Alkane degradation under anoxic conditions by a nitrate-reducing bacterium with possible involvement of the electron acceptor in substrate activation

摘要: Microorganisms can degrade saturated hydrocarbons (alkanes) not only under oxic but also anoxic conditions. Three denitrifying isolates (strains HxN1, OcN1, HdN1) able to grow conditions by coupling alkane oxidation CO2 with NO3− reduction N2 were compared respect their metabolism. Strains HxN1 and which are both Betaproteobacteria, utilized n-alkanes from C6 C8 C12 respectively. Both activate alkanes anaerobically in a fumarate-dependent reaction yielding alkylsuccinates, as suggested present previous metabolite gene analyses. However, strain HdN1 was unique several respects. It belongs the Gammaproteobacteria more versatile towards alkanes, utilizing range C30. Neither analysis of metabolites nor genes complete genome sequence hinted at activation. Moreover, whereas strains OcN1 grew NO3−, NO2− or N2O added medium, oxidized N2O; readily used for growth long-chain alcohols fatty acids. Results suggest that subsequently formed nitrogen compound other than is needed activation HdN1. From an energetic point view, nitrogen–oxygen species generally rather strong oxidants. They may enable enzymatic mechanisms possible sulfate methanogenesis thus allow special mode