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The production by Arthrobacter globiformis of an extracellular red pigment in synthetic mineral salts medium was governed by both the conditions of aeration and the trace metals present. Pigment production was the same with either ammonium or nitrate as the nitrogen source. Stand flasks gave approximately the same cell yield as shake cultures but growth was much slower and no pigment was produced. Mn ++ was required for maximal pigment production. Zn ++ and Co ++ enhanced pigment production in the presence of Mn ++ but could only partially replace it. The pigment was ether-extractable from culture supernatant fluid acidified with acetic acid.Absorption spectra showed peaks at 620, 565, 527, 495, and 395 mμ. These as well as the extraction properties of the pigment coincided with those reported for coproporphyrin-III.
Middleton et al. (Tue,) studied this question.