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Zhonggui Mao

Publications and source records attributed to Zhonggui Mao.

9 recordsLinked to original sources
PubMed2006

Electrotransformation of Thermoanaerobacter ethanolicus JW200.

Electrotransformation of Thermoanaerobacter ethanolicus JW200 was achieved using the plasmid, pTE16, and a pUC-based suicide vector, pTEA2. The construct pTE16 is based on the Escherichia coli-Clostridium perfringens shuttle vector pJIR715 and contains a thermostable chloramphenicol (Cm) resistance cassette. Evidence supporting transformation was provided by extracting plasmid pTE16 from presumptive transformants of T. ethanolicus and by PCR specific to the chloramphenicol acetyltransferase (cat) gene on the vector pTEA2. Transformation frequencies of plasmid pTE16 and pTEA2 were 50 +/- 7.4 and 30 +/- 4.2 transformants per mug plasmid DNA. The results provide the first unequivocal gene transfer method functional in T. ethanolicus.

Biotechnology↗
PubMed2006

On-line optimization of glutamate production based on balanced metabolic control by RQ.

In glutamate fermentations by Corynebacterium glutamicum, higher glutamate concentration could be achieved by constantly controlling dissolved oxygen concentration (DO) at a lower level; however, by-product lactate also severely accumulated. The results of analyzing activities changes of the two key enzymes, glutamate and lactate dehydrogenases involved with the fermentation, and the entire metabolic network flux analysis showed that the lactate overproduction was because the metabolic flux in TCA cycle was too low to balance the glucose glycolysis rate. As a result, the respiratory quotient (RQ) adaptive control based "balanced metabolic control" (BMC) strategy was proposed and used to regulate the TCA metabolic flux rate at an appropriate level to achieve the metabolic balance among glycolysis, glutamate synthesis, and TCA metabolic flux. Compared with the best results of various DO constant controls, the BMC strategy increased the maximal glutamate concentration by about 15% and almost completely repressed the lactate accumulation with competitively high glutamate productivity.

Citric Acid Cycle↗
PubMed2005

Effects of molecular weight and concentration of arabinoxylans on the membrane plugging.

In this paper, arabinoxylans from wheat were isolated, purified, and degraded into four fractions with different molecular weight. The distribution of particle size was employed to evaluate the membrane plugging by beer. These arabinoxylans fractions were added into arabinoxylan-free beer to investigate the effects of molecular weight and concentration on the distribution of particle size in beer. Results showed that the fraction of arabinoxylans retained by a 0.22-mum pore size membrane was more easily affected by shearing and arabinoxylan concentration than the fraction of arabinoxylans retained by a 0.45-mum membrane. The effects of shearing, pH, and ethanol concentration of beer on the particle size distribution of the highest molecular weight arabinoxylan fraction in beer were also examined. General linear models (GLM) equations indicated that there was a positive correlation between the particle size distributions of arabinoxylans and shearing and ethanol content, while high molecular weight arabinoxylans particle size retained by the 0.45-mum membrane was not significantly (p > 0.05) influenced by pH value. Scanning electron microscope (SEM) photos showed that membrane plugging was significantly affected by the molecular weight of the arabinoxylans.

Beer↗
PubMed2005

Performance evaluation of acetone-butanol continuous flash extractive fermentation process.

A general mathematical model for performance evaluation of acetone-butanol continuous flash extractive fermentation system was formulated in the terms of productivity, energy requirement (energy utilization efficiency) and product purity. The simulation results based on experimental data showed that the most pronounced performance improvement could be achieved by using highly concentrated substrate as feed and the increase in solvent dilution rate could only improve the total productivity at the expense of energy utilization efficiency. A two-vessel partial flash system, with the first vessel of two to three plates and the second vessel as a complete flash vessel, is required to ensure high product purity. This method of mathematical formulation and analysis could be used and extended as a general tool to other bioprocesses equipped with multiple in situ recovery systems.

Acetone↗
PubMed2004

Dietary diacylglycerol prevents high-fat diet-induced lipid accumulation in rat liver and abdominal adipose tissue.

The inhibitory effects of 1,3-diacylglycerol (DAG) on diet-induced lipid accumulation in liver and abdominal adipose tissue of rats were investigated in the present study. Male Sprague-Dawley rats were given free access to diets containing 7 wt% TAG (low TAG), 20 wt% TAG (high TAG), or 20 wt% DAG (high DAG), respectively, for 8 wk. The body weight of rats in the 20% high-TAG group increased significantly, and the weights of their abdominal adipose tissue and liver also showed a significant increase compared with rats in the low-TAG group. However, the high-DAG diet resulted in both a significant reduction in body weight gain (with a decrease of 70.5%) and an increase in the ratio of abdominal fat to body weight (by 127%) compared with the high-TAG diet. As well, the liver TAG and serum TAG levels of the high-DAG group were significantly lower than those of the high-TAG group. These effects were associated with up-regulation of acyl-CoA carnitine acyltransferase (ACAT) and down-regulation of acyl-CoA DAG acyltransferase (DGAT) in the liver. However, no significant difference was observed in the activities of alanine aminotransferase and aspartate aminotransferase among the groups (P > 0.05). The present results indicate that dietary DAG reduced fat accumulation in viscera and body, and these effects may be involved with up-regulation of ACAT and down-regulation of DGAT in the liver.

Abdomen↗
PubMed2004

Mathematical modeling for prediction of endo-xylanase activity and arabinoxylans concentration during mashing of barley malts for brewing.

A mathematical model describing the degradation of arabinoxylans by endo-xylanase during mashing process was developed. Endo-xylanase activities and arabinoxylans concentrations in laboratory scale mashing process at different temperature profiles were measured and then used for identifying the model parameters for Harrington barley malt. The modeling errors range for the final concentration of arabinoxylans in wort was -4% to +11.9%. The model developed was also used for predicting the other three different malts mashing processes in laboratory scale, and the prediction errors ranged from -9.5% to +13.6%. The model prediction accuracy for industrial scale mashing process was lower than that in laboratory scale. The simulation results showed that, a lower concentration of arabinoxylans could be achieved when maintaining the mashing-in at 45 degrees C and prolonging the mashing-in time.

Computer Simulation↗
PubMed2003

A novel, repeated fed-batch, ethanol production system with extremely long term stability achieved by fully recycling fermented supernatants.

Using Saccharomyces cerevisiae, a novel, repeated fed-batch ethanol production system from corn flour by fully recycling fermented supernatants is demonstrated. With recovery of ethanol by evaporation coupled with consecutive removal of the insoluble and soluble inhibitory substances accumulated, either completely or partially by filtration, the concentrations of the soluble inhibitors in the system could be maintained at their equilibria. As a result, a sustained high concentration of ethanol (up to 15% v/v) and significant pollution control performance were obtained.

Bioreactors↗
PubMed2003

[The product identification study on the isolating process of strains produced trehalose].

In the isolating process of stains whose endocellular enzymes can produce trehalose on starch or maltooligosaccharides, we discovered the components of enzymatic reactant were complicated and it was difficult to purify them each other, however, we have to know quickly whether there was tehalose in the enzymatic reactant above. In order to make it clearly, thinner layer chromatography, high performance liquid chromatography-electrospray ionization mass spectrometry and 13C-nuclear magnetic resonance were adopted. The unknown oligosaccharide produced by Arthrobacter nicotinovorus D-97 was identified rapidly and this unknown oligosaccharide needn't be purified from the enzymatic reactant solely. The production on starch or maltooligosaccharides by endocellular enzymes of Arthrobacter nicotinovorus D-97 is trehalose. This research method in our paper can be applied in the isolating process of production trehalose and other functional glucobioses strains.

Arthrobacter↗