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1.
Yi-Xin Guan Hai-Xue Pan Yong-Gui Gao Shan-Jing Yao Man-Gi Cho 《Biotechnology and Bioprocess Engineering》2005,10(2):122-127
A size exclusion chromatography (SEC) process, in the presence of denaturant in the refolding buffer was developed to refold
recombinant human interferon-γ (rhIFN-γ) at a high concentration. The rhIFN-γ was overexpressed inE. coli, resulting in the formation of inactive inclusion bodies (IBs). The IBs were first solubilized in 8 M urea as the denaturant,
and then the refolding process performed by decreasing the urea concentration on the SEC column to suppress protein aggregation.
The effects of the urea concentration, protein loading mode and column height during the refolding step were investigated.
The combination of the bufferexchange effect of SEC and a moderate urea concentration in the refolding buffer resulted in
an efficient route for producing correctly folded rhIFN-γ, with protein recovery of 67.1% and specific activity up to 1.2×107 IU/mg. 相似文献
2.
S. V. Zubova D. S. Kabanov A. Yu. Ivanov E. V. Voloshina I. I. Proskuryakov I. B. Klenina I. R. Prokhorenko 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2011,5(2):135-142
Undifferentiated THP-1 cells from Cell Culture Collection of the Institute of Cytology, RAS (St. Petersburg), are characterized
by weak expression of Toll-like receptor-4 (TLR4) on the cell surface (up to 2%) and by almost undetectable expression of
CD14 and CD11b receptors. Differentiation agent phorbol-12-myristate-13-acetate independently of its concentration (2 × 10−7 M or 10−8 M) and incubation time (24 or 48 h) did not initiate CD11b surface expression and did not change the parameter Sapp (0.605 ± 0.005 at 37°C) reflecting the cell membrane viscosity. Differentiation of THP-1 cells induced by another differentiation
agent, 1α,25-dihydroxyvitamin D3, caused expression of CD14 (up to 70–80%) and CD11b (up to 15–20%) receptors, again without changes in plasma membrane viscosity.
The rate constants of the reduction of 5- and 16-doxyl-stearic acids by THP-1 cells were in the range of 6–8 × 10−3 s−1 at 37°C. During cell differentiation significant changes in cell electrophoretic mobility (EM, μm s−1 V−1 cm) were observed. Mean value of EM for undifferentiated THP-1 cells was −1.332 ± 0.011, whereas for phorbol-12-myristate-13-acetate-
and 1α,25-dihydroxyvitamin D3-treated cells it was −1.432 ± 0.030 and −1.212 ± 0.016, respectively. 相似文献
3.
The bioelectrochemistry of the blue copper protein, pseudoazurin, at glassy carbon and platinum electrodes that were modified
with single-wall carbon nanotubes (SWNTs) was investigated by multiple scan rate cyclic voltammetry. The protein showed reversible
electrochemical behavior at both bare glassy carbon electrodes (GCEs) and SWNT-modified GCEs (SWNT|GCEs); however, direct
electrochemistry was not observed at any of the platinum electrodes. The effect of the carbon nanotubes at the GCE was to
amplify the current response 1000-fold (nA at bare GCE to μA at SWNT|GCE), increase the apparent diffusion coefficient D
app of the solution-borne protein by three orders of magnitude, from 1.35 × 10−11 at bare GCE to 7.06 × 10−8 cm2 s-1 at SWNT|GCE, and increase the heterogeneous electron transfer rate constant k
s threefold, from 1.7 × 10−2 cm s−1 at bare GCE to 5.3 × 10−2 cm s−1 at SWNT|GCE. Pseudoazurin was also found to spontaneously adsorb onto the nanotube-modified GCE surface. Well-resolved voltammograms
indicating quasi-reversible faradaic responses were obtained for the adsorbed protein in phosphate buffer, with I
pc
and I
pa
values now greater than corresponding values for solution-borne pseudoazurin at SWNT|GCEs and with significantly reduced
ΔE
p
values. The largest electron transfer rate constant of 1.7 × 10−1 cm s−1 was achieved with adsorbed pseudoazurin at the SWNT|GCE surface in deaerated buffer solution consistent with its presumed
role in anaerobic respiration of some bacteria. 相似文献
4.
Kyoung Song In-Soo Yoon Nam Ah Kim Dong-Hwan Kim Jongmin Lee Hee Jung Lee Saehyung Lee Sunghyun Choi Min-Koo Choi Ha Hyung Kim Seong Hoon Jeong Woo Sung Son Dae-Duk Kim Young Kee Shin 《PloS one》2014,9(5)
The purpose of this study was to develop a biobetter version of recombinant human interferon-β 1a (rhIFN-β 1a) to improve its biophysical properties, such as aggregation, production and stability, and pharmacokinetic properties without jeopardizing its activity. To achieve this, we introduced additional glycosylation into rhIFN-β 1a via site-directed mutagenesis. Glycoengineering of rhIFN-β 1a resulted in a new molecular entity, termed R27T, which was defined as a rhIFN-β mutein with two N-glycosylation sites at 80th (original site) and at an additional 25th amino acid due to a mutation of Thr for Arg at position 27th of rhIFN-β 1a. Glycoengineering had no effect on rhIFN-β ligand-receptor binding, as no loss of specific activity was observed. R27T showed improved stability and had a reduced propensity for aggregation and an increased half-life. Therefore, hyperglycosylated rhIFN-β could be a biobetter version of rhIFN-β 1a with a potential for use as a drug against multiple sclerosis. 相似文献
5.
P. C. Tiburcio F. C. F. Galvez L. J. Cruz V. C. Gavino 《Journal of applied phycology》2007,19(6):727-731
Gamma linolenic acid (GLA) degradation in Spirulina followed first-order reaction kinetics. At an accelerated temperature range of 45 to 55°C, the degradation rate constants
(k
r) of GLA obtained were 4.0 × 10−2 to 8.8 × 10−2 day−1. The energy of activation (E
a) was 16.53 kcal mol−1, and the Q10 was 2.22. Based on 20% GLA degradation, the shelf life of sun-dried Spirulina at 30°C is 263 days or 8.6 months using the Arrhenius plot, and 258 days or 8.5 months using the Q
10 approach.
Presented at the 6th Meeting of the Asia Pacific Society of Applied Phycology, Manila, Philippines. 相似文献
6.
Culture of human hepatocytes from small surgical liver biopsies. Biochemical characterization and comparison with in vivo 总被引:4,自引:0,他引:4
M. José Gómez-Lechón Pilar López Teresa Donato Angel Montoya Amparo Larrauri Patricia Giménez Ramón Trullenque Ricardo Fabra José V. Castell 《In vitro cellular & developmental biology. Plant》1990,26(1):67-74
Summary High yields of human hepatocytes (up to 23×106 viable cells/g) were obtained from small surgical liver biopsies (1 to 3 g) by a two-step collagenase microperfusion method.
Cell viability was about 95%, attachment efficiency of hepatocytes seeded on fibronectin-coated plates was 80% within 1 h
after plating, and cells survived for about 2 wk in serum-free Ham’s F12 containing 0.2% bovine serum albumin, 10−8
M insulin, and 10−8
M dexamethasone. To evaluate the metabolism of human hepatocytes in serum-free conditions, we measured their most characteristic
biochemical functions and compared them to those reported for human liver. After 24 h in culture, glycogen content was 1250±177
nmol glucose/mg cell protein and remained stable for several days. Gluconeogenesis from lactate in hormone-free media was
(3.50±0.17 nmol glucose·mg−1·min−1) similar to that reported for human liver. Insulin at 10−8
M activated glycolysis (×1.40) and glycogenesis (×1.34), and glucagon at 10−9
M stimulated gluconeogenesis (×1.35) and glycogenolysis (×2.18). Human hepatocytes synthesized albumin, transferrin, fibrinogen,
α1-antitrypsin, α1-antichymotrypsin, α1-acid glycoprotein, haptoglobin, α2-macroglobulin, and plasma fibronectin and excreted them to the culture medium. Maximum protein synthesis was stimulated by
10−9
M dexamethasone. Basal urea synthesis oscillated between 2.5 and 3.5 nmol·mg−1 cell protein·min−1, about 5 times the value estimated for human liver. Cytochrome P-450 decreased in culture but it was still 20% of freshly
isolated hepatocytes by Day 5 in culture. In addition, ethoxycumarin-O-deethylase and aryl hydrocarbon hydroxylase could be
induced in vitro by treatment with methyl cholanthrene. Glutathione levels were similar to those reported for human liver
(35 nmol·mg−1).
The results of our work show that adult human hepatocytes obtained from small surgical biopsies and cultured in chemically
defined conditions express their most important metabolic functions to an extent that is similar to that reported for adult
human liver. 相似文献
7.
Moro D Bradshaw SD 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(8):538-548
A laboratory study investigated the metabolic physiology, and response to variable periods of water and sodium supply, of
two arid-zone rodents, the house mouse (Mus domesticus) and the Lakeland Downs short-tailed mouse (Leggadina lakedownensis) under controlled conditions. Fractional water fluxes for M. domesticus (24 ± 0.8%) were significantly higher than those of L. lakedownensis (17 ± 0.7%) when provided with food ad libitum. In addition, the amount of water produced by M. domesticus and by L. lakedownensis from metabolic processes (1.3 ± 0.4 ml · day−1 and 1.2 ± 0.4 ml · day−1, respectively) was insufficient to provide them with their minimum water requirement (1.4 ± 0.2 ml · day−1 and 2.0 ± 0.3 ml · day−1, respectively). For both species of rodent, evaporative water loss was lowest at 25 °C, but remained significantly higher
in M. domesticus (1.1 ± 0.1 mg H2O · g−0.122 · h−1) than in L. lakedownensis (0.6 ± 0.1 mg H2O · g−0.122 · h−1). When deprived of drinking water, mice of both species initially lost body mass, but regained it within 18 days following
an increase in the amount of seed consumed. Both species were capable of drinking water of variable saline concentrations
up to 1 mol · l−1, and compensated for the increased sodium in the water by excreting more urine to remove the sodium. Basal metabolic rate
was significantly higher in M. domesticus (3.3 ± 0.2 mg O2 · g−0.75 · h−1) than in L. lakedownensis (2.5 ± 0.1 mg O2 · g−0.75 · h−1). The study provides good evidence that water flux differences between M. domesticus and L. lakedownensis in the field are due to a requirement for more water in M. domesticus to meet their physiological and metabolic demands. Sodium fluxes were lower than those observed in free-ranging mice, whose
relatively high sodium fluxes may reflect sodium associated with available food.
Accepted: 16 August 1999 相似文献
8.
Nitrogen and Phosphorous Excretion Rates by Tubificids from the Prahova River (Romania) 总被引:2,自引:0,他引:2
Nitrogen and phosphorous exchange at the water–sediment interface is controlled both by complex physico-chemical factors and
biological processes. Zoobenthos excretion is one of the most important processes in the mineralization of sedimented organic
mater. In polluted freshwaters, tubificid worms are among the dominant components of the benthic community. Rates of ammonium
and inorganic phosphate excretion by tubificids were experimentally assessed. They were related to the tubificid abundance
in a stream ecosystem polluted with municipal and industrial wastewater. The relationship between these rates and temperature
were investigated within the range of 4–23 °C. Relatively constant excretion rates were obtained for both nutrients in the
first 8 h of excretion, ranging between 0.076 and 0.226 μg N mg d.w.−1 h−1 and 0.0065–0.01 μg P mg d.w.−1 h−1, respectively. Q10 values of 2.52 for ammonium and 1.31 for phosphate were calculated. If we presume that all excreta eventually enters the
water column, then we can calculate that these invertebrates potentially add 39.17 mg N m−2 day−1 and 0.49 mg P m−2 day−1. These values accounts for 17.16 and 7.56% of the nutrient load in the river water, respectively. 相似文献
9.
Tatiana G. Sazykina A. I. Kryshev K. D. Sanina 《Radiation and environmental biophysics》2009,48(4):391-404
Databases on effects of chronic low-LET radiation exposure were analyzed by non-parametric statistical methods, to estimate
the threshold dose rates above which radiation effects can be expected in vertebrate organisms. Data were grouped under three
umbrella endpoints: effects on morbidity, reproduction, and life shortening. The data sets were compiled on a simple ‘yes’
or ‘no’ basis. Each data set included dose rates at which effects were reported without further details about the size or
peculiarity of the effects. In total, the data sets include 84 values for endpoint “morbidity”, 77 values for reproduction,
and 41 values for life shortening. The dose rates in each set were ranked from low to higher values. The threshold TDR5 for
radiation effects of a given umbrella type was estimated as a dose rate below which only a small percentage (5%) of data reported
statistically significant radiation effects. The statistical treatment of the data sets was performed using non-parametric
order statistics, and the bootstrap method. The resulting thresholds estimated by the order statistics are for morbidity effects
8.1 × 10−4 Gy day−1 (2.0 × 10−4–1.0 × 10−3), reproduction effects 6.0 × 10−4 Gy day−1 (4.0 × 10−4–1.5 × 10−3), and life shortening 3.0 × 10−3 Gy day−1 (1.0 × 10−3–6.0 × 10−3), respectively. The bootstrap method gave slightly lower values: 2.1 × 10−4 Gy day−1 (1.4 × 10−4–3.2 × 10−4) (morbidity), 4.1 × 10−4 Gy day−1 (3.0 × 10−4–5.7 × 10−4) (reproduction), and 1.1 × 10−3 Gy day−1 (7.9 × 10−4–1.3 × 10−3) (life shortening), respectively. The generic threshold dose rate (based on all umbrella types of effects) was estimated
at 1.0 × 10−3 Gy day−1. 相似文献
10.
Litter Decomposition and Nutrient Dynamics in a Phosphorus Enriched Everglades Marsh 总被引:3,自引:0,他引:3
A field study was conducted in a nutrient-impacted marsh in Water Conservation Area 2A (WCA-2A) of the Everglades in southern
Florida, USA, to evaluate early stages of plant litter (detritus) decomposition along a well-documented trophic gradient,
and to determine the relative importance of environmental factors and substrate composition in governing decomposition rate.
Vertically stratified decomposition chambers containing native plant litter (cattail and sawgrass leaves) were placed in the
soil and water column along a 10-km transect coinciding with a gradient of soil phosphorus (P) enrichment. Decomposition rate
varied significantly along the vertical water–soil profile, with rates typically higher in the water column and litter layer
than below the soil surface, presumably in response to vertical gradients of such environmental factors as O2 and nutrient availability. An overall decrease in decomposition rate occurred along the soil P gradient (from high- to low-impact).
First-order rate constant (k) values for decomposition ranged from 1.0 to 9.2 × 10−3 day−1 (mean = 2.8 ×10−3 day−1) for cattails, and from 6.7 × 10−4 to 3.0 × 10−3 day−1 (mean = 1.7 × 10−3 day−1) for sawgrass. Substantial N and P immobilization occurred within the litter layer, being most pronounced at nutrient-impacted
sites. Nutrient content of the decomposing plant tissue was more strongly correlated to decomposition rate than was the nutrient
content of the surrounding soil and water. Our experimental results suggest that, although decomposition rate was significantly
affected by initial substrate composition, the external supply or availability of nutrients probably played a greater role
in controlling decomposition rate. It was also evident that nutrient availability for litter decomposition was not accurately
reflected by ambient nutrient concentration, e.g., water and soil porewater nutrient concentration. 相似文献
11.
The optical activity induced on binding the drug netrospin (NET) in the minor groove of DNA is studied in five oligonucleotides
(OGNs) as a function of (1) the size of the binding site in (5′-(GC)2AATT(GC)2-3′)2 (OGN 1a) versus (5′-(GC)2AAATTT(GC)2-3′)2 (OGN 1b) and (2) the distance between two AATT binding sites in (5′-(GC)2AATT(GC)
x
AATT(GC)2-3′)2, with x = 1, 2, or 3 (OGNs 2a, b, c, respectively). NET binding is monitored via the induced circular dichroism (CD) at ~315 nm,
where the nucleic acids are optically inactive. The CD titrations, fit to a tight binding model, yield lower limits for the
binding constant, Ka, ≥8 × 107 M−1 for OGN 1a and ≥2 × 108 M−1 for OGNs 2a, b, c in 1 mM buffer. In 100 mM buffer, tight binding occurs in all five OGNs with Ka ≥ 8 × 107 M−1 for OGN 1a and ≥1 × 108 M−1 for OGNs 1b and 2a, b, c. In contrast, the elongated AAATTT binding site of OGN 1b results in weak binding of NET in 1 mM
buffer, where competing electrostatic interactions with the solvent environment are lower. In the constructs with two binding
sites, the increase in flexibility introduced by intervening GC base pairs does not induce co-operative binding, although
differences in the number of binding sites, n (2.05–2.65), indicate that there may be differences in the way NET is bound in OGNs 2a, b, c. In addition, the large shifts
in the absorption spectra induced in bound versus free NET, and effects on the CD spectral bands at higher energy, are discussed
in terms of electrostatic and excitonic interactions. 相似文献
12.
The harmful effects of surfactants to the environment are well known. We were interested in investigating their potential
toxicity in a pure culture of Acinetobacter junii, a phosphate (P)-accumulating bacterium. Results showed a high acute toxicity of sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium
bromide (HDTMA) against A. junii. The estimated EC50 values of the HDTMA for the inhibition of CFUs in the pure culture of A. junii was 3.27 ± 1.12 × 10−7 mol L−1 and for the inhibition of the P-uptake rates 2.47 ± 0.51 × 10−6 mol L−1. For SDS, estimated EC50 values for the inhibition of CFUs in the pure culture of A. junii was 5.00 ± 2.95 × 10−6 mol L−1 and for the inhibition of the P-uptake rates 3.33 ± 0.96 × 10−4 mol L−1. The obtained EC50 values in the standardised yeast toxicity test using Saccharomyces cerevisiae were 3.03 ± 0.38 × 10−4 and 4.33 ± 0.32 × 10−5 mol L−1 for SDS and HDTMA, respectively. These results emphasized the need to control concentrations of surfactants entering the
activated sludge system. The negative effects of these toxicants could greatly decrease populations of P-accumulating bacteria,
as well as eukaryotic organisms, inhabiting activated sludge systems, which in turn could result in the decrease of the system
efficiency. 相似文献
13.
M. R. de la Peña 《Journal of applied phycology》2007,19(6):647-655
Two series of experiments were conducted to determine suitable growth factors for the mass propagation of the local algal
isolate Amphora sp. A higher growth rate of 0.2 doubling (μ) day−1 was attained at a lower photosynthetic photon flux density (PPFD; 11.4 μmol photon m−2s−1) compared to cultures exposed to higher levels of PPFD (16.1 μmol photon m−2s−1, −0.1 μ day −1; 31.3 μmol photon m−2s−1, 0.0 μ day−1). Cultures located inside the laboratory had a significantly higher cell density (133 × 104 cells cm−2) and growth rate (0.3 μ day−1) compared to those located outdoors (100 × 104 cells cm−2, 0.2 μ day−1). A comparison of nutrient medium across two locations showed that lipid content was significantly higher in cultures enriched
with F/2MTM (macronutrients + trace metals) and F/2MV (macronutrients + vitamins). Saturated fatty acids were also present
in high concentrations in cultures enriched with F/2M (macronutrients only). Significantly higher amounts of saturated fatty
acids were observed in cultures located outdoors (33.1%) compared to those located indoors (26.6%). The protein, carbohydrates
and n-6 fatty acid content of Amphora sp. were influenced by the location and enrichment of the cultures. This study has identified growth conditions for mass
culture of Amphora sp. and determined biochemical composition under those culture conditions.
Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines. 相似文献
14.
Jasna Hrenovic Tomislav Ivankovic Lavoslav Sekovanic Mirela Rozic 《Central European Journal of Biology》2008,3(2):143-148
The antibacterial effect of cationic surfactants against the pure culture of phosphate (P)-accumulating bacterium Acinetobacter junii was investigated. The estimated EC50 values of the N-dodecylpyridinium chloride (DPC) for growth inhibition was 1.4±0.5 × 10−6 mol L−1 and for the inhibition of the P-uptake rates 7.3±2.6 × 10−5 mol L−1. The estimated EC50 values of the N-cetylpyridinium chloride (CPC) for growth inhibition was 4.9±1.3 × 10−7 mol L−1 and for the inhibition of the P-uptake rates 7.7±2.9 × 10−6 mol L−1. This suggests the importance of controlling the amounts of cationic surfactants in influent of the wastewater treatment
systems in order to avoid the possible failure of the biological P removal from wastewaters. 相似文献
15.
Chul Soo Shin Min Seon Hong Hang-Cheol Shin Jeewon Lee 《Biotechnology and Bioprocess Engineering》2001,6(4):301-305
The co-expression of theargU gene in a double-vector expression system of recombinantEscherichia coli BL21(DE3)[pET-IFN2a+pAC-argU] significantly enhanced the production level of recombinant human interferon-α2a (rhIFN-α2a)
in high cell density cultures compared to a recombinantE coli culture containing only the single expression vector, pET-IFN2a. The dry cell mass concentration increased to almost 100
g/L, and more than 4 g/L of rhIFN-α2a was accumulated in the culture broth. Evidently, the synthesis of rhIFN-α2a was strongly
dependent on the pre-induction growth rate and more efficient at a higher specific growth rate. The additional supply of tRNAArg(AGG/AGA) enhanced the expression level of the rhIFN-α2a gene in the early stage of the post-induction phase, yet thereafter the specific
production rate of rhIFN-α2a rapidly decreased due to severe segregational instability of plasmid vector pET-IFN2a. It would
appear that the plasmid instability, which only occurred to pET-IFN2a in the double vector system, was related to the effect
of translational stress due to the overexpression of rhIFN-α2a. 相似文献
16.
M. C. V. Egas M. S. da Costa Don A. Cowan Euclides M. V. Pires 《Extremophiles : life under extreme conditions》1998,2(1):23-32
An extracellular α-amylase produced by the thermophilic bacterium Thermus filiformis Ork A2 was purified from cell-free culture supernatant by ion exchange chromatography. The molecular mass was estimated to
be 60 000 Da by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme was rich in both basic and hydrophobic
amino acids, presenting the following NH2-terminal amino acid sequence: Thr-Ala-Asp-Leu-Ile-Val-Lys-Ile-Asn-Phe. Amylolytic activity on soluble starch was optimal
at pH 5.5–6.0 and 95°C, and the enzyme was stable in the pH range of 4.0–8.0. Calcium enhanced thermostability at temperatures
above 80°C, increasing the half-life of activity to more than 8 h at 85°C, 80 min at 90°C, and 19 min at 95°C. Ethylenediaminetetraacetic
acid (EDTA) inhibited amylase activity, the inhibition being reversed by the addition of calcium or strontium ions. The α-amylase
was also inhibited by copper and mercuric ions, and p-chloromercuribenzoic acid, the latter being reversed in the presence of dithiothreitol. Dithiothreitol and β-mercaptoethanol
activated the enzyme. The α-amylase exhibited Michaelis-Menten kinetics for starch, with a K
m of 5.0 mg·ml−1 and k
cat/K
m of 5.2 × 105 ml·mg−1 s−1. Similar values were obtained for amylose, amylopectin, and glycogen. The hydrolysis pattern was similar for maltooligosaccharides
and polysaccharides, with maltose being the major hydrolysis product. Glucose and maltotriose were generated as secondary
products, although glucose was produced in high levels after a 6-h digestion. To our knowledge this is the first report of
the characterization of an α-amylase from a strain of the genus Thermus.
Received: June 2, 1997 / Accepted: September 16, 1997 相似文献
17.
The deposition and cycling of carbon and nitrogen in carbonate sediments located between coral reefs on the northern and central
sections of the Great Barrier Reef were examined. Rates of mass sediment accumulation ranged from 1.9 kg m−2 year−1 (inshore reefs) to 2.1–4.9 kg m−2 year−1 (between mid-shelf reefs); sedimentation was minimal off outer-shelf reefs. Rates of total organic carbon decomposition ranged
from 1.7 to 11.4 mol C m−2 year−1 and total nitrogen mineralization ranged from 77 to 438 mmol N m−2 year−1, declining significantly with distance from land. Sediment organic matter was highly reactive, with mineralization efficiencies
ranging from 81 to 99% for organic carbon and 64–100% for nitrogen, with little C and N burial. There was no evidence of carbonate
dissolution/precipitation in short-term incubation experiments. Rates of sulfate reduction (range 0–3.4 mmol S m−2 day−1) and methane release (range 0–12.8 μmol CH4 m−2 day−1) were minor or modest pathways of carbon decomposition. Aerobic respiration, estimated by difference between total O2 consumption and the sum of the other pathways, accounted for 55–98% of total carbon mineralization. Rates of ammonification
ranged from 150 to 1,725 μmol NH4 m−2 day−1, sufficient to support high rates of denitrification (range 30–2,235 μmol N2 m−2 day−1). N2O release was not detected and rates of NH4
+ and NO2
− + NO3
− efflux were low, indicating that most mineralized N was denitrified. The percentage of total N input removed via denitrification
averaged ≈75% (range 28–100%) with little regenerated N available for primary producers. Inter-reef environments are therefore
significant sites of energy and nutrient flow, especially in spatially complex reef matrices such as the Great Barrier Reef. 相似文献
18.
G. Selvakumar S. Kundu Piyush Joshi Sehar Nazim A. D. Gupta P. K. Mishra H. S. Gupta 《World journal of microbiology & biotechnology》2008,24(7):955-960
Pantoea dispersa strain 1A is a Gram-negative rod-shaped, yellow-pigmented bacterium isolated on nutrient agar plates incubated at 4°C. The
identity of the bacterium was confirmed by sequencing of the 16 S rRNA gene. It was capable of growing at temperatures ranging
from 4 to 42°C, but maximum growth was observed at 30°C. It is endowed with multiple plant growth promotion attributes such
as phosphate solubilization, IAA production, siderophore production and HCN production, which are expressed differentially
at sub-optimal temperatures (15 and 4°C). It was able to solubilize phosphate (17.6 μg of P2O5 ml−1 day−1), and produce IAA (3.7 μg ml−1 day−1), at 15°C. Qualitative detection of siderophore production and HCN were also observed at 15°C. At 4°C it was found to express
all the plant growth promotion attributes. This bacterial isolate was able to positively influence and promote the growth
and nutrient uptake parameters of wheat (cv. VL.802) under glasshouse conditions. Hence in the context, of cold wheat-growing
environments, it is proposed that Pantoea dispersa 1A (MTCC 8706), could be deployed as an inoculant to attain the desired results of bacterization. 相似文献
19.
Kakeshita H Kageyama Y Ara K Ozaki K Nakamura K 《Applied microbiology and biotechnology》2011,89(5):1509-1517
The Gram-positive bacterium, Bacillus subtilis and related species are widely used industrially as hosts for producing enzymes. These species possess a high potential to
produce secreted proteins into the culture medium. Nevertheless, the secretion of heterologous proteins by these species is
frequently inefficient. In this study, the human interferon-α2b (hIFN-α2b) was used as a heterologous model protein, to investigate
the effect of B. subtilis AmyE propeptide in enhancing the secretion of heterologous proteins in B. subtilis. We found that the secretion production and activity of hIFN-α2b with AmyE propeptide increased by more than threefold, compared
to that without AmyE propeptide. The maximum amount of secreted hIFN-α2b with propeptide was 14.8 ± 0.6 μg ml−1. In addition, the pro-hIFN-α2b bioactivity reached 5.4 ± 0.5 × 107 U mg−1, which is roughly the same level as that of the non-propeptide hIFN-α2b. These results indicated that AmyE propeptide enhanced
the secretion of the hIFN-α2b protein from B. subtilis. This study provides a useful method to enhance the extracellular production of heterologous proteins in B. subtilis. 相似文献
20.
Han Gil Choi Ki Hoon Lee Hyun Il Yoo Pil Jun Kang Young Sik Kim Ki Wan Nam 《Journal of applied phycology》2008,20(5):729-735
The effects of temperature, irradiance, and daylength on Sargassum horneri growth were examined at the germling and adult stages to discern their physiological differences. Temperature–irradiance
(10, 15, 20, 25, 30°C × 20, 40, 80 μmol photons m−2s−1) and daylength (8, 12, 16, 24 h) experiments were carried out. The germlings and blades of S. horneri grew over a wide range of temperatures (10–25°C), irradiances (20–80 μmol photons m−2s−1), and daylengths (8–24 h). At the optimal growth conditions, the relative growth rates (RGR) of the germlings were 21% day−1 (25°C, 20 μmol photons m−2s−1) and 13% day−1 (8 h daylength). In contrast, the RGRs of the blade weights were 4% day−1 (15°C, 20 μmol photons m−2s−1) and 5% day−1 (12 h daylength). Negative growth rates were found at 20 μmol photons m−2s−1 of 20°C and 25°C treatments after 12 days. This phenomenon coincides with the necrosis of S. horneri blades in field populations. In conclusion, we found physiological differences between S. horneri germlings and adults with respect to daylength and temperature optima. The growth of S. horneri germlings could be enhanced at 25°C, 20 μmol photons m−2s−1, and 8 h daylength for construction of Sargassum beds and restoration of barren areas. 相似文献