title: [Cryoprotection of compatible-solutes for Methanolobus psychrophilus R15].
abstract: Methanolobus psychrophilus R15, isolated from the Zogei wetland at Tibetan plateau, is a cold-active methanogenic archaeon growing from 0 to 30 degrees C and optimally at 18 degrees C. R15 grew in the NaCl concentrations ranging from 5 to 800 mmol/L.
  
  
  OBJECTIVE
  This study aimed to find compatible solutes that can improve the growth of R15 at cold, and the possible function as cryoprotectant.
  
  
  METHODS
  Using LC-MC we determined the accumulated substances in the R15 cells growing at lower temperatures, as well as in the cold-shocked cells; by supplementing the accumulated substances and the chemicals known as the bacterial compatible solutes in the R15 culture, we detected their functions of assisting the cold-growth of R15; by adding the detected compatible solutes into the glutamate dehydrogenase (GDH), we determined the enzymatic stabilities at lower temperatures.
  
  
  RESULTS
  Choline and betaine were accumulated both in the 4 degrees C-cultured and 4 degrees C -shocked 30 degrees C culture of R15. It was determined that choline, betaine, glycine, carnitine, acetoin and ectoine all improved the growth of R15 at cold. Choline, betaine and glycine could enhance the stability of GDH at low temperature.
  
  
  CONCLUSIONS
  Some compatible solutes can act as the cryoprotectant for methanogenic archaea, which expands our knowledge of the physiological functions of the compatible solutes.
authors.affiliation: State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China. wuyue3000@sina.com
authors.forename: Yue
authors.initials: Y
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Guomin
authors.initials: G
authors.lastname: Ai
authors.affiliation: State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Xiuzhu
authors.initials: X
authors.lastname: Dong
mesh_terms: D000599:Amino Acids, Diamino / Q000378:metabolism; D019843:Archaeal Proteins / Q000378:metabolism; D001622:Betaine / Q000378:metabolism*; D002794:Choline / Q000378:metabolism*; D003080:Cold Temperature; D003451:Cryoprotective Agents / Q000378:metabolism*; D019605:Euryarchaeota / Q000737:chemistry / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism*; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D050296:Microbial Viability
chemical_list: D000599:Amino Acids, Diamino; D019843:Archaeal Proteins; D003451:Cryoprotective Agents; D001622:Betaine; C045628:ectoine; D005969:Glutamate Dehydrogenase; D002794:Choline