ABSTRACT
The dialysis for three species of poplar stems apoplast was obtained by microdialysis method, and then the concentration of Na+, K+, Ca2+ in the dialysis sample was directly measured by graphite furnace atomic absorption spectrometry ( GF-AAS) . The flow rate of perfusate was 1μL/min and the cut-off molecular weight of probe was 30 kDa. The real-time and non-destructive test technique established for the detection of ion concentration could be applied in research of poplar biochemical physiology. The recovery of the proposed method was 95. 8%-103. 1%. The contents of sodium ion in Populus wutunensis, Populus simonii and Salix matsudana were 1034-1156 μg/L, 1493-1611 μg/L and 1586-1703 μg/L; potassium ion were 1012-1237 μg/L, 941-964 μg/L and 1095-1201 μg/L; calcium ion were 4976-5237 μg/L, 4786-5042 μg/L and 5893-6142 μg/L. The method could provide reliable data for the study of ion concentration changes of plant response to adapt to all kinds of external environment.
ABSTRACT
Sodium cellulose sulfate (NaCS)/Ploy-dimethyl-dially-ammonium-chloride (PDMDAAC) microcapsules were used as a novel pseudo "Cell Factory" to immobilize mixed bacteria for hydrogen production under anaerobic conditions. Compared to free cells, the hydrogen production was increased more than 30% with NaCS/PDMDAAC microcapsules as the pseudo "Cell Factory". The biomass was increased from 1.5 g/L in free cell culture to 3.2 g/L in the pseudo "Cell Factory". This pseudo "Cell Factory" system showed the excellent stability during 15 repeated-batches. The hydrogen yield maintained 1.73-1.81 mol H2/mol glucose. The fermentation cycle was shortened from 48 h to 24 h, resulting in an increase of 198.6% in the hydrogen production rate. There were high percentage of butyric acid and acetic acid in the culture broth, which meant that the pseudo "Cell Factory" established in the present work could be used for the multi-product system.
Subject(s)
Bacteria , Classification , Genetics , Metabolism , Capsules , Cells, Immobilized , Metabolism , Cellulose , Chemistry , Fermentation , Hydrogen , Metabolism , Polyethylenes , Chemistry , Quaternary Ammonium Compounds , ChemistryABSTRACT
The asymmetric hydrolyzation of racemic ibuprofen ester is one of the most important methods for chiral separation of ibuprofen. A catalytic antibody that accelerates the rate of enantioselective hydrolysis of ibuprofen methyl ester was successfully elicited against an immunogen consisting of tetrahedral sulfate hapten attached to bovine serum albumin (BSA). The rate constant enhancement factor Kcat/Kuncat was about 1.6x104. The catalytic activity of the catalytic antibody in a reverse micelle reaction system based on sodium b/s (2-ethylhexyl) sodium sulfosuccinate (AOT) in isooctane was studied. Kinetic analysis of the catalytic antibody-catalyzed reaction was found to be possible in this system. Kinetic studies showed that hydrolysis in the microemulsion system follow Michaelis-Menten kinetics. The catalytic antibody can also accelerate catalysis of S-ibuprofen methyl ester in the microemulsion system. Temperature effects, the pH profile, Km,app and Kcat were determined. The dependence of the catalytic antibody hydrolytic activity on the Wo (molar ratio of water to surfactant) showed a bell-shaped curve, presenting a maximum at about wo = 21.
ABSTRACT
We studied the ability of lpdA gene knockout Escherichia coli to ferment different sugars in mineral salts medium for the production of pyruvate. The sugars studied were glucose, fructose, xylose and mannose at a concentration of 10 g/L. At the same time, effect of inoculum size on lpdA fermentation with glucose was studied. The strain was able to use all sugars for biomass generation and pyruvate production. The lpdA knockout mutant converted glucose, fructose, xylose and mannose to pyruvate with yields of 0.884 g/g, 0.802 g/g, 0.817 g/g and 0.808 g/L, respectively. The pyruvate accumulation curve coupled with cell growth except for mannose as carbon source. When the inoculation size increased, the rate of glucose consumption, pyruvate accumulation and cell growth increased but lower pyruvate concentration. This study demonstrates that E. coli lpdA mutant has the potential to produce pyruvic acid from xylose and mannose.