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γ-aminobutyric acid (GABA) is a widely distributed in plants, microorganisms, non-protein naturally occurring amino acids. In animals, GABA primarily as an inhibitory neurotransmitter present in the cerebral circulation physiological activity, have lower blood pressure, promote growth, epilepsy treatment, anti-aging, promote feeding behavior, prevention of obesity, improving reproductive, liver function activation other functions, in the food and pharmaceutical industries are widely used. This separation from the natural environment to a Monascus the 27th, by mutagenesis, medium components optimization, optimization of fermentation conditions increase GABA production, optimize data based on a small test pilot to complete industrialization. First of all, from red yeast rice, red bean curd, wine, music, red bean paste aspergillosis 300 separated by paper chromatography improved screening, including a 27 strains GABA production was 2.32g / L. Was identified by morphological means red Monascus (Monascus ruber), and determine its departure for future mutagenesis experiments strain. By UV mutagenesis, nitrous acid mutagenesis, mutagenesis and cobalt chloride, nitrite - UV mutagenesis to obtain a high yield of GABA 3.12g / L of the mutant strain (strain No. 27-A015), through the continuous passage experiments ( 20 consecutive passages), reverse mutation does not appear that this strain has a stable genetic, and grow faster, so that the strains of red yeast strains used for subsequent experiments starting strain, and was named Monascus X27. Secondly, the use of Plackett-Burman method (PB method) determine Monascus liquid fermentation GABA have important implications for three factors are temperature, pH and aeration. RSM experimentally determined through experiments climbing center. Response surface methodology was experimentally obtained regression coefficient, regression equation: Y = -209.366 3.435X1 55.945X2 0.103X3-0.059X12-5.135X22-0.0002X32-0.081X1X2-0.001X1X3-0.019X2X3, by calculating the optimum fermentation conditions to: 34 ℃, pH 5.5, ventilation 120L / h, a seed tank pressure 0.3 MPa, 5% inoculum size, stirring paddle speed of 200 r / min. optimized GABA production reached 9.18g / L, compared to unoptimized increased 74.7 percent. To red aspergillosis X27 for carbon, nitrogen, sodium glutamate fed-batch study found that sodium glutamate X27 Monascus inhibit the growth of certain fermented initial low concentration of sodium glutamate Growth is the key to making a lot of bacteria and shorten the lag phase and fermentation cycle, making the cost of production has been effectively controlled. By feeding on nitrogen optimized, GABA maximum yield of 9.91g / L. Finally, the optimal formula has received medium and fermentation tanks optimal conditions for the 300L X27 Monascus fermentation experiments, namely industrialization pilot. Compared with small fermenters, large fermentation tanks of oxygen utilization increased, the volume of oxygen transfer coefficient KLa value growth is relatively slow (with built-tank liquid level increased, KLa value growth rate eased off), making In a small pilot fermentor required parameters on the basis of a regulation of the production. Finally determined through experiments, pre-fermentation (12 h, the) mixing paddle speed increases, the amount of dissolved oxygen can be improved fermentation broth, to stimulate cell growth, but should not exceed impeller speed 250 r / min, in order to avoid excessive shearing force damage cells. In the fermentation medium term (24 h before and after), the amount of glucose added to improve the fermenter pH, inhibit the rapid rise in pH toxic effects on cells.
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