青藏高原不同海拔梯度厌氧氨氧化细菌丰度及其生物多样性空间分布

厌氧氨氧化作为新型微生物氮循环过程,已经成为国内外研究热点.目前对厌氧氨氧化细菌的研究主要集中在海洋生态系统中,而在陆地生态系统外源氮污染物较少的地区是否存在厌氧氨氧化过程且其在氮循环中发挥的作用,还很少有相关报道.本研究应用分子生物学技术研究了氮污染负荷较低的青藏高原地区不同海拔湿地和旱地土壤样品中厌氧氨氧化细菌的丰度及其生物多样性.结果表明,在青藏高原地区,普遍存在厌氧氨氧化细菌.使用厌氧氨氧化细菌特异性引物HSBeta396f/HSBeta742r进行定量发现,厌氧氨氧化细菌丰度随着海拔的升高而降低.垂向尺度上,海拔较低地区表层样品厌氧氨氧化细菌丰度高于底层样品,海拔较高地区则相反.通过构建厌氧氨氧化细菌系统发育分析发现,青藏高原地区厌氧氨氧化细菌的生物多样性较高,且多数可能属于新型厌氧氨氧化细菌.该区域湿地沉积物样品厌氧氨氧化细菌生物多样性明显低于旱地土壤样品.湿地沉积物样品厌氧氨氧化细菌生物多样性与海拔无明显关系,但旱地土壤样品厌氧氨氧化细菌生物多样性随着海拔的增高有上升趋势.

Spatial distribution of anammox bacteria abundance and biodiversity along altitude gradient in Qinghai-Tibet Plateau

As a new microbial nitrogen cycle process, anaerobic ammonium oxidation (anammox) has become a hot spot of scientific research all over the world in recent years. Current research on anammox is mainly concentrated on the marine ecosystem, and there are few reports on whether anammox process exists in areas with less allochthonous nitrogen sources and its role in the nitrogen cycle in terrestrial ecosystem. Using molecular biology methods, the abundance and biodiversity of anammox bacteria in sediment/soil samples from wetlands and drylands along the altitude gradient in Qinghai-Tibet Plateau region with low nitrogen pollution were studied in this article. The results showed that anammox existed widely in Qinghai-Tibet Plateau. Moreover, the quantification of anammox bacteria using the specific primers (HSBeta396f/HSBeta742r) showed that the abundance of anammox bacteria decreased while altitude increased. On the vertical scale, anammox bacterial abundance in samples from surface layers was higher than that in deeper layers in the area with low altitude (2000~4000 m), and the opposite is the case in the area with high altitude (5000 m). The biodiversity of anammox bacteria in Qinghai-Tibet Plateau was very high based on the analysis of phylogenetic tree, and most of them might belong to some new types of anammox bacteria. Anammox bacterial biodiversity of wetland sediment samples was obviously lower than that of dryland soil samples in this area. Moreover, there was no significant relationship between anammox bacterial biodiversity and altitude in wetland sediment samples, but anammox bacterial biodiversity in dryland soil samples had a rising trend when the altitude increased.