Effect of sodium chloride on growth and methane production of methanogens.

The effect of up to 263.7 mM sodium chloride on the growth and methane production by pure cultures of Methanospirillum hungatii GP1, Methanobacterium MOH, Methanobacterium thermoautotrophicum, and an unidentified methanogen was studied. Growth and methane production by M. hungatii GP1 were not affected up to 97.3 mM NaCl but there was some inhibition of growth at higher concentrations. Growth of Methanobacterium MOH was independent of sodium chloride concentration within the range investigated. For the unidentified methanogen, optimum growth and methane production occurred at 15.2 mM NaCl, while growth of M. thermoautotrophicum was not affected by sodium chloride concentrations up to 15.2 mM. Concentrations over 15.2 mM were inhibitory to these two organisms. The 15 mM sodium chloride concentration used by some investigators appears suitable for isolation and cultivation of methanogens since all the organisms tested in this study exhibited good growth and methane production at this salt concentration.