Coryneform bacteria of the Arthrobacter type and their reserve material

Summary

Soil arthrobacters in contrast with coryneform bacteria from cheese surfaces may accumulate large amounts of an intracellular polysaccharide. This accumulation of reserve material leads to a much enlarged cell size.

The highest polysaccharide contents were found in nutrient media containing relatively high amounts of glucose and inadequate amounts of nitrogen or phosphorus. Sulphur deficiency and a low pH of the media also favoured accumulation of the reserve material.

Investigation of the structure of the isolated polysaccharide by the methylation technique, the periodate method and β-amylolysis showed that it was a glycogen with an exceptionally high degree of branching $(\overline {CL} 7 - 9,\overline { ECL} 4 - 5 and \overline {ICL} 2 - 3 {\text{of glucose units)}}$. This structure is very similar to that of glycogen phosphorylase limit dextrin.

Of the various enzymes required for the synthesis and breakdown of glycogen the debranching enzyme was found to be absent from cell-free extracts of soil arthrobacters. This suggests that in vivo the poor activity of this enzyme is responsible for the accumulation of a divergent type of glycogen viz. glycogen phosphorylase limit dextrin.

Nitrogen deficiency promotes polysaccharide accumulation by increasing the supply of glucose-1-phosphate, the essential precursor of glycogen.