ISSN:
1432-072X
Keywords:
Methane-oxidizing bacterium
;
Obligate methylotroph
;
Ribulose-monophosphate pathway
;
Internal membrane structure
;
Methylococcus
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract A methane-assimilating coccus was isolated from a continuous culture. Under certain conditions, in pure culture the cells grew in sarcina-like, refractile clusters. That these clusters resembled multiple-bodied cysts was confirmed by electron microscopy. In addition, tube-like structures, not previously reported in methane-oxidizing bacteria, were found. Motile cells, with one or, rarely, two flagella were occasionally observed. Methane and methanol were exclusively assimilated as the sole source of carbon and energy. Formaldehyde, formate, lower alkanes, alcohols and aldehydes, with the exception of acetaldehyde, were oxidized by cell suspensions. The presence of a number of key enzymes in cell-free extracts suggested that the ribulose-monophosphate pathway of carbon assimilation is active. This agreed with the internal membrane structure found (type I organism). Nitrate, ammonia, peptone, yeast extract, asparagine, aspartic acid and glutamic acid were assimilated as sources of nitrogen. No nitrogen fixation could be demonstrated. The cells contained 9.1–9.7% nitrogen and 7–10% lipid, dependent on the growth conditions. Poly-β-hydroxybutyric acid could not be detected. The guanine+cytosine (G+C) content of the DNA was found to be 56.3%. As a name for the organism Methylococcus mobilis sp. nov. is proposed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00427729
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