AUTHOR=Zhao Guihua , He Hui , Yue Ming , Wang Hualong , Shao Hongbing , Wang Min 

TITLE=Differential responding patterns of the nirK-type and nirS-type denitrifying bacterial communities to an Ulva prolifera green tide in coastal Qingdao areas

JOURNAL=Frontiers in Marine Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.1063585

DOI=10.3389/fmars.2022.1063585

ISSN=2296-7745

ABSTRACT=<p>Coastal eutrophication may be a vital inducement of green tide. Denitrification is an important nitrogen removal pathway that involves a series of enzymatic reactions. The rate-limiting step in the conversion of nitrite to nitric oxide is encoded by two functionally equivalent but structurally distinct genes, copper-containing nitrite reductase gene (<italic>nirK</italic>) and cytochrome cd1-containing nitrite reductase gene (<italic>nirS</italic>). Here, we used Illumina Miseq sequencing approach to examine the variations in denitrifying bacterial community characteristics and interactions during an <italic>Ulva prolifera</italic> green tide in coastal Qingdao areas. Our findings suggested that the variations in the denitrifying bacterial community structure during the green tide were closely related to the changes of chlorophyll <italic>a</italic> content, salinity and dissolved oxygen content. The <italic>nirK</italic>-type denitrifying bacteria were more sensitive to green tide than the <italic>nirS</italic>-type denitrifying bacteria. Additionally, the <italic>nirK</italic>-type denitrifying bacterial interactions were more stable and complex during the outbreak phase, while the <italic>nirS</italic>-type denitrifying bacterial interactions were more stable and complex during the decline phase. All of these characters demonstrated that the <italic>nirK</italic>-type and <italic>nirS</italic>-type denitrifying bacteria respond differently to the green tide, implying that they may occupy different niches during the green tide in coastal Qingdao areas.</p>