Amplicon sequencing of functional genes is a powerful technique to explore the diversity and abundance of microbes involved in biogeochemical processes. One such key process, denitrification, is of particular importance because it can transform nitrate (NO3−) to N2 gas that is released to the atmosphere. In nitrogen limited alpine wetlands, assessing bacterial denitrification under the stress of wetland desertification is fundamental to understand nutrients, especially nitrogen cycling in alpine wetlands, and thus imperative for the maintenance of healthy alpine wetland ecosystems. We applied amplicon sequencing of the nirS gene to analyze the response of denitrifying bacterial community to alpine wetland desertification in Zoige, China. Raw reads were processed for quality, translated with frameshift correction, and a total of 95,316 nirS gene sequences were used for rarefaction analysis, and 1011 OTUs were detected and used in downstream analysis. Compared to the pristine swamp soil, edaphic parameters including water content, organic carbon, total nitrogen, total phosphorous, available nitrogen, available phosphorous and potential denitrification rate were significantly decreased in the moderately degraded meadow soil and in severely degraded sandy soil. Diversity of the soil nirS-type denitrifying bacteria communities increased along the Zoige wetland desertification, and Proteobacteria and Chloroflexi were the dominant denitrifying bacterial species. Genus Cupriavidus (formerly Wautersia), Azoarcus, Azospira, Thiothrix, and Rhizobiales were significantly (P<0.05) depleted along the wetland desertification succession. Soil available phosphorous was the key determinant of the composition of the nirS gene containing denitrifying bacterial communities. The proportion of depleted taxa increased along the desertification of the Zoige wetland, suggesting that wetland desertification created specific physicochemical conditions that decreased the microhabitats for bacterial denitrifiers and the denitrification related genetic diversity.
Abell GCJ, Ross DJ, Keane JP, et al. (2013) Nitrifying and denitrifying microbial communities and their relationship to nutrient fluxes and sediment geochemistry in the Derwent Estuary, Tasmania. Aquatic Microbial Ecology 70(1): 63–75. https://doi.org/10.3354/ame01642CrossRefGoogle Scholar
Bremer C, Braker G, Matthies D, et al. (2007) Impact of plant functional group, plant species and sampling time on the composition of nirK–type denitifier communities in soil. Applied and Environmental Microbiology 73(21): 6876–6884. https://doi.org/10.1128/AEM.01536-07CrossRefGoogle Scholar
Cytryn E, Minz D, Gelfand I, et al. (2005) Sulfide–oxidizing activity and bacterial community structure in a fluidized bed reactor from a zero–discharge mariculture system. Environmental Science and Technology 39(6): 1802–1810. https://doi.org/10.1021/es0491533CrossRefGoogle Scholar
Kim YM, Cho HU, Lee DS, et al. (2011) Influence of operational parameters on nitrogen removal efficiency and microbial communities in a full–scale activated sludge process. Water research 45(17): 5785–5795. https://doi.org/10.1016 /j.watres.2011.08.063CrossRefGoogle Scholar
Smith CJ, Nedwell DB, Dong LF, et al. (2007) Diversity and abundance of nitrate reductase genes (narG and napA), nitrite reductase genes (nirS and nrfA), and their transcripts in estuarine sediments. Applied and Environmental Microbiology 73(11): 3612–3622. https://doi.org/10.1002/gepi.10246CrossRefGoogle Scholar
Yang YD, Hu YG, Wang ZM, et al. (2018) Variations of the nirS–, nirK–, and nosZ–denitrifying bacterial communities in a northern Chinese soil as affected by different long–term irrigation regimes. Environmental Science and Pollution Research 25 (14): 14057–14067. https://doi.org/10.1007/s11356-018-1548-7Google Scholar