Hopanoid production by Desulfovibrio bastinii isolated from oilfield formation water
Résumé
Hopanoids are important lipid components of many bacterial groups and are therefore ubiquitous in soils, sediments, and rocks. Until recently, it was believed that the synthesis of hopanoids is restricted to at least microaerophilic bacteria and consequently geological findings of hopanoids were used as an indication for oxygenated settings. Recent studies, however, demonstrated the biosynthesis of hopanoids under strictly anoxic conditions by a few bacterial groups, although their relevance is still unclear. We therefore extended our previous work studying hopanoid production among members of the genus Desulfovibrio, a group of sulphate-reducing bacteria (SRB) widely distributed in marine sediments, water-logged soils, and oil reservoirs. We found three species (Desulfovibrio halophilus, Desulfovibrio vulgaris Hildenborough, and Desulfovibrio africanus) to be devoid of hopanoids. In contrast, Desulfovibrio bastinii contains high amounts of nonextended hopanoids and bacteriohopanepolyols, with diploptene, 17β(H),21β(H)- bacteriohopane-32,33,34,35-tetrol, and 17β(H),21β(H)-35- aminobacteriohopane-32,33,34-triol being the major compounds. Because the moderately halophilic D. bastinii was isolated from a deep subsurface oil formation water, a contribution of hopanoids by SRB to the intrinsic oil hopanoid inventory is feasible, which would influence hopanoidal compositions often used for organic-geochemical characterization purposes. Nevertheless, our data indicate that hopanoid production might be common, but not obligate in the genus Desulfovibrio. © 2009 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.