Showing papers on "Methanosarcina barkeri published in 1977"

Lack of peptidoglycan in the cell walls of Methanosarcina barkeri

Abstract: Neither muramic acid and glucosamine nor d-glutamic acid or other amino acids typical of peptidoglycan were found in cell walls of two strains of Methanosarcina barkeri. The main components are galactosamine, neutral sugars and uronic acids. Therefore, the structural component of the cell wall most likely consists of an acid heteropolysaccharide, resembling that of Halococcus morrhuae. It is, however, not sulfated.

Acetate, a key intermediate in methanogenesis

Abstract: Acetate is the chief precursor of methane in anaerobic fermentations. Methane can be formed from H 2 and CO 2 by most methanogenic bacteria, but these substrates can also be converted to acetate by Clostridium aceticum , isolated from sludge. Its activity may increase the fraction of methane arising from acetate. Anaerobic 2% Ca acetate mineral enrichments forming methane were transferred weekly with a one-sixth volume inoculum. The rate of methane production was 9 μmoles ml −1 day −1 . Methanosarcina barkeri was the chief methanogen in the enrichment but numerous non-methanogens were present, three of which were isolated. In pure cultures of M. barkeri in medium supplemented with trypticase and yeast extract the rate of methanogenesis was 20 ymoles ml −1 day −1 , and similar supplementation of the enrichment culture increased the rate from 9 to 23 μmoles ml −1 day −1 . The rate of methane production was affected not only by M . barkeri but also by the non-methanogens in the enrichment. Microbiological analyses of methanogenic ecosystems is recommended as a means to provide clues of value in practical applications.