a Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, People's Republic of China.
Can J Microbiol. 2013 Dec;59(12):825-36. doi: 10.1139/cjm-2013-0516.
Nitrite reduction is regulated by nitrite reductase encoded by nirK and nirS genes. This study aimed to investigate the abundance and composition of nirK- and nirS-containing denitrifiers in response to Spartina alterniflora invasion at the Jiulong River estuary, China. The sediment samples (depth: 0-5.0 and 5.1-20 cm) were collected from 3 vegetation zones, 1 dominated by the exotic plant S. alterniflora, 1 dominated by the native plant Kandelia candel, and 1 dominated by the native plant Cyperus malaccensis, and from an unvegetated flat zone. nirK- and nirS-containing denitrifier population sizes were lower in the invaded and nonvegetated zones than in those dominated by native K. candel and C. malaccensis, which were impacted by depth - vegetation species interaction. The ratios of nirS to nirK abundance ranged from 42.10 to 677.27, with the lowest ratio found for the upper layer in the invaded zone. The nirK-containing denitrifier compositions showed a 35% similarity between invaded zone and others. Most of the sequences of nirK genes recovered from the S. alterniflora zone were specific and distinct from those of nirK genes recovered from other vegetation types; nirS genes in the invaded zone were highly divergent. These results reveal that S. alterniflora invasion has a significant effect on the abundance and composition of both nirK- and nirS-containing denitrifiers, and nirS-containing denitrifiers were less responsive to invasion than nirK-containing denitrifiers.
亚硝酸盐还原受编码 nirK 和 nirS 基因的亚硝酸盐还原酶调控。本研究旨在调查九龙江河口外来植物互花米草入侵后nirK-和 nirS-反硝化微生物的丰度和组成。从 3 种植被带（1 种主要为外来植物互花米草，1 种主要为本地植物秋茄，1 种主要为本地植物海三棱藨草，以及 1 种无植被带）和一个无植被的平坦区采集了 0-5.0 和 5.1-20 cm 深度的沉积物样品。与受深度-植被物种相互作用影响的本地秋茄和海三棱藨草占主导地位的区域相比，入侵和无植被区域的 nirK-和 nirS-反硝化微生物种群较小。nirS 与 nirK 丰度的比值范围为 42.10 至 677.27，入侵区上层的比值最低。nirK-反硝化微生物组成在入侵区和其他地区之间的相似度为 35%。从互花米草区回收的 nirK 基因序列中，有 35%与从其他植被类型回收的 nirK 基因序列具有相似性；而入侵区的 nirS 基因高度多样化。这些结果表明，互花米草入侵对 nirK-和 nirS-反硝化微生物的丰度和组成有显著影响，并且 nirS-反硝化微生物对入侵的响应程度低于 nirK-反硝化微生物。
