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1.
The conversion of glucose and fructose into gluconic acid (GA) and sorbitol (SOR) was conducted in a batch reactor with free
(CTAB-treated or not) or immobilized cells of Zymomonas mobilis. High yields (more than 90%) of gluconic acid and sorbitol were attained at initial substrate concentration of 600 g/L (glucose
plus fructose at 1:1 ratio), using cells with glucose-fructose-oxidoreductase activity of 75 U/L. The concentration of the
products varied hyperbolically with time according to the equations (GA)= t(GA) max/(W GA + t), (SOR)= t (SOR) max/(W Sor+ t), v GA=[W GA (GA) max]/(W GA+ t) 2 and V SOR=[W SOR (SOR) max]/(W SOR+ t) 2. Taking the test carried out with free CTAB-treated cells as an example, the constant parameters were (GA) max= 541 g/L, (SOR) max=552 g/L, W GA=4.8h, W SOR=4.9h, υ GA=112.7 g/L· and υ SOR=112.7 g/L·. 相似文献
2.
Gibberellic acid (GA 3) is reported to have diverse effects on hairy root cultures of many plant species; therefore, the effects of GA 3 on the growth, secondary metabolite production (caffeic acid derivatives and lignin), phenylalanine ammonia lyase (PAL) activity, and free radical scavenging activity of light-grown Echinacea purpurea L. hairy roots were investigated. Eight concentrations of GA 3, ranging from 0.005 to 1.0 μM, were added to shake flask cultures. The moderate GA 3 concentration, 0.025 μM, resulted in the highest concentrations of cichoric acid, caftaric acid, and chlorogenic acid, as well as increased PAL activity, cell viability, and free radical scavenging activity, while higher and lower GA 3 concentrations resulted in reduced levels compared to the control (lacking GA 3). The moderate GA 3 concentration also affected root morphogenesis; supplementation with 0.025 μM GA 3 resulted in the development of thick, dense, purple-colored roots, while roots exposed to the higher and lower concentrations of GA 3 were thin and off-white. This study demonstrates that supplementation with GA 3 may be an excellent strategy to optimize the production of secondary metabolites from E. purpurea hairy root cultures; however, the GA 3 concentration is a critical factor. 相似文献
3.
Five strains of Gibberella fujikuroi and one of Fusarium moniliforme were screened for the production of gibberellic acid (GA 3) in coffee husk, and based on the results, one strain, G. fujikuroi LPB-06, was selected. The comparative production of GA 3 by solid-state fermentation and submerged fermentation indicated better productivity with the former technique, mainly with
pretreated substrate. The GA 3 accumulation was 6.1 times higher in the case of solid-state fermentation. Considering the C:N relation, higher yields of
GA 3 were achieved using a mixed substrate comprising coffee husk and cassava bagasse (7:3, dry wt), increasing the results twice.
Supplementation of an optimized saline solution containing 0.03% FeSO 4 and 0.01% (NH 4) 2SO 4 enhanced the accumulation of GA 3 1.7 times in the fermented substrate. Under the finally optimized condition, the culture gave a maximum of 492.5 mg of GA 3/kg of dry substrate, with a pH of 5.3, moisture of 75%, and incubation temperature of 29°C. GA 3 yield was almost 13 times more than the initial results. 相似文献
4.
Conidia of Aspergillus niger were immobilized in calcium alginate gel for the production of citric acid. First, the type of the preactivation medium,
together with the preactivation period, was investigated. It was found that A. niger requires a 2-d preactivation period at a 0.05 g/L NH 4NO 3 concentration. Second, preactivated cells were used to determine the effects of nitrogen concentration and the flow rate
of oxygen and air on the production of citric acid. Maximum citric acid production was attained with medium containing 0.01
g/L of NH 4NO 3. The rate of citric acid production in the nitrogenous medium was 33% higher when oxygen was used instead of air during the
production phase. This corresponds to an increase of 85% when compared to production when neither oxygen nor air was fed into
the system. In the nonnitrogenous medium citric acid concentration remained similar regardless of the use of air or oxygen.
However, in the nonnitrogenous production medium, citric acid production was not influenced considerably when oxygen was used
instead of air. The advantage of using immobilized cells is that production is achieved easily in the continuous system. Therefore,
citric acid production was also tested using a packed-bed bioreactor, and an increase in productivity by a factor of 22 was
achieved compared to the batch system. 相似文献
5.
Aspergillus niger ATCC 9142 mycelium was entrapped in calcium alginate beads and employed in an air-lift completely stirred reactor for continuous
production of citric acid. Maximum yield obtained from 10% (w/v) sucrose was 12 g dm -3 with about 40% fermentation efficiency. Maximum rate of production 70 mg g -1 h -1 was about five times that obtained in classical batch fermentation. 相似文献
6.
A new acetic acid-producing microorganism, Acetobacter sp. RKY4, was isolated from Korean traditional persimmon vinegar, and we optimized the culture medium for acetic acid production
from ethanol using the newly isolated Acetobacter sp. RKY4. The optimized culture medium for acetic acid production using this microorganism was found to be 40 g/L ethanol,
10 g/L glycerol, 10 g/L corn steep liquor, 0.5 g/L MgSO 4·7H 2O, and 1.0 g/L (NH 4H 2PO 4. Acetobacter sp. RKY4 produced 47.1 g/L of acetic acid after 48 h of fermentation in a 250 mL Erlenmeyer flask containing 50 mL of the
optimized medium. 相似文献
7.
Microalgae lipids and oils are potential candidates for renewable biofuels and nutritional inventions. Recent studies from our lab have shown that two plant hormones, auxin and jasmonic acid, influence microalgae growth and fatty acid accumulation. Therefore, in this study, a high oil-producing strain Chlorella vulgaris UMT-M1 was selected for hormonal study using gibberellin (GA). Exogenous GA3 was applied to early stationary culture of C. vulgaris UMT-M1. Results showed that GA3 gradually increases the cell density of C. vulgaris to up to 42% on days after treatment (DAT)-8 and also capable of delaying the algal senescence. However, the increment in cell density did not enhance the total oil production albeit transient modification of fatty acid compositions was observed for saturated (SFA) and polyunsaturated (PUFA) fatty acids. This illustrates that GA3 only promotes cell division and growth but not the oil accumulation. In addition, application of GA3 in culture medium was shown to promote transient increment of palmitic (C16:0) and stearic (C18:0) acids from DAT-4 to DAT-6 and these changes are correlated with the expression of β-ketoacyl ACP synthase I (KAS I) gene. 相似文献
8.
The optimum fermentation medium for the production of bacterial cellulose (BC) by a newly isolated Gluconacetobacter sp. RKY5 was investigated. The optimized medium composition for cellulose production was determined to be 15 g/L glycerol,
8 g/L yeast extract, 3 g/L K 2HPO 4, and 3 g/L acetic acid. Under these optimized culture medium, Gluconacetobacter sp. RKY5 produced 5.63 g/L of BC after 144 h of shaken culture, although 4.59 g/L of BC was produced after 144 h of static
culture. The amount of BC produced by Gluconacetobacter sp. RKY5 was more than 2 times in the optimized medium found in this study than in a standard Hestrin and Shramm medium,
which was generally used for the cultivation of BC-producing organisms. 相似文献
9.
The microorganism Pseudomonas denitrificans was immobilized in alginate. These immobilized cells were capable of reducing 0.8 mg NO
3
-
/min/g wet weight of cells. 相似文献
11.
The root explants of the germinated seedlings of Podophyllum hexandrum were grown in MS medium supplemented with indole acetic acid (IAA) (2 mg/L) and activated charcoal (0.5%), and healthy callus
culture was obtained after incubation for 3 wk at 20°C. The cultivation of plant cells in shake flask was associated with
problems such as clumping of cells and browning of media, which were solved by the addition of pectinase and polyvinylpyrrolidone.
The effect of major media components and carbon source was studied on the growth and podophyllotoxin production in suspension
culture. It was found that glucose was a better carbon source than sucrose and that NH 4
+:NO 3
− ratio (total nitrogen concentration of 60 m M) and PO 4
3− did not have much effect on the growth and product formation. The relative effect of culture parameters (inoculum level,
pH, IAA, glucose, NH 4
+:NO 3
− ratio, and PO 4
3−) on the overall growth and product response of the plant cell suspension culture was further investigated by Plackett-Burman
design. This indicated that inoculum level, glucose, IAA, and pH had significant effects on growth and production of podophyllotoxin.
To identify the exact optimum concentrations of these parameters on culture growth and podophyllotoxin production, central
composite design experiments were formulated. The overall response equations with respect to growth and podophyllotoxin production
as a function of these culture parameters were developed and used to determine the optimum concentrations of these parameters,
which were pH 6.0, 1.25 mg/L of IAA, 72 g/L of glucose, and inoculum level of 8 g/L. 相似文献
12.
A new phenolic glucoside, abeliaside, along with four known compounds, 5,6,7,4′-tetrahydroxy flavones, caffeic acid, 4- O-caffeoylquinic acid and caffeic acid glucoside, was isolated from the leaves of Abelia triflora R. Br. (Caprifoliaceae). The structure of the new compound was elucidated by different spectroscopic techniques. Compounds 1– 5 were assayed for their anticancer activities against two cancerous human cell lines, MCF-7 and PC-3 cells, and normal Vero cell line using the crystal violet staining method. From the results it could be seen that caffeic acid possessed the highest anticancer effect against MCF-7 (IC 50: 17 μg/mL) and PC-3 (IC 50: 20.1 μg/mL) compared to vinblastine sulphate as reference drug (IC 50: 4.6, 2.8 μg/mL). The other compounds showed weak anticancer activity on both cell lines. 相似文献
13.
The effect of an external supply of carbon dioxide and pH on the production of succinic acid by Anaerobiospirillum succiniciproducens was studied. In a rich medium containing yeast extract and peptone, when the external carbon dioxide supply was provided
by a 1.5M Na 2CO 3 solution that also was used to maintain the pH at 6.0, no additional carbon dioxide supply was needed. In fact, sparging
CO 2 gas into the fermenter at 0.025 L/L-min or higher rates resulted in significant decreases in both production rate and yield
of succinate. Under the same conditions, the production of the main by-product acetate was not affected by sparging CO 2 gas into the fermenter. The optimum pH (pH 6.0) for the production of succinic acid was found to be in agreement with results
previously reported in the literature. Succinic acid production also was studied in an industrial-type inexpensive medium
in which light steep water was the only source of organic nutrients. At pH 6.0 and with a CO 2 gas sparge rate of 0.08 L/L-min, succinate concentration reached a maximum of 32 g/L in 27 h with a yield of 0.99 g succinate/g
glucose consumed. 相似文献
14.
Spore germination in Anemia phyllitidis can be induced by red light (R) via the phytochrome system and by gibberellic acid (GA 3) in the dark. An enhancing effect of NO 3-ions on the Pfr-mediated germination could be demonstrated. This NO 3-effect was found to be pronounced during the preinduction phase and could be described by biphasic kinetics depending on the formation of Pfr by the R-irradiation. Besides NO 3, other electron accepting substances also increased germination significantly. In contrast to Pfr-mediated germination, no enhancing effect by NO 3 could be obtained for the GA 3-induced germination response. The application of an inhibitor of gibberellic acid synthesis, AMO1618, as well as the analysis of combined R and GA 3 treatment, support the hypothesis that for germination of Anemia phyllitidis spores no synergism between the factors exists. Thus, it is proposed that the gibberellic acid receptor starts a signal-transduction pathway resulting in germination which is in part independent of the Pfr-mediated signal-transduction chain. The NO 3-effect is specific for the Pfr-mediated signal-transduction chain. 相似文献
15.
In this study, the immobilization characteristics of Enterococcus faecalis RKY1 for succinate production were examined. At first, three natural polymers—agar, κ-carrageenan, and sodium alginate—were
tried as immobilizing matrices. Among these, sodium alginate was selected as the best gel for immobilization of E. faecalis RKY1. Efficient conditions for immobilization were established to be with a 2% (w/v) sodium alginate solution and 2-mm-diameter
bead. The bioconversion characteristics of the immobilized cellsat various pH values and temperatures were examined and compared
with those of free cells. The optimum pH and temperature of the immobilized cells were the same as for free cells, 7.0 and
38°C respectively, but the conversion ratio was higher by immobilization for all the other pH and temperature conditions tested.
When the seed volume of the immobilized cells was adjusted to 10% (v/v), 30 g/L of fumarate was completely converted tosuccinate
(0.973 g/g conversion ratio) after 12 h. In addition, the immobilized cells maintained a conversion ratio of >0.95 g/g during
4wk of storageat 4°C in a 2% (w/v) CaCl 2 solution. In repetitive bioconversion experiments, the activity of the immobilized cells decreased linearly according to
the number of times of reuse. 相似文献
16.
Trimming vine shoot samples were treated with water under selected operational conditions (autohydrolysis reaction) to obtain
a liquid phase containing hemicellulose-decomposition products. In a further acid-catalyzed step (posthydrolysis reaction),
xylooligosaccharides were converted into single sugars for the biotechnological production of lactic acid using Lactobacillus
pentosus. A wide range of temperatures, reaction times, and acid concentrations were tested during the autohydrolysis–posthydrolysis
process to investigate their influence on hemicellulose solubilization and reaction products. The maximum concentration of
hemicellulosic sugars was achieved using autohydrolysis at 210 °C followed by posthydrolysis with 1% H 2SO 4 during 2 h. Data from autohydrolysis–posthydrolysis were compared with the results obtained at the optima conditions assayed
for prehydrolysis (3% H 2SO 4 at 130 °C during 15 min) based on previous works. Prehydrolysis extracted more hemicellulosic sugars from trimming vine shoots;
however, the protein content in the hydrolysates from autohydrolysis–posthydrolysis was higher. The harsher conditions assayed
during the autohydrolysis process and the higher content of protein after this treatment could induce Maillard reactions decreasing
consequently the concentration of hemicellulosic sugars in the hydrolysates. Therefore, despite the several advantages of
autohydrolysis (less equipment caused by the absence of mineral acid, less generation of neutralized sludges, and low cost
of reagents) the poor results obtained in this work with no detoxified hydrolysates ( Q
P = 0.36 g/L h, Q
S = 0.79 g/L h, Y
P/S = 0.45 g/g, Y
P/Sth = 61.5 %) or charcoal-treated hydrolysates ( Q
P = 0.76 g/L h, Q
S = 1.47 g/L h, Y
P/S = 0.52 g/g, Y
P/Sth = 71.5 %) suggest that prehydrolysis of trimming vine shoots with diluted H 2SO 4 is more attractive than autohydrolysis-posthydrolysis for obtaining lactic acid through fermentation of hemicellulosic sugars
with L. pentosus. Besides the higher hemicellulosic sugars concentration achieved when using the prehydrolysis technology, no detoxification
steps are required to produce efficiently lactic acid ( Q
P = 1.14 g/L h; Q
S = 1.64 g/L h; Y
P/S = 0.70 g/g; Y
P/Sth = 92.6 %), even when vinification lees are used as nutrients ( Q
P = 0.89 g/L h; Q
S = 1.54 g/L h; Y
P/S = 0.58 g/g; Y
P/Sth = 76.1 %). 相似文献
17.
Salvia miltiorrhiza is a medicinal plant that synthesises biologically-active tanshinones with numerous therapeutic properties. An important rate-limiting enzyme in the biosynthesis of their precursors is 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR). This study presents the organ-specific expression profile of the S. miltiorrhiza HMGR4 gene and its sensitivity to potential regulators, viz. gibberellic acid (GA 3), indole-3-acetic acid (IAA) and salicylic acid (SA). In addition, it demonstrates the importance of the HMGR4 gene, the hormone used, the plant organ, and the culture environment for the biosynthesis of tanshinones. HMGR4 overexpression was found to significantly boost the accumulation of dihydrotanshinone I (DHTI), cryptotanshinone (CT), tanshinone I (TI) and tanshinone IIA (TIIA) in roots by 0.44 to 5.39 mg/g dry weight (DW), as well as TIIA in stems and leaves. S. miltiorrhiza roots cultivated in soil demonstrated higher concentrations of the examined metabolites than those grown in vitro. GA 3 caused a considerable increase in the quantity of CT (by 794.2 µg/g DW) and TIIA (by 88.1 µg/g DW) in roots. In turn, IAA significantly inhibited the biosynthesis of the studied tanshinones in root material. 相似文献
18.
Surface-engineered yeast Saccharomyces cerevisiae codisplaying Rhizopus oryzae glucoamylase and Streptococcus bovis α-amylase on the cell surface was used for direct production of ethanol from uncooked raw starch. By using 50 g/L cells during
batch fermentation, ethanol concentration could reach 53 g/L in 7 days. During repeated batch fermentation, the production
of ethanol could be maintained for seven consecutive cycles. For cells immobilized in loofa sponge, the concentration of ethanol
could reach 42 g/L in 3 days in a circulating packed-bed bioreactor. However, the production of ethanol stopped thereafter
because of limited contact between cells and starch. The bioreactor could be operated for repeated batch production of ethanol,
but ethanol concentration dropped to 55% of its initial value after five cycles because of a decrease in cell mass and cell
viability in the bioreactor. Adding cells to the bioreactor could partially restore ethanol production to 75% of its initial
value. 相似文献
19.
The effect of ammonium nitrate concentration in the citric acid biosynthesis by Aspergillus niger NC-12 in single-stage continuous cultures with biomass retention was investigated. Experiments were carried out in a BIOMER
laboratory fermenter with 5 dm 3 working volume. At the initial stage of each cultivation, the substrate in the bioreactor contained 1.5 g NH 4NO 3 dm −3. After 120 h onwards, the bioreactor was fed continuously at a constant dilution rate of 0.009 h −1. NH 4NO 3 concentration in the feed was varied from one culture to another, ranging between 0.5 g dm −3 and 2.5 g dm −3. Promising results were obtained when NH 4NO 3 concentration of 1.5 g dm −3 was used. The observed concentration of citric acid ( c
P) and yield of citric acid with respect to the introduced sucrose ( Y
P/S) were 117.88 g dm −3 and 78.59 %, respectively. The efficiency coefficient of citric acid biosynthesis ( K
ef) was very high, amounting to 83.38.
Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May
2006. 相似文献
20.
Chelating resins with thioglycolate anchor groups have been synthesized by reaction of sucrosemethacrylate gels with thioglycolic acid. The capacities of the gels were found to be extremely high for Ag + (5,3 mmol/g) and Hg 2+ (4,9 mmol/g). About 1 mmol Hg 2+/g could be recovered from the gel reversibly by treatment with hydrochloric acid. The removal of Hg 2+ from aqueous 3 M alkalichloride solutions was possible with capacities of 1 mmol/g.Sucrosemethacrylate gels with primary aromatic amino group were reacted with CS 2/NH 3 to yield gels with dithiocarbamate groups. Gels with thiorea groups were prepared by reaction of the amino groups with NH 4SCN/HCl. Diazotation of the amino groups, subsequent reaction with potassium xanthogenate and hydrolysis afforded gels with thiol groups. Thiol containing gels were synthesized also by reaction of the diazotised gels with Na 2S 2 and subsequent reduction with Na 2S. Reaction of the diazotised gels with mercaptans yielded resins with thioether anchor groups. The capacities of the sulfur containing gels were found to be max. 4,1 mmol/g for Hg 2+ and 5,9 mmol/g for Ag +. About 35% of the bonded Hg 2+ could be eluted resersibly with 3 N-HCl. 相似文献
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