Gao Meng, Song Huiyi, Zheng Huizhen, Ren Ying, Li Shen, Liu Xiudong, Yu Weiting, Ma Xiaojun
Laboratory of Biomedical Material Engineering, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, PR China; University of the Chinese Academy of Sciences, Beijing 100049, PR China.
College of Environment and Chemical Engineering, Dalian University, Dalian Economic Technological Development Zone, Dalian 116622, PR China.
Carbohydr Polym. 2016 May 5;141:160-5. doi: 10.1016/j.carbpol.2016.01.011. Epub 2016 Jan 9.
Entrapped low density cells with culture (ELDCwc) have been proved as a more effective way than direct entrapped high density cells (dEHDC) and free cells to protect probiotics from harsh environment, that is, to improve their stress resistance. The aim of this study was to investigate whether bacterial quorum sensing (QS) facilitated the stress resistance of Escherichia coli in microcapsules by detecting the expression of luxS/AI-2 system. As a result, both the expression of luxS gene and the concentration of autoinducer-2 (AI-2, QS signal molecule) have been discovered higher in ELDCwc than in dEHDC and free cells. Besides that, the luxS mutant E. coli strain was used as a negative control of QS to verify the influence of QS on bacterial stress resistance in microcapsules. The significantly decreased viability of luxS mutant strain in simulated gastric fluid also indicated that the QS played a critical role in protecting microorganisms from severe environment.
经培养的低密度包埋细胞（ELDCwc）已被证明是一种比直接包埋高密度细胞（dEHDC）和游离细胞更有效的保护益生菌免受恶劣环境影响的方法，即提高其抗逆性。本研究的目的是通过检测luxS/AI-2系统的表达，研究细菌群体感应（QS）是否促进了微胶囊中大肠杆菌的抗逆性。结果发现，ELDCwc中luxS基因的表达和自诱导物-2（AI-2，QS信号分子）的浓度均高于dEHDC和游离细胞。除此之外，luxS突变型大肠杆菌菌株被用作QS的阴性对照，以验证QS对微胶囊中细菌抗逆性的影响。luxS突变株在模拟胃液中的活力显著降低，这也表明QS在保护微生物免受恶劣环境影响方面起着关键作用。
