Growth and physiological properties of wild type and mutants of Halomonas subglaciescola DH-1 in saline environment.
A halophilic bacterium was isolated from fermented seafood. The 16S rDNA sequence identity between the isolate and Halomonas subglaciescola AJ306801 was above 95%. The isolate that did not grow in the condition without NaCl or in the condition with other sodium (Na+) or chloride ions (Cl-) instead of NaCl was named H. subglaciescola DH-1. Two mutants capable of growing without NaCl were obtained by random mutagenesis, of which their total soluble protein profiles were compared with those of the wild type by two-dimensional electrophoresis. The external compatible solutes (betaine and choline) and cell extract of the wild type did not function as osmoprotectants, and these parameters within the mutants did not enhance their growth in the saline environment. In the proton translocation test, rapid acidification of the reactant was not detected for the wild type, but it was detected for the mutant in the condition without NaCl. From these results, we derived the hypothesis that NaCl may be absolutely required for the energy metabolism of H. subglaciescola DH-1 but not for its osmoregulation, and the mutants may have another modified proton translocation system that is independent of NaCl, except for those mutants with an NaCl-dependent system.
Department of Biological Engineering, Seokyeong University, Seoul 136-704, Korea.
Hye Jeong
HJ
Ryu
Yoo Jung
YJ
Jeong
Doo Hyun
DH
Park
D001622:Betaine / Q000378:metabolism; D002794:Choline / Q000378:metabolism; D003470:Culture Media; D020632:Halomonas / Q000235:genetics / Q000254:growth & development* / Q000502:physiology*; D009154:Mutation; D009994:Osmolar Concentration; D012965:Sodium Chloride / Q000378:metabolism* / Q000494:pharmacology; D014882:Water-Electrolyte Balance
D003470:Culture Media; D001622:Betaine; D012965:Sodium Chloride; D002794:Choline