食品科学 ›› 2021, Vol. 42 ›› Issue (10): 79-85.doi: 10.7506/spkx1002-6630-20200102-012

• 生物工程 • 上一篇    下一篇

基于基因组挖掘技术的新型谷氨酸脱羧酶基因挖掘及表达鉴定

李祥,解玉丽,贾园园,张闪,王红艳,刘先吏,罗湘艳,唐存多   

  1. (1.南阳师范学院 昆虫生物反应器河南省工程实验室,河南 南阳 473061;2.车用生物燃料技术国家重点实验室,河南 南阳 473061)
  • 出版日期:2021-05-25 发布日期:2021-06-02
  • 基金资助:
    国家自然科学基金青年科学基金项目(31900916);国家自然科学基金面上项目(31870917); 车用生物燃料技术国家重点实验室开放课题(KFKT2018003);南阳师范学院青年项目(2018QN004); 河南省科研服务平台专项(2016151);河南省南水北调中线水源区水生态安全创新型科技团队专项(17454); 河南省高校科技创新团队项目(20IRTSTHN024);河南省高校省级大学生创新创业训练计划项目(S201910481006)

Gene Mining, Expression and Identification of Novel Glutamate Decarboxylases Based on Genome Mining

LI Xiang, XIE Yuli, JIA Yuanyuan, ZHANG Shan, WANG Hongyan, LIU Xianli, LUO Xiangyan, TANG Cunduo   

  1. (1. Henan Provincial Engineering Laboratory of Insect Bio-reactor, Nanyang Normal University, Nanyang 473061, China; 2. State Key Laboratory of Automotive Biofuel Technology, Nanyang 473061, China)
  • Online:2021-05-25 Published:2021-06-02

摘要: 采用基因组挖掘技术,以来源于Lactobacillus brevis活性较高的谷氨酸脱羧酶(glutamate decarboxylase,GAD)LbGAD为探针,从乳酸菌(Lactococcus lactis、Lactobacillus senmaizukei)和肠球菌(Enterococcus sulfureus)的基因组中挖掘到了3 个假定的GAD基因(LlGAD、LsGAD和EsGAD)。借助pET28a质粒分别实现了这4 个基因在大肠杆菌BL21中的表达,其中LsGAD和LlGAD的表达产物可溶性较好,相应发酵液中GAD活力分别为34.17、38.91 U/mL。LsGAD的比活力、温度特性、pH值特性和Kcat/Km值也明显优于其他几个酶。此外,初步研究了全细胞催化L-谷氨酸制备γ-氨基丁酸(γ-aminobutyric acid,GABA)的工艺,6 g/L的L-谷氨酸经过24 h转化后,GABA得率最高可达58%。本研究实现了GAD从基因组数据到真实酶的跨越,获得了1 个性能优良的GAD,并初步实现了GABA的生物合成,为实现GABA低成本、规模化的生物合成提供了科学依据。

关键词: 谷氨酸脱羧酶;基因组挖掘;表达;鉴定;生物催化

Abstract: In this study, three hypothesized glutamate decarboxylases (GAD) genes from Lactococcus lactis, Lactobacillus senmaizukei and Enterococcus sulfureus, respectively named as LlGAD, LsGAD and EsGAD, were excavated using genome mining technology with the high-activity GAD gene (LbGAD) from Lactobacillus brevis as the probe. By means of pET28a plasmid, these four genes were expressed in E. coli BL21. The expressed products of LsGAD and LlGAD had a good solubility, exhibiting GAD activity of 34.17 and 38.91 U/mL, respectively in the fermentation broths. The specific activity, temperature characteristics, pH characteristics and Kcat/Km value of LsGAD were significantly superior to those of the other GAD enzymes. In addition, the biosynthesis of γ-aminobutyric acid (GABA) from L-glutamic acid by whole-cell catalysis was studied. When L-glutamic acid at 6 g/L was transformed for 24 h, the maximum yield of GABA of 58% was obtained. In conclusion, this study has realized a leap from genomic data to real enzymes by obtaining GAD with excellent performance as well as the biosynthesis of GABA, which will lay a solid foundation for the low-cost and large-scale biosynthesis of GABA.

Key words: glutamate decarboxylase; genome mining; expression; identification; biocatalysis

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