谷氨酸（钠）对人体肠道菌群影响的体外发酵研究

doi:10.13560/j.cnki.biotech.bull.1985.2020-0600

摘要/Abstract

摘要：

为了研究谷氨酸对人体肠道微生物组成及功能的影响,以谷氨酸钠为底物进行肠道微生物的体外发酵,并测定发酵液中短链脂肪酸（SCFA）、γ-氨基丁酸（GABA）的含量。结果表明,添加谷氨酸钠的发酵液中总酸产量显著高于无底物添加的空白对照组（P<0.01）,其中丁酸的含量增加了26倍;且体外发酵后,谷氨酸钠的转化率达72.36%。16S微生物多样性分析结果显示,与原始粪便样本相比,添加谷氨酸钠体外发酵后拟杆菌门（Bacteroidete）和变形菌门（Proteobateria）相对丰度升高（P<0.05）,厚壁菌门（Firmicutes）和放线菌门（Actinobacteria）相对丰度降低（P<0.01）;添加谷氨酸钠显著提高了埃希氏菌属（Escherichia-Shigella）和拟杆菌属（Bacteroides）的相对丰度（P<0.01）。研究表明,谷氨酸钠体外发酵可以提高发酵液中短链脂肪酸尤其是丁酸的产量,影响肠道微生物的组成结构及功能,并且谷氨酸钠可通过肠道微生物体外发酵转化生成GABA。

关键词: 谷氨酸, 体外发酵, 肠道微生物, γ-氨基丁酸;, 短链脂肪酸

Abstract:

This study aims to investigate the effects of monosodium glutamate on the composition and functions of human gut microbes. In vitro fermentation of gut microbes using sodium glutamate as substrate was conducted,and the content of short-chain fatty acids（SCFA）and γ-aminobutyric acid（GABA）in the fermentation broth was determined. The results showed that the total SCFA yield in the fermentation with monosodium glutamate was significantly higher than the control without substrate（P<0.01）,and the content of butyric acid increased by 26 times. The conversion rate of monosodium glutamate reached 72.36% after in vitro fermentation. The results from in vitro fermentation with monosodium glutamate showed that the relative abundance of Bacteroidete and Proteobateria phyla in vitro fermentation with monosodium glutamate increased（P<0.05）if compared with the original feces,while that of Firmicutes and Actinobacteria phyla decreased（P<0.01）. Escherichia-Shigella and Bacteroides genera increased（P<0.01）while monosodium glutamate was added. Our results indicate that in vitro fermentation with monosodium glutamate increase the content of SCFAs in fermentation broths,especially the butyric acid,and affect the composition and function of human gut microbes;moreover,monosodium glutamate may convert into GABA via in vitro fermentation with gut microbes.

Key words: glutamate, in vitro fermentation, gut microbes, γ-aminobutyric acid;, short-chain fatty acid

刘淑君, 陈苗, 王凤忠, 包郁明, 辛凤姣, 温博婷. 谷氨酸（钠）对人体肠道菌群影响的体外发酵研究[J]. 生物技术通报, 2020, 36(12): 104-112.

LIU Shu-jun, CHEN Miao, WANG Feng-zhong, BAO Yu-ming, XIN Feng-jiao, WEN Bo-ting. In Vitro Fermentation of Monosodium Glutamate with Human Gut Microbes[J]. Biotechnology Bulletin, 2020, 36(12): 104-112.

图/表 8

图1 谷氨酸钠体外发酵24 h发酵液产气气压值 CK：空白对照组;FS：谷氨酸钠添加组,***P<0.001

表1 谷氨酸钠体外发酵24 h SCFAs产量（N=10）

项目/（mmol·L^-1）	CK	FS	P
总酸	13.37±0.67	62.26±10.91	<0.01
乙酸	10.47±0.31	47.73±9.54	<0.01
丙酸	1.69±0.27	5.79±0.39	<0.01
丁酸	0.24±0.02	6.28±1.92	<0.01
异丁酸	0.25±0.09	0.30±0.13	0.74
戊酸	0.04±0.01	1.02±0.72	0.19
异戊酸	0.67±0.25	1.12±0.48	0.42

图2 谷氨酸钠体外发酵24 h发酵液的pH值 CK：空白对照组;FS：谷氨酸钠添加组,* P<0.05

图3 谷氨酸钠体外发酵24 h发酵液的GABA含量 HF：原始粪便组;FS：谷氨酸钠添加组,**** P<0.0001,下同

图4 谷氨酸钠体外发酵24 h发酵液中GAD的活力

图5 谷氨酸钠体外发酵前后群落Alpha多样性（A）和主坐标分析（PCoA）（B） ** P<0.01

图6 谷氨酸钠体外发酵过程中肠道微生物群落组成变化门水平（A）和属水平（B）

图7 谷氨酸钠体外发酵氨基酸代谢通路图

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