The constituent sugars of the extracellular polysaccharide produced by an enrichment culture, growing on methane as sole carbon source, were identified as glucose, galactose, mannose, fucose and rhamnose, in the approximate molar ratios of 1·00: o· 36: 0·19 : O· 31 : 0·16. When the culture was grown on methanol as sole carbon source, only glucose, galactose and mannose, in the approximate molar ratios of 1 ·00 : 0·67 : 0·42, were identified as components of the extracellular polysaccharide.The data support the concept that a methanol-utilizer, incapable of methane-utilization, produced a polysaccharide which was partially deoxygenated by a methane-utilizer when the two organisms were present in a mixed culture growing on methane as sole carbon source. An alternate possibility, that each polysaccharide was produced by a different organism, is discussed.

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