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1.
The regulatory function of global regulator NtrC on curdlan biosynthesis and nitrogen consumption under nitrogen-limited condition
in Agrobacterium sp. ATCC 31749 was investigated. The ntrC mutant of Agrobacterium sp. was constructed by homologous recombination. The ability to utilize NH4Cl and KNO3 was impaired in the mutant. Other nitrogenous compounds, such as glutamic acid and glutamine, were utilized normally. Curdlan
production capability was impaired severely in the mutant. Curdlan production was 5-fold lower than the wild type strain in
batch fermentation with NH4Cl as the sole nitrogen source. However, up to 6.5 g l−1 of a newly found alkali-insoluble biopolymer was produced by the ntrC mutant when glutamic acid was used as nitrogen source. The new biopolymer had glycosidic bond and hydroxyl group but no β-configuration
absorption peak on IR spectrum was found as different from curdlan. In addition, the mutant exhibited a rapid morphological
change from the dot to rod form. These results deduced that the global regulator NtrC was involved in curdlan and other biopolymer
biosynthesis in Agrobacterium sp. ATCC 31749 in response to nitrogen-limited condition. 相似文献
2.
L. J. Yu J. R. Wu Z. Z. Zheng C. C. Lin X. B. Zhan 《Applied Biochemistry and Microbiology》2011,47(5):487-493
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Hongtao Zhang Joao Carlos Setubal Xiaobei Zhan Zhiyong Zheng Lijun Yu Jianrong Wu Dingqiang Chen 《Journal of industrial microbiology & biotechnology》2011,38(6):667-677
Agrobacterium sp. ATCC 31749 (formerly named Alcaligenes faecalis var. myxogenes) is a non-pathogenic aerobic soil bacterium used in large scale biotechnological production of curdlan. However, little is
known about its genomic information. DNA partial sequence of electron transport chains (ETCs) protein genes were obtained
in order to understand the components of ETC and genomic-specificity in Agrobacterium sp. ATCC 31749. Degenerate primers were designed according to ETC conserved sequences in other reported species. DNA partial
sequences of ETC genes in Agrobacterium sp. ATCC 31749 were cloned by the PCR method using degenerate primers. Based on comparative genomic analysis, nine electron
transport elements were ascertained, including NADH ubiquinone oxidoreductase, succinate dehydrogenase complex II, complex
III, cytochrome c, ubiquinone biosynthesis protein ubiB, cytochrome d terminal oxidase, cytochrome bo terminal oxidase, cytochrome cbb
3-type terminal oxidase and cytochrome caa
3-type terminal oxidase. Similarity and phylogenetic analyses of these genes revealed that among fully sequenced Agrobacterium species, Agrobacterium sp. ATCC 31749 is closest to Agrobacterium tumefaciens C58. Based on these results a comprehensive ETC model for Agrobacterium sp. ATCC 31749 is proposed. 相似文献
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Thomas P. West 《Preparative biochemistry & biotechnology》2016,46(1):85-90
The effect of nitrogen source concentration on the production of the polysaccharide curdlan by the bacterium Agrobacterium sp. ATCC 31749 from hydrolysates of prairie cordgrass was examined. The highest curdlan concentrations were produced by ATCC 31749 when grown on a medium containing a solids-only hydrolysate and the nitrogen source ammonium phosphate (2.2 mM) or on a medium containing a complete hydrolysate and 3.3 mM ammonium phosphate. The latter medium sustained a higher level of bacterial curdlan production than the former medium after 144 hr. Biomass production by ATCC 31749 was highest after 144 hr when grown on a medium containing a solids-only hydrolysate and 2.2 or 8.7 mM ammonium phosphate. On the medium containing the complete hydrolysate, biomass production by ATCC 31749 was highest after 144 hr when 3.3 mM ammonium phosphate was present. Bacterial biomass production after 144 hr was greater on the complete hydrolysate medium compared to the solids-only hydrolysate medium. Curdlan yield produced by ATCC 31749 after 144 hr from the complete hydrolysate medium containing 3.3 mM ammonium phosphate was higher than from the solids-only hydrolysate medium containing 2.2 mM ammonium phosphate. 相似文献
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Z. Y. Zheng Y. Jiang X. B. Zhan L. W. Ma J. R. Wu L. M. Zhang C. C. Lin 《Applied Biochemistry and Microbiology》2014,50(1):35-42
Curdlan is produced by Agrobacterium sp. ATCC 31749 under nitrogen-limited conditions not associated with cell growth. A novel curdlan production process was developed based on the different nutrient requirements for microbial cell growth and its efficiency was increased by integrating carbon/nitrogen sources control and sequencing dual fed-batch fermentors operation. By feeding ammonium solution to supply abundant nitrogen source and controlling pH in Fermentor I, cell growth was accelerated. High cell density of 29 g/L was attained. The culture broth in Fermentor I was then inoculated into sequencing Fermentor II which alleviated the high requirement for dissolved oxygen and accumulation of inhibitory metabolic by-products during curdlan production. Fermentor I promoted cell growth. Curdlan production started instantaneously in Fermentor II. By feeding nutrient solution with high carbon/nitrogen ratio and NaOH solution for pH adjustment, a feasible and optimal curdlan production process was formulated. The productivity, conversion efficiency and curdlan yield were achieved of 0.98 g/(L h), 57% (w) and 67 g/L, respectively. Such novel process can be scaled up for significant cost reduction at the industrial level. 相似文献
10.
Dae-Young Jung Young-Su Cho Chung-Han Chung Dai-Il Jung Kwang Kim Jin-Woo Lee 《Biotechnology and Bioprocess Engineering》2001,6(2):107-111
The addition of a limited concentration of yeast extract to a minimal salt medium (MSM) enhanced cell growth and increased
the production of curdlan whereas nitrogenlimitation was found to be essential for the higher production of curdlan byAgrobacterium sp. ATCC 31749. As the amount of the inoculum increased, the cell growth as well as the production of curdlan also increased
in the MSM without a nitrogen source. The cell growth and production of curdlan increased as the initial pH of the medium
decreased as low as 5.0. The conversion rate and concentration of curdlan from 2% (w/v) glucose in the MSM with concentrated
cells under nitrogen deletion was 67% and 13.4 g/L, respectively. The highest conversion rate of curdlan under the conditions
optimized in this study was 71% when the glucose concentration was 1% (w/v). 相似文献
11.
Agrobacterium sp. ATCC 31749 is an industrial strain for the commercial production of curdlan, an important exopolysaccharide with food and medical applications. Here we report the genome sequence of the curdlan-producing strain ATCC 31749. Genome sequencing is the first step toward the understanding of regulation of curdlan biosynthesis. 相似文献
12.
Zhang HT Zhan XB Zheng ZY Wu JR English N Yu XB Lin CC 《Applied microbiology and biotechnology》2012,93(1):367-379
A significant problem in scale-down cultures, rarely studied for metabolic characterization and curdlan-producing Agrobacterium sp. ATCC 31749, is the presence of dissolved oxygen (DO) gradients combined with pH control. Constant DO, between 5% and
75%, was maintained during batch fermentations by manipulating the agitation with PID system. Fermentation, metabolic and
kinetic characterization studies were conducted in a scale-down system. The curdlan yield, intracellular nucleotide levels
and glucose conversion efficiency into curdlan were significantly affected by DO concentrations. The optimum DO concentrations
for curdlan production were 45–60%. The average curdlan yield, curdlan productivity and glucose conversion efficiency into
curdlan were enhanced by 80%, 66% and 32%, respectively, compared to that at 15% DO. No apparent difference in the gel strength
of the resulting curdlan was detected. The comparison of curdlan biosynthesis and cellular nucleotide levels showed that curdlan
production had positive relationship with intracellular levels of UTP, ADP, AMP, NAD+, NADH and UDP-glucose. The curdlan productivity under 45% DO and 60% DO was different during 20–50 h. However, after 60 h
curdlan productivity of both conditions was similar. On that basis, a simple and reproducible two-stage DO control process
for curdlan production was developed. Curdlan production yield reached 42.8 g/l, an increase of 30% compared to that of the
single agitation speed control process. 相似文献
13.
R. Maharaj E. Rumbak W. A. Jones S. M. Robb F. T. Robb D. R. Woods 《Archives of microbiology》1989,152(6):542-549
The nucleotide sequence of a 4 kb fragment containing the Vibrio alginolyticus glnA, ntrB and ntrC genes was determined. The upstream region of the glnA gene contained tandem promoters. The upstream promoter resembled the consensus sequence for Escherichia coli 70 promoters whereas the presumptive downstream promoter showed homology with nitrogen regulated promoters. Four putative NRI binding sites were located between the tandem promoters. The ntrB gene was preceded by a single presumptive NRI binding site. The ntrC gene was located 45 base pairs downstream from the ntrB gene. The V. alginolyticus ntrB and ntrC genes were able to complement ntrB, ntrC deletions in E. coli.Abbreviations bp
base pair(s)
- CAP
catabolite-activating protein
- GS
glutamine synthetase
- kb
kilobase(s)
- ORF
open reading frame
- SD
Shine-Dalgarno 相似文献
14.
Ing-Lung Shih Jin-Yee Yu Chienyan Hsieh Jane-Yii Wu 《Biochemical Engineering Journal》2009,43(1):33-40
Agrobacterium sp. was studied for the production of curdlan by conventional one-factor-at-a-time technique and response surface methodology. Factors such as initial pH, urea concentration, sucrose concentration having the greatest influence on the curdlan production were identified. By using response surface methodology (RSM), the curdlan production by Agrobacterium sp. was increased significantly by 109%, from 2.4 g/L to 5.02 g/L when the strain was cultivated in the optimal medium developed by RSM as compared to conventional one-factor-at-a-time technique. The curdlan production rate of 0.84 g/(L h) was obtained when Agrobacterium sp. was cultivated in the optimal medium developed by RSM, which was the highest curdlan production rate reported to date. The infrared (IR) and NMR spectra, the thermogram of DSC and pattern of X-ray diffraction for the curdlan of the present study were almost identical to those of the authentic curdlan sample (from Alcaligenes faecalis; Sigma). The purified curdlan was a linear polysaccharide composed of exclusively β-(1,3)-glucosidic linkages with the molecular weight of 160,000 Da by GPC. The crystalline melting point (Tm), glass transition temperature (Tg) and X-ray diffraction of the sample indicated low crystallinity in the structure. 相似文献
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Lijun Yu Jianrong Wu Jia Liu Xiaobei Zhan Zhiyong Zheng Chi Chung Lin 《Biotechnology and Bioprocess Engineering》2011,16(1):34-41
A large amount of adenosine triphosphate with high energy phosphate bonds is required for uridine triphosphate regeneration
during curdlan biosynthesis by Agrobacterium sp. ATCC 31749. To supply high energy for curdlan synthesis, three low-polyphosphates (Na4P2O7, Na5P3O10, and (NaPO3)6) with higher energy phosphate bonds were employed to substitute for KH2PO4-K2HPO4 in fermentation medium. Two genes encoding the polyphosphate metabolizing enzymes, polyphosphate kinase and exopolyphosphatase,
were amplified and showed 95% homology to those in Agrobacterium sp. C58 by sequence analysis. The curdlan yields were enhanced by 23 and 134% when phosphate concentrations 0.024 mol/L of
Na5P3O10 and 0.048 mol/L of (NaPO3)6 respectively, were added in the medium. The maximum curdlan yield of 30 ± 1.02 g/L was obtained with the addition of 0.048
mol/L of (NaPO3)6 with 5 g/L CaCO3 in the medium. When CaCO3 was removed from the culture and the three lowpolyphosphates were added, the pH and biomass yield dropped remarkably and
little or no curdlan was produced. The culture containing 0.048 mol/L of (NaPO3)6 was mixed with KH2PO4-K2HPO4 and CaCO3 in the medium, but showed no effect on curdlan production. However, curdlan yield was improved by 49 ∼ 60% when CaCO3 was removed from the medium and KH2PO4-K2HPO4 acted as a buffer. It appears that the positive effect of (NaPO3)6 on curdlan production required the buffering capacity of CaCO3 and the absence of KH2PO4-K2HPO4 competing as a phosphate supplier. 相似文献
16.
Uracil, acting as a precursor of UDP-glucose, served as an activator on the production of curdlan with Agrobacterium sp. (ATCC 31750). The time of adding uracil was important to improve curdlan production. When uracil was added after ammonium depletion (at 26 h), it was used as a nitrogen source for cell growth. Although the cell concentration increased, the curdlan production was decreased. If uracil was added at 46 h, then uracil was degraded slowly but still activated curdlan production. With the addition of both sucrose (200 g) and uracil (1.5 g), the curdlan production was increased up to 93 g l–1 after 160 h fermentation. 相似文献
17.
The ntrB and ntrC Genes Are Involved in the Regulation of Poly-3-Hydroxybutyrate Biosynthesis by Ammonia in Azospirillum brasilense Sp7
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Azospirillum brasilense Sp7 and its ntrA (rpoN), ntrBC, and ntrC mutants have been evaluated for their capabilities of poly-3-hydroxybutyrate (PHB) accumulation in media with high and low ammonia concentrations. It was observed that the ntrBC and ntrC mutants can produce PHB in both low- and high-C/N-ratio media, while no significant PHB production was observed for the wild type or the ntrA mutant in low-C/N-ratio media. Further investigation by fermentation analysis indicated that the ntrBC and ntrC mutants were able to grow and accumulate PHB simultaneously in the presence of a high concentration of ammonia in the medium, while little PHB was produced in the wild type and ntrA (rpoN) mutant during active growth phase. These results provide the first genetic evidence that the ntrB and ntrC genes are involved in the regulation of PHB synthesis by ammonia in A. brasilense Sp7. 相似文献
18.
I-Y Lee W T Seo G J Kim M K Kim C S Park Y H Park 《Journal of industrial microbiology & biotechnology》1997,18(4):255-259
Maltose and sucrose were efficient carbon sources for the production of curdlan by a strain of Agrobacterium sp. A two-step, fed-batch operation was designed in which biomass was first produced, followed by curdlan production which
was stimulated by nitrogen limitation. There exists an optimal timing for nitrogen limitation for curdlan production in the
two-step, fed-batch operation. Maximum curdlan production (60 g L−1) was obtained from sucrose with a productivity of 0.2 g L−1 h−1 when nitrogen was limited at a cell concentration of 16.0 g L−1. It was also noted that the curdlan yield from sucrose was as high as 0.45 g curdlan g−1 sucrose, and the highest specific production rate was 1.0 g curdlan g−1 cells h−1 right after nitrogen limitation. Of particular importance was the use of molasses as a cheap carbon source to produce curdlan
in the two-step, fed-batch cultivation. As high as 42 g L−1 of curdlan with a yield of 0.35 g curdlan g−1 total sugar was obtained after 120 h of fed-batch cultivation.
Received 20 August 1996/ Accepted in revised form 26 November 1996 相似文献
19.
The pH control was important for curdlan production with Agrobacterium sp. ATCC31750. Specific cell growth rate was the highest at pH 7 and the specific curdlan production rate was at pH 5.5. The pH profiles maximizing curdlan production was changed from pH 7 optimal for cell growth to pH 5.5 optimal for curdlan production after ammonium consumption. The feedback inferential control methods, with easily measurable variables such as NaOH addition for pH control and dissolved oxygen (DO), were also applied. The pH was successfully controlled to follow optimal profiles and the maximal production of curdlan (60 g l–1 in 120 h) was achieved with feedback optimal control. 相似文献
20.
Christian Fleige Gunda Hansen Jens Kroll Alexander Steinbüchel 《Applied and environmental microbiology》2013,79(1):81-90
The actinomycete Amycolatopsis sp. strain ATCC 39116 is capable of synthesizing large amounts of vanillin from ferulic acid, which is a natural cell wall component of higher plants. The desired intermediate vanillin is subject to undesired catabolism caused by the metabolic activity of a hitherto unknown vanillin dehydrogenase (VDHATCC 39116). In order to prevent the oxidation of vanillin to vanillic acid and thereby to obtain higher yields and concentrations of vanillin, the responsible vanillin dehydrogenase in Amycolatopsis sp. ATCC 39116 was investigated for the first time by using data from our genome sequence analysis and further bioinformatic approaches. The vdh gene was heterologously expressed in Escherichia coli, and the encoded vanillin dehydrogenase was characterized in detail. VDHATCC 39116 was purified to apparent electrophoretic homogeneity and exhibited NAD+-dependent activity toward vanillin, coniferylaldehyde, cinnamaldehyde, and benzaldehyde. The enzyme showed its highest level of activity toward vanillin at pH 8.0 and at a temperature of 44°C. In a next step, a precise vdh deletion mutant of Amycolatopsis sp. ATCC 39116 was generated. The mutant lost its ability to grow on vanillin and did not show vanillin dehydrogenase activity. A 2.3-times-higher vanillin concentration and a substantially reduced amount of vanillic acid occurred with the Amycolatopsis sp. ATCC 39116 Δvdh::Kmr mutant when ferulic acid was provided for biotransformation in a cultivation experiment on a 2-liter-bioreactor scale. Based on these results and taking further metabolic engineering into account, the Amycolatopsis sp. ATCC 39116 Δvdh::Kmr mutant represents an optimized and industrially applicable platform for the biotechnological production of natural vanillin. 相似文献