Steroids and Squalene in Methylococcus capsulatus grown on Methane

Abstract

THE ubiquitous occurrence of steroids in nature, and their fundamental importance for plant and animal life, are well known. Until 1967, steroids had been encountered only in eukaryotic organisms, and had not been detected in prokaryotic organisms, the bacteria and blue–green algae. In recent years, sterols and the sterol precursor, squalene, have been detected in several classes of such organisms (Table 1). Quantitative studies are few, but they indicate that the amounts of steroids (expressed as a percentage of dry weight of organism) found in the prokaryotes are substantially lower than those of eukaryotes. Here we report that the bacterium Methylococcus capsulatus, grown on methane as the sole carbon source, contains comparatively large amounts of squalene and sterols.