title: Culture of low density E. coli cells in alginate-chitosan microcapsules facilitates stress resistance by up-regulating luxS/AI-2 system.
abstract: 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.
authors.affiliation: 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.
authors.forename: Meng
authors.initials: M
authors.lastname: Gao
authors.affiliation: 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.
authors.forename: Huiyi
authors.initials: H
authors.lastname: Song
authors.affiliation: 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.
authors.forename: Huizhen
authors.initials: H
authors.lastname: Zheng
authors.affiliation: 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.
authors.forename: Ying
authors.initials: Y
authors.lastname: Ren
authors.affiliation: 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.
authors.forename: Shen
authors.initials: S
authors.lastname: Li
authors.affiliation: College of Environment and Chemical Engineering, Dalian University, Dalian Economic Technological Development Zone, Dalian 116622, PR China. Electronic address: liuxd@dicp.ac.cn.
authors.forename: Xiudong
authors.initials: X
authors.lastname: Liu
authors.affiliation: Laboratory of Biomedical Material Engineering, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, PR China. Electronic address: yuwt@dicp.ac.cn.
authors.forename: Weiting
authors.initials: W
authors.lastname: Yu
authors.affiliation: Laboratory of Biomedical Material Engineering, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, PR China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Ma
mesh_terms: D000143:Acids / Q000633:toxicity; D000464:Alginates / Q000737:chemistry; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002214:Capsules / Q000737:chemistry / Q000494:pharmacology*; D013437:Carbon-Sulfur Lyases / Q000235:genetics / Q000378:metabolism*; D048271:Chitosan / Q000031:analogs & derivatives*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D006714:Homoserine / Q000031:analogs & derivatives* / Q000378:metabolism; D007783:Lactones / Q000378:metabolism*; D053038:Quorum Sensing; D013312:Stress, Physiological; D015854:Up-Regulation
chemical_list: D000143:Acids; D000464:Alginates; D001426:Bacterial Proteins; D002214:Capsules; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D006714:Homoserine; D048271:Chitosan; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria
keywords: Alginate–chitosan; Entrapped low-density cells with culture; Microencapsulation; Quorum sensing; Viability