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1.
The prehydrolysis liquor (PHL) of the kraft‐based dissolving pulp production process contains various amounts of hemicelluloses that can be utilized in the production of value‐added products. In this work, a new process was proposed for removing the inhibitors of PHL via employing a flocculation concept to facilitate the utilization of hemicelluloses. Lignin, lignocelluloses/cationic polymer complexes, and possibly ethanol are the main products of this process. This process has been experimentally evaluated with an industrially produced PHL and cationic polymers. The results showed that 16% of lignin, 19% of acetic acid, 43% of furfural, and insignificant amount of sugars were removed from PHL via pretreating PHL with acid and lime at pH 7. Furthermore, by adding 0.4–0.5 mg g?1 polydiallyldimethylammonium chloride (PDADMAC) or chitosan to the pretreated PHL, 12–14% acetic acid, 40–50% furfural, 5–6% monomeric sugars, and 25% oligomeric sugars were removed from the PHL. The complexes made from these components may be applied as organic fillers in various industries. Alternatively, by adding 1.2 or 1.4 mg g?1 PDADMAC or chitosan to the pretreated PHL, 30 or 35% of lignin was removed, respectively, which induced complexes that could be used as a fuel source. The composition of the complexes formed was also determined in this work. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 998–1004, 2012  相似文献   

2.
The spent liquor (SL) of a neutral sulfite semichemical (NSSC) pulping process contains a considerable amount of lignocelluloses and is treated in wastewater systems. The lignocelluloses, however, can be used for producing value‐added products if they are isolated from the SL. In this article, solvent treatment (mixing acetone, ethanol, or isopropyl with SL) was used as a method for isolating lignosulfonate from SL. The maximum lignosulfonate removal was obtained via mixing isopropyl alcohol with SL at the weight ratio of 20/80, room temperature, and 5.7 pH. The results also showed that the molecular weight and anionic charge density of the precipitates were in the range of 5,000–70,000 g/mol and 0.2–1.8 meq/g, respectively. Based on these results, a process was proposed for isolating lignosulfonate from SL and converting the NSSC process to an NSSC‐based biorefinery. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1508–1514, 2015  相似文献   

3.
The effects of polymer flocculation before manure separation were investigated, through testing both a linear and a branched polymer. Centrifugation removed 60% of phosphorus from raw manure (control), whereas raw manure clogged the filters during gravity drainage and pressure filtration. At optimum flocculation, 95% of phosphorus was removed using any of the three methods. Optimum flocculation was achieved when 2.8meq of polymer charge was added per kg of manure, corresponding to 0.6g/kg of highly charged, branched polymer or 0.85g/kg of less-charged, linear polymer. If 10mmol of ferric chloride was added per kg of manure, 2% more phosphorus was precipitated and removed. The linear polymer formed loose flocs and was superior for reducing turbidity, whereas the branched polymer formed compact flocs that deflocculated at high polymer doses. The branched polymer, however, was best for pressure filtration, as overdosing with the linear polymer resulted in high resistance.  相似文献   

4.
In the biological pretreatment process, white-rot fungi are mostly used to degrade lignin and carbohydrates in lignocellulosic biomass. In this study, water-soluble hemicelluloses were recovered from birch wood (Betula alnoides) decayed by white-rot fungi (Ganoderma lucidum C7016) for different durations up to 16 weeks. Accordingly, the dimethyl sulfoxide (DMSO)-soluble hemicelluloses were isolated from the untreated birch wood as a comparison. Results showed that the fungal-degraded polysaccharides were acidic hemicelluloses having a high content of uronic acids ranging from 20.6 to 22.5 %. Gel permeation chromatography analysis demonstrated that the recovered water-soluble hemicelluloses had a lower average molecular weight (M w, 15,990–27,560 g?mol?1) than that of the DMSO-soluble hemicelluloses (M w , 33,960 g?mol?1). Fourier transform infrared spectroscopy, scanning electron microscopy, one- and two-dimensional nuclear magnetic resonance spectroscopy also revealed significantly changes between those of fungal degraded and DMSO-soluble hemicelluloses. It was proposed that the hemicelluloses with low molecular weights were easily removed from wood by fungal degradation. This research revealed the changes of hemicelluloses in fungal degradation in the natural environment, which may enable the exploration of novel methods in bioconversion of lignocellulosic biomass for the production of biofuels and biopolymers, in addition to the development of new and better ways to protect wood from biodegradation by microorganisms.  相似文献   

5.
Membrane vesicles were prepared from pigeon erythrocytes. The effect of various treatments on the ability of these vesicles to trap and transport glycine was measured. Most of the work concerned the effects of the nonionic detergent, Triton X-100 (Triton).Triton inhibits the capacity of membrane vesicles to trap and transport glycine. The effects of Triton depend on temperaature and pH. At neutral pH and 41°C, the half-inactivating dose of Triton is 6 μl/g wet weight of membrane, while at neutral pH and O°C it is approx. 60 μl/g. At pH 8.5–8.8 and 0°C the half-inactivating dose is 15–20 μl/g. The Triton effect depends on the ratio of Triton to membrane, not the Triton ‘concentration’ in the aqueous phase.Protein is released from the membrane by Triton treatment at 0°C. At pH 8.5–8.8, the dose-response curve for protein release is very similar to the dose-response curve for inhibition of the capacities to trap and take up glycine. All three curves have steep and shallow regions, respectively below and above a Triton dose of 15 μl/g. The protein released by Triton treatment at 0°C is largely the lower molecular weight classes and the maximum protein release is 50–60% of the total membrane protein. The percent of this protein class released by a given Triton dose equals the percent inhibition of the capacity to trap glycine.Triton is bound by the membranes. In the dose range of 0–10 μl Triton/g wet membrane, about half of the added Triton is bound. This bound Triton is not readily removed by washing. Like protein release and inhibition of trapping and transport capacities, the binding process has two phases, one above and one below a dose of 15 μl/g. The membrane is saturated with Triton at a dose of 15 μl/g with 4.5 μl Triton bound/g wet weight, corresponding to 85–90 μl bound/g remaining membrane protein.Bovine serum high density lipoprotein efficiently removes bound Triton from the membrane. By removing Triton bound at 0°C with lipoprotein, the effects of Triton at 0 and 41°C could be distinguished and the time course of Triton action at 0°C could be measured. Triton action was nearly complete by 10 min at 0°C.Possible modes of action of Triton on these membranes are discussed. At least part of the action of Triton can be described as a process in which membrane proteins are partitioned between the membrane phase and an extramembranal Triton micelle phase.  相似文献   

6.
An ultrafiltration-light absorption spectrometric method for soluble molybdate-reactive silicon was assessed and applied to bovine and ovine blood plasma and sera, giving precise analytical results. Interfering protein above molecular weight 10,000–25,000 was removed by ultrafiltration, and silicon in ultrafiltrates was quantitated by measuring light absorption at 810 nm of the 1,2,4-aminonaphthol sulfonic acid/ascorbic acid-reduced silicomolybdate. Chemical interferences on the color-forming reaction of remaining blood components were tested by measuring recoveries of silicon added to real blood plasma samples and to synthetic blood plasma solutions, the latter containing typical levels of the major ions Na+, K+, Ca2+, HCO3?, and Cl?, together with varying quantities of the potential interferants (amount per analytical reaction): phosphate (0–0.5 mg P), ferric ion (0–3 mg), fluoride (0–1.25 mg), vanadate (0–0.5 mg V), arsenate (0–10 μg As), and germanate (0–0.5 μg Ge). The mean recovery of added 0.8–9 μg silicon/g of bovine and ovine plasma was 97.7% (SE = 1.0, n = 17); the mean recovery of 1 and 5 μg silicon from synthetic blood plasma solutions with interferant levels up to 50-fold that in normal plasma was 99.2% (SE = 0.3, n = 47). Silicon concentrations found in bovine and ovine blood plasma and sera were typically around 7 μg/ml with procedural reagent blanks consistently low at a mean of 0.12 μg/test (SD = 0.011, n = 20). The silicon level in Center for Disease Control bovine serum (reference specimen Lot R-2274) was found to be (mean ± SE, n = 10) 1.147 ± 0.013 μg/g or 1.172 ± 0.013 μg/ml (25°C). The method detectivity (detection limit) was estimated at 0.03 μg.  相似文献   

7.
Separation and cells concentration constitute important stages in most biotechnological processes. Particularly, use of flocculation/sedimentation can improve significantly the extraction of biopolymers accumulated by microorganisms and the biodegradation of xenobiotic compounds by cell sludge. In this work the use of tannin and aluminum sulphate (Al2(SO4)3) as flocculating agents for concentration of cells of Cupriavidus necator DSM 545 is evaluated. Cells were grown in broth nutrient medium in Erlenmeyer flasks, submitted to orbital agitation of 160 rpm at 30 °C for 21 h. The optimal concentrations of flocculating agents, as determined with a standard jar test method, were equal to 2,800 mg/L for tannin and 800 mg/L for Al2(SO4)3, allowing for recovery of 95% of the cells in both cases. Obtained flocs presented density and average diameter of 1.03 g/mL ± 0.01 g/mL and 158 μm ± 19 μm for tannin and of 1.05 g/mL ± 0.01 g/mL and 146 μm ± 14 μm for Al2(SO4)3, respectively. Batch settling tests were performed in order to determine the operational capacity of continuous settlers to be used for separation of the investigated flocculent suspensions. Finally, cultivation of cells using flocs as inoculum indicated that the cells remained viable after flocculation with usage of the optimum flocculating agent concentrations.  相似文献   

8.
An extracellular low temperature-active alkaline stable peptidase from Acinetobacter sp. MN 12 was purified to homogeneity with a purification fold of 9.8. The enzyme exhibited specific activity of 6,540 U/mg protein, with an apparent molecular weight of 35 kDa. The purified enzyme was active over broad range of temperature from 4 to 60 °C with optimum activity at 40 °C. The enzyme retained more than 75 % of activity over a broad range of pH (7.0–11.0) with optimum activity at pH 9.0. The purified peptidase was strongly inhibited by phenylmethylsulfonyl fluoride, giving an indication of serine type. The K m and V max for casein and gelatin were 0.3529, 2.03 mg/ml and 294.11, 384.61 μg/ml/min respectively. The peptidase was compatible with surfactants, oxidizing agents and commercial detergents, and effectively removed dried blood stains on cotton fabrics at low temperature ranging from 15 to 35 °C.  相似文献   

9.
A component responsible for flocculation was extracted from Pseudomonas strain C-120 by treating the cells with 3 M guanidine hydrochloride. The guanidine hydrochloride-extracted cells were reflocculated, not only with the guanidine hydrochloride extract but with DNA prepared from various bacteria. The reconstituted flocs were deflocculated by deoxyribonuclease or guanidine hydrochloride which indicated that the reconstituted flocs closely resembled natural flocs. In reconstitution experiments using Escherichia coli DNA at different molecular weights, it was found that DNA with a molecular weight higher than about 6 × 106 was required to flocculate the guanidine hydrochloride-extracted cells. Heat-denatured DNA did not flocculate the guanidine hydrochloride-extracted cells. DNA with a high molecular weight was detected in the guanidine hydrochloride extract. It was concluded that the component involved in flocculation of this organism was highly polymerized double stranded DNA.  相似文献   

10.
《MABS-AUSTIN》2013,5(2):413-427
High titer (>10 g/L) monoclonal antibody (mAb) cell culture processes are typically achieved by maintaining high viable cell densities over longer culture durations. A corresponding increase in the solids and sub-micron cellular debris particle levels are also observed. This higher burden of solids (≥15%) and sub-micron particles typically exceeds the capabilities of a continuous centrifuge to effectively remove the solids without a substantial loss of product and/or the capacity of the harvest filtration train (depth filter followed by membrane filter) used to clarify the centrate. We discuss here the use of a novel and simple two-polymer flocculation method used to harvest mAb from high cell mass cell culture processes. The addition of the polycationic polymer, poly diallyldimethylammonium chloride (PDADMAC) to the cell culture broth flocculates negatively-charged cells and cellular debris via an ionic interaction mechanism. Incorporation of a non-ionic polymer such as polyethylene glycol (PEG) into the PDADMAC flocculation results in larger flocculated particles with faster settling rate compared to PDADMAC-only flocculation. PDADMAC also flocculates the negatively-charged sub-micron particles to produce a feed stream with a significantly higher harvest filter train throughput compared to a typical centrifuged harvest feed stream. Cell culture process variability such as lactate production, cellular debris and cellular densities were investigated to determine the effect on flocculation. Since PDADMAC is cytotoxic, purification process clearance and toxicity assessment were performed.  相似文献   

11.
For insight into the physiological indicators of diapause in Pieris melete, water and carbohydrate (glycogen and trehalose) levels were measured under both natural and laboratory conditions. The highest water content (3.71–3.79 mg/mg dry weight) was found in larvae and developing pupae, which was substantially higher than in diapausing pupae (2.59 mg/mg dry weight). Water content was almost stable during diapause, except for individuals approaching diapause termination (3.43–3.58 mg/mg dry weight). The total carbohydrate level was significantly higher in pre‐pupae (47.41 μg/mg) compared to larvae (22.80 μg/mg) and developing pupae (21.48 μg/mg). The highest level of trehalose was detected in winter diapausing pupae, and no trehalose was found in larvae or developing pupae. Levels of glycogen were highest in pre‐pupae and lowest in diapausing pupae. Levels of total carbohydrate decreased as diapause proceeded, and no significant changes were found in trehalose levels for diapausing pupae under natural conditions or treated for 60–90 days at 5°C. Pupae treated at 20°C for 60–90 days had significantly lower levels of trehalose than those treated for 30 days. Glycogen content was relatively stable at 5°C, but increased after treatment under natural conditions and 20°C for more than 60 days. These results suggest that the dynamics of water and carbohydrate levels are potential physiological diapause indicators, which show metabolic differences between trehalose and glycogen during diapause development.  相似文献   

12.
Microalgal bacterial floc (MaB‐floc) reactors have been suggested as a more sustainable secondary wastewater treatment. We investigated whether MaB‐flocs could be used as tertiary treatment. Tertiary influent has a high inorganic/organic carbon ratio, depending on the efficiency of the secondary treatment. In this study, the effect of this inorganic/organic carbon ratio on the MaB‐flocs performance was determined, using three sequencing batch photobioreactors. The MaB‐flocs were fed with synthetic wastewater containing 84, 42, and 0 mg L−1 C‐KHCO3 supplemented with 0, 42, 84 mg L−1 C‐sucrose, respectively, representing inorganic versus organic carbon. Bicarbonate significantly decreased the autotrophic index of the MaB‐flocs and resulted in poorly settling flocs. Moreover, sole bicarbonate addition led to a high pH of 9.5 and significant lower nitrogen removal efficiencies. Sucrose without bicarbonate resulted in good settling MaB‐flocs, high nitrogen removal efficiencies and neutral pH levels. Despite the lower chlorophyll a content of the biomass and the lower in situ oxygen concentration, 92–96% of the soluble COD‐sucrose was removed. This study shows that the inorganic/organic carbon ratio of the wastewater is of major importance and that organic carbon is requisite to guarantee a good performance of the MaB‐flocs for wastewater treatment. Biotechnol. Bioeng. 2011; 108:549–558. © 2010 Wiley Periodicals, Inc.  相似文献   

13.
An integrated procedure for the recovery of polyhydroxybutyrate (PHB) produced by Cupriavidus necator based on the extraction with 1,2‐propylene carbonate was evaluated. The effect of temperature (100–145°C) and contact time (15–45 min), precipitation period, and biomass pretreatments (pH shock and/or thermal treatments) on PHB extraction efficiency and polymer properties was evaluated. The highest yield (95%) and purity (84%) were obtained with the combination of a temperature of 130°C and a contact time of 30 min, with a precipitation period of 48 h. Under these conditions, PHB had a molecular weight of 7.4×105, which was the highest value obtained. Lower values (2.2×105) were obtained for higher temperatures (145°C), while lower temperatures resulted in incomplete extraction yields (45–54%). No further yield improvement was achieved with the pH/heat pretreatments, but the polymer's molecular weight was increased to 1.3×106. The PHB physical properties were not significantly affected by any of the tested procedures, as shown by the narrow ranges obtained for the glass transition temperature (4.8–5.0°C), melting temperature (170.1–180.1°C), melting enthalpy (77.8–88.5 J/g) and crystallinity (55–62%). 1,2‐Propylene carbonate was shown to be an efficient solvent for the extraction of PHB from biomass. The precipitation procedure was found to highly influence the polymer recovery and its molecular weight. Although polymer molecular weight and purity were improved by applying pH/heat pretreatment to the biomass, the procedure involves the use of large amounts of chemicals, which increases the recovery costs and makes the process environmentally unfriendly.  相似文献   

14.
A dipeptide of the formula Fmoc-Leu-Asp and some other related dipeptides were synthesized in solution by standard methods. When such peptides are dissolved in water at concentrations below 1% at 100 °C and cooled below 60 °C they form turbid solutions and eventaully visocelastic gels at lower temperatures. Such gels are thermoreversible and can also be disrupted by mechanical agitation. At a concentration of 2 mg/ml the peptide Fmoc-Leu-Asp forms an aqueous gel at 60 °C with a shear modulus of 80 Pa measured at a frequency of 1 rad/s. Peptide solutions undergo an abrupt increase in light scattering between 1 and 1.5 mg/ml at both 23 and 60 °C. By analogy with previous observations of other systems, this increse appears to be due to the formation of filamentous micelles and the aggregation of filamaents into a three-dimensional network. When low molecular weight adamantanamine derivatives, which are inherently non-antigenci antiviral drugs, were incorporated into the Fmoc-Leu-Asp gel and injected into rabbits, high titre specific antibodies were efficiently produced without the need for additional adjuvant. Both the physical properties of the gel and its effect on the antigenicity of low molecular weight compounds suggest a number of practical applications.  相似文献   

15.
The flocculation of cell debris from a beta-galactosidase constitutive E. coli with chitosan as a flocculant was studied to investigate the possibility of obtaining a selective flocculation in cell disintegrates with high product recoveries. The flocculation removed 98% of the cell debris by 30 min sedimentation under gravity, which should be compared to a separation of the cell debris without flocculation of only 70% by centrifugation at 15,000 g. Optimal flocculation dosages varied between 12 and 43 mg chitosan g-1 dry weight of cells, depending on pH. The yield of the product beta-galactosidase reached 60% at optimal pH. Hydrolysis of the nucleic acids by DNAase and RNAase decreased the optimal flocculation dosages considerably. The study showed that the flocculation is somewhat selective, since chitosan also removed 85% of the nucleic acids and 50% of the proteins, which contributed to the purification of the protein solution.  相似文献   

16.
A bacterium belonging to Pseudomonas which was isolated from activated sludge formed flocs in glycerol-containing medium. The flocs were deflocculated by deoxyribonuclease treatment in the presence of magnesium ions. Flocs were also deflocculated by 2 m NaCl, heating at temperatures higher than 50°C, and at pH below 1 or above 11. The observations suggest that deoxyribonucleic acid is directly involved in the association of cells and that ionic bonds are responsible for the flocculation of cells.  相似文献   

17.
Shen J  Fatehi P  Soleimani P  Ni Y 《Bioresource technology》2011,102(21):10035-10039
Dissolved lignocelluloses from the pre-hydrolysis liquor (PHL) of kraft-based dissolving pulp production process were recovered by adsorption to lime mud produced in the causticizing plant of the kraft process. The adsorption of lignocelluloses was a fast process, and could be completed within one hour. The addition of polydiallyldimethylammonium chloride (PDADMAC) significantly increased the amounts of adsorbed lignin and hemicelluloses, which more than doubled at the PDADMAC dosage of 0.1% (based on the weight of PHL). The measured heating values of the adsorbed lignocelluloses indicate that adsorption of lignocelluloses to lime mud may result in the energy saving of the lime kiln. The process proposed in this study could also be adapted to decrease inhibitor concentrations (lignin and acetic acid) if the dissolved hemicelluloses in the PHL were used to produce value-added products, e.g., ethanol, xylitol, based on the fermentation process.  相似文献   

18.
Very efficient hydrogen producing photosynthetic bacteria, strains SL1, SL3, SL16 and TG28 newly isolated in Korea, and strain KM113 newly isolated in the Sendai area, were found to be Rhodopseudomonas spp. To examine the stability of cell suspensions of the cultures for hydrogen production, which is closely associated with light absorption, we conducted larger scale cultures under periodic illumination (12-hr intervals) without stirring at 30°C using strains SL1 and Rhodopseudomonas sphaeroides B5, the latter was isolated in the Bangkok area. Both strains gave homogeneous cell suspensions throughout the incubation period and larger amounts of hydrogen were produced in a shorter period of time by both cultures than obtained with Rhodopseudomonas sp. TN3, an isolate from the Sendai area which was reported previously. With the cells of the new isolates and strains TN3 and B5 grown on glutamate-malate medium at 30°C, we measured hydrogen production at 20, 30 and 40°C in the same medium. Among them, strains SL1, SL16 and KM113 showed the highest hydrogen production activity at 30°C. The maximum hydrogen production rates with these strains were over 130 µ1/hr/mg dry cells, but at 40°C, the highest activity (138 µl/hr/mg dry cells) was obtained with strain B5. Since strain B5 also showed good activities at 20 and 30°C, we suggest that this strain might be suitable for hydrogen production in outdoor cultures.  相似文献   

19.
Removal and modification of southern red oak hemicelluloses and lignin in a 0.05%(w/v) sulfuric acid hydrolysis were investigated. The hydrolysis profile was to raise the reaction from room temperature to 150 degrees C for in 38 min and to extend the hydrolysis at 150 degrees C for 1 h. At the end of the hydrolysis, 25.5% of red oak components were dissolved, of which 58% was xylose and 17% lignin. As the hydrolysis proceeded from room temperature to 150 degrees C, a part of red oak xylan was removed to yield an oligomer fraction having maximal yield and average molecular weight of 3460 at 150 degrees C. This fraction and the bulk xylan extracted during the first 30 min at 150 degrees C were further degraded to give a lower molecular weight oligomer fraction, of which the yield and average molecular weight (2610) were highest at the end of the bulk removal of xylan. Red oak lignin, syringyl and guaiacyl units in particular, was increasingly removed with the progress of the hydrolysis. Lignin derivatives and a part of red oak extractives soluble in the hydrolysate were identified.  相似文献   

20.
The currrent California condor (Gymnogyps californianus) recovery plan entails increasing the reproductive rate via replacement-clutch manipulation of eggs. During the period from 1983 to 1985, 15 eggs were removed from wild nesting pairs for artificial incubation. The eggs were incubated at a dry bulb temperature of 36.4°C in modified forced-air Lyon Electric incubators. The incubation humidity was adjusted for individual eggs based on weight loss data (water = weight), 25.6–30.0°C wet bulb (41.0–63.0% Relative Humidity (RH)). The chicks were hatched initially under forced-air conditions of 36.1°C dry bulb, 31.1–01.7°C wet bulb (70.0–73.0% RH). In 1984, hatching parameters were changed to still-air conditions, 36.1°C dry bulb (top of the egg), 35.0°C dry bulb (bottom of the egg), 31.1–31.7°C wet bulb (70.0-73.0% RH). Tactile and auditory stimulation was utilized during the pip-to-hatch interval. From among 15 eggs collected, 13 hatched, and 12 condor chicks were raised successfully (hatchability: 86.7%; survivability: 92.3%).  相似文献   

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