Methanosarcina mazei JC2, a new methanogenic strain isolated from lake sediments, that does not use H2/CO2.

A new mesophilic methanogenic strain, which produced methane from acetate, methanol, and methylamines, was isolated from lake sediments obtained from the lake Banyoles, near Girona (Spain). The cells were irregular in shape, from 1 to 3 micron in diameter, aggregated in masses of a few to several hundred units. Colonies were about 1-2 mm and irregularly shaped. Their color was yellow or white. Growth occurred throughout the pH range of 5 to 9 with optimal growth around pH 7. The optimal growth temperature was 37 degrees C. The molar deoxiribonucleic acid base composition was 37.2% (G + C). Studies of DNA homologies showed that this isolated was a strain of Methanosarcina mazei, but it differs from other reported strains, in that was not able to use H2/CO2 for growth or methane production.