共查询到20条相似文献,搜索用时 15 毫秒
1.
Sipma J Osuna MB Parshina SN Lettinga G Stams AJ Lens PN 《Applied microbiology and biotechnology》2007,76(2):339-347
Desulfotomaculum carboxydivorans, recently isolated from a full-scale anaerobic wastewater treatment facility, is a sulfate reducer capable of hydrogenogenic
growth on carbon monoxide (CO). In the presence of sulfate, the hydrogen formed is used for sulfate reduction. The organism
grows rapidly at 200 kPa CO, pH 7.0, and 55°C, with a generation time of 100 min, producing nearly equimolar amounts of H2 and CO2 from CO and H2O. The high specific CO conversion rates, exceeding 0.8 mol CO (g protein)−1 h−1, makes this bacterium an interesting candidate for a biological alternative of the currently employed chemical catalytic
water–gas shift reaction to purify synthesis gas (contains mainly H2, CO, and CO2). Furthermore, as D. carboxydivorans is capable of hydrogenotrophic sulfate reduction at partial CO pressures exceeding 100 kPa, it is also a good candidate for
biodesulfurization processes using synthesis gas as electron donor at elevated temperatures, e.g., in biological flue gas
desulfurization. Although high maximal specific sulfate reduction rates (32 mmol (g protein)−1 h−1) can be obtained, its sulfide tolerance is rather low and pH dependent, i.e., maximally 9 and 5 mM sulfide at pH 7.2 and
pH 6.5, respectively. 相似文献
2.
Hydrogen production with high yield and high evolution rate by self-flocculated cells of Enterobacter aerogenes in a packed-bed reactor 总被引:6,自引:1,他引:5
M. A. Rachman Y. Nakashimada T. Kakizono N. Nishio 《Applied microbiology and biotechnology》1998,49(4):450-454
Continuous hydrogen gas evolution by self-flocculated cells of Enterobacter aerogenes, a natural isolate HU-101 and its mutant AY-2, was performed in a packed-bed reactor under glucose-limiting conditions in
a minimal medium. The flocs that formed during the continuous culture were retained even when the dilution rate was increased
to 0.9 h−1. The H2 production rate increased linearly with increases in the dilution rate up to 0.67 h−1, giving maximum H2 production rates of 31 and 58 mmol l−1 h−1 in HU-101 and AY-2 respectively, at a dilution rate of more than 0.67 h−1. The molar H2 yield from glucose in AY-2 was maintained at about 1.1 at dilution rates between 0.08 h−1 and 0.67 h−1, but it decreased rapidly at dilution rates more than 0.8 h−1.
Received: 27 August 1997 / Received revision: 11 November 1997 / Accepted: 14 December 1997 相似文献
3.
Actual and potential rates of hydrogen photoproduction by continuous culture of the purple non-sulphur bacterium Rhodobacter capsulatus 总被引:1,自引:1,他引:0
A. A. Tsygankov A. S. Fedorov T. V. Laurinavichene I. N. Gogotov K. K. Rao D. O. Hall 《Applied microbiology and biotechnology》1998,49(1):102-107
The influence of (NH4)2SO4 concentration and dilution rate (D) on actual and potential H2 photoproduction has been studied in ammonium-limited chemostat cultures of Rhodobacter capsulatus B10. The actual H2 production in a photobioreactor was maximal (approx. 80 ml h−1 l−1) at D = 0.06 h−1 and 4 mM (NH4)2SO4. However, it was lower than the potential H2 evolution (calculated from hydrogen evolution rates in incubation vials), which amounted to 100–120 ml h−1 l−1 at D = 0.03–0.08 h−1. Taking into account the fact that H2 production in the photobioreactor under these conditions was not limited by light or lactate, another limiting (inhibiting)
factor should be sought. One possibility is an inhibition of H2 production by the H2 accumulated in the gas phase. This is apparent from the non-linear kinetics of H2 evolution in the vials or from its inhibition by the addition of H2; initial rates were restored in both cases after the vials had been refilled with argon. The actual H2 production in the photobioreactor at D = 0.06 h−1 was shown to increase from approximately 80 ml h−1 l−1 to approximately 100 ml h−1 l−1 under an argon flow at 100 ml min−1. Under maximal H2 production rates in the photobioreactor, up to 30% of the lactate feedstock was utilised for H2 production and 50% for biomass synthesis.
Received: 22 April 1997 / Received revision: 14 July 1997 / Accepted: 27 July 1997 相似文献
4.
Gyoo Yeol Jung Jung Rae Kim Hyun Ok Jung Ji-Young Park Sunghoon Park 《Biotechnology letters》1999,21(10):869-873
A new bacterium, Citrobacter sp. Y19, catalyzing the water-gas shift reaction was isolated from an anaerobic wastewater sludge digester. It grew aerobically with a high specific growth rate of 0.7 h–1 in a mineral salt medium supplemented with yeast extract and Bacto-tryptone, and produced H2 under anaerobic conditions after the cells were transferred to tryptone-deleted medium. The maximum H2 production rate was 33 mmol H2 g–1 cell h, which was maintained for about 200 h. This is the first report on a chemoheterotrophic bacterium which utilizes CO with the production of H2 and CO2. 相似文献
5.
Kiviharju K Moilanen U Leisola M Eerikäinen T 《Applied microbiology and biotechnology》2007,73(6):1267-1274
The behavior of Streptomyces peucetius var. caesius N47 was studied in a glucose limited chemostat with a complex cultivation medium. The steady-state study yielded the characteristic
constants μ
max over 0.10 h−1, Y
XS 0.536 g g−1, and mS 0.54 mg g−1 h−1. The product of secondary metabolism, ɛ-rhodomycinone, was produced with characteristics Y
PX 12.99 mg g−1 and m
P 1.20 mg g−1 h−1. Significant correlations were found for phosphate and glucose consumption with biomass and ɛ-rhodomycinone production. Metabolic
flux analysis was conducted to estimate intracellular fluxes at different dilution rates. TCA, PPP, and shikimate pathway
fluxes exhibited bigger values with production than with growth. Environmental perturbation experiments with temperature,
airflow, and pH changes on a steady-state chemostat implied that an elevation of pH could be the most effective way to shift
the cells from growing to producing, as the pH change induced the biggest transient increase to the calculated ɛ-rhodomycinone
flux. 相似文献
6.
Automated feeding strategies for high-cell-density fed-batch cultivation of Pseudomonas putida KT2440 总被引:1,自引:0,他引:1
Four automatic substrate feeding strategies were developed and investigated in this study to obtain rapid, repeatable, and reliable high cell densities of Pseudomonas putida KT2440 from glucose. Growth yield data of the key nutrients, Y
X/Glucose, Y
X/NH4, Y
X/PO4, Y
X/Mg, and Y
CO2/Glucose, were determined to be 0.41, 5.44, 13.70, 236, and 0.65 g g−1, respectively. Although standard exponential feeding strategy worked well when the predetermined μ was set at 0.25 h−1, an exponential glucose feeding strategy with online μ
max estimation resulted in a higher average biomass productivity (3.4 vs 2.8 g l−1 h−1). A CO2 production rate based pulse glucose feeding strategy also resulted in good overall productivity (3.0 g l−1 h−1) and can be used as an alternative to pH-stat or DO-stat feeding. A cumulative CO2 production based continuous feed with real-time cumulative glucose consumption estimation resulted in much higher biomass productivity (4.3 g l−1 h−1) and appears to be an excellent and reliable approach to fully automating high-cell-density fed-batch cultivation of P. putida. 相似文献
7.
Thompson LJ Gray VM Kalala B Lindsay D Reynolds K von Holy A 《Biotechnology letters》2008,30(2):271-274
Carrier induced granular particles comprising Enterobacter cloacae and Citrobacter freundii were used to generate H2 from sucrose in an anaerobic fluidized bed bioreactor. At a hydraulic retention time of 4.5 h, 95.8% of the sucrose was consumed
and the rate of H2 production reached 180 mmol H2 l h−1. Biogas composition for H2 and CO2 was 42 and 55%, respectively.
Alex von Holy—Deceased 相似文献
8.
de Vrije T Mars AE Budde MA Lai MH Dijkema C de Waard P Claassen PA 《Applied microbiology and biotechnology》2007,74(6):1358-1367
NMR analysis of 13C-labelling patterns showed that the Embden–Meyerhof (EM) pathway is the main route for glycolysis in the extreme thermophile
Caldicellulosiruptor saccharolyticus. Glucose fermentation via the EM pathway to acetate results in a theoretical yield of 4 mol of hydrogen and 2 mol of acetate
per mole of glucose. Previously, approximately 70% of the theoretical maximum hydrogen yield has been reached in batch fermentations.
In this study, hydrogen and acetate yields have been determined at different dilution rates during continuous cultivation.
The yields were dependent on the growth rate. The highest hydrogen yields of 82 to 90% of theoretical maximum (3.3 to 3.6 mol
H2 per mol glucose) were obtained at low growth rates when a relatively larger part of the consumed glucose is used for maintenance.
The hydrogen productivity showed the opposite effect. Both the specific and the volumetric hydrogen production rates were
highest at the higher growth rates, reaching values of respectively 30 mmol g−1 h−1 and 20 mmol l−1 h−1. An industrial process for biohydrogen production will require a bioreactor design, which enables an optimal mix of high
productivity and high yield. 相似文献
9.
Citric acid production from sucrose using a recombinant strain of the yeast Yarrowia lipolytica 总被引:1,自引:0,他引:1
Förster A Aurich A Mauersberger S Barth G 《Applied microbiology and biotechnology》2007,75(6):1409-1417
The yeast Yarrowia lipolytica is able to secrete high amounts of several organic acids under conditions of growth limitation and carbon source excess.
Here we report the production of citric acid (CA) in a fed-batch cultivation process on sucrose using the recombinant Y. lipolytica strain H222-S4(p67ICL1) T5, harbouring the invertase encoding ScSUC2 gene of Saccharomyces cerevisiae under the inducible XPR2 promoter control and multiple ICL1 copies (10–15). The pH-dependent expression of invertase was low at pH 5.0 and was identified as limiting factor of the CA-production
bioprocess. The invertase expression was sufficiently enhanced at pH 6.0–6.8 and resulted in production of 127–140 g l−1 CA with a yield Y
CA of 0.75–0.82 g g−1, whereas at pH 5.0, 87 g l −1 with a yield Y
CA of 0.51 gg−1 were produced. The CA-productivity Q
CA increased from 0.40 g l −1 h−1 at pH 5.0 up to 0.73 g l −1 h−1 at pH 6.8. Accumulation of glucose and fructose at high invertase expression level at pH 6.8 indicated a limitation of CA
production by sugar uptake. The strain H222-S4(p67ICL1) T5 also exhibited a gene–dose-dependent high isocitrate lyase expression
resulting in strong reduction (<5%) of isocitric acid, a by-product during CA production. 相似文献
10.
Influence of initial cellulose concentration on the carbon flow distribution during batch fermentation by Clostridium thermocellum ATCC 27405 总被引:1,自引:0,他引:1
The objective of this research was to understand how carbon loading influences hydrogen (H2) synthesis and metabolic flow patterns in the thermophilic, cellulolytic bacterium, Clostridium thermocellum. C. thermocellum was cultivated in batch cultures with high (5 g L−1) and low (1 g L−1) initial concentrations of α-cellulose at 60°C. The growth rate of C. thermocellum was 22% lower (0.15 h−1) in cultures with low-cellulose concentration compared with cultures with high-cellulose concentrations. Although substrate
depletion coincided with the end of log-growth in low-cellulose cultures, the prime reason for growth arrest in high-cellulose
cultures was not identified. Ethanol, acetate, and formate were the major soluble end-products with concomitant release of
H2 and CO2 under both conditions. Lactate appeared during the late log phase in high-carbon cultures when pH dropped below 6.4 and became
the major end-product in stationary phase. During the exponential phase of cell growth, significantly higher yields for H2 and acetate (1.90 ± 0.14 and 1.11 ± 0.04 mol/mol glucose equivalent, respectively) were obtained from low-cellulose cultures
compared to those from high-cellulose cultures. The maximum specific rate of H2 production, 6.41 ± 0.13 mmol H2/g dry cell/h, obtained during the exponential phase from low-carbon cultures was about 37% higher than that obtained from
high-carbon cultures. 相似文献
11.
A new hydrogen producing bacterium, Rhodopseudomonas palustris P4, originally isolated under an anaerobic/phototrophic condition, grew well under aerobic/chemoheterotrophic or anaerobic/chemoheterotrophic conditions and showed CO-dependent, H2 production activity when transferred to anaerobic conditions. Cell growth was best under an aerobic/chemoheterotrophic condition as the doubling time of 1 h, while the H2 production activity was highest in the cells grown under an aerobic/chemoheterotrophic condition at 20 mmol g–1 cell–1 h–1. 相似文献
12.
The objective of this study was to improve the biological water–gas shift reaction for producing hydrogen (H2) by conversion of carbon monoxide (CO) using an anaerobic thermophilic pure strain, Carboxydothermus hydrogenoformans. Specific hydrogen production rates and yields were investigated at initial biomass densities varying from 5 to 20 mg volatile
suspended solid (VSS) L−1. Results showed that the gas–liquid mass transfer limits the CO conversion rate at high biomass concentrations. At 100-rpm
agitation and at CO partial pressure of 1 atm, the optimal substrate/biomass ratio must exceed 5 mol CO g−1 biomass VSS in order to avoid gas–liquid substrate transfer limitation. An average H2 yield of 94 ± 3% and a specific hydrogen production rate of ca. 3 mol g−1 VSS day−1 were obtained at initial biomass densities between 5 and 8 mg VSS−1. In addition, CO bioconversion kinetics was assessed at CO partial pressure from 0.16 to 2 atm, corresponding to a dissolved
CO concentration at 70°C from 0.09 to 1.1 mM. Specific bioactivity was maximal at 3.5 mol CO g−1 VSS day−1 for a dissolved CO concentration of 0.55 mM in the culture. This optimal concentration is higher than with most other hydrogenogenic
carboxydotrophic species. 相似文献
13.
Microbial conversion of lignocellulose to hydrogen is a fascinating way to provide a renewable energy source. A mesophilic
bacterium strain G1 that had high cellulose degradation and hydrogen production activity (2.38 mmol H2 g−1 cellulose) was isolated from rumen fluid and identified as the Enterococcus gallinarum. Hydrogen production from cellulose by using sequential co-cultures of a cellulosic-hydrolysis bacterium G1 and Ethanoigenens harbinense B49 was investigated. With an initial Avicel concentration of 5 g l−l, the sequential co-culture with G1 and strain Ethanoigenens harbinense B49 produced H2 yield approximately 2.97 mmol H2 g−1 cellulose for the co-culture system. 相似文献
14.
A. Quesada-Chanto M. M. Silveira A. C. Schmid-Meyer A. G. Schroeder J. P. C. L. da Costa J. López M. F. Carvalho-Jonas M. J. Artolozaga R. Jonas 《Applied microbiology and biotechnology》1998,49(6):732-736
Propionibacterium shermanii CDB 10014 is able to grow even at high oxygen transfer rates (24.0 mmol O2 l−1 h−1), in contrast to reports in the specialised literature, where all Propionibacteria are considered oxygen-sensitive microorganisms.
Propionic acid is the main product in anaerobiosis. The presence of oxygen in the system leads to an inhibition of propionic
acid production while acetic acid formation is enhanced. At high oxygen supply rates no propionic acid is produced and acetic
acid is the main product. Lactic acid is also produced in reasonable quantities (2.7 g l−1). The growth rate (μmax) is higher in anaerobiosis (0.19 h−1) than in aerobiosis (0.12–0.15 h−1). The cell yield is higher in aerobiosis (0.18–0.22 g g−1) than in anaerobiosis (0.14 g g−1) suggesting the oxidative metabolism of glucose by Propionibacterium shermanii CDB 10014. No corrinoid production was detected at oxygen transfer rates of more than 13.6 mmol l−1 h−1.
Received: 10 September 1997 / Received revision: 6 January 1998 / Accepted: 9 January 1998 相似文献
15.
This investigation represents the first integrated study of primary production, nutrient dynamics and mineralisation in a
northeastern fjord of Greenland. The data presented represent conditions and activities during the early summer thaw (first
2 weeks of July). Primary production (5.3 mmol C m−2 d−2) and chlorophylla (4.1 μg 1−1) values were found to be comparable with measurements from other Arctic regions. Water column N-fixation rates were low (<0.02
μmol N m−1 d−1), but comparable with other estuarine systems. Despite a constant low temperature in the bottom waters (-1.0 to -1.8°C),
a high sedimentary O2 uptake (740 μmol m−2 h−2) was observed and was primarily caused by the presence of benthic infauna. Bioturbation by benthic infauna was reflected
in both homogeneous210Pb and137Cs profiles in the upper 4 cm of the sediment. Permanent accumulation within Young Sound was measured to 0.12 cm/year corresponding
to 153 mmol C m−2 year−1 and 15 mmol N m−2 year−1. Rates of nitrification (22 μmol m−2 h−1) and denitrification (9 μmol m−2 h−1) were comparable with rates reported for other sediments with much higher environmental temperatures. Suphate reduction rates
integrated over the upper 12 cm of the sediment were calculated to be 44 μmol m−2h−1. 相似文献
16.
Extracellular human granulocyte-macrophage colony stimulating factor (hGM-CSF) expression was studied under the control of
the GAP promoter in recombinant Pichia pastoris in a series of continuous culture runs (dilution rates from 0.025 to 0.2 h−1). The inlet feed concentration was also varied and the steady state biomass concentration increased proportionally demonstrating
efficient substrate utilization and constancy of the biomass yield coefficient (Yx/s) for a given dilution rate. The specific product formation rate (qP) showed a strong correlation with dilution rates demonstrating growth associated product formation of hGM-CSF. The volumetric
product concentration achieved at the highest feed concentration (4×) and a dilution rate of 0.2 h−1 was 82 mg l−1 which was 5-fold higher compared to the continuous culture run with 1× feed concentration at the lowest dilution rate thus
translating to a 40 fold increase in the volumetric productivity. The specific product yield (YP/X) increased slightly from 2 to 2.5 mg g−1, with increasing dilution rates, while it remained fairly invariant, for all feed concentrations demonstrating negligible
product degradation or feed back inhibition. The robust nature of this expression system would make it easily amenable to
scale up for industrial production. 相似文献
17.
Collet C Girbal L Péringer P Schwitzguébel JP Soucaille P 《Archives of microbiology》2006,185(5):331-339
The objective of the present study was to characterize the metabolism of Clostridium thermolacticum, a thermophilic anaerobic bacterium, growing continuously on lactose (10 g l−1) and to determine the enzymes involved in the pathways leading to the formation of the fermentation products. Biomass and metabolites concentration were measured at steady-state for different dilution rates, from 0.013 to 0.19 h−1. Acetate, ethanol, hydrogen and carbon dioxide were produced at all dilution rates, whereas lactate was detected only for dilution rates below 0.06 h−1. The presence of several key enzymes involved in lactose metabolism, including beta-galactosidase, glyceraldehyde-3-phosphate dehydrogenase, pyruvate:ferredoxin oxidoreductase, acetate kinase, ethanol dehydrogenase and lactate dehydrogenase, was demonstrated. Finally, the intracellular level of NADH, NAD+, ATP and ADP was also measured for different dilution rates. The production of ethanol and lactate appeared to be linked with the re-oxidation of NADH produced during glycolysis, whereas hydrogen produced should come from reduced ferredoxin generated during pyruvate decarboxylation. To produce more hydrogen or more acetate from lactose, it thus appears that an efficient H2 removal system should be used, based on a physical (membrane) or a biological approach, respectively, by cultivating C. thermolacticum with efficient H2 scavenging and acetate producing microorganisms. 相似文献
18.
Aquaporins seem essential for the regulation of plant water status and expenses. Richter-110 is a Vitis hybrid (Vitis
berlandieri × rupestris) reputed to be strongly drought-tolerant. Three irrigation treatments were established in Richter-110 plants growing outdoors
defined by the resulting maximum stomatal conductance (g
s), and ensuring water stress situations not severe enough as to stop photosynthesis and growth: well-watered plants (g
s about 250 mmol H2O m−2 s−1), moderate water stress (g
s about 150 mmol H2O m−2 s−1) and severe water stress (g
s about 50 mmol H2O m−2 s−1). Plants under water stress were kept at constant water availability for 7 days to check for possible acclimation. Finally,
plants were re-watered, and allowed to recover, for 3 days. Stomatal conductance, leaf water potential, xylem abscisic acid
(ABA) content and root and stem hydraulic conductivity were determined. The relative amounts of expression of mRNA encoding
seven putative aquaporins were determined in roots and leaves by RT-PCR. The decrease in stomatal conductance with moderate
and severe water stress was associated with increasing ABA contents, but not with the leaf water potential and hydraulic conductivities,
which remained unchanged during the entire experiment. Aquaporin gene expression varied depending on which aquaporin, water
stress level and the plant organ. We suggest that aquaporin expression was responsive to water stress as part of the homeostasis,
which resulted in constant leaf water potential and hydraulic conductivity. 相似文献
19.
Fructose and H2 were compared as electron donors for hydrogenation of carbon-carbon double bonds using Acetobacterium woodii. Caffeate was used as a model substrate. An electron donor was required and both fructose and H2 were suitable. With fructose as the donor, the K
s for caffeate was 0.5 mM and the V
max was 678 mmol kgdry weight
−1 h−1.␣Fructose oxidation was coupled very efficiently to caffeate reduction by an alteration in the fructose fermentation so that
acetate was no longer produced.
Received: 24 June 1996 / Accepted: 1 July 1996 相似文献
20.
The impact of the oxygen supply rate (OSR) on the metabolic activity and on the composition of hexadecane-degrading bacterial
communities in a quasi-anoxic milieu (nominal DOT=0%) was studied in continuous cultures containing intertidal sediment. The
dilution rate was kept constant at 0.035 h−1. The OSR was stepwise reduced from 3.5 mmol O2L−1 h−1 to 0.06 mmol O2L−1 h−1. Activity was determined by analyzing the respiration quotient (RQ) and the rates of hexadecane degradation (QHex), of hexadecane mineralization, and of protein production (PPR). The community composition and size were investigated by
fluorescence in situ hybridization (FISH), by dilution plating (colony forming units or CFU), and by most probable number (MPN). The culture showed
an aerobic hexadecane metabolism down to an OSR of 0.35 mmol O2L−1 h−1. Below this OSR, anaerobic metabolism was initiated. The relationship among the RQ, PPR, QHex, and the OSR can be approximated by hyperbola (Michaelis-Menten kinetics). We suggest that the metabolic adaptation of the
culture to low OSRs is due to regulation of protein expression and enzyme activity. Reducing the OSR resulted in minor but
significant changes in the concentration of different physiological and phylogenetic groups. This means that, in addition
to protein expression and activity regulation, the adaptation of the population to low OSRs is due to changes in the community
composition. 相似文献