Temperature response of denitrification and anammox reveals the adaptation of microbial communities to in situ temperatures in permeable marine sediments that span 50° in latitude

[摘要] Despite decades of research on the physiology and biochemistry of nitrate/nitrite-respiring microorganisms, little is known regarding their metabolicresponse to temperature, especially under in situ conditions. Thetemperature regulation of microbial communities that mediate anammox anddenitrification was investigated in near shore permeable sediments at polar,temperate, and subtropical sites with annual mean temperatures ranging from−5 to 23 °C. Total N₂ production rates were determined usingthe isotope pairing technique in intact core incubations under diffusive andsimulated advection conditions and ranged from 2 to 359 μmol N m⁻² d⁻¹.For the majority of sites studied, N₂ removal was 2–7 times more rapid under simulated advective flow conditions. Anammoxcomprised 6–14% of total N₂ production at temperate and polarsites and was not detected at the subtropical site. Potential rates ofdenitrification and anammox were determined in anaerobic slurries in atemperature gradient block incubator across a temperature range of −1 °Cto 42 °C. The highest optimum temperature(T_opt) for denitrification was 36 °C and was observed insubtropical sediments, while the lowest T_opt of 21 °C wasobserved at the polar site. Seasonal variation in the T_opt was observedat the temperate site with values of 26 and 34 °Cin winter and summer, respectively. The T_opt values for anammox were9 and 26 °C at the polar and temperate sites,respectively. The results demonstrate adaptation of denitrifying communitiesto in situ temperatures in permeable marine sediments across a wide range oftemperatures, whereas marine anammox bacteria may be predominatelypsychrophilic to psychrotolerant. The adaptation of microbial communities toin situ temperatures suggests that the relationship between temperature andrates of N removal is highly dependent on community structure.

[学科分类] 地球化学与岩石