Uni-Bayreuth grafik-uni-bayreuth


Palmer, K; Drake, HL; Horn, MA: Association of Novel and Highly Diverse Acid-Tolerant Denitrifiers with N2O Fluxes of an Acidic Fen, Applied and Environmental Microbiology, 76 (4), 1125-1134 (2010)
Wetlands are sources of denitrification-derived nitrous oxide (N2O). Thus, the denitrifier community of an N2O-emitting fen (pH 4.7 to 5.2) was investigated. N2O was produced and consumed to sub-atmospheric concentrations in unsupplemented anoxic soil microcosms. Total cell counts and most probable numbers of denitrifiers approximated 1011 cells g and 108 cells g , respectively, in both 0 to 10 cm and 30 to 40 cm depths. Despite this uniformity, depth-related vmax values for denitrification in anoxic microcosms ranged from 1 to 24 and -19 to -105 nmol N2O h g , with maximal values occurring in the upper soil layers. Denitrification was enhanced by substrates that might be formed via fermentation in anoxic microzones of soil. N2O approximated 40% of total nitrogenous gases produced at in situ pH, which was likewise the optimal pH for denitrification. Gene libraries of narG and nosZ (encoding nitrate reductase and nitrous oxide reductase, respectively) from fen soil DNA yielded 15 and 18 species-level operational taxonomic units, respectively, many of which displayed phylogenetic novelty and were not closely related to cultured organisms. Although statistical analyses of narG and nosZ sequences indicated that the upper 20 cm of soil contained the highest denitrifier diversity and species richness, terminal restriction fragment length polymorphism analyses of narG and nosZ revealed only minor differences in denitrifier community composition from 0 to 40 cm soil depth. The collective data indicate that the regional fen harbors novel, highly diverse, acid-tolerant denitrifier communities capable of complete denitrification and consumption of atmospheric N2O at in situ pH.

last modified 2010-03-25