Microbial Metabolism of Isoprenoid Alkane Pristane

Abstract

Rhodococcus (a group of Nocardia spp. in the eighth edition of Bergey's Manual of Determinative Bacteriology; now re-classified as Rhodococcus spp. by Goodfellow and Alderson, 1977) sp. BPM 1613 isolated from soil utilized pristane as the sole source of carbon, and produced monoterminal oxidation products and other pristane-derived metabolites. Results on monoterminal oxidation products, pristanol, pristanic acid, pristyl pristanate and pristyl aldehyde have been reported in our previous paper. In the present work, three acidic metabolites (products A, B and C) and the monoterminal oxidation products were isolated and their chemical structures were determined. The products were extracted with diethyl ether from the culture broth and purified by column chromatography and preparative thin-layer chromatography on silica gel. The yields of products A, B and C were 38mg, 138mg and 90mg/liter, respectively. On the basis of instrumental analysis, products A, B and C were determined as 2, 6-dimethylnonanedioic acid, 2, 6-dimethylheptanedioic acid and 2-methylpentanedioic acid, respectively. These products were recognized to be intermediates in the metabolic pathway of pristane, and this strain metabolized pristane through the following two pathways: (1) pristane→pristanic acid→β-oxidation, and (2) pristanic acid→pristanedioic acid (ω-oxidation)→β-oxidation.
The detailed characteristics of the BPM 1613 strain were examined. This strain was found to belong to Rhodococcus sp. on the basis of morphological and cultural characteristics. The physiological properties of BPM 1613 were similar to those of R. erythropolis, but some properties (not changing litmus milk, not decomposing adenine and L-tyrosine, not producing acid from inositol and trehalose, and not assimilating citrate, formate and lactate) were not consistent with those of R. erythropolis.