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1.
A photobioreactor was constructed in the form of a Perspex column 900 mm tall with an internal diameter of 70 mm. The reactor
volume was 1.8 L and the light source consisted of a metal-halide lamp to reproduce sunlight. Light was distributed through
the culture using a new type of optical fiber that diffuses light out through its surface, perpendicular to the fiber axis.
A cluster of 661 light-diffusing optical fibers (LDOFs) pass from the light source through the reactor column (60-cm culture
depth) and are connected to a mirror at the top of the reactor. This biosolar reactor has been used for the production of
glutamate from CO 2 by the marine cyanobacterium Synechococcus sp. NKBG040607. We present here details of the construction of the biosolar reactor
and characterization of its properties. The effect of light intensity on glutamate production was measured. Carbon dioxide-to-glutamate
conversion ratios were determined at different cell densities: the maximum conversion ratio (28%) was achieved at a cell density
of 3x10 8 cells/mL. A comparison of glutamate production using the LDOF biosolar reactor described here with production by batch culture
using free or immobilized cells showed that use of an optical-fiber biosolar reactor increased glutamate-production efficiency
6.75-fold. We conclude that as a result of its high surface-to-volume ratio (692/m) increased photoproduction of useful compounds
may be achieved. Such a system is generally applicable to all aspects of photobiotechnology. 相似文献
2.
Recently, several microorganisms have been shown to be capable of directly solubilizing low-rank coals. This bioextract has
a high molecular weight and is water soluble, but is not useful as a liquid fuel. This paper presents the results of studies
to biologically solubilize coal and convert the solubilized coal into more useful compounds. Preliminary experiments have
been conducted to isolate cultures for the serial biological conversion of coal into liquid fuels. Coal particles have been
solubilized employing an isolate from the surface of Arkansas lignite. Natural inocula, such as sheep rumen and sewage sludge,
are then employed in developing cultures for converting the bioextract into fuels. This paper presents preliminary results
of experiments in coal solubilization and bioextract conversion. 相似文献
3.
Growth and lipid production of microalgae were investigated, with attention to the feasibility of making use of flue gas CO 2 as a carbon source. The effect of a high CO 2 level in artificial seawater differed from strain to strain. Three algal strains from the Solar Energy Research Institute
(Golden, CO) collection were selected as good fixers of CO 2 when the level of CO 2 in the sparging gas was high. These algae also accumulated large amounts of crude lipids. SO X and NO X inhibited algal growth, but a green alga, Nannochloris sp. NANNO2 grew after a lag period, even when it received NO gas at the concentration of 300 ppm. 相似文献
4.
A two-compartment model of an enzyme system with substrate inhibition kinetics and hydrogen ion production is investigated.
The model is used to study the bifurcation, instability, and chaotic behavior of the system. The investigation, although in
a restricted region of the parameters’ space, has uncovered a good part of the rich dynamic characteristics of this system,
including: period doubling sequences leading to chaos, banded chaos, fully developed chaos, interior crisis, tangent bifurcation
leading to intermittency, periodic windows interrupting chaotic regions, and alternating periodic chaotic sequences. The results
relate to the phenomena occurring in physiological experiments, such as the periodic stimulation of neural cells and the voltagegated
ion channel dynamics. 相似文献
5.
Kraft pulp was delignified using laccase produced by the white rot fungusTrametes versicolor immobilized in solid support under specific conditions. The stability tests showed that this enzyme was stable for 6 h at 55°C and pH 8.0, allowing its use under pH and temperature conditions very close to those used in industrial bleaching. In this work, unbleached hardwood Kraft pulp was submitted to prebleaching using 2 U laccase/g pulp basis. Reaction time, temperature, and pH of the enzymatic treatment were investigated. Good results regarding Kappa number reduction, selectivities, and high viscosities were obtained when prebleaching was performed for 1 h at temperature of 55©C and pH 8.0 followed by alkaline extraction and ECF bleaching sequences. 相似文献
6.
We have studied the transfer coefficients for O 2 transport to and CO 2 removal from a model cell-free system using microporous hydrophobic hollow fibers axially placed along a tubular bioreactor
for ethanol production with immobilized yeast in the shell. In this locally integrated bioreactor, O 2 and CO 2 transfer rates depend strongly on the shell side liquid flow rate; O 2 flow rate in the fiber bore influences O 2 transport only at very low flow rates. Diffusion of CO 2 does not affect O 2 transport. Local and overall O 2 and CO 2 transfer coefficients have been determined for a wide range of Reynolds Numbers. The efficiency of such transfers has been
demonstrated for alcohol fermentation. 相似文献
7.
Cells of Cephalosporium acretnonium ATCC 48272 immobilized in calcium alginate beads were utilized for cephalosporin C production and the results were compared
with those obtained with free cells. The experiments were performed with synthetic medium containing glucose and sucrose as
carbon and energy sources. Experimental effectiveness factor values were obtained at various cell and dissolved-oxygen concentrations,
considering Monod kinetics for the respiration rate, and were compared with the values calculated with zero-order kinetics
in spherical bioparticle. The results showed that the assumption of oxygen limitation by diffusion in the bioparticle was
correct, and that cephalosporin C production with immobilized cells is perfectly viable, although a slightly lower rate than
that obtained in the free cell process was observed. 相似文献
8.
A potent indigenous bacillus isolate identified as Bacillus cereus (RJ-30) was found to produce Cyclodextrin Glucosyl Transferase (CGTase) extracellularly. Process optimization of various
fermentation parameters has been established for optimal growth of bacillus and the maximum enzyme synthesis. The organism
had the highest specific growth rate (0.7μ) with a generation time of 1 h in glucose containing medium at the conditions of
pH 7.0, 37°C at 300 rpm, 1.5 vvm of agitation, and aeration. At these conditions, it exhibited the maximum activity of 54
U/mL at the synthesis rate of 2.7 U/L/h. CGTase was produced from the early exponential growth and peaked during the midsporulating
stage of about 16 h thereafter maintained at the same level of 50 U/mL. Saccharides containing media were better inducers
than starch, and the influence of carbohydrate substrates has shown that enzyme synthesis is promoted by xylose (65 U/mL)
and, more remarkably, by the supplementation of wheat bran extract in glucose medium (106 U/mL). This organism produced CGTase
stably in a chemostat culturing over a period of 400 h with a maximum productivity of 5.4 kU/L/h (threefold higher than obtained
in batch culturing [1.75 kU/L/h]). Comparatively, CGTase was produced by immobilized cells in a continuous fluidized bed reactor
for over approx 360 h, at a relatively high dilution rate of 0.88 h −1 resulting in the productivity of 23.0 kU/L/h. 相似文献
9.
Refinery spent-sulfidic caustic, containing only inorganic sulfides, has previously been shown to be amenable to biotreatment
with Thiobacillus denitrificans strain F with complete oxidation of sulfides to sulfate. However, many spent caustics contain mercaptans that cannot be metabolized
by this strict autotroph. An aerobic enrichment culture was developed from mixed Thiobacilli and activated sludge that was capable of simultaneous oxidation of inorganic sulfide and mercaptans using hydrogen sulfide
(H 2S) and methylmercaptan (MeSH) gas feeds used to simulate the inorganic and organic sulfur of a spent-sulfidic caustic. The
enrichment culture was also capable of biotreatment of an actual mercaptancontaining, spent-sulfidic caustic but at lower
rates than predicted by operation on MeSH and H 2S fed to the culture in the gas phase, indicating that the caustic contained other inhibitory components. 相似文献
10.
The previous modified two-orthogonal state expansion method with the initial united-atom effect is extended to study the charge transfer for the resonant and nonresonant reactions at low and high energies and the theory is no longer restricted to low capture probabilities. The impact energy covers a wide range: 0.17 eV–200 keV and 0.1–200 keV for p-H and H 2 collisions, respectively. The present calculations show good agreement with experimental data at energies 0.17 eV–10 keV and 75–200 keV for the p-H reaction and 0.2–200 keV for the p-H 2 reaction. 相似文献
11.
In ethanol production from lignocellulose by enzymatic hydrolysis and fermentation, it is desirable to minimize addition of
fresh-water and waste-water streams, which leads to an accumulation of substances in the process. This study shows that the
amount of fresh water used and the amount of waste water thereby produced in the production of fuel ethanol from softwood,
can be reduced to a large extent by recycling of either the stillage stream or part of the liquid stream from the fermenter.
A reduction in fresh-water demand of more than 50%, from 3 kg/kg dry raw material to 1.5 kg/kg dry raw material was obtained
without any negative effects on either hydrolysis or fermentation. A further decrease in the amount of fresh water, to one-fourth
of what was used without recycling of process streams, resulted in a considerable decrease in the ethanol productivity and
a slight decrease in the ethanol yield 相似文献
12.
Several methanotrophic microorganisms, i.e., Methylococcus capsulatus (Bath), Methylomonas albus (BG-8), Methylosinus trichosporium OB3b, and Methylocystis parvus (OBBP), were evaluated for growth and methane utilization. The effect of temperature was examined in the range of 25 to 45°C
for growth and methane utilization. The temperature variations (25–35°C) had minimal effect on growth of M. albus and M. parvus. Methane consumption varied at different temperatures with a maximum of 0.67 mol%/h and 0.53 mol%/h. at 30 and 35°C, respectively,
for M. albus and M. parvus. The growth and methane consumption was slower for M. trichosporium OB3b as a maximum methane consumption of 0.07 mol%/h was obtained at 25°C and growth was inhibited at 35°C. M. capsulatus grew the best at 37°C and growth was affected at higher temperature of 45°C. Of the different cultures examined, M. albus and M. capsulatus grew the best and were further evaluated for the effect of pressure in the range of 10–50 psi. The results obtained using M. albus demonstrated an enhancement in methane consumption rate by fourfold and final cell concentration by 40% at a pressure of
20 psi by injecting a methane/oxygen mixture, however further increase in the pressure up to 50 psi inhibited the growth.
The inhibition was not seen with nitrogen incorporated mixture of oxygen and methane, which suggest that the high partial
pressure of methane and/or oxygen are inhibitory for the growth of M. albus. M. capsulatus was more sensitive to pressure as evidenced by inhibition at the relatively low pressure of 10 psi 相似文献
13.
Simultaneous saccharification and fermentation (SSF) processes for producing ethanol from lignocellulose are capable of improved
hydrolysis rates, yields, and product concentrations compared to separate hydrolysis and fermentation (SHF) systems, because
the continuous removal of the sugars by the yeasts reduces the end-product inhibition of the enzyme complex. Recent experiments
using Genencor 150L cellulase and mixed yeast cultures have produced yields and concentrations of ethanol from cellulose of
80% and 4.5%, respectively. The mixed culture was employed because B. clausenii has the ability to ferment cellobiose (further reducing end-product inhibition), while the brewing yeast S. cerevisiae provides a robust ability to ferment the monomeric sugars. These experimental results are combined with a process model to
evaluate the economics of the process and to investigate the effect of alternative processes, conditions, and organisms. 相似文献
15.
A two-stage process for the manufacture of propylene oxide is described. The preliminary economics based on use of methanol
as a regeneration factor has resulted in a production cost of $12.10/lb of propylene oxide based on propylene oxide production
rate of 40 mg/g-cell/h in conventional reactor. Increasing the propylene oxide production from 40 to 500 mg/g-cell/h resulted
in a cost reduction from $12.10 to 5.8/lb of propylene oxide. The granular-activated, carbon-fluidized bed reactor (GAC-FBR)
absorbs the propylene oxide and when saturated is eluted with ethyl acetate, and the bed is regenerated by steam to drive
off the residual solvents. The estimated manufacturing costs are approx 59% lower (from $12.10/lb in conventional reactors
to $5.00/lb for GAC-FBRs) for products that are highly inhibitory such as epoxides. In the GAC-FBR reactor, enhancing the
propylene oxide production rate from 120 to 1500 mg/g-cell/h has resulted in the cost reduction to $2.00/lb. Enhancing the
production capacity from 1 million lb to 10 million lb/yr has further reduced the cost of production to $1.00/lb. 相似文献
16.
The aim of preclarification is to minimize sludge going to yeast separators. This purpose is partially fulfilled. However,
it has been measured during the plant trial runs that preclarification does not noticeably improve fermentation.
The aim of postclarification is to minimize sludge going to distillation. This purpose is well served as noted from the fact
that cycle run of distillation columns using postclarification is three times longer (9–12 mo) as compared to the normal one
(3–4 mo). 相似文献
17.
Two additional electrophoretically distinct molecular forms, isoforms (iso) 2 and 3, with lectin properties were isolated
from Cratylia mollis Mart, seeds (FABACEAE), by extraction with 0.15M NaCl and ammonium sulfate fractionation, followed by chromatography on Sephadex
G-75 and Bio-Gel P-200 (iso 2), as well as CM-Cellulose and Sephadex G-75 (iso 3). Both isoforms were human group nonspecific
and showed distinct specificity. Polyacrylamide gel electrophoresis resolved iso 2 and 3 in polypeptides of apparent mol wts
60 and 31 kDa, respectively; a distinct isoelectric focusing pattern was obtained for iso 2 and 3, under denaturing and reducing
conditions. 相似文献
18.
Xylans are the major components of the hemicellulosic fraction of lignocellulosic biomass and their hydrolysis can be obtained
using xylanases from Penicillium janthinellum. In this work, sugarcane bagasse hemicellulosic hydrolysate was used as the substrate for producing xylanase. The precipitation
of these enzymes was studied using ethanol and Na 2SO 4 as precipitating agents. Ethanol precipitation experiments were performed batchwise in concentrations ranging from 10 to
80%, pH 4.0 to 7.0, at 4áC. The concentrations used in the precipitations with Na 2SO 4 were from 5 to 60% at pH 5.5 and 25áC. Solubility curves as a function of xylanase activity and total protein for both precipitating
agents were made. According to the results, Na 2SO 4 is not appropriate for precipitating xylanases in this medium since at salt concentrations higher than 25%, the enzyme was
denaturated and at this concentration less than 80% of the enzyme and total protein were precipitated. Because of differences
in xylanase and total protein solubility, a fractionated precipitation using ethanol can be performed, since with 40% ethanol,
49% of the total protein was precipitated and more than 95% of the enzyme was kept in solution. On the other hand approx 100%
of the xylanases were recovered by precipitation after adding 80% ethanol. 相似文献
19.
The pretreatment of softwood with sulfuric acid impregnation in the production of ethanol, based on enzymatic hydrolysis,
has been investigated. The parameters investigated were: H 2SO 4 concentration (0.5 – 4.4% w/w liquid), temperature (180 – 240°C), and residence time (1-20 minutes). The combined severity
(log Ro-pH) was used to combine the parameters into a single reaction ordinate. The highest yields of fermentable sugars,
i.e., glucose and mannose, were obtained at a combined severity of 3. At this severity, however, the fermentability declined
and the ethanol yield decreased. In a comparison with previous results, SO 2 impregnation was found to be preferable, since it resulted in approximately the same sugar yields, but better fermentability. 相似文献
20.
The reaction characteristics of prostaglandin E2 biosynthesis by PGH-synthase and PGE2 isomerase and the substrate dependency of this biosynthesis were studied. The activity of PG-synthases was blocked by the inhibitory action of one or more byproducts, probably resulting from the action of PGH-synthase. This inhibitory action then appeared to be partly reversible, indicating that the substrate and the inhibitor compete for the catalytic sites. According to these findings, the feasibility of a successful semibatch biosynthesis was investigated. A combination of the substrate concentration reducing procedure and the semibatch process resulted in an about 3.5-fold higher increase in the total amount of PGE2 formed in comparison with the batch results obtained at the substrate concentration of 1.0 mg/cm3. Since the cost of enzyme is a governing factor in this biosynthesis, development of semibatch biosynthesis of PGE2 becomes a matter of economic importance. 相似文献
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