Studies upon the methane-producing bacteria

Summary

• 1. A survey has been given of the non-spore-forming methaneproducing organisms on the basis of the rare descriptions scattered throughout the literature.

• 2. The reasons for the great difficulty of isolating these organisms have been discussed and as a result methods have been developed which make possible the growth of various representatives of this group in solid media.

• 3. For the first time highly purified cultures of four different types have been obtained by transferring single colonies into appropriate culture media but it has not as yet been possible to isolate strictly pure cultures.

• 4. Nevertheless, the purified cultures allowed of a positive identification on the basis of morphological and physiological characters of four clearly distinct types of methane-producing organisms which have been described under the names of Methanosarcina methanica, Methanococcus Mazei, Methanobacterium Söhngenii, and Methanobacterium Omelianskii.