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1.
Effect of Substrate Concentration on Dark Fermentation Hydrogen Production Using an Anaerobic Fluidized Bed Reactor 总被引:1,自引:0,他引:1
The effect of substrate (glucose) concentration on the stability and yield of a continuous fermentative process that produces
hydrogen was studied. Four anaerobic fluidized bed reactors (AFBRs) were operated with a hydraulic retention time (HRT) from
1 to 8 h and an influent glucose concentration from 2 to 25 g L−1. The reactors were inoculated with thermally pre-treated anaerobic sludge and operated at a temperature of 30 °C with an
influent pH around 5.5 and an effluent pH of about 3.5. The AFBRs with a HRT of 2 h and a feed strength of 2, 4, and 10 g L−1 showed satisfactory H2 production performance, but the reactor fed with 25 g L−1 of glucose did not. The highest hydrogen yield value was obtained in the reactor with a glucose concentration of 2 g L−1 when it was operated at a HRT of 2 h. The maximum hydrogen production rate value was achieved in the reactor with a HRT of
1 h and a feed strength of 10 g L−1. The AFBRs operated with glucose concentrations of 2 and 4 g L−1 produced greater amounts of acetic and butyric acids, while AFBRs with higher glucose concentrations produced a greater amount
of solvents. 相似文献
2.
Hossein Amani Mohammad Reza Mehrnia Mohammad Hossein Sarrafzadeh Manouchehr Haghighi Mohammad Reza Soudi 《Applied biochemistry and biotechnology》2010,162(2):510-523
There is a lack of fundamental knowledge about the scale up of biosurfactant production. In order to develop suitable technology
of commercialization, carrying out tests in shake flasks and bioreactors was essential. A reactor with integrated foam collector
was designed for biosurfactant production using Bacillus subtilis isolated from agricultural soil. The yield of biosurfactant on biomass (Y
p/x), biosurfactant on sucrose (Y
p/s), and the volumetric production rate (Y) for shake flask were obtained about 0.45 g g−1, 0.18 g g−1, and 0.03 g l−1 h−1, respectively. The best condition for bioreactor was 300 rpm and 1.5 vvm, giving Y
x/s, Y
p/x, Y
p/s, and Y of 0.42 g g−1, 0.595 g g−1, 0.25 g g−1, and 0.057 g l−1 h−1, respectively. The biosurfactant maximum production, 2.5 g l−1, was reached in 44 h of growth, which was 28% better than the shake flask. The obtained volumetric oxygen transfer coefficient
(K
L
a) values at optimum conditions in the shake flask and the bioreactor were found to be around 0.01 and 0.0117 s−1, respectively. Comparison of K
L
a values at optimum conditions shows that biosurfactant production scaling up from shake flask to bioreactor can be done with
K
L
a as scale up criterion very accurately. Nearly 8% of original oil in place was recovered using this biosurfactant after water
flooding in the sand pack. 相似文献
3.
Hong WK Rairakhwada D Seo PS Park SY Hur BK Kim CH Seo JW 《Applied biochemistry and biotechnology》2011,164(8):1468-1480
In the present study, a novel oleaginous Thraustochytrid containing a high content of docosahexaenoic acid (DHA) was isolated
from a mangrove ecosystem in Malaysia. The strain identified as an Aurantiochytrium sp. by 18S rRNA sequencing and named KRS101 used various carbon and nitrogen sources, indicating metabolic versatility. Optimal
culture conditions, thus maximizing cell growth, and high levels of lipid and DHA production, were attained using glucose
(60 g l−1) as carbon source, corn steep solid (10 g l−1) as nitrogen source, and sea salt (15 g l−1). The highest biomass, lipid, and DHA production of KRS101 upon fed-batch fermentation were 50.2 g l−1 (16.7 g l−1 day−1), 21.8 g l−1 (44% DCW), and 8.8 g l−1 (40% TFA), respectively. Similar values were obtained when a cheap substrate like molasses, rather than glucose, was used
as the carbon source (DCW of 52.44 g l−1, lipid and DHA levels of 20.2 and 8.83 g l−1, respectively), indicating that production of microbial oils containing high levels of DHA can be produced economically when
the novel strain is used. 相似文献
4.
Bezerra RA Rodrigues JA Ratusznei SM Canto CS Zaiat M 《Applied biochemistry and biotechnology》2011,165(1):347-368
Currently, there is an increasing demand for the production of biodiesel and, consequently, there will be an increasing need
to treat wastewaters resulting from the production process of this biofuel. The main objective of this work was, therefore,
to investigate the effect of applied volumetric organic load (AVOL) on the efficiency, stability, and methane production of
an anaerobic sequencing batch biofilm reactor applied to the treatment of effluent from biodiesel production. As inert support,
polyurethane foam cubes were used in the reactor and mixing was accomplished by recirculating the liquid phase. Increase in
AVOL resulted in a drop in organic matter removal efficiency and increase in total volatile acids in the effluent. AVOLs of
1.5, 3.0, 4.5 and 6.0 g COD L−1 day−1 resulted in removal efficiencies of 92%, 81%, 67%, and 50%, for effluent filtered samples, and 91%, 80%, 63%, and 47%, for
non-filtered samples, respectively, whereas total volatile acids concentrations in the effluent amounted to 42, 145, 386 and
729 mg HAc L−1, respectively. Moreover, on increasing AVOL from 1.5 to 4.5 g COD L−1 day−1 methane production increased from 29.5 to 55.5 N mL CH4 g COD−1. However, this production dropped to 36.0 N mL CH4 g COD−1 when AVOL was increased to 6.0 g COD L−1 day−1, likely due to the higher concentration of volatile acids in the reactor. Despite the higher concentration of volatile acids
at the highest AVOL, alkalinity supplementation to the influent, in the form of sodium bicarbonate, at a ratio of 0.5–1.3 g NaHCO3 g CODfed−1, was sufficient to maintain the pH near neutral and guarantee process stability during reactor operation. 相似文献
5.
M. López-Sánchez M. J. Ayora-Cañada A. Molina-Díaz M. Siam W. Huber G. Quintás S. Armenta B. Lendl 《Analytical and bioanalytical chemistry》2009,394(8):2137-2144
A mid-infrared enzymatic assay for label-free monitoring of the enzymatic reaction of fructose-1,6-bisphosphatase with fructose
1,6-bisphosphate has been proposed. The whole procedure was done in an automated way operating in the stopped flow mode by
incorporating a temperature-controlled flow cell in a sequential injection manifold. Fourier transform infrared difference
spectra were evaluated for kinetic parameters, like the Michaelis–Menten constant (K
M) of the enzyme and V
max of the reaction. The obtained K
M of the reaction was 14 ± 3 g L−1 (41 μM). Furthermore, inhibition by adenosine 5′-monophosphate (AMP) was evaluated, and the K
MApp value was determined to be 12 ± 2 g L−1 (35 μM) for 7.5 and 15 μM AMP, respectively, with V
max decreasing from 0.1 ± 0.03 to 0.05 ± 0.01 g L−1 min−1. Therefore, AMP exerted a non-competitive inhibition. 相似文献
6.
Jun Yao Hong Xu Ningning Shi Xin Cao Xiaohai Feng Sha Li Pingkai Ouyang 《Applied biochemistry and biotechnology》2010,160(8):2332-2341
Bacillus subtilis NX-2 produces γ-polyglutamic acid (γ-PGA) when using glucose and l-glutamate as carbon sources. The conversion of carbon sources into γ-PGA was analyzed with the 13C-NMR method after enriching the media with 13C-labeled glucose. The results showed that the percentage of γ-PGA monomers derived from glucose was relatively low, approximately
6% and 9%, respectively, with an initial glucose concentration of 30 and 40 g L−1. It was concluded that glucose was utilized mainly as the growth-limiting substrate for cell growth and supplied the required
energy during γ-PGA biosynthesis, while l-glutamate was preferred as the main substrate for γ-PGA formation. To achieve an efficient conversion of l-glutamate and enhance the γ-PGA production, a fed-batch culture was proposed by feeding of glucose. By this method, supplied
l-glutamate (40 g L−1) was completely depleted, and γ-PGA yield was attained 42 g L−1. 相似文献
7.
Sensitive fluorescent probes for determination of hydrogen peroxide and glucose based on enzyme-immobilized magnetite/silica nanoparticles 总被引:2,自引:0,他引:2
Qing Chang Lihua Zhu Guodong Jiang Heqing Tang 《Analytical and bioanalytical chemistry》2009,395(7):2377-2385
Sensitive fluorescent probes for the determination of hydrogen peroxide and glucose were developed by immobilizing enzyme
horseradish peroxidase (HRP) on Fe3O4/SiO2 magnetic core–shell nanoparticles in the presence of glutaraldehyde. Besides its excellent catalytic activity, the immobilized
enzyme could be easily and completely recovered by a magnetic separation, and the recovered HRP-immobilized Fe3O4/SiO2 nanoparticles were able to be used repeatedly as catalysts without deactivation. The HRP-immobilized nanoparticles were able
to activate hydrogen peroxide (H2O2), which oxidized non-fluorescent 3-(4-hydroxyphenyl)propionic acid to a fluorescent product with an emission maximum at 409 nm.
Under optimized conditions, a linear calibration curve was obtained over the H2O2 concentrations ranging from 5.0 × 10−9 to 1.0 × 10−5 mol L−1, with a detection limit of 2.1 × 10−9 mol L−1. By simultaneously using glucose oxidase and HRP-immobilized Fe3O4/SiO2 nanoparticles, a sensitive and selective analytical method for the glucose detection was established. The fluorescence intensity
of the product responded well linearly to glucose concentration in the range from 5.0 × 10−8 to 5.0 × 10−5 mol L−1 with a detection limit of 1.8 × 10−8 mol L−1. The proposed method was successfully applied for the determination of glucose in human serum sample. 相似文献
8.
An anodic stripping voltammetric procedure for the determination of Cu(II) at an in situ-plated stannum film electrode (SnFE)
was described. The results indicated that the SnFE had an attractive electroanalytical performance, with two distinct voltammetric
stripping signals for copper and stannum, and showed the superior advantage for the determination of copper compared with
the bismuth film electrode. Several experimental parameters were optimized. The SnFE exhibited highly linear behavior in the
concentration range from 1.0 to 100.0 μg L−1 of Cu(II) (r = 0.994) with the detection limit of 0.61 μg L−1 (S/N = 3), and the relative standard deviation for a solution containing 40.0 μg L−1 Cu(II) was 2.2% (n = 8). The procedure has been successfully applied for the determination of Cu(II) in lake water sample. 相似文献
9.
Natalia García-Otero Carmen Teijeiro-Valiño Jacobo Otero-Romaní Elena Peña-Vázquez Antonio Moreda-Piñeiro Pilar Bermejo-Barrera 《Analytical and bioanalytical chemistry》2009,395(4):1107-1115
Nickel(II) and lead(II) ionic imprinted 8-hydroxyquinoline polymers were synthesized by a precipitation polymerization technique
and were used as selective solid phase extraction supports for the determination of nickel and lead in seawater by flow injection
solid phase extraction on-line inductively coupled plasma-optical emission spectrometry. An optimum loading flow rate of 2.25 mL min−1 for 2 min and an elution flow rate of 2.25 mL min−1 for 1 min gave an enrichment factor of 15 for nickel. However, a low dynamic capacity and/or rate for adsorption and desorption
was found for lead ionic imprinted polymer and a flow rate of 3.00 mL min−1 for 4-min loading and a flow rate of 2.25 mL min−1 for 1-min elution gave a enrichment factor of 5. The limit of detection was 0.33 μg L−1 for nickel and 1.88 μg L−1 for lead, with a precision (n = 11) of 8% (2.37 μg Ni L−1) for nickel and 11% (8.38 μg Pb L−1) for lead. Accuracy was also assessed by analyzing SLEW-3 (estuarine water) and TM-24 (lake water) certified reference materials,
and the values determined were in good agreement with the certified concentrations. 相似文献
10.
Liu X Xu J Li Y Dong F Li J Song W Zheng Y 《Analytical and bioanalytical chemistry》2011,399(7):2539-2547
A sensitive and effective method for simultaneous determination of triazolopyrimidine sulfonamide herbicide residues in soil,
water, and wheat was developed using ultra-performance liquid chromatography coupled with tandem mass spectrometry. The four
herbicides (pyroxsulam, flumetsulam, metosulam, and diclosulam) were cleaned up with an off-line C18 SPE cartridge and detected
by tandem mass spectrometry using an electrospray ionization source in positive mode (ESI+). The determination of the target
compounds was achieved in <2.0 min. The limits of detection were below 1 μg kg−1, while the limits of quantification did not exceed 3 μg kg−1 in different matrices. Quantitation was determined from calibration curves of standards containing 0.05–100 μg L−1 with r
2 > 0.997. Recovery studies were conducted at three spiked levels (0.2, 1, and 5 μg kg−1 for water; 5, 10, and 100 μg kg−1 for soil and wheat). The overall average recoveries for this method in water, soil, wheat plants, and seeds at three levels
ranged from 75.4% to 106.0%, with relative standard deviations in the range of 2.1–12.5% (n = 5) for all analytes. 相似文献
11.
The development and characterization of one rat monoclonal antibody (mAb) for 2,4-dinitroaniline and of two rat mAbs for 2,6-dinitroaniline
are described. With the immunization of rats with 2,4,6-trinitrophenyl-glycylglycine–keyhole limpet hemocyanine (KLH) conjugate
one mAb (PK 5H6) has been developed and formatted into a competitive enzyme-linked immunosorbent assay (ELISA). This assay
no. 1 is very sensitive for 2,4-dinitroaniline with a test midpoint of 0.24 ± 0.06 μg L−1 (n = 19) in 40 mM phosphate-buffered saline (PBS). A second hapten, 3-(4-amino-2,6-dinitrophenyl)propionic acid, which was also
conjugated to KLH and used for the immunization of rats, led to two sensitive ELISAs for 2,6-dinitroaniline in 40 mM PBS with
test midpoints of 0.61 ± 0.08 μg L−1 (n = 15; mAb DNT4 3C6; assay no. 2) and 0.94 ± 0.29 μg L−1 (n = 17; mAb DNT4 1A7, assay no. 3). Selectivities of all mAbs were checked with more than 20 compounds, including nitroaromatic
compounds, 2,6-dinitroaniline pesticides, and other substituted derivatives of aniline. As very noticeable cross-reactivities,
all mAbs recognize 2-chloro-4,6-dinitroaniline, 4-chloro-2,6-dinitroaniline and 2-bromo-4,6-dinitroaniline, the last of these
being a major metabolite of the azo dye Disperse Blue 79. As first demonstrations of applications, two ELISAs (assays no.
1 and 2) were used for the analysis of 2,4- or 2,6-dinitroaniline in spiked water and soil samples. Recovery data were determined
and the majority of these data were in the range of 90–120%. These assays can contribute to a very cost-effective and environmentally
friendly immunochemical surveillance monitoring of environmental samples for contaminations with these compounds. To the best
of the authors’ knowledge, these are the first antibodies described for 2,4-dinitroaniline and for 2,6-dinitroaniline. 相似文献
12.
The precipitation polymerizations of N-tert-butylacrylamide (NtBAM) in water are demonstrated; for example, the polymerization with potassium peroxodisulfate using a 15 g L−1 (118 mmol L−1) concentration of NtBAM in the feed ([NtBAM]0) was performed at 70 °C for 12 h, quantitatively producing poly(N-tert-butylacrylamide) particles with a number-average diameter (d
n) of 203 nm and a coefficient of variation (C
v) of 4.7%. The particle sizes were controlled in the d
ns range between 75 and 494 nm by changing the monomer feeds or adding an electrolyte such as NaCl. The solid contents in the
resulting aqueous latex solutions ranged from 0.1 to 1.5%, whereas it increased to 4.8% by applying a “shot-growth” technique.
The polymerization in water under a somewhat unique condition is described, which was started from a heterogeneous system
due to the presence of significantly large amounts of monomers ([NtBAM]0 = 50 g L−1). This also provided monodisperse latexes with the d
n of 370 nm in 96% yield, in which the solid content reached 4.9%. 相似文献
13.
Repizo LM Martinez LD Olsina RA Cerutti S Raba J 《Analytical and bioanalytical chemistry》2012,402(2):965-973
A novel, simple, and rapid reversed-phase liquid chromatography–tandem mass spectrometric methodology was developed for the
analysis of natamycin in wine samples. Natamycin was protonated to form singly charged ions in an electrospray positive ion
mode. Data acquisition under MS/MS was achieved by applying multiple reaction monitoring (MRM) of three fragment ion transitions
(666.3 → 648.2, 666.3 → 503.3, and 666.3 → 485.2) to provide a high degree of sensitivity and specificity. Chromatographic
separation was performed on a rapid resolution column using a mobile phase consisting of an acetonitrile/water mixture with
a total run time of 5.0 min. After only filtration as pretreatment, the sample was injected into the chromatographic system.
The proposed method was validated in terms of selectivity, trueness, precision, decision limit (CCα), and detection capability (CCβ) according to 2002/657/EC Commission decision. The values for trueness, reported as bias (%), agreed with those established
by the aforementioned document. Repeatability (intraday variability) values were 12.37% at a concentration of 1.0 μg L−1 and 8.99–4.19% at concentrations between 2.5 and 10 μg L−1. The overall within-laboratory (interday variability) reproducibility was 15.47% at a concentration of 1.0 μg L−1, which was significantly lower than the indicative value reported in the EU decision. The results indicated that the proposed
approach is a sensitive, fast, reproducible, and robust methodology suitable for the analysis of natamycin levels in wine
samples. 相似文献
14.
Neopterin is a valuable biomarker of cellular immunity associated with various pathological situations such as viral and bacterial
infections, autoimmune, cardiovascular, neurodegenerative and malignant disorders. To produce specific antibodies against
neopterin for a rapid multi-biomarker-based diagnosis, a novel hapten derivative was synthesized and attached to carrier proteins.
The thoroughly characterized conjugates were used for immunization of BALB/c mice and rabbits. The produced monoclonal antibody
reached in both direct and indirect enzyme-linked immunosorbent assay (ELISA) format LoD of 0.18 and 0.45 μg L−1, respectively, and was a superior immunoreagent for further biosensor developments with regard to assay sensitivity and material
availability. The best polyclonal antibody was somewhat more sensitive in direct ELISA with LoD of 0.05 μg L−1. The optimized ELISA method was evaluated with blood samples collected from patients with renal insufficiency, patients with
sepsis, patients without confirmed clinical diagnosis, and healthy volunteers. In plasma samples, neopterin concentrations
ranging from 3.2 to 103 μg L−1 could be determined with the monoclonal ELISA whereas twofold lower results were obtained with the polyclonal ELISA. A satisfactory
correlation of results was found between the polyclonal ELISA and IBL Neopterin ELISA kit within the concentration range 0.5–16 μg L−1 (R = 0.874; n = 40), and slightly lower correlation was found for monoclonal-based ELISA (R = 0.819; n = 40). These data show that the generated antibodies may be used as functional analytical reagents for the integration into
multianalyte biochip detection systems. 相似文献
15.
Giovannoli C Anfossi L Baggiani C Giraudi G 《Analytical and bioanalytical chemistry》2008,392(3):385-393
Experimental work performed was aimed at the assessment of a competitive capillary electrophoresis immunoassay with laser-induced
fluorescence (CEIA-LIF) detection for the determination of the Cry1Ab endotoxin from Bacillus thuringensis. The binding constant of a monoclonal antibody, raised against the insecticide protein Cry1Ab, was determined on a microplate
by indirect enzyme-linked immunosorbent assay (ELISA) and compared with that obtained in-capillary under nonequilibrium separation
conditions. The two binding constants appear comparable—(5.0 ± 1.2) × 106 M−1 and (9.06 ± 5.7) × 106 M−1—reflecting good preservation of the antibody binding behavior in the capillary electrophoresis format. These results allow
use of a calibration curve possible between 0.2 and 150 nM of endotoxin protein, with a limit of detection of 0.5 nM (33 μg L−1). Preliminary recovery experiments on maize extracts spiked with known amounts of Cry1Ab endotoxin also showed promising
results in detecting the toxin in complex real matrices. 相似文献
16.
Kinetics of Growth and Enhanced Sophorolipids Production by Candida bombicola Using a Low-Cost Fermentative Medium 总被引:1,自引:0,他引:1
In this study, effect of various parameters on sophorolipid (SL) production by the yeast Candida bombicola was investigated for the enhancing of its production by employing L18 orthogonal array design of experiments. At optimum
conditions of sugarcane molasses 50 g l−1, soybean oil 50 g l−1, inoculum size 5% (v/v), temperature 30 °C, inoculum age 2 days, and agitation 200 rpm, the yeast produced almost equal amounts of the product in
batch shake flasks and in a 3-l fermentor without any pH control (45 and 47 g l−1, respectively). However, the yield increased to 60 g l−1 in the fermentor under controlled pH environment. Time course of SL production, yeast biomass growth, and utilization of
sugarcane molasses and soybean oil at these optimized conditions were fitted to existing kinetic models reported in the literature.
Estimated kinetic parameters from these models suggested that conventional medium containing glucose can very well be replaced
with the present low-cost fermentative medium. 相似文献
17.
A. Vonaparti E. Lyris I. Panderi M. Koupparis C. Georgakopoulos 《Analytical and bioanalytical chemistry》2009,395(5):1403-1410
In equine sport, salicylic acid is prohibited with a threshold level of 750 μg mL−1 in urine; hence, doping control laboratories have to establish quantitative and qualitative methods for its determination.
A simple and rapid liquid chromatographic/mass spectrometric method was developed and validated for the quantification and
identification of salicylic acid. Urine samples after 900-fold dilution and addition of the internal standard (4-methylsalicylic
acid) were directly injected to the liquid chromatography/quadrupole time-of-flight mass spectrometry system. Electrospray
ionization in negative mode with full scan acquisition mode and product ion scan mode were chosen for the quantification and
identification of salicylic acid, respectively. Run time was 2.0 min. The tested linear range was 2.5–50 μg mL−1 (after 100-fold sample dilution). The relative standard deviations of intra- and inter-assay analysis of salicylic acid in
horse urine were lower than 2.5% and 2.8%, respectively. Overall accuracy (relative percentage error) was less than 3.3%.
Method was applied to two real samples found to be positive for salicylic acid, demonstrating simplicity, accuracy, and selectivity. 相似文献
18.
The worldwide contamination of winery by-products by mycotoxins may present a serious hazard to human and animal health. Mycotoxins
are secondary metabolites of fungi with possible adverse effects on humans, animals, and crops that result in illnesses and
economic losses. Mycotoxins are under continuous survey in Europe, but the regulatory aspects still need to be set up for
winery by-products, which may be used in animal feed. The aim of this study was to implement a simple but reliable analytical
methodology for ochratoxin A (OTA) quantification in grape pomaces in order to perform a survey of samples from the Douro
Demarcated Region, Portugal. The method involved a unique preparation step, solvent extraction, followed by high-performance
liquid chromatography (HPLC) with fluorescence (FL) detection. A comparative study was performed with two extraction solvents
(ethyl acetate and methanol) as well as using extraction on an immunoaffinity column. The linearity range for OTA analysis
was 0.05–23.5 μg L−1 with a detection limit of 0.05 μg L−1 and a precision (expressed by the coefficient of variation under repeatability conditions) of 0.4–14.7%. The percentage of
recovery was on average 23.5 ± 3.6% (extraction with ethyl acetate) or 70.1 ± 2.5% (extraction with 70% methanol). Accounting
for the recovery factor and the chromatographic detection limit, as well as the preconcentration factor, the limit of detection
in grape pomaces is 0.04 μg kg−1 (ethyl acetate extraction) and 0.33 μg kg−1 (methanol extraction). Samples from 12 out of 13 sites in the Douro Demarcated Region showed OTA presence with concentrations
not exceeding 0.4 μg kg−1. Both developed methods for evaluation of OTA in grape pomace are simple but efficient.
Figure Extraction of ochratoxin A (OTA) from grape pomaces allows simple but efficient quantification of OTA in winery by-products
by HPLC-FL 相似文献
19.
Ashengroph M Nahvi I Zarkesh-Esfahani H Momenbeik F 《Applied biochemistry and biotechnology》2012,166(1):1-12
To screen strains of halotolerant or halophile bacteria which are able to convert isoeugenol to vanillin, 36 different strains
of bacteria isolated from the salty environments in Iran were investigated. During growth on isoeugenol, a moderately halotolerant
Gram-negative coccobacil showed capability of converting isoeugenol to vanillin. Based on morphological, physiological, and
phylogenetic studies, strain CSW4 was classified as a bacterium belonging to the genus Psychrobacter. The bioconversion products were confirmed by thin-layer chromatography, high-performance liquid chromatography, and spectral
data obtained from UV/Vis spectroscopy, FTIR, and mass-spectroscopy. Using growing cells, vanillin reached its maximum level
of 88.18 mg L−1 after 24 h of reaction time in the presence of 1 g L−1 isoeugenol, resulting in a molar yield of 10.2%. The use of resting cells led to the optimal yield of vanillin (16.4%) which
was obtained after 18-h reaction using 1 g L−1 isoeugenol and 3.1 g of dry weight of cells per liter harvested at the end of the exponential growth phase. To improve vanillin
yield, the effect of substrate concentration on vanillin production under resting cells conditions was also investigated.
Using 10 g L−1 isoeugenol, the maximal vanillin concentration (1.28 g L−1) was achieved after a 48-h reaction, without further optimization. The present study brings the first evidence for biotransformation
of isoeugenol to vanillin in the genus Psychrobacter. 相似文献
20.
Sonia Herranz Markéta Bocková María Dolores Marazuela Ji?í Homola María Cruz Moreno-Bondi 《Analytical and bioanalytical chemistry》2010,398(6):2625-2634
A surface plasmon resonance (SPR) biosensor for the detection of microcystins (MCs) in drinking water has been developed.
Several assay formats have been evaluated. The selected format is based on a competitive inhibition assay, in which microcystin-LR
(MCLR) has been covalently immobilized onto the surface of an SPR chip functionalized with a self-assembled monolayer. The
influence of several factors affecting sensor performance, such as the nature and concentration of the antibody, the composition
of the carrier buffer, and the blocking and regeneration solutions, has been evaluated. The optimized SPR biosensor provides
an IC50 0.67 ± 0.09 μg L−1, a detection limit of 73 ± 8 ng L−1, and a dynamic range from 0.2 to 2.0 μg L−1 for MCLR. Cross-reactivity to other related MCs, such as microcystin-RR (88%) and microcystin-YR (94%), has also been measured.
The SPR biosensor can perform four simultaneous determinations in 60 min, and each SPR chip can be reused for at least 40
assay–regeneration cycles without significant binding capacity loss. The biosensor has been successfully applied to the direct
analysis of MCLR in drinking water samples, below the provisional guideline value of 1 μg L−1 established by the World Health Organization for drinking water. 相似文献