Content and composition of hopanoids in Zymomonas mobilis under various growth conditions

Abstract

By using a new method for quantification of the different hopanoid derivatives, a total hopanoid content of about 30 mg/g (dry cell weight) was observed in Zymomonas mobilis. This value is the highest reported for bacteria so far. The major hopanoids in Z. mobilis were the ether and glycosidic derivatives of tetrahydroxy-bacteriohopane, constituting about 41 and 49% of the total hopanoids. Tetrahydroxybacteriohopane itself, diplopterol, and hopene made up about 6, 3, and 1%, respectively. Only minor changes in hopanoid composition were observed with changes in growth conditions. Earlier reports on a correlation between hopanoid content and ethanol concentration in the medium could not be confirmed. Over a wide range of ethanol concentrations (5 to 60 g/liter), growth rates (0.08 to 0.25 h-1), and temperatures (25 to 37 degrees C), the molar ratio of hopanoids to phospholipids in the cells amounted to about 0.7. Only at growth rates of greater than 0.30 h-1 did the molar ratio increase to about 1.