Microbial Transformation of Phenazines by Aspergillus Sclerotiorum

SUMMARY

Aspergillus sclerotiorum Huber was observed to produce a bright red pigment (Compound A) when grown in mixed culture with a bacterium, Pseudomonas chlororaphis (Guignard & Sauvageau) Bergey et al. The stimulatory factor provided by the pseudomonad was established as oxychlororaphine (phenazine-1-carboxamide). A. sclerotiorum was the only organism among 64 microbial species, including 25 aspergilli, to produce Compound A from oxychlororaphine under the conditions of our test. Further, among 19 structurally related compounds tested, only oxychlororaphine and phenazine-1-carboxylic acid led to the production of Compound A.

Compound A was isolated by solvent extraction and crystallized by sublimation as small yellow needles, mp > 300 C (dec), molecular weight 240. The compound is bright red in solutions of pH 4.5 to 8.5, but is yellow in strongly acid solutions and orange in strongly basic ones. Experimental evidence presented indicates crystalline Compound A is probably 3-hydroxyphenazine-1-carboxylic acid, and that its production by A. sclerotiorum involves the microbial transformation of a phenazine, i.e., the hydroxylation of phenazine-1-carboxylic acid, or the deamination and hydroxylation of phenazine-1-carboxamide.