探讨了短乳杆菌(Lactobacillus brevis)L2菌株利用麦麸为培养基原料发酵生产γ-氨基丁酸(GABA),并对GABA的分离纯化工艺进行了研究.对6种大孔树脂和活性炭进行脱色效果筛选,ADS-7树脂对L2菌株发酵液具有最高的脱色率和GABA得率;优化了ADS-7大孔树脂脱色条件:在pH 5.0,脱色温度25℃,脱色时间1h时,脱色效率大于95％,GABA得率达93％.优化了阳离子交换树脂D001分离纯化GABA的工艺条件:在25℃、上样脱色发酵液pH 5.0,流速为1 BV/h下,用去离子水和1 mol/L氨水分步洗脱效果最好.通过收集、浓缩及结晶等工艺得到针状GABA晶体,氢核磁共振(1H NMR)分析氢谱图与GABA标准品一致.

In order to improve the γ-aminobutyric acid(GABA) production of Lactobacillus brevis strain L2 and establish a model refl ecting the nonlinear relationship between the factor and yield, the Plackett-Burman(PB) design and central composite design(CCD) were used to optimize the medium component and culture condition. By analyzing the statistical regression, we found peptone, glucose, MSG and initial pH were the most important factors. On this basis, error back propagation neural network(BPN) and genetic algorithm(GA) were applied to determine the optimum fermentation parameters as peptone 21.185 g/L, glucose 3.857 g/L, MSG 48.948 g/L and initial pH 4.05. Ultimately, the GABA production of strain L2 was up to 27.765 g/L, more than doubling the original yield(13.452 g/L), which indicated that using BPN-GA method to optimized fermentation conditions is an effective way.

A Lactobacillus strain L2 that produced a higher amount of gamma(gamma)-aminobutyric acid (GABA) was isolated from traditional pickles. Phylogenetic analysis based on the 16S rDNA sequence and morphological and biochemical studies indicated that it may belong to Lactobacillus brevis. Under un-optimized conditions in MRS broth with 2% monosodium glutamate (L-MSG), it produced GABA at a concentration of 9.822 g/L after 48 h. On the principle of maximum economic benefit, the next work describes the optimization of fermentation variables for the production of GABA by Lactobacillus brevis L2 using wheat bran (WB) and millet bran (MB) supplemented with L-MSG. Based on a single-factor-at- a-time optimization strategy, we determined the optimal cultivation conditions of the GABA production using WB and MB as described below: initial pH 4.00, reaction temperature 30 degrees C and the reaction time 72 h. Subsequently, the D-optimal mixture design was applied to optimize the ratio of the three kinds of components above-mentioned for GABA production. The results showed that when the mixing ratio of WB, MB and L-MSG reached 22.454: 20.000: 57.546 (g/L), the maximum GABA yield of Lactobacillus brevis L2 reached 27.2069 g/L. Analysis of variance for the regression model suggested that the GABA yield showed close agreement with the model prediction.

Fermentative production of γ-aminobutyric acid(GABA) by Lactobacillus brevis using millet bran as the sole raw material,supplemented with L-MSG as the synthetic substrate was studied.Through analyzing the influence of pH,culture temperature,fermentation time and the quantity of millet bran and L-MSG,the GABA production’s characteristic of Lactobacillus brevis were investigated.The results showed that the optimal fermentation conditions were as follows: pH 4.00,culture temperature 30 ℃,fermentation time 72 h;and the optimum medium constitutions were millet bran 70 g/L,glutamate 50 g/L.Under the optimal conditions,the production of GABA in optimum fermentation medium could reach 32.037 g/L.It provided a novel method of GABA production effectively utilizing millet bran.

A yeast strain MJ2 that was found to produce a higher amount of γ-aminobutyric acid (GABA) was isolated from the surface of kiwi. Phylogenetic analysis based on the ITS sequence and morphological, biochemical studies indicated that it may belong to Saccharomyces cerevisiae . Under optimum conditions in Czapek’s broth medium with 0.5 % monosodium glutamate, it produced GABA at a concentration of 5.823 g/L after 48 h. A full-length glutamate decarboxylase gene ( Scgad ) was cloned by PCR amplification. The open reading frame (ORF) of the Scgad gene was composed of 1,755 nucleotides and encoded a protein (585 amino acids) with a predicted molecular weight of 65.897 kDa. The deduced amino acids sequence of Scgad shows 100 %, 65 % and 62 % similarity with S. cerevisiae , Candida glabrata and Kluyveromyces lactis GAD in the polypeptide level, respectively. The Scgad gene was expressed in Escherichia coli BL21 (DE3) cells, and the expression was confirmed by Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) analysis. The results suggested that the S. cerevisiae GAD ( Sc GAD) was successfully encoded in E. coli BL21 (DE3) cells. Furthermore, the enzyme activity of Sc GAD encoded in E. coli BL21 (DE3) had been significantly enhanced using artificial neural network linked with genetic algorithm (ANN-GA) method.

Four hundred and six actinomycetes were isolated from sixty eight soil samples which were collected from different areas of Jinhua.Forty-two strains had been proved to have antagonistic activity against Rhizoctonia solani by confronting cultivation on PDA plates.Among them,the strain Sh-43 exhibited the strongest antibiosis capacity with an inhibition zone of 28.3 mm.The strain Sh-43 was identified as Streptomyces hygroscopicus on the cultural,morphological,physiological,biochemical characteristics and 16S rDNA gene sequence analysis.

The invention belongs to the field of biotechnological medicine and life and particularly relates to a high-prodigiosin-yield serratia marcescens strain Sm-128 and use thereof. The high-prodigiosin-yield serratia marcescens strain Sm-128 was collected in China Center for Type Culture Collection on November 13, 2010. The collection number of the strain is CCTCC No.M2010347. The serratia marcescens strain Sm-128 can be used for synthesizing prodigiosin. According to ultraviolet absorption spectrum and Fourier H nuclear magnetic resonance (H-NMR) spectrum analysis, the pigment produced by the Sm-128 strain is prodigiosin and the yield of the prodigiosin reaches 3 to 5 g/L. The pigment has high thermostability, oxidant resistance and reducer resistance and low photostability.