Studies on the Metabolism of Arthrobacter globiformis

SUMMARY: A strain of Arthrobacter globiformis grew on a glucose + ammonium + salts medium (pH 7) when this was supplemented with biotin (10−8 m). Maximal and most rapid growth was obtained by aerobic incubation in shaken culture at 30°. A variety of sugars, sugar alcohols, dicarboxylic acids, some amino acids and miscellaneous compounds could replace the glucose in this medium, but various aromatic compounds, purines, pyrimidines and other amino acids did not support growth, though several of these substances were oxidized by washed suspensions. The organism was an obligate aerobe whose terminal electron transport was mediated by a cytochrome system. Enzymic analysis showed that glucose could be metabolized by the hexose monophosphate oxidation and Embden-Meyerhof pathways. No direct oxidation of glucose to gluconic and 2-oxogluconic acids, and no Entner-Dou- doroff pathway for the utilization of 6-phosphogluconate were demonstrable. Studies with differently 14C-labelled samples of glucose confirmed these findings and showed that in suspensions of organisms depleted of endogenous metabolites, the Embden-Meyerhof pathway was fully functional, accounting for c. 65 % of glucose utilization, the remaining 35 % proceeding by way of the hexose monophosphate cycle. The pyruvate so formed was normally further oxidized by the tricarboxylic acid cycle. The growth yield of A. globiformis on limiting amounts of glucose was no greater than that of Escherichia coli under the same condition. These observations are considered in relation to the allocation of A. globiformis in the autochthonous group of soil micro-organisms.