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.

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

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 siturecovery systems.

The experimental data showed that, in glutamate fermentation with strain Corynebacterium glutamicum S9114, glutamate produced in different ways with different patterns of OUR, CER and lactate accumulation at different DO levels. A metabolic network model combined with the linear programming optimization was thus developed to on-line predict glutamate production under different DO levels, with only OUR and CER be on-line measured. The results indicated the advantages of the metabolic network model over the traditional unstructured models, in terms of easy parameter identification, prediction accuracy, and the universal abilities. The proposed model potentially supplies an alternative way for on-line control and optimization of fermentation processes.

The most important non-starch polysaccharides in barley grain are b-glucan and arabinoxylans. Arabinoxylans are partially water-extractable, high-molecular-weight polymers that contribute to viscosity and membrane filterability. Changes to arabinoxylans content and endo-xylanase activity during germination and kilning were studied. This paper was aimed at etermining the composition of total arabinoxylans and water-extractable arabinoxylans in malt and observing their changes during brewing. The water-extractable and total arabinoxylans contents of six barley malts and wheat malt varied in the range of 0.42-0.98% and 3.84-6.90%, respectively. Their L-arabinose-to-D-xylose ratio ranged between 0.49-0.59 (total arabinoxylans) and 0.60-0.85 (water-extractable arabinoxylans). Contents of arabinoxylans in worts mainly originated from the soluble part of arabinoxylans in malt. The use of rice adjunct decreased arabinoxylans contents of wort and beer. The correlation between arabinoxylans and viscosity was investigated. Results showed that water-extractable arabinoxylans in wort have positive and higher correlation value with wort viscosity than those of b-glucan in wort, and both water-extractable arabinoxylans and b-glucan in beer have significant correlation (p<0.01) with beer viscosity.