Breeding And Optimization Of Fermentation Conditions Of Monascus Spp Producing γ-Aminobutyric Acid

γ-aminobutyric acid(GABA),a four-carbon nonprotein amino acid, serves as a major inhibitory neurotransmitter in mammalian nervous systems.Glutamate decarboxylase(GAD,EC4.1.1.15)catalyse the irreversibleα-decarboxylation of L-glutamate toγ-aminobutyric acid (GABA).GABA has several physiological functions such as hypotensive activity,treatment of epilepsy,tranquilizing and allaying excitement, enhancing memory,controlling asthma,regulating hormone secretion promoting reproduction and activating liver and kidney function. Preparation and application of GABA are concerned.In 1979,Endo A in Japan found that Monascus spp could produce something,which has hypotensive activity.Researchers both in china and abroad have been making study of it since then.Up to now,reasons that the production of GABA is low and operating costs is high in our country are the lack of GABA Monascus strains and the lack of qualified industrial fermentation.Therefore,the breeding of Monascus strains that is over-production GABA is very important.In this experiment,Monascus ruber M6-13 which could produceγ-aminobutyric acid was breeded,and the biology characteristic was studied,the culture substrate and fermentation conditions were optimized in order to improve the production of GABA.First,γ-aminobutyric acid-producing M.ruber M6 was isolated from nature and identified.The production of GABA reach at 3.160g/L when it liquid-ferment PDA in taper bottle.The mutant strain of M.ruber M6-13 from M.ruber M-6 was acquired,and the production of GABA reach at 5.527g/L.After 15 generation the mutant strain had stable yield of GABA and no reverse mutation.Second,the biology characteristic of M.ruber M6-13 was studied. the biology characteristic is:growing temperature of M6-13 mycelium is 20—42℃,more suitable temperature of M6-13 is 35℃;pH of M6-13 mycelium grow is wide,more suitable pH is 4.5—5.5;endurance degree of spore to alcohol is 15%,spore is not grow when degree to alcohol is higher than 15%.M6-13 has high performance diastatic power.Third,the culture substrate and fermentation conditions of M.ruber M6-13 were optimized by ways of single factor experiment and L₉(3³) orthogonal test.Single factors are carbon source,nitrogen source, growing temperature,beginning pH and shaking speed.The results showed that beginning pH 5.0,culture temperature at 35℃,shaking speed 120 r/min,the higher yield ofγ-Aminobutyric acid could be reached.The content of GABA was 7.826g/L in the optimum culture conditions.Finally,the batch fermentations of M6-13 were studied on the optimum condition.The effects of operation conditions(inoculation and volume of gas)on GABA batch fermentation of M6-13 in a 3.7 liters stirred fermenter were investigated.The results showed that operation condition(5.0%inoculation and 100L/h)was advantageous to GABA accumulation.The last,the low-cost farm produce were studied as culture medium to produce GABA.The result show that the content of GABA reached at 12.470g/L in the wheat flour culture conditions on optimum fermentation...