es504251v_si_001.pdf (2.52 MB)
Zinc Oxide Nanoparticles Cause Inhibition of Microbial Denitrification by Affecting Transcriptional Regulation and Enzyme Activity
journal contribution
posted on 2014-12-02, 00:00 authored by Xiong Zheng, Yinglong Su, Yinguang Chen, Rui Wan, Kun Liu, Mu Li, Daqiang YinOver the past few decades, human
activities have accelerated the
rates and extents of water eutrophication and global warming through
increasing delivery of biologically available nitrogen such as nitrate
and large emissions of anthropogenic greenhouse gases. In particular,
nitrous oxide (N2O) is one of the most important greenhouse
gases, because it has a 300-fold higher global warming potential than
carbon dioxide. Microbial denitrification is a major pathway responsible
for nitrate removal, and also a dominant source of N2O
emissions from terrestrial or aquatic environments. However, whether
the release of zinc oxide nanoparticles (ZnO NPs) into the environment
affects microbial denitrification is largely unknown. Here we show
that the presence of ZnO NPs lead to great increases in nitrate delivery
(9.8-fold higher) and N2O emissions (350- and 174-fold
higher in the gas and liquid phases, respectively). Our data further
reveal that ZnO NPs significantly change the transcriptional regulations
of glycolysis and polyhydroxybutyrate synthesis, which causes the
decrease in reducing powers available for the reduction of nitrate
and N2O. Moreover, ZnO NPs substantially inhibit the gene
expressions and catalytic activities of key denitrifying enzymes.
These negative effects of ZnO NPs on microbial denitrification finally
cause lower nitrate removal and higher N2O emissions, which
is likely to exacerbate water eutrophication and global warming.