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SUMMARY: The lipids of soil micro-organisms harvested from simple and complex media varied from 2 to 20% in bacteria, 10 to 20% in fungi, 2.5 to 15% (w/w) in algae. The bulk of the lipid usually consisted of polar compounds; paraffinic hydrocarbons comprised 0.008 to 2.7% in bacteria, 0.04 to 0.7% in fungi, 0.08 to 2.9% (w/w) in algae. Lipid contents of algae were more affected by growth medium composition than were those of the bacteria and fungi. Gas–liquid chromatography showed that the hydrocarbons were paraffins in the range C16–36. The hydrocarbon patterns varied with species and growth medium. A peak in the range C27–31 was usual in bacteria with sometimes a minor peak in the range C18–22. The fungi exhibited slightly more stable hydrocarbon patterns (except Trichoderma viride) than bacteria and most showed major and minor paraffin peaks in similar regions.
The algae showed a peak at C17 regardless of the growth medium but Tetraspora gelatinosa showed an increase in C25 and C27 paraffin content when grown with acetate. The ratio of paraffin chains consisting of odd numbers of carbon atoms to those containing even numbers of carbon atoms was around unity for bacteria and fungi, also for T. gelatinosa when it was grown on CO2 as sole carbon source. The Nostoc sp. and T. gelatinosa (grown with CO2 plus acetate) contained predominantly Codd paraffins.