic conditions via incorporation of [13C-2]acetate as a cosubstrate and its intracellular degradation under anaerobic conditions in a Type II methanotroph was studied
by 13C NMR. During PHB synthesis in the presence of labelled acetate, low levels of β-hydroxybutyrate, butyrate, acetone, isopropanol,
2,3-butanediol and succinate were observed. Subsequent anaerobic PHB breakdown showed enhanced levels of these products at
the expense of PHB. Fermentative metabolism occurring during anaerobic PHB degradation was confirmed in experiments with fully
13C-enriched cells, which were grown on 13C-labelled methane. β-hydroxybutyrate, butyrate, acetate, acetone, isopropanol, 2,3-butanediol and succinate were detected
as multiple 13C-labelled compounds in the culture medium. Our results suggest that intracellular PHB degradation can be used as a reserve
energy source by methanotrophs under anoxic conditions. Journal of Industrial Microbiology & Biotechnology (2001) 26, 15–21. 相似文献
14.
I. N. Gogotov V. A. Gerasin Ya. V. Knyazev E. M. Antipov S. Kh. Barazov 《Applied Biochemistry and Microbiology》2010,46(6):607-613
Conditions for the processing and mixing of biodegradable polymers at temperatures less than their thermal destruction (130–150°C)
using standard equipment have been identified. The structure of the polyhydroxybutyrate/valerate (PHB/V) copolymer has been
revealed and peculiarities of the crystal phase formation at different monomer ratios have been investigated. It was shown
that pure PHB with molecular mass 180–270 kDa has elastic module approximately 1.2 GPa, strength approximately 25 MPa, and
elongation at break approximately 10%. The most active biodestructors of PHB, PHB/V, and their composites have been selected
(Aspergillus caespitosus), and the ability of basidiomycete Panus tigrinus to biodegrade polyalkanoates was demonstrated for the first time. It was shown that A. caespitosus degraded PHB/V and Biopol films along with the PHB with the destruction rate depending on the technology of the film production,
on the molecular mass, and on the extend of the polymer crystallinity. 相似文献
15.
Cold stress resulted in a decrease in the poly-β-hydroxybutyrate (PHB) content of non-cold-acclimated Rhizobium DDSS69 cultures. Analysis of the specific activity of β-ketothiolase and β-hydroxybutyrate dehydrogenase revealed that decrease
in PHB levels was a result of the inhibition of synthesis of PHB rather than an increase in its breakdown. Rhizobium ATR1, a cold-acclimated strain, revealed the presence of a stable PHB metabolism that did not show any significant differences
either in PHB levels or in the activity of enzymes of the PHB metabolism under cold stress, suggesting that PHB is not involved
in cold tolerance. Analysis of specific activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase
of the pentose phosphate pathway showed the upward regulation of alternate pathways of carbohydrate metabolism under cold
stress to rapidly generate energy to overcome the stress. There is diversity in the switching mechanisms of carbon metabolism
among cold-acclimated and non-cold-acclimated Rhizobium isolates. Upward regulation of malate dehydrogenase in both isolates suggests that it is a critical input for cold tolerance.
Received: 26 June 2000 / Accepted: 31 July 2000 相似文献
16.
E. J. Bormann M. Leißner M. Roth B. Beer K. Metzner 《Applied microbiology and biotechnology》1998,50(5):604-607
Polyhydroxybutyrate (PHB) was produced by Ralstonia eutropha DSM 11348 (formerly Alicaligenes eutrophus) in media containing 20–30 g l−1 casein peptone or casamino acids as sole sources of nitrogen. In fermentations using media based on casein peptone, permanent
growth up to a cell dry mass of 65 g l−1 was observed. PHB accumulated in cells up to 60%–80% of dry weight. The lowest yields were found in media without any trace
elements or with casamino acids added only. The residual cell dry masses were limited to 10–15 g l−1 and did not contain PHB. The highest productivity amounted to 1.2 g PHB l−1 h−1. The mean molecular mass of the biopolymer was determined as 750 kDa. The proportion of polyhydroxyvalerate was less than
0.2% in PHB. The bioprocess was scaled up to a 300-l plant. During a fermentation time of 39 h the cells accumulated PHB to
78% w/w. The productivity was 0.98 g PHB l−1 h1.
Received: 8 July 1998 / Accepted: 26 August 1998 相似文献
17.
Maple sap, an abundant natural product especially in Canada, is rich in sucrose and thus may represent an ideal renewable
feedstock for the production of a wide variety of value-added products. In the present study, maple sap or sucrose was employed
as a carbon source to Alcaligenes latus for the production of poly-β-hydroxybutyrate (PHB). In shake flasks, the biomass obtained from both the sap and sucrose were
4.4 ± 0.5 and 2.9 ± 0.3 g/L, and the PHB contents were 77.6 ± 1.5 and 74.1 ± 2.0%, respectively. Subsequent batch fermentation
(10 L sap) resulted in the formation of 4.2 ± 0.3 g/L biomass and a PHB content of 77.0 ± 2.6%. The number average molecular
weights of the PHB produced by A. latus from maple sap and pure sucrose media were 300 ± 66 × 103 and 313 ± 104 × 103 g/mol, respectively. Near-infrared, 1H magnetic resonance imaging (MRI), and 13C-MRI spectra of the microbially produced PHB completely matched those obtained with a reference material of poly[(R)-3-hydroxybutyric
acid]. The polymer was found to be optically active with [α]25
D equaled to −7.87 in chloroform. The melting point (177.0°C) and enthalpy of fusion (77.2 J/g) of the polymer were also in
line with those reported, i.e., 177°C and 81 J/g, respectively. 相似文献
18.
Background
Poly-β-hydroxybutyrate (PHB) mobilization in bacteria has been proposed as a mechanism that can benefit their host for survival under stress conditions. Here we reported for the first time that a stress-induced system enabled E. coli, a non-PHB producer, to mobilize PHB in vivo by mimicking natural PHB accumulation bacteria. 相似文献19.
Stanislav Obruca Ivana Marova Marie Stankova Ludmila Mravcova Zdenek Svoboda 《World journal of microbiology & biotechnology》2010,26(7):1261-1267
Exposition of Cupriavidus necator to ethanol or hydrogen peroxide at the beginning of the stationary phase increases poly(3-hydroxybutyrate) (PHB) yields about
30%. Hydrogen peroxide enhances activity of pentose phosphate pathway that probably consequently increases intracellular ratio
NADPH/NADP+. This effect leads to stimulation of the flux of acetyl-CoA into PHB biosynthetic pathway and to an increase of enzymatic
activities of β-ketothiolase and acetoacetyl-CoA reductase while activity of PHB synthase remains uninfluenced. During ethanol
metabolisation, in which alcohol dehydrogenase is involved, acetyl-CoA and reduced coenzymes NAD(P)H are formed. These metabolites
could again slightly inhibit TCA cycle while flux of acetyl-CoA into PHB biosynthetic pathway is likely to be supported. As
a consequence of TCA cycle inhibition also less free CoA is formed. Similarly with hydrogen peroxide, activities of β-ketothiolase
and acetoacetyl-CoA reductase are increased which results in over-production of PHB. Molecular weight of PHB produced under
stress conditions was significantly higher as compared to control cultivation. Particular molecular weight values were dependent
on stress factor concentrations. This could indicate some interconnection among activities of β-ketothiolase, acetoacetyl-CoA
reductase and PHB molecular weight control in vivo. 相似文献
20.
Sandra Mareike Haase Bernhard Huchzermeyer Thomas Rath 《Journal of applied phycology》2012,24(2):157-162
Use of algae for intracellular poly-β-hydroxybutyrate (PHB) accumulation for bioplastic production offers an opportunity in
economic efficiency by reduced costs. The cyanobacterium Nostoc muscorum is a PHB accumulator which presents a great potential as raw material supplier because of short generation cycles. Here,
we examined a range of experimental conditions including different growth conditions of phosphate-starved cells with the addition
of external carbon sources. The highest, absolute PHB accumulation was measured in a phosphate-starved medium with 1% (w/w) glucose and 1% (w/w) acetate. PHB accumulated inside algae cells. After 23 days of growth in phosphate-starved medium, 1 L of culture contained
up to 145.1 mg PHB. The highest PHB accumulation based on the cell dry weight was in an experiment with aeration and CO2 addition. The intracellular level of PHB was up to 21.5% cell dry weight after 8 days. 相似文献