Hopanoids content

Poralla, K., T. Hartner, and E. Kannenberg (1984). Effect of temperature and pH on the hopanoid content of Bacillus acidocaldarius. FEMS Microbiol. Lett. 113 107-110. 

The concentrations of the total alkylthiophenes (except thiophene hopanoids) in the bitumens show a depth profile somewhat similar to that of the total sulfur content (cf. Figures 6a and Id). The high concentrations of alkylthiophenes in Facies B compared to A and C are consistent with the proposed incorporation of inorganic sulfur species into specific funtionalised lipids in anoxic marine environments (6-12). 

In bacteria, a family of molecules with a striking chemical similarity to cholesterol, the hopanoids, insert into the membrane hemilayer and stabilize membrane structure (figure 7.28 bacteriohopanetetrol). The effects of these prokaryotic cholesterol analogs are similar to those of cholesterol they broaden the gel-fluid phase transition, condense the bilayer, and reduce bilayer permeability. Contents of hopanoids in bacterial membranes may rise with acclimation temperature (Poralla et ah, 1984). 

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