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Disaster and Earth Science

Sources of hopanoid

Hopanoid

Hopanoid lipids are largely confined to eubacteria although the knowledge of their phylogenetic distribution is incomplete. Both Gram-positive and Gram-negative eubacteria produce hopanoids. Hopanoids are relatively abundant in cyanobacteria, methanotrophic bacteria, and members of alpha-proteobacteria particularly the nitrogen-fixing eubacteria. Hopanoids commonly occur in bacterial strains with high guanine and cytosine characteristics of species that occupy stressful ecological niches.

Hopanoid

Their abundance may vary in response to osmotic stress (e.g. high salinity, sugar, or ethanol concentration) which increases the greater membrane stability. Hopanoid biosynthesis does not require molecular oxygen, these compounds have not yet been discovered in obligate anaerobes. Hopanoids have been detected in only approx. 30% of the bacterial species analyzed. The hopanoids also have not been detected in archaea or animals but small amounts occur in some ferns, mosses, and fungi.

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