Microbial Oxidatin of the Isioprenid Hydricarbon Squalene (Microbial Oxidation of Isoprenoid Hydrocarbons. Part III)

Abstract

Nocardia sp. BPM 1613, which was isolated from soil, utilized squalene (2, 6, 10, 15, 19, 23-hexamethyl-2, 6, 10, 14, 18, 22-tetracosahexaene) as the sole source of carbon and accumulated an oxidation product in the culture broth. The product was extracted with diethyl ether, chromatographed on a silica gel column and purified by repeated recrystallizations from hexane. On the basis of instrumental analyses, the structure of the product was confirmed as squalenedioic acid (2, 6, 10, 15, 19, 23-hexamethyl-2, 6, 10, 14, 18, 22-tetracosahexaene-1, 24-dioic acid). Cultural conditions were examined for production of squalenedioic acid from squalene by this strain. When urea was employed as a nitrogen source, the yield of squalenedioic acid was 3.41g/liter.
The assimilability of isoprenoid hydrocarbons (pristane, squalene and squalane) and monomethyl paraffins (2-, 3- and 4-methyldodecanes and 2-, 3-, 4- and 5-methylundecanes) was tested by ten strains of standard cultures (Candida lipolytica, Can. rugosa, Can. tropicalis, Pichia farinosa, Arthrobacter simplex, Corynebacterium equi, Cor. fascians, Mycobacterium smegmatis, Nocardia asteroides and N. corallina) and four strains of isolated cultures (BPM 7713, BPI 3143 and NB 1802), including Nocardia sp. BPM 1613. In the case of isoprenoid hydrocarbons, pris-tane was easily assimilated by one standard culture (N. corallina) and all strains of isolated cultures, and squalene was utilized by the majority of tested strains, but squalane was assimilated only by NB 1802. In general, monomethyl paraffins having an internal methyl branch such as 4-methyldodecane were more resistant to microbial assimilation than those having an external branch such as 2-methyldodecane. Oxidation products of pristane, squalene, squalane and 2-, 3- and 4-methyldodecane were also examined by six strains (Can. lipolytica, Cor. equi, M. smegmatis, Nocardia sp. BPM 1613, BPM 7713 and NB 1802). All strains produced monoalcohol (pristanol) and monocarboxylic acid (pristanic acid) from pristane, and four strains (Can. lipolytica, Cor. equi, Nocardia sp. BPM 1613 and NB 1802) produced dicarboxylic acid (squalenedioic acid) from squalene. On the other hand, no strain tested accumulated oxidation products from squalane. In the case of monomethyldodecanes, all strains produced considerable amounts of monoalcohol from 4-methyldodecane, which has an internal methyl branch.