Neglected Dissimilatory
Nitrate Reduction to Ammonium
Pathway of Nitrate Reduction in the Chinese Marginal Sea and Its Microbial
Community Assembly Driven by Stochastic Processes
posted on 2024-02-10, 14:11authored byYiyi Zhao, Tong Zhang, Daqian Qi, Liangke Xie, Shou-Qing Ni
Nitrate
reduction as a key process of the marine biological nitrogen
cycle has received significant attention, yet little is known about
the transformation and fate of nitrate in marginal seas, which bear
higher loads of nitrogen pollution. In this study, we took the Bohai
and Yellow Sea (BYS) as an example and proposed a large-scale measurement
of nitrogen transformations in marginal sea, with the aim of exploring
the imprint of nitrate reduction and microbial transformation mechanisms
in BYS. Our results showed that dissimilatory nitrate reduction to
ammonium (DNRA) made a non-negligible contribution to nitrate reduction
in BYS, particularly in the Bohai Sea, with an average DNRA rate up
to 8.15 ± 6.30 μmol N/L/h. Pelobacter and Opitutus played important roles
as “module hubs” and “connectors” in the
DNRA intraspecific network. The moisture content, the concentration
of total nitrogen, total sulfur, and NH4+–N
of sediments, as well as the bottom water temperature and conductivity
had a significant correlation with DNRA-dominant and keystone species.
However, DNRA microbial community assembly was strongly driven by
stochastic processes in the BYS. Specifically, homogeneous dispersal
and ecological drift contributed 16.3% and 72.1% to DNRA community
assembly in the BYS, respectively. To the best of our knowledge, this
is the first report on the assembly mechanism of marine DNRA microbial
communities. The patterns and drivers of DNRA processes detected in
this study may induce novel insights into nitrate release, retention,
and removal in marginal seas.