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1.
Stephen E. Harding Gisela Berth Jürgen Hartmann Kornelia Jumel Helmut Clfen Bjrn E. Christensen 《Biopolymers》1996,39(5):729-736
A laboratory-made sample of the polysaccharide xylinan (acetan) has been further characterized with respect to (i) purity, (ii) molar mass and polydispersity, and (iii) gross conformation by a combination of hydrodynamic measurements (sedimentation velocity and equilibrium analytical ultracentrifugation, viscometry, and dynamic light scattering) in aqueous NaCl (I = 0.10 mol·L−1). Sedimentation velocity diagrams recorded using Schlieren optics revealed highly pure material sedimenting as a single boundary [so20.w = 9.5 ± 0.7) S; ks = (273 ± 112) mL/g]. The hypersharp nature of these boundaries is symptomatic of a polydisperse and highly nonideal (in the thermodynamic sense) system. Low speed sedimentation equilibrium in the analytical ultracentrifuge using Rayleigh interference optics and two different types of extrapolation procedure (involving point and whole-cell molar masses) gave a weight average molar mass Mw of (2.5 ± 0.5) × 10−6 g·mol−1 and also a second virial coefficient, B = (2.8 ± 0.7) × 10−4 mL·mol·g−2, both values in good agreement with those from light scattering-based procedures (Part II of this series). A dynamic Zimm plot from dynamic light scattering measurements gave a z-average translational diffusion coefficient Do20.w = (3.02 ± 0.05) × 10−8 cm2·s−1 and the concentration-dependence parameter kD = (370 ± 15) mL/g. Combination of so20.w with Do20.w via the Svedberg equation gave another estimate for Mw of ≅ 2.4 × 106 g/mol, again in good agreement. Both the Wales-van Holde ratio (ks/[η]) ≅ 0.4 (with [η] = (760 ± 77) mL/g) and the ρ-parameter (ratio of the radius of gyration from static light scattering to the hydrodynamic radius from dynamic light scattering) as ρ > 2.0 all indicate an extended conformation for the macromolecules in solution. These findings, plus Rinde-type simulations of the sedimentation equilibrium data are all consistent with the interpretation in terms of a unimodal wormlike coil model performed earlier. © 1996 John Wiley & Sons, Inc. 相似文献
2.
J. A. Ramsay E. Berger R. Voyer C. Chavarie B. A. Ramsay 《Biotechnology Techniques》1994,8(8):589-594
Summary Recovery of poly-3-hydroxybutyrate (PHB) in three chlorinated solvents with or without acetone pretreatment and degradation of extracted PHB (99% pure) in hot chloroform were studied. When lyophilized Alcaligenes eutrophus biomass was used, the best results were obtained with acetone pretreatment and solvent reflux for 15 min in methylene chloride or chloroform. Recovered PHB had a 95% purity and molecular weights (Mw) of 1,050,000 and 930,000 g/mol respectively. Further heating resulted in a serious Mw, loss at reflux temperatures. Degradation of extracted PHB at 110°C in chloroform was due to random and chain-end scission, the former being predominant. 相似文献
3.
《BBA》1986,848(3):402-410
Effects of temperature and dehydration on the efficiency of electron transfer from membrane-bound high-potential cytochromes ch to the reaction-center bacteriochlorophyll (P-890) in Ectothiorhodospira shaposhnikovii have been studied. A kinetic analysis of the cytochrome oxidation suggests that there are at least two conformational states of the ch-P-890 complex, of which only one allows photoinduced electron transfer from cytochrome to P-890+. Lowering the temperature of dehydration leads to a change in the proportion of the populations in the two conformations. The observed 2-fold deceleration of cytochrome oxidation can be related only to the diminution of the amount of photoactive cytochromes per reaction center. The rate constant for the transfer of an electron from cytochrome ch to bacteriochlorophyll is 2.8 · 105 s−1 and is independent of temperature and dehydration (as estimated within the accuracy of the experiments). The effects produced by low temperature and dehydration are completely reversible. The thermodynamic parameters of the transition of the cytochrome from the nontransfer to electron-transfer conformation were estimated. For room temperature (+ 20°C) in chromatophore preparations, ΔG = −5.4 kJ · M−1, ΔH = 60 kJ · M−1, ΔS = 0.22 kJ · M−1 · K−1. For Triton X-100 subchromatophore preparations, the absolute values of the above parameters are significantly lower: ΔG = −2.8 kJ · M−1, ΔH = 18 kJ · M−1, and ΔS = 0.075 kJ · M−1 · K−1. To a larger extent, the above parameters are diminished for chromatophore preparations in an 80% glycerol solution: ΔG = −1.7 kJ · M−1, ΔH = 6 kJ · M−1, ΔS = 0.025 kJ · M−1 · K−1. The data suggest the hydrophobic character of the forces that maintain the P-890-ch complex in the electron-transfer conformation. The results obtained suggest that electron tunneling within the complex cannot occur until a specific conformational configuration of the complex is formed. The efficiency of cytochrome ch oxidation is determined by the temperature, the degree of dehydration and the environmental conditions, whereas the transfer of an electron itself in the electron-transfer configuration is essentially independent of temperature and hydration. 相似文献
4.
《Biomass》1989,18(2):109-126
In a comparative investigation of the chemical composition of Arundo donax L. and Miscanthus sinensis Anderss. the following experiments were performed: ash determination and ash characterization by energy dispersive X-ray analysis; determination of solubility in cyclohexane/ ethanol, hot water, 1% hydrochloric acid and sodium hydroxide; C, H and N determination; determination of Klason lignin and acid soluble lignin content; sulfuric acid hydrolysis followed by borate complex ion exchange chromatography of the monomeric sugars; isolation of milled wood lignins (MWL) and dioxane lignins (DIL) and their analysis by C, H, and OMe determination; quantitative FTIR spectroscopy of MWL; recording the molecular weight distribution curves using high performance size exclusion chromatography (HPSEC); calculation of average molecular weights, such as Mw and Mn; calculation of the heating values of the lignocellulosics and their components. The quantitative composition of the lignin from the three basic phenylpropane units is presented.M. sinensis was submitted to hydroliquefaction. The conversion process yielded 35% of a net product oil (NPO) with low oxygen content (11%), low viscosity (10−2 NS m−2), low asphaltene content (3·5%) low molecular weight (Mw 200) and with a specific gravity of c. 0·93 g cm−3. The NPO has a heating value of 39·4 MJ kg−1 and contains 55% of the carbon of the starting material and 59% of the combined heating value from the biomass and the hydrogen used for hydroliquefaction. The process yields 28% water which contains 58% of the original oxygen of the biomass. The process gives rise to 9 g solids and 32–35 g gases, whose energy content can easily be recovered. 相似文献
5.
Quagliano J.C. Amarilla F. Fernandes E.G. Mata D. Miyazaki S.S. 《World journal of microbiology & biotechnology》2001,17(1):9-14
The molecular weight (M
w) of poly-3-hydroxybutyrate (PHB), produced by shake-flask culture of Azotobacter chroococcum showed little variation with increasing glucose concentration as carbon source (being in the range of 400–500 kDa), while M
w increased from 300–400 to 640 kDa when grown with increasing concentration of sugar cane molasses. Molecular weight increased nearly 30% from 48 to 72 h culture time when 5% molasses as carbon source was used, while with glucose the highest M
w was reached at 48 h. Under fermentor cultivation A. chroococcum produced PHB with a relatively high M
w of 1590 kDa at 53 h culture time when grown in modified Burk's medium with glucose as carbon source at an initial C/N ratio (molar basis) of 69 under fermentor cultivation. A batch glucose-grown ammonium-limited fermentor culture was repeatedly fed with sugar cane molasses (initial C/N ratio 69) and it was observed that PHB content curve decreased at a slower rate than in the fed-batch culture in which glucose and sucrose were not consumed in the culture medium after the feed. 相似文献
6.
Bacillus mycoides strain RIJ B-017, a growth-associated poly-3-hydroxybutyrate (PHB) producer was grown on sucrose-containing media. PHB accumulated
in cells up to 72% of dry cell mass. The overall maximum value of PHB yield (Y
p/s) and productivities (Q
p andq
p) 250 mgp/gs, 120 mgp L−1 h−1 and 30 mgp gx
−1 h−1, respectively, were obtained at 15 g/L sucrose. Differential scanning calorimeter heating curve showed two peaks, one at
95.9 °C and another at 165.4°C with a shoulder around 154.6 °C. The viscosity-average molar mass in chloroform at 27°C was
505 kDa. The carbon content of PHB was 55.4% of the mass. 相似文献
7.
Quillaguamán J Doan-Van T Guzmán H Guzmán D Martín J Everest A Hatti-Kaul R 《Applied microbiology and biotechnology》2008,78(2):227-232
High poly(3-hydroxybutyrate) (PHB) content and volumetric productivity were achieved by fed-batch culture of Halomonas boliviensis using a defined medium. Initial shake flask cultivations in a minimal medium revealed that the growth of H. boliviensis was supported only when the medium was supplemented with aspartic acid, glycine, or glutamine. Addition of 0.1% (w/v) glutamine in the medium resulted in the highest cell dry weight (CDW; 3.9 g l−1). Glutamine was replaced by the less expensive monosodium glutamate (MSG) in the medium without any notable change in the
final cell density. Effect of initial concentrations of NH4Cl and K2HPO4 on cell growth and PHB accumulation by H. boliviensis was then analyzed using a fed-batch fermentation system. The best conditions for PHB production by H. boliviensis were attained using 0.4% (w/v) NH4Cl and 0.22% (w/v) K2HPO4 and adding MSG intermittently to the fermentor. Poly(3-hydroxybutyrate) content and CDW reached 90 wt.% and 23 g l−1, respectively, after 18 h of cultivation. In order to increase CDW and PHB content, MSG, NH4Cl, and K2HPO4 were initially fed to the fermentor to maintain their concentrations at 2%, 0.4%, and 0.22% (w/v), respectively, and subsequently their feed was suppressed. This resulted in a CDW of 44 g l−1, PHB content of 81 wt.%, and PHB volumetric productivity of 1.1 g l−1 h−1. 相似文献
8.
A water soluble acidic heteropolysaccharide named WAF was isolated from Auricularia auricula‐judae by extracting with 0.9% NaCl solution. By using gas chromatography, gas chromatography‐mass spectrometry, and NMR, its chemical structure was determined to be composed of a backbone of α‐(1→3)‐linked D ‐mannopyranose residues with pendant side groups of β‐D ‐xylose, β‐D ‐glucose, or β‐D ‐glucuronic acid at position O6 or O2. Six fractions prepared from WAF with a weight‐average molecular mass (Mw) between 5.9 × 104 and 64.7 × 104 g/mol were characterized with laser light scattering and viscometry in 0.1M NaCl at 25°C. The dependence of intrinsic viscosity ([η]) and radius of gyration (Rg) on Mw for this polysaccharide were found to be [η] = 1.79 × 10?3Mw0.96 cm3 g?1 and Rg = 6.99 × 10?2 Mw0.54 nm. The molar mass per unit contour length (ML) and the persistence length (Lp) were estimated to be 1124 nm?1 and 11 nm, respectively. The WAF exhibited a semirigid character typical of linear polysaccharides. Molecular modeling was then used to predict the ordered and disordered states of WAF; the simulated ML and Lp were however much smaller than the experimental values. Taken altogether, the results suggested that WAF formed a duplex in solution. © 2010 Wiley Periodicals, Inc. Biopolymers 95: 217–227, 2011. 相似文献
9.
Behnam Taidi Alistair J. Anderson Edwin A. Dawes David Byrom 《Applied microbiology and biotechnology》1994,40(6):786-790
In shake-flask culture, Methylobacterium extorquens accumulated poly(3-hydroxybutyrate) (PHB) possessing a substantially higher weight-average molecular mass (MW) than previously reported for this organism. The MW of PHB produced by M. extorquens was dependent on the initial concentration of methanol or sodium succinate, used as sole carbon sources. The highest MW values (0.6 and 1.7 × 106) were obtained with low initial concentrations of methanol or sodium succinate (4.0 and 3.0 g l–1, respectively) and the latter substrate always yielded PHB of higher MW than that produced from methanol. Thus PHB with an MW in the range 0.2–1.7 × 106 could be produced by selection of the carbon source and its concentration. In contrast to the findings with M. extorquens, the MW of PHB produced by Alcaligenes eutrophus was high (1.1–1.6 × 106) and generally unaffected by the choice or concentration of the carbon source. The use of glycerol as sole carbon source did, however, result in the accumulation of PHB with a markedly lower MW (5.5–8.5 × 105) than that produced from other sole carbon sources by this organism under similar conditions.
Correspondence to: A. J. Anderson 相似文献
10.
Fuqian Xu Shaobin Huang Yong Liu Yongqing Zhang Shaowei Chen 《Applied microbiology and biotechnology》2014,98(9):3965-3974
In spite of numerous advantages on operating fermentation at elevated temperatures, very few thermophilic bacteria with polyhydroxyalkanoates (PHAs)-accumulating ability have yet been found in contrast to the tremendous mesophiles with the same ability. In this study, a thermophilic poly(3-hydroxybutyrate) (PHB)-accumulating bacteria (Chelatococcus daeguensis TAD1), isolated from the biofilm of a biotrickling filter used for NOx removal, was extensively investigated and compared to other PHB-accumulating bacteria. The results demonstrate that C. daeguensis TAD1 is a growth-associated PHB-accumulating bacterium without obvious nutrient limitation, which was capable of accumulating PHB up to 83.6 % of cell dry weight (CDW, w/w) within just 24 h at 45 °C from glucose. Surprisingly, the PHB production of C. daeguensis TAD1 exhibited strong tolerance to high heat stress as well as nitrogen loads compared to that of other PHB-accumulating bacterium, while the optimal PHB amount (3.44?±?0.3 g l?1) occurred at 50 °C and C/N?=?30 (molar) with glucose as the sole carbon source. In addition, C. daeguensis TAD1 could effectively utilize various cheap substrates (starch or glycerol) for PHB production without pre-hydrolyzed, particularly the glycerol, exhibiting the highest product yield (Y P/S, 0.26 g PHB per gram substrate used) as well as PHB content (80.4 % of CDW, w/w) compared to other carbon sources. Consequently, C. daeguensis TAD1 is a viable candidate for large-scale production of PHB via utilizing starch or glycerol as the raw materials. 相似文献
11.
《Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology》1989,994(3):285-288
At pH 8.0 and 25°C α1-proteinase inhibitor and α2-macroglobulin bind human pancreatic elastase with rate constants of 4.7·105 M−1·s−1 and 6.4·106 M−1·s−1, respectively. The corresponding delay times of elastase inhibition in plasma are 0.4 s and 0.2 s, respectively, indicating that both inhibitors may act as physiological antielastases. Elastin impairs the elastase inhibitory capacity of α1-proteinase inhibitor and α2-macroglobulin. In presence of human elastin, the former behaves like a slow-binding elastase inhibitor, with a rate constant of about 260 M−1·s−1. In contrast, α2-macroglobulin is a fast-binding inhibitor of elastin-bound elastase, but only one of its two sites is functioning in presence of elastin. 相似文献
12.
Tissue kallikrein may play a role in processing precursor polypeptide hormones. We investigated whether hydrolysis of natural enkephalin precursors, peptide F and bovine adrenal medulla docosapeptide (BAM-22P), by hog pancreatic kallikrein is consistent with this concept. Incubation of peptide F with this tissue kallikrein resulted in the release of Met5-enkephalin and Met5-Lys6-enkephalin. Met5-Lys6-enkephalin was the main peptide released, indicating that the major cleavage site was between two lysine residues. At 37°C and pH 8.5, the KM values for formation of Met5-enkephalin and Met5-Lys6-enkephalin were 129 and 191 μM, respectively. Corresponding kcat values were 0.001 and 0.03 s−1 and kcat/KM ratios were 8 and 1.6·102 M−1 · s−1, respectively. Cleavage of peptide F at acidic pH (5.5) was negligible. When BAM-22P was used as a substrate, Met5-Arg6-enkephalin was released, thus indicating cleavage between two arginine residues. At pH 8.5, KM was 64 μM, kcat was 4.5 s−1, and the kcat/KM ratio was 7 · 104 M−1 · s−1. At 5.5, the pH of the secretory granules, KM, kcat and kcat/KM were 184 μM, 1.9 s−1 and 104 M−1 · s−1, respectively. It is unlikely that peptide F could be a substrate for kallikrein in vivo; however, tissue kallikrein could aid in processing proenkephalin precursors such as BAM-22P by cleaving Arg-Arg peptide bonds. 相似文献
13.
Conformation of mucous glycoproteins in aqueous solvents 总被引:5,自引:0,他引:5
Light-scattering techniques have been used to measure the z-average radius of gyration Rg z-average translational diffusion coefficient Dt and weight–average molecular weight Mw of porcine submaxillary mucin (PSM) in solution. PSM isolated at low shear in the presence of protease inhibitors has a Mw about twice as large as a sample prepared without these precautions. The former sample has a Mw of 17 × 106 in 0.1M NaCl, which decreases to 8 × 106 in 6M guanidine hydrochloride (GdnHCl) and then to 2 × 106 on addition of 0.1M mercaptoethanol to the 6M GdnHCl solution. The Rg or D values obtained for PSM in this work superimpose with those of other authors for different mucin glycoproteins, leading to linear log–log relationships to the molecular weight of the protein core. Comparison of these results with those in the literature for denatured proteins suggest that mucins are linear random coils in which the protein core is stiffened by the presence of the oligosaccharide side chains. The length of the oligosaccharides and the nature of the solvent have little effect on the extension of the protein core. This suggests that the stiffness of the protein core is maintained by steric repulsion of the residues at the beginning of the oligosaccharide chains. 相似文献
14.
The reaction between ligninase and hydrogen peroxide yielding Compound I has been investigated using a stopped-flow rapid-scan spectrophotometer. The optical absorption spectrum of Compound I appears different to that reported by Andrawis, A. et al. (1987) and Renganathan, V. and Gold, M.H. (1986), in that the Soret-maximum is at 401 nm rather than 408 nm. The second-order rate constant (4.2·105 M−1·s−1) for the formation of Compound I was independent of pH (pH 3.0–6.0). In the absence of external electron donors, Compound I decayed to Compound II with a half-life of 5–10 s at pH 3.1. The rate of this reaction was not affected by the H2O2 concentration used. In the presence of either veratryl alcohol or ferrocyanide, Compound II was rapidly generated. With ferrocyanide, the second-order rate constant increased from 1.9·104 M−1·s−1 to 6.8·106 M−1·s−1 when the pH was lowered from 6.0 to 3.1. With veratryl alcohol as an electron donor, the second-order rate constant for the formation of Compound II increased from 7.0·103 M−1·s−1 at pH 6.0 to 1.0·105 M−1·s−1 at pH 4.5. At lower pH values the rate of Compound II formation no longer followed an exponential relationship and the steady-state spectral properties differed to those recorded in the presence of ferrocyanide. Our data support a model of enzyme catalysis in which veratryl alcohol is oxidized in one-electron steps and strengthen the view that veratryl alcohol oxidation involves a substrate-modified Compound II intermediate which is rapidly reduced to the native enzyme. 相似文献
15.
《Biomass》1988,15(4):249-257
An experiment was conducted in the growth chamber to quantify the biomass production, N removal and N2 fixation from a synthetic medium by Chlamydomonas reinhardtii and Anabaena flos-aquae. Nitrogen was supplied at a concentration of 100 mg liter−1 of NO3−−15N and NH4+−15 (3·5 atom %), respectively. After 21 days Chlamydomonas reinhardtii removed an average of 83·8 and 78·7 mg N liter−1 as NO3− and NH4+, respectively. Averages of 0·89 and 0·71 g liter−1 (first batch), 1·63 and 0·95 g liter− (second batch) algal biomass were collected from NO3− and NH4+ media, respectively. Uptake rates of 0·11 mg 15N g−1 algae day−1 from NO3− medium and 0·10 mg 15N g−1 algae day−1 from NH4+ medium were calculated. Algal cells grown in NO3− and NH4+ medium contained 71 and 65 g N kg−1 (first batch), 39 and 58 g N kg−1 (second batch), respectively. Anabaena flos-aquae produced averages of 0·58 and 0·46 g liter−1 (first batch), 0·55 and 0·48 g liter−1 (second batch) after 14 days of growth from NO3− and NH4+ media, respectively. Blue-green algal biomass contained higher N (81–98 g kg−1) than green algae. Isotope dilution method for determining N2 fixation indicated that 55% and 77% of total N of blue-green algae grown in NO3− and NH4+ media, respectively, was derived from the atmosphere. 相似文献
16.
《Journal of Fermentation and Bioengineering》1995,79(6):566-571
To determine the most favorable conditions for the production of ethanol by Pachysolen tannophilus, this yeast was grown in batch cultures with various initial concentrations of two of the constituents of the culture medium: d-xylose (so), ranging from 1 g·l−1 to 200 g·l−1, and yeast extract (lo), ranging from 0 g·l−1 to 8 g·l−1. The most favorable conditions proved to be initial concentrations of So=25 g·l−1 and lo=4 g·l−1, which gave a maximum specific growth rate of 0.26 h−1, biomass productivity of 0.023 g·l−1·h−1, overall biomass yield of 0.094 g·g−1, specific xylose-uptake rate (qs) of 0.3 g·g−1·h−1 (for t=50 h), specific ethanol-production rate (qE) of 0.065 g·g−1·h−1 and overall ethanol yield of 0.34 g·g−1; qs values decreased after the exponential growth phase while qE remained practically constant. 相似文献
17.
《Process Biochemistry》2014,49(1):33-37
The ectoine-excreting bacterial strain of Halomonas salina was employed in the co-production of poly-β-hydroxybutyrate (PHB) and ectoine (Ect) during a fermentation process (PHB/Ect co-production). An efficient PHB/Ect co-production process was carried out at low NaCl concentration (30 g L−1). It was established using 1H Nuclear Magnetic Resonance spectroscopy that H. salina produces PHB. The effects of the NaCl concentration, the initial C/N ratio, the phosphate concentration and mixed carbon sources were investigated with respect to PHB/Ect co-production. The PHB/Ect co-production system comprised growing and non-growing cell phases and was developed with NaCl concentration of 30 g L−1. The optimal conditions for PHB/Ect co-production by the ectoine-excreting strain of H. salina were 30 g L−1 NaCl, with an initial C/N ratio of 15, an initial phosphate concentration of 12 g L−1 and mixed carbon sources of 55 g L−1 glucose and 25 g L−1 monosodium glutamate. Using a PHB/Ect co-production system with growing and non-growing cell phases prevents the inhibition of PHB synthesis by high concentration of NaCl and significantly reduces ectoine degradation. PHB and ectoine concentrations as high as 35.3 g L−1 and 8.6 g L−1, respectively, were achieved. The efficient co-production of PHB and ectoine at a low NaCl concentration has been realised. 相似文献
18.
Chen Ling Guan-Qing Qiao Bo-Wen Shuai Kun-Nan Song Wen-Xi Yao Xiao-Ran Jiang Guo-Qiang Chen 《Biotechnology and bioengineering》2019,116(4):805-815
Halomonas has been developed as a platform for the next generation industrial biotechnology allowing open and nonsterile growth without microbial contamination under a high-salt concentration and alkali pH. To reduce downstream cost associated with continuous centrifugation and salt containing wastewater treatment, Halomonas campaniensis strain LS21 was engineered to become self-flocculating by knocking out an etf operon encoding two subunits of an electron transferring flavoprotein in the predicted electron transfer chain. Self-flocculation could be attributed to the decrease of the surface charge and increase of the cellular hydrophobicity resulted from deleted etf. A wastewaterless fermentation strategy based on the self-flocculating H. campaniensis was developed for growth and the production of poly-3-hydroxybutyrate (PHB) as an example. Most microbial cells flocculated and precipitated to the bottom of the bioreactor within 1 min after stopping the aeration and agitation. The supernatant can be used again without sterilization or inoculation for the growth of the next batch after collecting the precipitated cell mass. The wastewaterless process was conducted for four runs without generating wastewater. PHB accumulation by the self-flocculent strain was enhanced via promoter and ribosome binding site optimizations, the productivities of cell dry weight and PHB were increased from 0.45 and 0.18 g·L −1·hr −1 for the batch process compared to 0.82 and 0.33 g·L −1·hr −1 for the wastewaterless continuous process, respectively. This has clearly demonstrated the advantages of the wastewaterless process in that it not only reduces wastewater but also increases cell growth and product formation efficiency in a given period of time. 相似文献
19.
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
20.
María García-Torreiro Thelmo A. Lu-Chau Juan M. Lema 《Bioprocess and biosystems engineering》2016,39(9):1365-1374
The behaviour of Halomonas boliviensis during growth in fed-batch culture under different kind of nutrient restrictions was examined. The metabolic switch between growth and accumulation phase is determined by the limitation in one or more essential nutrient for bacterial growth. The aim of this study was to test the effect of applying limitations of a essential nutrient, such as nitrogen, and the influence of different O2 concentrations on poly(3-hydroxybutyrate) (PHB) production during the accumulation phase. Single limitations of nitrogen and oxygen provoke PHB accumulations of 45 and 37 % (g g?1), respectively, while N limitation with low O2 supply causes the highest PHB accumulation of 73 %. The characterization of the PHB production with the strain H. boliviensis would allow a better optimization of the process and enrich the knowledge about the PHB production from strains different than Cupriavidus necator. 相似文献