Center for Environmental Diagnostics and Bioremediation, University of West Florida, 11000 University Parkway, Pensacola, FL 32514, USA.
Department of Geology, Lund University, Solvegatan 12, SE-223 62 Lund, Sweden.
FEMS Microbiol Lett. 2019 Jan 1;366(1). doi: 10.1093/femsle/fny288.
Increased organic loading to sediments from eutrophication often results in hypoxia, reduced nitrification and increased production of hydrogen sulfide, altering the balance between nitrogen removal and retention. We examined the effect of short-term exposure to various oxygen and sulfide concentrations on sediment nitrification, denitrification and DNRA from a chronically hypoxic basin in Roskilde Fjord, Denmark. Surprisingly, nitrification rates were highest in the hypoxic and anoxic treatments (about 5 μmol cm-3 d-1) and the high sulfide treatment was not significantly different than the oxic treatment. Denitrification in the hypoxic treatment was highest at 1.4 μmol cm-3 d-1 and significantly higher than the high sulfide treatment. For DNRA, the rate in high sulfide treatment was 2 μmol cm-3 d-1. This was significantly higher than all oxygen treatments that were near zero. In this system, nitrifiers rapidly recovered from conditions typically considered inhibiting, while denitrifiers had a more muted response. DNRA bacteria appear to depend on sulfide for nitrate reduction. Anammox was insignificant. Thus, in estuaries and coastal systems that experience short-term variations in oxygen and sulfide, capabilities of microbial communities are more diverse and tolerant of suboptimal conditions than some paradigms suggest.
富营养化导致沉积物中有机负荷增加，通常会导致缺氧、硝化作用减弱和硫化氢产量增加，从而改变氮去除和保留之间的平衡。我们研究了短期暴露于不同氧气和硫化物浓度对丹麦罗斯基勒峡湾长期缺氧盆地沉积物硝化、反硝化和DNRA 的影响。令人惊讶的是，缺氧和无氧处理中的硝化速率最高（约 5 μmol cm-3 d-1），而高硫化物处理与好氧处理没有显著差异。缺氧处理中的反硝化作用最高，为 1.4 μmol cm-3 d-1，明显高于高硫化物处理。对于 DNRA，高硫化物处理中的速率为 2 μmol cm-3 d-1，明显高于所有氧气处理，后者接近于零。在这个系统中，硝化菌迅速从通常被认为是抑制的条件中恢复过来，而反硝化菌的反应则较为温和。厌氧氨氧化作用不显著。因此，在经历氧气和硫化物短期变化的河口和沿海系统中，微生物群落的能力比一些范例所表明的更加多样化和能够耐受次优条件。
