The widespread occurrence of extended hopanoids in sediments and petroleums illustrates
the importance of bacterial lipid contributions to geological materials1. In archaebacteria …

Isoprenoids, the general class of natural products biosynthesized from isoprene units, are
abundant in nature. Many isoprenoids are also found in sediments, sedimentary rocks and …

Glycerol tetraethers with head-to-head isoprenoid 40-carbon chains that are typical of
archaebacteria, in particular of methanogens, were identified in the polar lipids of sediments …

Sulphur is a significant component of the organic matter in recent and ancient sediments
and in petroleums1, 2, yet the precise nature of its association and incorporation is poorly …

ISOPRENOID hydrocarbons, fatty acids and alcohols occur in ancient rocks, oil shales,
young sediments and living organisms1, 2. During thermal alteration experiments on a …

Large amounts of methane are produced in marine sediments but are then consumed
before contacting aerobic waters or the atmosphere. Although no organism that can …

The sediments that now comprise the Messel shale1 accumulated 47±2 million years ago in
anaerobic waters at the bottom of a lake2. Subsequent depths of burial have not exceeded …

DURING the past decade, C27, C29, C30, and C31 modified pentacyclic triterpane
hydrocarbons, mainly hopanes, have been discovered in fossil fuels1–4. Besides their …

Biological formation of methane is the terminal process of biomass degradation in aquatic
habitats where oxygen, nitrate, ferric iron and sulphate have been depleted as electron …

Microbial lipids play an important role in the formation of geologically derived organic
matter1. Among these lipids the hopanoids have a key function as they show an almost …