共查询到20条相似文献,搜索用时 31 毫秒
1.
Kaloyan K. Petrov Penka M. Petrova Venko N. Beschkov 《World journal of microbiology & biotechnology》2007,23(3):423-428
A new procedure for improved immobilization of Lactobacillus rhamnosus ATCC 7469, producing solely l(+)-lactic acid, in polyacrylamide was developed. A series of gels with varied ingredients concentrations and order of addition
was prepared and were tested in batch and repeat-batch processes. Our results revealed that the crucial step for successful
immobilization was the initial incubation of the cells in pure 10% AA that leads to improved entrapment in the polyacrylamide
gel. In contrast, all gels derived from previously prepared stock AA/MBAA released high amount of cells and free biomass was
formed. The most efficient immobilization was achieved using gel, containing L. rhamnosus, incubated in 10% AA (acrylamide) and with 1% MBAA (N,N′-methylene-bis-acrylamide) added. This gel possessed optimal permeation characteristics and at the same time, the cells were
completely retained in the polymer lattice (0.03 g free biomass/l at 48 h of the batch process). In addition, it yielded highly
concentrated lactic acid: the conversion ratio was about 85% without pH-control for initial lactose concentrations of up to
30 g/l. A series of additional immobilization experiments showed the potential of physicochemical interactions between the
monomers of acrylamide and the cell surface of L. rhamnosus. 相似文献
2.
Qi Wang Cui Min Tingting Yan Hefang Pu Yinqiang Xin Shuangquan Zhang Lan Luo Zhimin Yin 《World journal of microbiology & biotechnology》2011,27(11):2603-2610
l-glutamine (Gln) is an important conditionally necessary amino acid in human body and potential demand in food or medicine
industry is expected. High efficiency of l-Gln production by coupling genetic engineered bacterial glutamine synthetase (GS) with yeast alcoholic fermentation system
has been developed. We report here first the application of small ubiquitin-related modifier (SUMO) fusion technology to the
expression and purification of recombinant Bacillus subtilis GS. In order to obtain GS with high Gln-forming activity, safety and low cost for food and pharmaceutics industry, 0.1% (w/v)
lactose was selected as inducer. The fusion protein was expressed in totally soluble form in E. coli, and expression was verified by SDS–PAGE and western blot analysis. The fusion protein was purified to 90% purity by nickel
nitrilo-triacetic acid (Ni–NTA) resin chromatography with a yield of 625 mg per liter fermentation culture. After the SUMO/GS
fusion protein was cleaved by the SUMO protease, the cleaved sample was reapplied to a Ni–NTA column. Finally, about 121 mg
recombinant GS was obtained from 1 l fermentation culture with no less than 96% purity. The recombinant purified GS showed
great transferase activity (23 U/mg), with 25 U recombinant GS in a 50 ml reaction system, a biosynthesis yield of 27.5 g/l l-Gln was detected by high pressure liquid chromatography (HPLC) or thin-layer chromatography. Thus, the application of SUMO
technology to the expression and purification of GS potentially could be employed for the industrial production of l-Gln. 相似文献
3.
Assembly of mutations for improving thermostability of <Emphasis Type="Italic">Escherichia coli</Emphasis> AppA2 phytase 总被引:2,自引:0,他引:2
Maas RH Bakker RR Jansen ML Visser D de Jong E Eggink G Weusthuis RA 《Applied microbiology and biotechnology》2008,79(5):751-758
Conventional processes for lignocellulose-to-organic acid conversion requires pretreatment, enzymatic hydrolysis, and microbial
fermentation. In this study, lime-treated wheat straw was hydrolyzed and fermented simultaneously to lactic acid by an enzyme
preparation and Bacillus coagulans DSM 2314. Decrease in pH because of lactic acid formation was partially adjusted by automatic addition of the alkaline substrate.
After 55 h of incubation, the polymeric glucan, xylan, and arabinan present in the lime-treated straw were hydrolyzed for
55%, 75%, and 80%, respectively. Lactic acid (40.7 g/l) indicated a fermentation efficiency of 81% and a chiral l(+)-lactic acid purity of 97.2%. In total, 711 g lactic acid was produced out of 2,706 g lime-treated straw, representing
43% of the overall theoretical maximum yield. Approximately half of the lactic acid produced was neutralized by fed-batch
feeding of lime-treated straw, whereas the remaining half was neutralized during the batch phase with a Ca(OH)2 suspension. Of the lime added during the pretreatment of straw, 61% was used for the neutralization of lactic acid. This
is the first demonstration of a process having a combined alkaline pretreatment of lignocellulosic biomass and pH control
in fermentation resulting in a significant saving of lime consumption and avoiding the necessity to recycle lime. 相似文献
4.
Mark S. Ou Lonnie O. Ingram K. T. Shanmugam 《Journal of industrial microbiology & biotechnology》2011,38(5):599-605
Lactic acid is used as an additive in foods, pharmaceuticals, and cosmetics, and is also an industrial chemical. Optically
pure lactic acid is increasingly used as a renewable bio-based product to replace petroleum-based plastics. However, current
production of lactic acid depends on carbohydrate feedstocks that have alternate uses as foods. The use of non-food feedstocks
by current commercial biocatalysts is limited by inefficient pathways for pentose utilization. B. coagulans strain 36D1 is a thermotolerant bacterium that can grow and efficiently ferment pentoses using the pentose-phosphate pathway
and all other sugar constituents of lignocellulosic biomass at 50°C and pH 5.0, conditions that also favor simultaneous enzymatic
saccharification and fermentation (SSF) of cellulose. Using this bacterial biocatalyst, high levels (150–180 g l−1) of lactic acid were produced from xylose and glucose with minimal by-products in mineral salts medium. In a fed-batch SSF
of crystalline cellulose with fungal enzymes and B. coagulans, lactic acid titer was 80 g l−1 and the yield was close to 80%. These results demonstrate that B. coagulans can effectively ferment non-food carbohydrates from lignocellulose to l(+)-lactic acid at sufficient concentrations for commercial application. The high temperature fermentation of pentoses and
hexoses to lactic acid by B. coagulans has these additional advantages: reduction in cellulase loading in SSF of cellulose with a decrease in enzyme cost in the
process and a reduction in contamination of large-scale fermentations. 相似文献
5.
Yoshinori Takagi Teruhide Sugisawa Tatsuo Hoshino 《Applied microbiology and biotechnology》2009,82(6):1049-1056
A single-stage continuous fermentation process for the production of 2-keto-l-gulonic acid (2KGA) from l-sorbose using Ketogulonigenium vulgare DSM 4025 was developed. The chemostat culture with the dilution rate that was calculated based on the relationship between
the 2KGA production rate and the 2KGA concentration was feasible for production with high concentration of 2KGA. In this system,
112.2 g/L of 2KGA on the average was continuously produced from 114 g/L of l-sorbose. A steady state of the fermentation was maintained for the duration of more than 110 h. The dilution rate was kept
in the range of 0.035 and 0.043 h−1, and the 2KGA productivity was 3.90 to 4.80 g/L/h. The average molar conversion yield of 2KGA from l-sorbose was 91.3%. Under the optimal conditions, l-sorbose concentration was kept at 0 g/L. Meanwhile, the dissolved oxygen level was changing in response to the dilution rate
and 2KGA concentration. In the dissolved oxygen (DO) range of 16% to 58%, it was revealed that the relationship between DO
and D possessed high degree of positive correlation under the l-sorbose limiting condition (complete consumption of l-sorbose). Increasing D closer to the critical value for washing out point of the continuous fermentation, DO value tended to be gradually increased
up to 58%. In conclusion, an efficient and reproducible continuous fermentation process for 2KGA production by K. vulgare DSM 4025 could be developed using a medium containing baker’s yeast without using a second helper microorganism. 相似文献
6.
Lactobacillus casei was grown at 37 °C on sugarcane bagasse (5 g) soaked with cassava starch hydrolysate (final moistening volume 34 ml) containing
3 g reducing sugar in a solid-state condition. The maximum yield of l-lactic acid after various process optimisations was 2.9 g/5 g initial substrate corresponding to 97% conversion of sugar
to lactic acid with initial substrate moisture of 72%. 相似文献
7.
Production of <Emphasis Type="SmallCaps">l</Emphasis>-alanine by metabolically engineered <Emphasis Type="Italic">Escherichia coli</Emphasis> 总被引:2,自引:0,他引:2
Zhang X Jantama K Moore JC Shanmugam KT Ingram LO 《Applied microbiology and biotechnology》2007,77(2):355-366
Escherichia coli W was genetically engineered to produce l-alanine as the primary fermentation product from sugars by replacing the native d-lactate dehydrogenase of E. coli SZ194 with alanine dehydrogenase from Geobacillus stearothermophilus. As a result, the heterologous alanine dehydrogenase gene was integrated under the regulation of the native d-lactate dehydrogenase (ldhA) promoter. This homologous promoter is growth-regulated and provides high levels of expression during anaerobic fermentation.
Strain XZ111 accumulated alanine as the primary product during glucose fermentation. The methylglyoxal synthase gene (mgsA) was deleted to eliminate low levels of lactate and improve growth, and the catabolic alanine racemase gene (dadX) was deleted to minimize conversion of l-alanine to d-alanine. In these strains, reduced nicotinamide adenine dinucleotide oxidation during alanine biosynthesis is obligately
linked to adenosine triphosphate production and cell growth. This linkage provided a basis for metabolic evolution where selection
for improvements in growth coselected for increased glycolytic flux and alanine production. The resulting strain, XZ132, produced
1,279 mmol alanine from 120 g l−1 glucose within 48 h during batch fermentation in the mineral salts medium. The alanine yield was 95% on a weight basis (g
g−1 glucose) with a chiral purity greater than 99.5% l-alanine.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
8.
Sirisansaneeyakul S Luangpipat T Vanichsriratana W Srinophakun T Chen HH Chisti Y 《Journal of industrial microbiology & biotechnology》2007,34(5):381-391
Production of lactic acid from glucose by immobilized cells of Lactococcus lactis IO-1 was investigated using cells that had been immobilized by either entrapment in beads of alginate or encapsulation in
microcapsules of alginate membrane. The fermentation process was optimized in shake flasks using the Taguchi method and then
further assessed in a production bioreactor. The bioreactor consisted of a packed bed of immobilized cells and its operation
involved recycling of the broth through the bed. Both batch and continuous modes of operation of the reactor were investigated.
Microencapsulation proved to be the better method of immobilization. For microencapsulated cells at immobilized cell concentration
of 5.3 g l−1, the optimal production medium had the following initial concentrations of nutrients (g l−1): glucose 45, yeast extract 10, beef extract 10, peptone 7.5 and calcium chloride 10 at an initial pH of 6.85. Under these
conditions, at 37 °C, the volumetric productivity of lactic acid in shake flasks was 1.8 g l−1 h−1. Use of a packed bed of encapsulated cells with recycle of the broth through the bed, increased the volumetric productivity
to 4.5 g l−1 h−1. The packed bed could be used in repeated batch runs to produce lactic acid. 相似文献
9.
Lactobacillus delbrueckii was grown on sugarcane molasses, sugarcane juice and sugar beet juice in batch fermentation at pH 6 and at 40°C. After 72 h,
the lactic acid from 13% (w/v) sugarcane molasses (119 g total sugar l−1) and sugarcane juice (133 g total sugar l−1) was 107 g l−1 and 120 g l−1, respectively. With 10% (w/v) sugar beet juice (105 g total sugar l−1), 84 g lactic acid l−1 was produced. The optical purities of d-lactic acid from the feedstocks ranged from 97.2 to 98.3%. 相似文献
10.
Anne Deen Christensen Zsófia Kádár Piotr Oleskowicz-Popiel Mette Hedegaard Thomsen 《Journal of industrial microbiology & biotechnology》2011,38(2):283-289
Ethanol production by K. marxianus in whey from organic cheese production was examined in batch and continuous mode. The results showed that no pasteurization
or freezing of the whey was necessary and that K. marxianus was able to compete with the lactic acid bacteria added during cheese production. The results also showed that, even though
some lactic acid fermentation had taken place prior to ethanol fermentation, K. marxianus was able to take over and produce ethanol from the remaining lactose, since a significant amount of lactic acid was not produced
(1–2 g/l). Batch fermentations showed high ethanol yield (~0.50 g ethanol/g lactose) at both 30°C and 40°C using low pH (4.5)
or no pH control. Continuous fermentation of nonsterilized whey was performed using Ca-alginate-immobilized K. marxianus. High ethanol productivity (2.5–4.5 g/l/h) was achieved at dilution rate of 0.2/h, and it was concluded that K. marxianus is very suitable for industrial ethanol production from whey. 相似文献
11.
Xiong H Turunen O Pastinen O Leisola M von Weymarn N 《Applied microbiology and biotechnology》2004,64(3):353-358
Trichoderma reesei Rut C-30 was grown on eight different natural or rare aldopentoses as the main carbon source and on mixtures of an aldopentose with d-glucose or lactose. The fungal cells consumed all aldopentoses tested, except l-xylose and l-ribose. The highest total xylanase and cellulase activities were achieved when cells were grown on l-arabinose as the main carbon source. The total xylanase activity produced by cells grown on l-arabinose was even higher than that produced by cells grown on an equal amount of lactose. In co-metabolism of d-glucose (15 g l–1) and l-arabinose (5 g l–1), the total volumetric and specific xylanase productivities were improved (derepressed) approximately 23- and 18-fold, respectively, compared to a cultivation on only d-glucose (20 g l–1). In a similar experiment, in which cells were grown on a mixture of lactose and l-arabinose, the xylanase productivity was approximately doubled, compared to a cultivation on only lactose. The cellulase productivities, however, were not improved by the addition of l-arabinose. Compared with a typical industrial fungal enzyme production process with lactose as the main carbon source, better volumetric and specific xylanase productivities were achieved both on a lactose/arabinose mixture and on a glucose/arabinose mixture. 相似文献
12.
Kawaguchi H Sasaki M Vertès AA Inui M Yukawa H 《Applied microbiology and biotechnology》2008,77(5):1053-1062
Corynebacterium glutamicum was metabolically engineered to broaden its substrate utilization range to include the pentose sugar l-arabinose, a product of the degradation of lignocellulosic biomass. The resultant CRA1 recombinant strain expressed the Escherichia coli genes araA, araB, and araD encoding l-arabinose isomerase, l-ribulokinase, and l-ribulose-5-phosphate 4-epimerase, respectively, under the control of a constitutive promoter. Unlike the wild-type strain,
CRA1 was able to grow on mineral salts medium containing l-arabinose as the sole carbon and energy source. The three cloned genes were expressed to the same levels whether cells were
cultured in the presence of d-glucose or l-arabinose. Under oxygen deprivation and with l-arabinose as the sole carbon and energy source, strain CRA1 carbon flow was redirected to produce up to 40, 37, and 11%,
respectively, of the theoretical yields of succinic, lactic, and acetic acids. Using a sugar mixture containing 5% d-glucose and 1% l-arabinose under oxygen deprivation, CRA1 cells metabolized l-arabinose at a constant rate, resulting in combined organic acids yield based on the amount of sugar mixture consumed after
d-glucose depletion (83%) that was comparable to that before d-glucose depletion (89%). Strain CRA1 is, therefore, able to utilize l-arabinose as a substrate for organic acid production even in the presence of d-glucose. 相似文献
13.
Double d-amino acid oxidases (dRtDAO and dTvDAO) were previously genetically constructed by linking the C-terminus of one subunit
of their corresponding native DAOs from Rhodosporidium toruloides and Trigonopsis variabilis (RtDAO and TvDAO) to the N-terminus of the other identical subunit. We have now immobilized these double DAOs and their native
counterparts onto streptavidin-coated magnetic beads through the interaction between biotin and streptavidin. The catalytic
efficiencies (kcat/KM) of immobilized DAOs toward d-alanine and cepharosporin C remained similar to those of their soluble forms, except the catalytic efficiency of immobilized
TvDAO toward d-alanine was decreased by 56%. After immobilization, the Tm value for RtDAO was shifted 15°C higher to 60°C, while those for dRtDAO, TvDAO and dTvDAO were increased by 5–8°C to 56,
60 and 60°C, respectively. In the presence of 10 mM H2O2, immobilized RtDAO, dRtDAO, TvDAO and dTvDAO exhibited half-lives of about 8, 10, 3 and 5 h, respectively, giving 16-, 10-,
6- and 7-fold greater stability than their soluble forms, respectively. Therefore, immobilization through biotin–streptavidin
affinity binding enhances the thermal and oxidative stability of native and double DAOs studied, especially RtDAO. The additive
stabilizing effect of subunit fusion and immobilization was more pronounced in the case of RtDAO than TvDAO. 相似文献
14.
K. Kapsopoulou A. Mourtzini M. Anthoulas E. Nerantzis 《World journal of microbiology & biotechnology》2007,23(5):735-739
Four mixed culture fermentations of grape must were carried out with Kluyveromyces thermotolerans strain TH941 and Saccharomyces cerevisiae strain SCM952. In the first culture, both yeasts were added together, whereas in the remaining three cultures S. cerevisiae was added 1, 2, and 3 days after the inoculation of K. thermotolerans. The growth and survival of the K. thermotolerans strain and the amount of the produced l-lactic acid depend on the time of inoculation of the S. cerevisiae strain and provided an effective acidification during alcoholic fermentation. The four cultures contained, respectively,
at the end of fermentation 0.18, 1.80, 4.28, and 5.13 g l-lactic acid l−1. The grape must with an initial pH of 3.50 was effectively acidified (70% increase in titratable acidity, 0.30 pH unit decrease)
by the production of 5.13 g l-lactic acid l−1. 相似文献
15.
Three mutants, isolated by repeated UV mutagenesis of Lactobacillus lactis NCIM 2368, produced increased d-lactic acid concentrations. These mutants were compared with the wild type using 100 g hydrolyzed cane sugar/l in the fermentation
medium. One mutant, RM2-24, produced 81 g lactic acid/l which was over three times that of the wild type. The highest d-lactic acid (110 g/l) in batch fermentation was obtained with 150 g cane sugar/l with a 73% lactic acid yield. The mutant
utilizes cellobiose efficiently, converting it into d-lactic acid suggesting the presence of cellobiase. Thus, this strain could be used to obtain d-lactic acid from cellulosic materials that are pre-hydrolyzed with cellulase. 相似文献
16.
A recombinant d-lyxose isomerase from Providencia stuartii was immobilized on Duolite A568 beads which gave the highest conversion of d-fructose to d-mannose among the various immobilization beads evaluated. Maximum activities of both the free and immobilized enzymes for
fructose isomerization were at pH 7.5 and 45°C in the presence of 1 mM Mn2+. Enzyme half-lives were 14 and 30 h at 35°C and 3.4 and 5.1 h at 45°C, respectively. The immobilized enzyme in 300 g fructose/l
(replaced hourly), produced 75 g mannose/l at 35°C = 25% (w/w) yield with a productivity of 75 g mannose l−1 h−1 after 23 cycles. 相似文献
17.
Xuefeng Wu Shaotong Jiang Mo Liu Lijun Pan Zhi Zheng Shuizhong Luo 《Journal of industrial microbiology & biotechnology》2011,38(4):565-571
Semicontinuous fermentation using pellets of Rhizopus oryzae has been recognized as a promising technology for l-lactic acid production. In this work, semicontinuous fermentation of R. oryzae AS 3.819 for l-lactic acid production has been developed with high l-lactic acid yield and volumetric productivity. The effects of factors such as inoculations, CaCO3 addition time, and temperature on l-lactic acid yield and R. oryzae morphology were researched in detail. The results showed that optimal fermentation conditions for the first cycle were: inoculation
with 4% spore suspension, CaCO3 added to the culture medium at the beginning of culture, and culture temperature of 32–34°C. In orthogonal experiments, high
l-lactic acid yield was achieved when the feeding medium was (g/l): glucose, 100; (NH4)2SO4, 2; KH2PO4, 0.1; ZnSO4·7H2O, 0.33; MgSO4·7H2O, 0.15; CaCO3, 50. Twenty cycles of semicontinuous fermentation were carried out in flask culture. l-lactic acid yield was 78.75% for the first cycle and 80–90% for the repeated cycles; the activities of lactate dehydrogenases
(LDH) were 7.2–9.2 U/mg; fermentation was completed in 24 h for each repeated cycle. In a 7-l magnetically stirred fermentor,
semicontinuous fermentation lasted for 25 cycles using pellets of R. oryzae AS 3.819 under the optimal conditions determined from flask cultures. The final l-lactic acid concentration (LLAC) reached 103.7 g/l, and the volumetric productivity was 2.16 g/(l·h) for the first cycle;
in the following 19 repeated cycles, the final LLAC reached 81–95 g/l, and the volumetric productivities were 3.40–3.85 g/(l·h). 相似文献
18.
Previous work from our laboratory has shown that most of Bacillus thuringiensis strains possess the ability to produce melanin in the presence of l-tyrosine at elevated temperatures (42 °C). Furthermore, it was shown that the melanin produced by B. thuringiensis was synthesized by the action of tyrosinase, which catalyzed the conversion of l-tyrosine, via l-DOPA, to melanin. In this study, the tyrosinase-encoding gene (mel) from B. thuringiensis 4D11 was cloned using PCR techniques and expressed in Escherichia coli DH5 . A DNA fragment with 1179 bp which contained the intact mel gene in the recombinant plasmid pGEM1179 imparted the ability to synthesize melanin to the E. coli recipient strain. The nucleotide sequence of this DNA fragment revealed an open reading frame of 744 bp, encoding a protein of 248 amino acids. The novel mel gene from B.thuringiensis expressed in E. coli DH5 conferred UV protection on the recipient strain. 相似文献
19.
Rare sugars have many applications in food industry, as well as pharmaceutical and nutrition industries. Xylitol dehydrogenase
(XDH) can be used to synthesize various rare sugars enzymatically. However, the immobilization of XDH has not been performed
to improve the industrial production of rare sugars. In this study, silica nanoparticles which have high immobilization efficiency
were selected from among several carriers for immobilization of recombinant Rhizobium etli CFN42 xylitol dehydrogenase (ReXDH) and subjected to characterization. Among four different chemical modification methods
to give different functional groups, the silica nanoparticle derivatized with epoxy groups showed the highest immobilization
efficiency (92%). The thermostability of ReXDH was improved more than tenfold by immobilization on epoxy-silica nanoparticles;
the t
1/2
of the ReXDH was enhanced from 120 min to 1,410 min at 40 °C and from 30 min to 450 min at 50 °C. The K
m of ReXDH was slightly altered from 17.9 to only 19.2 mM by immobilization. The immobilized ReXDH had significant reusability,
as it retained 81% activity after eight cycles of batch conversion of xylitol into l-xylulose. A ∼ 71% conversion and a productivity of 10.7 g h-1 l-1 were achieved when the immobilized ReXDH was employed to catalyze the biotransformation of xylitol to l-xylulose, a sugar that has been used in medicine and in the diagnosis of hepatitis. These results suggest that immobilization
of ReXDH onto epoxy-silica nanoparticles has potential industrial application in rare sugar production. 相似文献
20.
Jei Oh Yon Ji Seon Lee Bo Geum Kim Sang Dal Kim Doo Hyun Nam 《Biotechnology and Bioprocess Engineering》2008,13(1):102-107
The immobilization of phospholipase D produced by Streptomyces sp. YU100 was evaluated to see it would be practical for industrial applications. To accomplish this, the purified enzyme,
which contained 53 unit/mg of protein, was subjected to immobilization on various matrices. When immobilization supports including
calcium alginate gel, polyacrylamide gel, and macroporous resin were evaluated, the highest enzyme retention ratio (> 42%)
was observed on a Dowex MSA-2 macro-porous resin. This may have occurred as a result of the ability of the hydrophobic domain
of phospholipase D to interact with the polystyrene backbone of the resin, as well as the ability of the dimethylethanolamine
group of the MSA-2 resin to retain the enzyme by forming hydrogen bonds with the acidic residues of the enzyme. Upon the operation
of a reactor packed with enzyme that had been immobilized on a Dowex MSA-2 resin, greater than 80% of the initial enzyme activity
was retained for 16 days. During the reaction, phosphatidylcholine became bound to the immobilized resin and interfered with
the enzyme reaction, therefore, the resin was washed with ethyl ether every 2 h. A process for recovering excessive l-serine from phospholipids using the Dowex MR-3 resin was designed, and the separated l
-serine was employed again after replacing the amount that was used. 相似文献