The Diversity and Nitrogen Metabolism of Culturable Nitrate-Utilizing Bacteria Within the Oxygen Minimum Zone of the Changjiang (Yangtze River) Estuary
The Diversity and Nitrogen Metabolism of Culturable Nitrate-Utilizing Bacteria Within the Oxygen Minimum Zone of the Changjiang (Yangtze River) Estuary
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长江口最低氧区内可培养硝酸盐利用细菌的多样性及氮代谢
DOI：
10.3389/fmars.2021.720413
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发表时间：
2021-11-26
影响因子：
3.7
通讯作者：
Zhang, Dechao
中科院分区：
文献类型：
--
作者：
He, Wenxuan;Liu, Sizhen;Zhang, Dechao
氮循环是海洋地球化学循环中不可或缺的一部分，海洋最低含氧带（OMZ）中发生的反应介导了全球海洋氮的大量流失。本文采用选择性培养基和培养依赖法从长江口OMZ内17个站位的水体中分离出硝酸盐利用细菌。对可培养异养菌的微生物多样性、氮代谢和硝酸盐还原试验进行了研究。共获得164株分离株，主要隶属于变形菌门（81.1%）、放射菌门（5.5%）、拟杆菌门（12.3%）和厚壁菌门（0.6%）。铜绿假单胞菌、萘鞘氨醇杆菌和Zunongwangia profunda在大多数站点被发现。在24株代表性菌株中，有8株硝酸盐还原反应阳性，分别属于橙黄单胞菌属、盐单胞菌属、海水单胞菌属、假单胞菌属、海螺菌属和弧菌属。铜绿假单胞菌含有用于完全反硝化的基因（napAB、norBC、nirS和nosZ），并且可能负责介导反硝化。66%的代表性菌株（16/24）含有将硝酸盐还原为亚硝酸盐的基因（nasA，napAB或narGHI），79%的代表性菌株（19/24）具有将亚硝酸盐转化为氨的基因（nirA或nirBD），表明硝酸盐和亚硝酸盐可以作为电子受体产生铵，随后被用作还原氮源。本研究为了解长江口外膜区微生物多样性提供了新的认识，也为氮循环相关细菌的培养和开发提供了依据。
The nitrogen cycle is an indispensable part of the biogeochemical cycle, and the reactions that occur in the ocean oxygen minimum zone (OMZ) mediate much of the loss of nitrogen from oceans worldwide. Here, nitrate-utilizing bacteria were isolated from the water column at 17 stations within the OMZ of the Changjiang (Yangtze River) Estuary using selective media and a culture-dependent method. The microbial diversity, nitrogen metabolism and nitrate reduction test of culturable heterotrophic bacteria were examined. A total of 164 isolates were obtained; they were mostly affiliated with Proteobacteria (81.1%), Actinobacteria (5.5%), Bacteroidetes (12.3%), and Firmicutes (0.6%). Pseudomonas aeruginosa, Sphingobium naphthae, and Zunongwangia profunda were found at most stations. Among 24 tested representative strains, 8 were positive for nitrate reduction; they belonged to genera Aurantimonas, Halomonas, Marinobacter, Pseudomonas, Thalassospira, and Vibrio. Pseudomonas aeruginosa contained the genes (napAB, norBC, nirS, and nosZ) for complete denitrification and may be responsible for mediating denitrification. 66% representative isolates (16/24) contained genes for reducing nitrate to nitrite (nasA, napAB, or narGHI) and 79% representative isolates (19/24) possessed genes for converting nitrite to ammonia (nirA or nirBD), suggesting that nitrate and nitrite could act as electron acceptors to generate ammonium, subsequently being utilized as a reduced nitrogen source. This study improves our understanding of the microbial diversity within the OMZ of Changjiang Estuary and may facilitate the cultivation and exploitation of bacteria involved in the nitrogen cycle.