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1.
Xiao-Jun Ji He Huang Jian-Guo Zhu Nan Hu Shuang Li 《Applied biochemistry and biotechnology》2009,159(3):605-613
The fermentative production of 1,3-propanediol (1,3-PD) by Klebsiella pneumoniae under different fed-batch strategies was investigated. pH-stat fed-batch strategies proved to be not effective for economical
1,3-PD production for the existence of relatively high concentration of byproducts and residual glycerol at the end of the
fermentation. However, in the pH-stat fed-batch strategy, an important phenomenon was observed that the yields of two main
byproducts, 2,3-butanediol and lactic acid, were closely related to pH value. The dominant byproduct was 2,3-butanediol at
a pH value of 5.0 to 6.5 but changed to be lactic acid at a pH value of 7.1 to 8.0. Based on the analysis of the phenomenon,
a self-protection mechanism in K. pneumoniae, namely that the growing K. pneumoniae cells switch the metabolic pathways responding to environmental pH changes, was proposed. Thus a kind of feeding strategy
was further applied during which the pH value was fluctuated between 6.3 and 7.3 periodically by feeding glycerol–ammonia
mixture and sulphuric acid to make the metabolic pathways of 2,3-butanediol and lactic acid sub-active under the periodical
low or high pH stress. At last, efficient 1,3-PD production was fulfilled under this fed-batch strategy, and the best results
were achieved leading to 70 g/l 1,3-PD with a yield of 0.70 mol/mol glycerol and productivity of 0.97 g/l/h, while the two
main byproducts and residual glycerol were under low concentrations. 相似文献
2.
Sene Luciane Felipe Maria G. A. Silva Silvio S. Vitolo Michele 《Applied biochemistry and biotechnology》2001,91(1-9):671-680
Candida guilliermondii FTI 20037 was cultured in sugarcane bagasse hydrolysate supplemented with 2.0 g/L of (NH4)2SO4, 0.1 g/L of CaCl2·2H2O, and 20.0 g/L of rice bran at 35°C; pH 4.0; agitation of 300 rpm; and aeration of 0.4, 0.6, or 0.8 vvm. The high xylitol
production (20.0 g/L) and xylose reductase (XR) activity (658.8 U/mg of protein) occurred at an aeration of 0.4 vvm. Under
this condition, the xylitol dehydrogenase (XD) activity was low. The apparent K
M for XR and XD against substrates and cofactors were as follows: for XR, 6.4×10−2
M (xylose) and 9.5×10−3 mM (NADPH); for XD, 1.6×10−1
M (xylitol) and 9.9×10−2 mM (NAD+). Because XR requires about 10-fold less xylose and cofactor than XD for the condition in which the reaction rate is
half of the V
max, some interference on the overall xylitol production by the yeast could be expected. 相似文献
3.
1,3-Propanediol (1,3-PD) biosynthesis plays a key role in NADH consumption to regulate the intracellular reducing equivalent balance of Klebsiella pneumoniae. This study aimed to increase reducing equivalent for enhancing 1,3-PD production through cofermentation of glycerol and xylose. Adding xylose as cosubstrate resulted in more reducing equivalent generation and higher cell growth. In batch fermentation under microaerobic condition, the 1,3-PD concentration, conversion from glycerol, and biomass (OD(600)) relative to cofermentation were increased significantly by 9.1%, 20%, and 15.8%, respectively. The reducing equivalent (NADH) was increased by 1-3 mg/g (cell dry weight) compared with that from glycerol alone. Furthermore, 2,3-butannediol was also doubly produced as major byproduct. In fed-batch fermentation with xylose as cosubstrate, the final 1,3-PD concentration, conversion from glycerol, and productivity were improved evidently from 60.78 to 67.21 g/l, 0.52 to 0.63 mol/mol, and 1.64 to 1.82 g/l/h, respectively. 相似文献
4.
This study investigated the biological conversion of crude glycerol generated from a commercial biodiesel production plant as a by-product to 1,3-propanediol (1,3-PD). Statistical analysis was employed to derive a statistical model for the individual and interactive effects of glycerol, (NH4)2SO4, trace elements, pH, and cultivation time on the four objectives: 1,3-PD concentration, yield, selectivity, and productivity. Optimum conditions for each objective with its maximum value were predicted by statistical optimization, and experiments under the optimum conditions verified the predictions. In addition, by systematic analysis of the values of four objectives, optimum conditions for 1,3-PD concentration (49.8 g/L initial glycerol, 4.0 g/L of (NH4)2SO4, 2.0 mL/L of trace element, pH 7.5, and 11.2 h of cultivation time) were determined to be the global optimum culture conditions for 1,3-PD production. Under these conditions, we could achieve high 1,3-PD yield (47.4%), 1,3-PD selectivity (88.8%), and 1,3-PD productivity (2.1/g/L/h) as well as high 1,3-PD concentration (23.6 g/L). 相似文献
5.
The effects of different aeration conditions on xylitol production from corncob hemicellulose hydrolysate by Candida sp. ZU04 were investigated. Batch fermentations were carried out in a 3.7-L fermentor at 30°C, pH5.5, and agitation of 300
rpm. It was found that the two-phase aeration process was more effective than the one-phase aeration process in xylitol production.
In the first 24h of the aerobic phase, a high aeration rate was applied, glucose was soon consumed, and biomass increased
quickly. In the second fermentation phase, aeration rate was reduced and an improved xylitol yield was obtained. The maximum
xylitol yield (0.76 g/g) was obtained with an aeration rate of 1.5 vvm (KLa of 37 h−1) for the first 24 h and 0.3 vvm (KLa of 6 h−1) from 24 to 96 h. 相似文献
6.
1,3-Propanediol (1,3-PD) is an intermediate in chemical and polymer synthesis. We have previously expressed the genes of a
biochemical pathway responsible for 1,3-PD production, thedha regulon ofKlebsiella pneumoniae, inEscherichia coli. An analysis of the maximum theoretical yield of 1,3-PD from glycerol indicates that the yield can be improved by the cofermentation
of sugars, provided that kinetic constraints are overcome. The yield of 1,3-PD from glycerol was improved from 0.46 mol/mol
with glycerol alone to 0.63 mol/mol with glucose cofermentation and 0.55 mol/mol with xylose cofermentation. The engineeredE. coli also provides a model system for the study of metabolic pathway engineering. 相似文献
7.
Enhanced production of laccases from Streptomyces psammoticus in solid-state fermentation was carried out using two different strategies: laccase inducers and scale-up process. Laccase
yield was enhanced by a wide range of aromatic inducers. The best inducer was pyrogallol, which yielded 116 U/g as compared
to the control (55.4 U/g). Scale-up studies in packed bed bioreactor was performed at different aeration rates. Aeration at
1.5 vvm was identified as the optimum condition for laccase production (75.4 U/g) in the column bioreactor. The enzyme yield
was enhanced further by combining the best conditions from the first two experiments. Fermentation was carried out in bioreactors
in the presence of 1 mM pyrogallol, which resulted in 3.9-fold increase in laccase yield (215.6 U/g). The role of laccase
in azo dye decolorization was evaluated in the presence of four different laccase mediators, at different concentrations.
1-Hydroxybenzotriazole (HOBT) proved to be the best mediator for S. psammoticus laccase and decolorized the azo dyes efficiently. Acid orange, Methyl orange, and Bismarck brown were decolorized at the
rates of 86%, 71%, and 75% respectively, by HOBT. 相似文献
8.
de Lima CJ Ribeiro EJ Sérvulo EF Resende MM Cardoso VL 《Applied biochemistry and biotechnology》2009,152(1):156-168
Pseudomonas aeruginosa PACL strain, isolated from oil-contaminated soil taken from a lagoon, was used to investigate the efficiency and magnitude
of biosurfactant production, using different waste frying soybean oils, by submerged fermentation in stirred tank reactors
of 6 and 10 l capacities. A complete factorial experimental design was used, with the goal of optimizing the aeration rate
(0.5, 1.0, and 1.5 vvm) and agitation speed (300, 550, and 800 rpm). Aeration was identified as the primary variable affecting
the process, with a maximum rhamnose concentration occurring at an aeration rate of 0.5 vvm. At optimum levels, a maximum
rhamnose concentration of 3.3 g/l, an emulsification index of 100%, and a minimum surface tension of 26.0 dynes/cm were achieved.
Under these conditions, the biosurfactant production derived from using a mixture of waste frying soybean oil (WFSO) as a
carbon source was compared to production when non-used soybean oil (NUSO), or waste soybean oils used to fry specific foods,
were used. NUSO produced the highest level of rhamnolipids, although the waste soybean oils also resulted in biosurfactant
production of 75–90% of the maximum value. Under ideal conditions, the kinetic behavior and the modeling of the rhamnose production,
nutrient consumption, and cellular growth were established. The resulting model predicted data points that corresponded well
to the empirical information. 相似文献
9.
Daniele Misturini Rossi Elisangela Aquino de Souza Marco Antônio Záchia Ayub 《Applied biochemistry and biotechnology》2013,169(6):1952-1964
The metabolism of residual glycerol from biodiesel synthesis by Klebsiella pneumoniae BLh-1 was investigated in this study. Batch and fed-batch cultivations were performed in bioreactors under anaerobic and oxygen limitation conditions. Results of batch cultivations showed that the main product was 1,3-propanediol (1,3-PD) in both conditions, although the higher yields and productivities (0.46 mol mol?1 glycerol and 1.22 g?L?1?h?1, respectively) were obtained under anaerobic condition. Large amounts of ethanol were also produced under batch anaerobic condition, peaking at 12.30 g?L?1. Batch cultivations under oxygen limitation were characterized by faster growth kinetics, with higher biomass production but lower conversions of glycerol into 1,3-PD, with yields and productivities of 0.33 mol mol?1 glycerol and 0.99 g?L?1?h?1, respectively. The fed-batch cultivations were carried out in order to investigate the effects of feeding of raw glycerol on cells. Fed-batch under anaerobiosis showed that 1,3-PD and ethanol concentrations increased with the feeding rate, with maximal productions of 26.12 and 19.2 g?L?1, respectively. The oxygen limitation conditions diverted the bacterium metabolism to an elevated lactic acid formation, reaching 59 g?L?1 in higher feeding rates of glycerol, but lowering the production of ethanol. 相似文献
10.
Rodrigues Denise C. G. A. Da Silva Silvio S. Almeida E Silva J. B. Vitolo Michele 《Applied biochemistry and biotechnology》2002,98(1-9):875-883
Xylose reductase activity of Candida guilliermondii FTI 20037 was evaluated during xylitol production by fed-batch fermentation of sugarcane bagasse hydrolysate. A 24-1 fractional factorial design was used to select process variables. The xylose concentrations in the feeding solution (S
F
) and in the fermentor (S
0), the pH, and the aeration rate were selected for optimization of this process, which will be undertaken in the near future.
The best experimental result was achieved at S
F
=45 g/L, S
0=40 g/L, pH controlled at 6.0, and aeration rate of 1.2 vvm. Under these conditions, the xylose reductase activity was 0.81
U/mg of protein and xylitol production was 26.3 g/L, corresponding to a volumetric productivity of 0.55 g/(L·h) and a xylose
xylitol yield factor of 0.68 g/g. 相似文献
11.
Escherichia coli grows fermentatively in glucose-containing medium under anaerobic condition with formation of a mixture of organic acids
(lactate, acetate, formate, and succinate) and ethanol to accommodate reducing equivalents generated during glycolysis. In
this paper, we tried to improve the lactate accumulation in E. coli by redox regulation genetically and physiologically. Our results indicated that genetic regulation of the host by reducing
the reductive by-product may improve the lactate production. In addition, lactate accumulation was also improved under reduced
and anaerobic cultivation conditions. Engineered E. coli SDU4 was able to accumulate lactate under strictly anaerobic conditions to 100 g/L with a yield of 1.97 mol/mol glucose. 相似文献
12.
Silva-Santisteban BO Converti A Filho FM 《Applied biochemistry and biotechnology》2009,152(2):249-261
Cultivations of Kluyveromyces marxianus var. bulgaricus ATCC 16045 were performed on both minimal and complex media using different carbon and nitrogen sources either in the presence
or absence of aeration. The results collected were worked out and compared so as to provide a useful contribution to the optimization
of inulinase production. Kinetics of extracellular inulinase release were similar on glucose, fructose, and sucrose. Inulinase
was detected at basal level since the beginning of batch runs on these three carbon sources and overproduced after their depletion.
The highest inulinase activity in minimal medium containing 10 g/l sucrose (6.4 IU/ml) was obtained at an initial (NH4)2SO4 concentration of 5 g/l, whereas it was reduced to about one fourth of this value and detected only at the beginning under
nitrogen-limited conditions. The best sucrose concentrations for the enzyme production were 30 and 20 g/l in minimal and complex
media, yielding 15.4 and 208 IU/ml, respectively. In general, the enzyme activity was much higher in complex than in minimal
medium under all conditions. O2-enriched air neither improved inulinase production nor prevented ethanol formation. 相似文献
13.
Gunasekaran Balamurugan Sundarraman Balaji Rengan Ramesh Nattamai S.P. Bhuvanesh 《应用有机金属化学》2019,33(1)
A panel of six new arene Ru (II)‐NHC complexes 2a‐f , (NHC = 1,3‐diethyl‐(5,6‐dimethyl)benzimidazolin‐2‐ylidene 1a , 1,3‐dicyclohexylmethyl‐(5,6‐dimethyl)benzimidazolin‐2‐ylidene 1b and 1,3‐dibenzyl‐(5,6‐dimethyl)benzimidazolin‐2‐ylidene 1c ) were synthesized from the transmetallation reaction of Ag‐NHC with [(η6‐arene)RuCl2]2 and characterized. The ruthenium (II)‐NHC complexes 2a‐f were developed as effective catalysts for α‐alkylation of ketones and synthesis of bioactive quinoline using primary/amino alcohols as coupling partners respectively. The reactions were performed with 0.5 mol% catalyst load in 8 h under aerobic condition and the maximum yield was up to 96%. Besides, the different alkyl wingtips on NHC and arene moieties were studied to differentiate the catalytic robustness of the complexes in the transformations. 相似文献
14.
Katrlík J Vostiar I Sefcovicová J Tkác J Mastihuba V Valach M Stefuca V Gemeiner P 《Analytical and bioanalytical chemistry》2007,388(1):287-295
Novel and selective microbial amperometric biosensors that use Gluconobacter oxydans cells to monitor the bacterial bioconversion of glycerol (Gly) to 1,3-propanediol (1,3-PD) are described. Two different mediators,
ferricyanide and flexible polyvinylimidazole osmium functionalized polymer (Os-polymer), were employed to prepare two different
microbial biosensors, both of which gave high detection performance. The good operational stabilities of both types of biosensor
were underlined by the ability to detect 1,3-PD throughout 140 h of continuous operation. Both microbial biosensor systems
showed excellent selectivity for 1,3-PD in the presence of a high excess of glycerol [selectivity ratios (1,3-PD/Gly) of 118
or 245 for the ferricyanide and Os-polymer systems, respectively]. Further, the robustness of each microbial biosensor was
highlighted by the high reliability of 1,3-PD detection achieved (average RSD of standards <2%, and well below 4% for samples).
The biosensor implementing the Os-polymer mediator exhibited high selectivity towards 1,3-PD detection and allowed moderate
sample throughput (up to 12 h−1) when integrated into a flow system. This system was used to monitor the concentration of 1,3-PD during a real bioprocess.
Results from biosensor assays of 1,3-PD in bioprocess samples taken throughout the fermentation were in a very good agreement
with results obtained from reference HPLC assays (R
2 = 0.999). 相似文献
15.
Inhibition of microbial xylitol production by acetic acid and its relation with fermentative parameters 总被引:5,自引:0,他引:5
Precipitated sugarcane bagasse hemicellulosic hydrolysate containing acetic acid was fermented by Candida guilliermondii FTI 20037 under different operational conditions (pH 4.0 and 7.0, three aeration rates). At pH 7.0 and k
L
a of 10 (0.75 vvm) and 22.5/h (3.0 vvm) the acetic acid had not been consumed until the end of the fermentations, whereas at
the same pH and k
L
a of 35/h (4.5 vvm) the acid was rapidly consumed and acetic acid inhibition was not important. On the other hand, fermentations
at an initial pH of 4.0 and k
L
a of 22.5 and 35/h required less time for the acid uptake than fermentations at k
L
a of 10/h. The acetic acid assimilation by the yeast indicates the ability of this strain to ferment in partially detoxified
medium, making possible the utilization of the sugarcane bagasse hydrolysate in this bioprocess. The effects on xylitol yield
and production are reported. 相似文献
16.
Inês C. Roberto Ismael M. de Mancilha Sunao Sato 《Applied biochemistry and biotechnology》1999,77(1-3):205-210
The fermentation kinetics for the conversion of rice straw hemicellulosic hydrolysate to xylitol by the yeast Candida guilliermondii was evaluated under batch conditions. The fermentation was accomplished in a 1 L working volume stirred-tank reactor with
aeration of 1.3 vvm and agitation of 300 rpm (kLa=15/h). The maximum specific rate of xylitol formation (0.12 g/g) was achieved when the specific growth rate was lowered
to 1/5 of its highest value. From analysis of the fermentation kinetics, a linear correlation between specific growth rate
(μx) and specific rate of xylitol formation (qp) was evident. Based on the Gaden model, this bioprocess was classified as growth-associated production and the relationship
between μx and qp can be described by the equation qp=6.31μx. 相似文献
17.
Leda M. F. Gottschalk Ronaldo Nobrega Elba P. S. Bon 《Applied biochemistry and biotechnology》2003,108(1-3):799-807
The effect of aeration on lignin peroxidase production by Streptomyces viridosporus T7A was studied in a bench-scale bioreactor using a previously optimized growth medium (0.65% yeast extract and 0.1% corn
oil, pH7.0) at 37°C and natural pH. Airflow rates of 0.3, 1.0, and 1.5 vvm and a fixed agitation of 200 rpm were initially
studied followed by 1.0 vvm and 200, 300, 400, and 500 rpm. The use of 1.0 vvm and 400 rpm increased enzyme concentration
1.8-fold (100–180 U/L) and process productivity 4.8-fold (1.4–6.7 U/[L·h]) in comparison with the use of 200 rpm and 0.3 vvm.
The inexpensive corn oil, used as carbon source, besides its antifoam properties, proved to be nonrepressive for enzyme production. 相似文献
18.
Oh BR Seo JW Heo SY Hong WK Luo LH Kim S Park DH Kim CH 《Applied biochemistry and biotechnology》2012,166(1):127-137
In the present work, mutant strains of Klebsiella pneumoniae with deletions of the als gene encoding acetolactate synthase involved in synthesis of 2,3-butanediol, the ldhA gene encoding lactate dehydrogenase required for lactate synthesis, or both genes, were prepared. Production of 1,3-propanediol
(1,3-PD) from glycerol was enhanced in the ldhA mutant strain (ΔldhA), but lower in Δals or Δals ΔldhA mutant strains compared to the parent strain, concomitant with a reduction in the glycerol consumption rate, indicating that
deletion of ldhA alone was useful to improve 1,3-PD production. Fed-batch fermentation analysis revealed that, in the ΔldhA mutant strain, 1,3-PD production was higher at low pH than at neutral pH; the reverse was true for the parent strain. Further
optimization of culture conditions, by variation of aeration and glycerol feed rates, dramatically improved the production
of 1,3-PD by the mutant strain. The maximum level attained was 102.7 g l−1 of 1,3-PD from glycerol. 相似文献
19.
The biodegradation of aromatic‐aliphatic biodegradable polyester poly (butylene adipate‐co‐terephthalate) (PBAT) was studied under mesophilic (37°C) and thermophilic (55°C) anaerobic conditions. Anaerobic sludge from municipal wastewater treatment plant was utilized as an inoculum. Non‐isothermal crystallization kinetics of PBAT before and after biodegradation was explored by differential scanning calorimetry. Under mesophilic anaerobic conditions (37°C), the biodegradation after 126 days was only 2.2%, molecular weight changed from 93 000 to 25 500 g/mol, and the crystallization behavior was changed only slightly. However, biodegradation under thermophilic anaerobic conditions (55°C) caused much bigger changes: biodegradation according to biogas production reached after 126 days 8.3%, molecular weight changed from 93 000 to 9430 g/mol, and the crystallization behavior was changed significantly. While Tm increased only slightly, Tc on the other hand increased significantly for the sample after biodegradation at 55°C. Also, the crystallization rate was slower (particularly at lower cooling rates), but crystallinity was slightly higher. The diffraction pattern was observed by X‐ray diffraction. 相似文献
20.
4-Vinyl guaiacol (3-methoxy 4-hydroxystyrene) can be obtained by decarboxylation of ferulic acid by the strain Streptomyces setonii ATCC 39116. The formation of this metabolite was favoured by microaerobic conditions and the culture medium employed, increasing
progressively the product concentration from 543.3 up to 885.1 mg/l when aeration level was diminished, reaching a highest
volumetric productivity of 70.4 mg/l h and a product yield of 1.11 mol/mol. The identity of the metabolite was confirmed by
gas chromatography–mass spectrometry. A metabolic study of ferulic acid and the main degradation products (ferulic acid, 4-vinyl
guaiacol, protocatechuic acid, vanillyl alcohol, vanillic acid and vanillin) suggested that ferulic acid was the only substrate
capable to be transformed into 4-vinyl guaiacol by this strain of S. setonii. 相似文献