聚γ-谷氨酸分子结构变化在氯化钾降低发酵液黏度中的作用

doi:10.7506/spkx1002-6630-20200731-414

食品科学 ›› 2021, Vol. 42 ›› Issue (22): 148-154.doi: 10.7506/spkx1002-6630-20200731-414

• 生物工程 • 上一篇

聚γ-谷氨酸分子结构变化在氯化钾降低发酵液黏度中的作用

李凌甫，蒋莉，刘瑶，丁苏，陈桂光，梁智群，曾伟

（广西大学生命科学与技术学院，亚热带农业生物资源保护与利用国家重点实验室，广西微生物与酶工程技术研究中心，广西南宁 530004）

发布日期:2021-11-23
基金资助:
国家自然科学基金地区科学基金项目（31760452）；广西自然科学基金面上项目（2018GXNSFAA294018）；广西八桂青年学者项目

Role of Molecular Structure Changes of Poly-γ-glutamate in Reducing the Viscosity of Fermentation Broth by Potassium Chloride

LI Lingfu, JIANG Li, LIU Yao, DING Su, CHEN Guiguang, LIANG Zhiqun, ZENG Wei

(State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Microorganism and Enzyme Research Center of Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning 530004, China)

Published:2021-11-23

摘要/Abstract

摘要： 为分析培养基中添加KCl能够显著降低聚γ-谷氨酸（poly-γ-glutamic acid，PGA）发酵液黏度的原因，从PGA分子结构方面开展相关研究。以培养基中不添加KCl为对照，利用凝胶渗透色谱、手性色谱、静态光散射、圆二色谱、红外光谱、热分析以及剪切黏度测定等方法，对培养基中添加15 g/L KCl的PGA分子结构进行系统表征。结果表明，培养基中添加15 g/L KCl时，PGA分子质量下降13.9%，PGA分子中D-谷氨酸比例从47.66%提高至53.77%，PGA在水溶液中更容易形成聚集态，构象由β-折叠转变为β-折叠和α-螺旋并存，PGA水溶液剪切黏度降低32.08%。KCl降低发酵液黏度可能与PGA分子结构变化有关。本研究从PGA分子结构方面为充分理解KCl降低发酵液黏度的原因提供了一些新信息。

关键词: 枯草芽孢杆菌；聚γ-谷氨酸；发酵液黏度；氯化钾；分子结构

Abstract: This study sought to analyze the reason why the viscosity of the fermentation broth containing poly-γ-glutamic acid (PGA) can be significantly reduced by adding KCl to the culture medium from the perspective of PGA’s molecular structure. The medium without KCl was used as a control. The molecular structure of PGA obtained from the medium with addition of 15 g/L KCl was characterized systematically by gel permeation chromatography (GPC), chiral chromatography (CC), static light scattering (SLS), circular dichroism (CD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermal analysis and shear viscosity measurement. The results showed that the molecular mass of PGA decreased by 13.9%, the proportion of D-glutamic acid in PGA increased from 47.66% to 53.77%, the PGA was more likely to form an aggregation state in aqueous solution, the conformation changed from single β-sheet to the co-existence of β-sheet and α-helix, and the shear viscosity of PGA aqueous solution decreased by 32.08% when 15 g/L KCl was added to the medium. The decrease of the fermentation broth’s viscosity by KCl may be related to the molecular structural change of PGA. This study provides some new information useful for understanding the mechanism of KCl for reducing the fermentation broth’s viscosity from the perspective of PGA’s molecular structure.

Key words: Bacillus subtilis; poly-γ-glutamic acid; fermentation broth viscosity; potassium chloride; molecular structure

中图分类号:

Q815

李凌甫，蒋莉，刘瑶，丁苏，陈桂光，梁智群，曾伟. 聚γ-谷氨酸分子结构变化在氯化钾降低发酵液黏度中的作用[J]. 食品科学, 2021, 42(22): 148-154.

LI Lingfu, JIANG Li, LIU Yao, DING Su, CHEN Guiguang, LIANG Zhiqun, ZENG Wei. Role of Molecular Structure Changes of Poly-γ-glutamate in Reducing the Viscosity of Fermentation Broth by Potassium Chloride[J]. FOOD SCIENCE, 2021, 42(22): 148-154.

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聚γ-谷氨酸分子结构变化在氯化钾降低发酵液黏度中的作用

Role of Molecular Structure Changes of Poly-γ-glutamate in Reducing the Viscosity of Fermentation Broth by Potassium Chloride

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