Production Of γ-aminobutiric Acid By Immobilized Lactobacillus Brevis, The Integrated Fermentation And Separation By Adsorbent Resin Procession

Gamma-aminobutyric acid(GABA),serves as a major inhibitory neurotrans mitter in mammalian nervous systems.GABA has several physiological functio ns such as hypotensive activity,treatment of epilepsy,tranquilizing and allaying excitement,enhancing memory,controlling asthma,regulating hormone secretio n,promoting reproduction and activating liver and kidney function.Preparation of GABA by Lactobacillus brevis,which generally recognized as safe food add itive,has been among the most remarkable research focuses in the realm of bi ology.To extend the application of immobilization technique in this bioconversi on,the sodium cellulose sulfate / poly-dimethyl-diallyl-ammonium chloride micr ocapsule encapsulated cells of Lactobacillus brevis hjxj-01 for dissimilating sodi um glutamate(L-MSG) to GABA.In addition,a new technique,the integrated fermentation and separation technology based on the in situ product removal t echnique by adsorbent resin,was developed to produce GABA.By virtue of a dvantages of encapsulated cells and adsorbent resin,this immobilization ferment ation aimed at enhancing GABA concentration,yield and productivity,reducing the product inhibition,simplifying separation of product,achieving cell reutiliz ation and continuous fermentation.The free cell culture was carried out with Lactobacillus brevis hjxj-01 and effects of pH,L-MSG,glucose,temperature on the formation of GABA were investigated and the fermentation information about Lactobacillus brevis hjxj-0 1 was obtained.The fermentation should be performed for 5 days at 30℃,pH 4.0,L-MSG 73.3g/L,glucose 20g/L and no aeration.After 50h fermentation,gl ucose was consumed.Then,GABA was synthesized rapidly.The GABA final c oncentration was 41.3 g/L,with maximum biomass of 2.48g/L.We studied the preparation and effects of the sodium cellulose sulfate / po ly-dimetbyl-diallyl-ammonium chloride microcapsule encapsulated cells of Lacto bacillus brevis hjxj-O1.The capsules were white and transparent,with an avera ge diameter 2.82mm.It's compression intensity was strong enough to keep the capsules in good condition after several cultivation.As nutrients like L-MSG and glucose can easily diffuse into the capsules,the sodium cellulose sulfate / poly-dimethyl-diallyl-ammonium chloride microcapsule showed a good biocompa tibility to the Lactobacillus brevis hjxj-01A serious of shake flask cultures with encapsulated Lactobacillus brevis hj xj-01 were performed to obtain the optimized fermentation conditions.Then the cell growth,L-MSG consumption and GABA production of encapsulated cells were investigated.Compared with free cell culture in the same condition,the encapsulated cells could endure higher concentration of L-MSG and glucose,th us got a higher productivity of GABA and biomass.GABA final concentration reached 50.1g/L.The biomass of encapsulated cell culture reached 21.9g/L,8-fold higher than that of free cell culture.After ten-time reutilization of the enc apsulated cells,the L-MSG conversion ratio still reached more than 60%and c apsules kept integrity.Taking the integrated bioreaction and separation process as guide,a new t echnique,the technique of in situ product removal based on the adsorption of product by macro-reticular resin D001 directly from the fermentation broth,wa s developed for GABA production.4h after 10%(w/v) resin D001 was added i nto the reaction solution,the conversion ratio of L-MSG reached 100%,while the conversion ratio of L-MSG was only 81.4%after 5h without addition of re sin.The adsorption capacity of resin D001 on GABA was about 1.43 mmol/g resin.GABA was separated initially without flocculation and decolorization afte r elution of the resin by 2mol/L ammonia,the recovery of GABA reached 9 3%.