Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (06): 1525-1530.doi: 10.3866/PKU.WHXB20110618

• BIOPHYSICAL CHEMISTRY • Previous Articles     Next Articles

Microcalorimetric Study of the Influence of Extracellular NaCl Concentration on the Growth Metabolism of Halobacterium halobiumZENG Chi1,* ZHU Jian-Yu

ZENG Chi1, ZHU Jian-Yu2   

  1. 1. School of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, P. R. China;
    2. School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, P. R. China
  • Received:2011-02-16 Revised:2011-04-05 Published:2011-05-31
  • Contact: ZENG Chi, ZHU Jian-Yu E-mail:zeng_chi@yahoo.com.cn; csuzhu@yahoo.com.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (31000050, 30700008) and Research Program of Hubei Provincial Department of Education, China (B20111701).

Abstract:

Microcalorimetry was used to study the influence of extracellular NaCl concentration on the growth metabolism of Halobacterium halobium (Hbt. halobium) using a TAM air isothermal microcalorimeter. The metabolic thermogenic curves of Hbt. halobium growth in different concentrations of NaCl were obtained using the ampoule method. The thermokinetic equations and parameters of Hbt. halobium growth were calculated and the relationship between each thermokinetic parameter and the concentration of NaCl was obtained. The results showed that the optimum NaCl concentration for Hbt. halobium growth was not a wide range from 3.5 mol L-1 to about 5.2 mol·L-1 (NaCl saturation), as is generally acknowledged, but just around 3.9 mol·L-1. For an extracellular NaCl concentration above 3.9 mol·L-1, the growth metabolism of Hbt. halobium decreased constantly with an increase in the NaCl concentration. Further investigation by transmission electron microscopy revealed that the Hbt. halobium cells growing in approaching NaCl saturation underwent plasmolysis, which interpreted the finding of microcalorimetry perfectly. All these results led to a new interpretation of the structural transformations of Hbt. halobium upon NaCl concentration altering.

Key words: Microcalorimetry, Haloarchaea, Extracellular NaCl concentration, Cell surface structure

MSC2000: 

  • O642