共查询到20条相似文献,搜索用时 359 毫秒
1.
Ye-Wang Zhang Ponnandy Prabhu Jung-Kul Lee 《Bioprocess and biosystems engineering》2010,33(6):741-748
Recombinant Escherichia coli whole cells harboring Bacillus licheniformis
l-arabinose isomerase (BLAI) were immobilized with alginate. The operational conditions for immobilization were optimized with
response surface methodology. Optimal alginate concentration, Ca2+ concentration, and cell mass loading were 1.8% (w/v), 0.1 M, and 44.5 g L−1, respectively. The interactions between Ca2+ concentration, alginate concentration, and initial cell mass were significant. After immobilization of BLAI, cross-linking
with 0.1% glutaraldehyde significantly reduced cell leakage. The half-life of immobilized whole cells was 150 days, which
was 50-fold longer than that of free cells. In seven repeated batches for l-ribulose production, the productivity was as high as 56.7 g L−1 h−1 at 400 g L−1 substrate concentration. The immobilized cells retained 89% of the initial yield after 33 days of reaction. Immobilization
of whole cells harboring BLAI, therefore, makes a suitable biocatalyst for the production of l-ribulose, particularly because of its high stability and low cost. 相似文献
2.
Bacillus coagulans has been of great commercial interest over the past decade owing to its strong ability of producing optical pure l-lactic acid from both hexose and pentose sugars including l-arabinose with high yield, titer and productivity under thermophilic conditions. The l-arabinose isomerase (L-AI) from Bacillus coagulans was heterologously over-expressed in Escherichia coli. The open reading frame of the L-AI has 1,422 nucleotides encoding a protein with 474 amino acid residues. The recombinant
L-AI was purified to homogeneity by one-step His-tag affinity chromatography. The molecular mass of the enzyme was estimated
to be 56 kDa by SDS-PAGE. The enzyme was most active at 70°C and pH 7.0. The metal ion Mn2+ was shown to be the best activator for enzymatic activity and thermostability. The enzyme showed higher activity at acidic
pH than at alkaline pH. The kinetic studies showed that the K
m, V
max and k
cat/K
m for the conversion of l-arabinose were 106 mM, 84 U/mg and 34.5 mM−1min−1, respectively. The equilibrium ratio of l-arabinose to l-ribulose was 78:22 under optimal conditions. l-ribulose (97 g/L) was obtained from 500 g/l of l-arabinose catalyzed by the enzyme (8.3 U/mL) under the optimal conditions within 1.5 h, giving at a substrate conversion
of 19.4% and a production rate of 65 g L−1 h−1. 相似文献
3.
Kim YS Lee JH Kim NH Yeom SJ Kim SW Oh DK 《Applied microbiology and biotechnology》2011,90(2):489-497
In the fed-batch culture of glycerol using a metabolically engineered strain of Escherichia coli, supplementation with glucose as an auxiliary carbon source increased lycopene production due to a significant increase in
cell mass, despite a reduction in specific lycopene content. l-Arabinose supplementation increased lycopene production due to increases in cell mass and specific lycopene content. Supplementation
with both glucose and l-arabinose increased lycopene production significantly due to the synergistic effect of the two sugars. Cell growth by the
consumption of carbon sources was related to endogenous metabolism in the host E. coli. Supplementation with l-arabinose stimulated only the mevalonate pathway for lycopene biosynthesis and supplementation with both glucose and l-arabinose stimulated synergistically only the mevalonate pathway. In the fed-batch culture of glycerol with 10 g l−1 glucose and 7.5 g l−1
l-arabinose, the cell mass, lycopene concentration, specific lycopene content, and lycopene productivity after 34 h were 42 g l−1, 1,350 mg l−1, 32 mg g cells−1, and 40 mg l−1 h−1, respectively. These values were 3.9-, 7.1-, 1.9-, and 11.7-fold higher than those without the auxiliary carbon sources,
respectively. This is the highest reported concentration and productivity of lycopene. 相似文献
4.
Yeasts that ferment both hexose and pentose are important for cost-effective ethanol production. We found that the soil yeast
strain NY7122 isolated from a blueberry field in Tsukuba (East Japan) could ferment both hexose and pentose (d-xylose and l-arabinose). NY7122 was closely related to Candida subhashii on the basis of the results of molecular identification using the sequence in the D1/D2 domains of 26S rDNA and 5.8S-internal
transcribed spacer region. NY7122 produced at least 7.40 and 3.86 g l−1 ethanol from 20 g l−1
d-xylose and l-arabinose within 24 h. NY7122 could produce ethanol from pentose and hexose sugars at 37°C. The highest ethanol productivity
of NY7122 was achieved under a low pH condition (pH 3.5). Fermentation of mixed sugars (50 g l−1 glucose, 20 g l−1
d-xylose, and 10 g l−1
l-arabinose) resulted in a maximum ethanol concentration of 27.3 g l−1 for the NY7122 strain versus 25.1 g l−1 for Scheffersomyces stipitis. This is the first study to report that Candida sp. NY7122 from a soil environment could produce ethanol from both d-xylose and l-arabinose. 相似文献
5.
Xylose reductase (XR) is a key enzyme in biological xylitol production, and most XRs have broad substrate specificities. During
xylitol production from biomass hydrolysate, non-specific XRs can reduce l-arabinose, which is the second-most abundant hemicellulosic sugar, to the undesirable byproduct arabitol, which interferes
with xylitol crystallization in downstream processing. To minimize the flux from l-arabinose to arabitol, the l-arabinose-preferring, endogenous XR was replaced by a d-xylose-preferring heterologous XR in Candida tropicalis. Then, Bacillus licheniformis
araA and Escherichia coli araB and araD were codon-optimized and expressed functionally in C. tropicalis for the efficient assimilation of l-arabinose. During xylitol fermentation, the control strains BSXDH-3 and KNV converted 9.9 g l-arabinose l−1 into 9.5 and 8.3 g arabitol l−1, respectively, whereas the recombinant strain JY consumed 10.5 g l-arabinose l−1 for cell growth without forming arabitol. Moreover, JY produced xylitol with 42 and 16% higher productivity than BSXDH-3
and KNV, respectively. 相似文献
6.
M. Helanto K. Kiviharju T. Granström M. Leisola A. Nyyssölä 《Applied microbiology and biotechnology》2009,83(1):77-83
l-Ribose is a rare and expensive sugar that can be used as a precursor for the production of l-nucleoside analogues, which are used as antiviral drugs. In this work, we describe a novel way of producing l-ribose from the readily available raw material l-arabinose. This was achieved by introducing l-ribose isomerase activity into l-ribulokinase-deficient Escherichia coli UP1110 and Lactobacillus plantarum BPT197 strains. The process for l-ribose production by resting cells was investigated. The initial l-ribose production rates at 39°C and pH 8 were 0.46 ± 0.01 g g−1 h−1 (1.84 ± 0.03 g l−1 h−1) and 0.27 ± 0.01 g g−1 h−1 (1.91 ± 0.1 g l−1 h−1) for E. coli and for L. plantarum, respectively. Conversions were around 20% at their highest in the experiments. Also partially purified protein precipitates
having both l-arabinose isomerase and l-ribose isomerase activity were successfully used for converting l-arabinose to l-ribose. 相似文献
7.
Takashi Nemoto Taisuke Watanabe Yutaka Mizogami Jun-ichi Maruyama Katsuhiko Kitamoto 《Applied microbiology and biotechnology》2009,82(6):1105-1114
The recombinant Pichia pastoris harboring an improved methionine adenosyltransferase (MAT) shuffled gene was employed to biosynthesize S-adenosyl-l-methionine (SAM). Two l-methionine (l-Met) addition strategies were used to supply the precursor: the batch addition strategy (l-Met was added separately at three time points) and the continuous feeding strategies (l-Met was fed continuously at the rate of 0.1, 0.2, and 0.5 g l−1 h−1, respectively). SAM accumulation, l-Met conversion rate, and SAM productivity with the continuous feeding strategies were all improved over the batch addition
strategy, which reached 8.46 ± 0.31 g l−1, 41.7 ± 1.4%, and 0.18 ± 0.01 g l−1 h−1 with the best continuous feeding strategy (0.2 g l−1 h−1), respectively. The bottleneck for SAM production with the low l-Met feeding rate (0.1 g L−1 h−1) was the insufficient l-Met supply. The analysis of the key enzyme activities indicated that the tricarboxylic acid cycle and glycolytic pathway
were reduced with the increasing l-Met feeding rate, which decreased the adenosine triphosphate (ATP) synthesis. The MAT activity also decreased as the l-Met feeding rate rose. The reduced ATP synthesis and MAT activity were probably the reason for the low SAM accumulation when
the l-Met feeding rate reached 0.5 g l−1 h−1. 相似文献
8.
Prabhu P Tiwari MK Jeya M Gunasekaran P Kim IW Lee JK 《Applied microbiology and biotechnology》2008,81(2):283-290
Based on analysis of the genome sequence of Bacillus licheniformis ATCC 14580, an isomerase-encoding gene (araA) was proposed as an l-arabinose isomerase (L-AI). The identified araA gene was cloned from B. licheniformis and overexpressed in Escherichia coli. DNA sequence analysis revealed an open reading frame of 1,422 bp, capable of encoding a polypeptide of 474 amino acid residues
with a calculated isoelectric point of pH 4.8 and a molecular mass of 53,500 Da. The gene was overexpressed in E. coli, and the protein was purified as an active soluble form using Ni–NTA chromatography. The molecular mass of the purified enzyme
was estimated to be ~53 kDa by sodium dodecyl sulfate–polyacrylamide gel electrophoresis and 113 kDa by gel filtration chromatography,
suggesting that the enzyme is a homodimer. The enzyme required a divalent metal ion, either Mn2+or Co2+, for enzymatic activity. The enzyme had an optimal pH and temperature of 7.5 and 50°C, respectively, with a k
cat of 12,455 min−1 and a k
cat/K
m of 34 min−1 mM−1 for l-arabinose, respectively. Although L-AIs have been characterized from several other sources, B. licheniformis L-AI is distinguished from other L-AIs by its wide pH range, high substrate specificity, and catalytic efficiency for l-arabinose, making B. licheniformis L-AI the ideal choice for industrial applications, including enzymatic synthesis of l-ribulose. This work describes one of the most catalytically efficient L-AIs characterized thus far. 相似文献
9.
Anne Usvalampi Kristiina Kiviharju Matti Leisola Antti Nyyssölä 《Journal of industrial microbiology & biotechnology》2009,36(10):1323-1330
Factors affecting the production of the rare sugar l-xylulose from xylitol using resting cells were investigated. An E. coli BPT228 strain that recombinantly expresses a gene for xylitol dehydrogenase was used in the experiments. The ratio of xylitol
to l-xylulose was three times lower in the cytoplasm than in the medium. The effects of pH, temperature, shaking speed, and initial
xylitol concentration on l-xylulose production were investigated in shaking flasks using statistical experimental design methods. The highest production
rates were found at high shaking speed and at high temperature (over 44°C). The optimal pH for both productivity and conversion
was between 7.5 and 8.0, and the optimal xylitol concentration was in the range 250–350 g l−1. A specific productivity of 1.09 ± 0.10 g g−1 h−1 was achieved in a bioreactor. The response surface model based on the data from the shake flask experiments predicted the
operation of the process in a bioreactor with reasonable accuracy. 相似文献
10.
d-Tagatose is a highly functional rare ketohexose and many attempts have been made to convert d-galactose into the valuable d-tagatose using l-arabinose isomerase (l-AI). In this study, a thermophilic strain possessing l-AI gene was isolated from hot spring sludge and identified as Anoxybacillus flavithermus based on its physio-biochemical characterization and phylogenetic analysis of its 16s rRNA gene. Furthermore, the gene encoding
l-AI from A. flavithermus (AFAI) was cloned and expressed at a high level in E. coli BL21(DE3). l-AI had a molecular weight of 55,876 Da, an optimum pH of 10.5 and temperature of 95°C. The results showed that the conversion
equilibrium shifted to more d-tagatose from d-galactose by raising the reaction temperatures and adding borate. A 60% conversion of d-galactose to d-tagatose was observed at an isomerization temperature of 95°C with borate. The catalytic efficiency (k
cat
/K
m) for d-galactose with borate was 9.47 mM−1 min−1, twice as much as that without borate. Our results indicate that AFAI is a novel hyperthermophilic and alkaliphilic isomerase
with a higher catalytic efficiency for d-galactose, suggesting its great potential for producing d-tagatose. 相似文献
11.
Chang-Su Park Soo-Jin Yeom Yu-Ri Lim Yeong-Su Kim Deok-Kun Oh 《World journal of microbiology & biotechnology》2011,27(4):743-750
A putative ribose-5-phosphate isomerase (RpiB) from Streptococcus pneumoniae was purified with a specific activity of 26.7 U mg−1 by Hi-Trap Q HP anion exchange and Sephacryl S-300 HR 16/60 gel filtration chromatographies. The native enzyme existed as
a 96-kDa tetramer with activity maxima at pH 7.5 and 35°C. The RpiB exhibited isomerization activity with l-lyxose, l-talose, d-gulose, d-ribose, l-mannose, d-allose, l-xylulose, l-tagatose, d-sorbose, d-ribulose, l-fructose, and d-psicose and exhibited particularly high activity with l-form monosaccharides such as l-lyxose, l-xylulose, l-talose, and l-tagatose. With l-xylulose (500 g l−1) and l-talose (500 g l−1) substrates, the optimum concentrations of RpiB were 300 and 600 U ml−1, respectively. The enzyme converted 500 g l−1
l-xylulose to 350 g l−1
l-lyxose after 3 h, and yielded 450 g l−1
l-tagatose from 500 g l−1
l-talose after 5 h. These results suggest that RpiB from S. pneumoniae can be employed as a potential producer of l-form monosaccharides. 相似文献
12.
Ran-Young Yoon Soo-Jin Yeom Chang-Su Park Deok-Kun Oh 《Applied microbiology and biotechnology》2009,83(2):295-303
We purified recombinant glucose-6-phosphate isomerase from Pyrococcus furiosus using heat treatment and Hi-Trap anion-exchange chromatography with a final specific activity of 0.39 U mg−1. The activity of the glucose-6-phosphate isomerase for l-talose isomerization was optimal at pH 7.0, 95°C, and 1.5 mM Co2+. The half-lives of the enzyme at 65°C, 75°C, 85°C, and 95°C were 170, 41, 19, and 7.9 h, respectively. Glucose-6-phosphate
isomerase catalyzed the interconversion between two different aldoses and ketose for all pentoses and hexoses via two isomerization
reactions. This enzyme has a unique activity order as follows: aldose substrates with hydroxyl groups oriented in the same
direction at C2, C3, and C4 > C2 and C4 > C2 and C3 > C3 and C4. l-Talose and d-ribulose exhibited the most preferred substrates among the aldoses and ketoses, respectively. l-Talose was converted to l-tagatose and l-galactose by glucose-6-phosphate isomerase with 80% and 5% conversion yields after about 420 min, respectively, whereas d-ribulose was converted to d-ribose and d-arabinose with 53% and 8% conversion yields after about 240 min, respectively. 相似文献
13.
A new bacterial strain producing succinic acid was enriched from bovine rumen content. It is facultatively anaerobic, belongs
to the family Pasteurellaceae and has similarity to the genus Mannheimia. In batch cultivations with D-glucose or sucrose the strain produced up to 5.8 g succinic acid l−1 with a productivity and a yield of up to 1.5 g l−1 h−1 and 0.6 g g−1, respectively. With crude glycerol up to 8.4 g l−1, 0.9 g l−1 h−1 and 1.2 g g−1 were obtained.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
14.
Methee Khamduang Kanoktip Packdibamrung Jarun Chutmanop Yusuf Chisti Penjit Srinophakun 《Journal of industrial microbiology & biotechnology》2009,36(10):1267-1274
The production of l-phenylalanine is conventionally carried out by fermentations that use glucose or sucrose as the carbon source. This work
reports on the use of glycerol as an inexpensive and abundant sole carbon source for producing l-phenylalanine using the genetically modified bacterium Escherichia coli BL21(DE3). Fermentations were carried out at 37°C, pH 7.4, using a defined medium in a stirred tank bioreactor at various
intensities of impeller agitation speeds (300–500 rpm corresponding to 0.97–1.62 m s−1 impeller tip speed) and aeration rates (2–8 L min−1, or 1–4 vvm). This highly aerobic fermentation required a good supply of oxygen, but intense agitation (impeller tip speed
~1.62 m s−1) reduced the biomass and l-phenylalanine productivity, possibly because of shear sensitivity of the recombinant bacterium. Production of l-phenylalanine was apparently strongly associated with growth. Under the best operating conditions (1.30 m s−1 impeller tip speed, 4 vvm aeration rate), the yield of l-phenylalanine on glycerol was 0.58 g g−1, or more than twice the best yield attainable on sucrose (0.25 g g−1). In the best case, the peak concentration of l-phenylalanine was 5.6 g L−1, or comparable to values attained in batch fermentations that use glucose or sucrose. The use of glycerol for the commercial
production of l-phenylalanine with E. coli BL21(DE3) has the potential to substantially reduce the cost of production compared to sucrose- and glucose-based fermentations. 相似文献
15.
Fábio Coelho Sampaio Janaína Teles de Faria Jane Sélia R. Coimbra Flávia M. Lopes Passos Attilio Converti Luis Antônio Minin 《Bioprocess and biosystems engineering》2009,32(6):747-754
To develop a new enzymatic xylose-to-xylitol conversion, deeper knowledge on the regulation of xylose reductase (XR) is needed.
To this purpose, a new strain of Debaryomyces hansenii (UFV-170), which proved a promising xylitol producer, was cultivated in semi-synthetic media containing different carbon
sources, specifically three aldo-hexoses (d-glucose, d-galactose and d-mannose), a keto-hexose (d-fructose), a keto-pentose (d-xylose), three aldo-pentoses (d-arabinose, l-arabinose and d-ribose), three disaccharides (maltose, lactose and sucrose) and a pentitol (xylitol). The best substrate was lactose on which
cell concentration reached about 20 g l−1 dry weight (DW), while the highest specific growth rates (0.58–0.61 h−1) were detected on lactose, d-mannose, d-glucose and d-galactose. The highest specific activity of XR (0.24 U mg−1) was obtained in raw extracts of cells grown on d-xylose and harvested in the stationary growth phase. When grown on cotton husk hemicellulose hydrolyzates, cells exhibited
XR activities five to seven times higher than on semi-synthetic media. 相似文献
16.
Dan Wang Qiang Li Yu Mao Jianmin Xing Zhiguo Su 《Applied microbiology and biotechnology》2010,87(6):2025-2035
Escherichia coli strains with foreign genes under the isopropyl-β-d-thiogalactopyranoside-inducible promoters such as lac, tac, and trc were engineered and considered as the promising succinic acid-producing bacteria in many reports. The promoters mentioned
above could also be induced by lactose, which had not been attempted for succinic acid production before. Here, the efficient
utilization of lactose as inducer was demonstrated in cultures of the ptsG, ldhA, and pflB mutant strain DC1515 with ppc overexpression. A fermentative process for succinic acid production at high level by this strain was developed. In flask
anaerobic culture, 14.86 g l−1 succinic acid was produced from 15 g l−1 glucose with a yield of 1.51 mol mol−1 glucose. In two-stage culture carried out in a 3-l bioreactor, the overall yield and concentration of succinic acid reached
to 1.67 mol mol−1 glucose and 99.7 g l−1, respectively, with a productivity of 1.7 g l−1 h−1 in the anaerobic stage. The efficient utilization of lactose as inducer made recombinant E. coli a more capable strain for succinic acid production at large scale. 相似文献
17.
A putative N-acyl-d-glucosamine 2-epimerase from Caldicellulosiruptor saccharolyticus was cloned and expressed in Escherichia coli. The recombinant enzyme was identified as a cellobiose 2-epimerase by the analysis of the activity for substrates, acid-hydrolyzed
products, and amino acid sequence. The cellobiose 2-epimerase was purified with a specific activity of 35 nmol min–1 mg–1 for d-glucose with a 47-kDa monomer. The epimerization activity for d-glucose was maximal at pH 7.5 and 75°C. The half-lives of the enzyme at 60°C, 65°C, 70°C, 75°C, and 80°C were 142, 71, 35,
18, and 4.6 h, respectively. The enzyme catalyzed the epimerization reactions of the aldoses harboring hydroxyl groups oriented
in the right-hand configuration at the C2 position and the left-hand configuration at the C3 position, such as d-glucose, d-xylose, l-altrose, l-idose, and l-arabinose, to their C2 epimers, such as d-mannose, d-lyxose, l-allose, l-gulose, and l-ribose, respectively. The enzyme catalyzed also the isomerization reactions. The enzyme exhibited the highest activity for
mannose among monosaccharides. Thus, mannose at 75 g l–1 and fructose at 47.5 g l–1 were produced from 500 g l–1 glucose at pH 7.5 and 75°C over 3 h by the enzyme. 相似文献
18.
Miho Sasaki Toru Jojima Masayuki Inui Hideaki Yukawa 《Applied microbiology and biotechnology》2010,86(4):1057-1066
Wild-type Corynebacterium glutamicum produced 0.6 g l−1 xylitol from xylose at a productivity of 0.01 g l−1 h−1 under oxygen deprivation. To increase this productivity, the pentose transporter gene (araE) from C. glutamicum ATCC31831 was integrated into the C. glutamicum R chromosome. Consequent disruption of its lactate dehydrogenase gene (ldhA), and expression of single-site mutant xylose reductase from Candida tenuis (CtXR (K274R)) resulted in recombinant C. glutamicum strain CtXR4 that produced 26.5 g l−1 xylitol at 3.1 g l−1 h−1. To eliminate possible formation of toxic intracellular xylitol phosphate, genes encoding xylulokinase (XylB) and phosphoenolpyruvate-dependent
fructose phosphotransferase (PTSfru) were disrupted to yield strain CtXR7. The productivity of strain CtXR7 increased 1.6-fold over that of strain CtXR4. A fed-batch
21-h CtXR7 culture in mineral salts medium under oxygen deprivation yielded 166 g l−1 xylitol at 7.9 g l−1 h−1, representing the highest bacterial xylitol productivity reported to date. 相似文献
19.
Soo-Jin Yeom Nam-Hee Kim Ran-Young Yoon Hyun-Jung Kwon Chang-Su Park Deok-Kun Oh 《Biotechnology letters》2009,31(8):1273-1278
A recombinant mannose-6-phosphate isomerase from Geobacillus thermodenitrificans (GTMpi) isomerizes aldose substrates possessing hydroxyl groups oriented in the same direction at the C2 and C3 positions
such as the d- and l-forms of ribose, lyxose, talose, mannose, and allose. The activity of GTMpi for d-lyxose isomerization was optimal at pH 7.0, 70°C and 1 mM Co2+. Under these conditions, the k
cat and K
m values were 74,300 s−1 and 390 mM for d-lyxose and 28,800 s−1 and 470 mM for l-ribose, respectively. The half-lives of the enzyme at 60, 65, and 70°C were 388, 73, and 27 h, respectively. GTMpi catalyzed
the conversion of d-lyxose to d-xylulose with a 38% conversion yield after 3 h, and converted l-ribose to l-ribulose with a 29% conversion yield. 相似文献
20.
Yang Guo Qiaojuan Yan Zhengqiang Jiang Chao Teng Xinlei Wang 《Journal of industrial microbiology & biotechnology》2010,37(11):1137-1143
The aim of this study is to investigate production of l-lactic acid from sucrose and corncob hydrolysate by the newly isolated R. oryzae GY18. R. oryzae GY18 was capable of utilizing sucrose as a sole source, producing 97.5 g l−1
l-lactic acid from 120 g l−1 sucrose. In addition, the strain was also efficiently able to utilize glucose and/or xylose to produce high yields of l-lactic acid. It was capable of producing up to 115 and 54.2 g l−1 lactic acid with yields of up to 0.81 g g−1 glucose and 0.90 g g−1 xylose, respectively. Corncob hydrolysates obtained by dilute acid hydrolysis and enzymatic hydrolysis of the cellulose-enriched
residue were used for lactic acid production by R. oryzae GY18. A yield of 355 g lactic acid per kg corncobs was obtained after 72 h incubation. Therefore, sucrose and corncobs could
serve as potential sources of raw materials for efficient production of lactic acid by R. oryzae GY18. 相似文献