■三江源自然保护区位于青藏高原的核心区域,与高山沼泽,草甸和草原为主要生态系统类型。然而,这些高山生态系统中的微生物群落,它们的碳和氮降解代谢网络和限制因素尚不清楚。
■我们对高山沼泽中细菌和真菌的多样性进行了测序,草地,大草原,及其退化和人工恢复的生态系统,并分析了土壤环境条件。
■结果表明,与降解和恢复相比,水分含量对土壤微生物群落结构的影响更大。在高水分的高山沼泽和高山草甸中占主导地位的变形杆菌,而放线菌在低水分高山草原和人工草地中占主导地位。使用宏基因组测序对碳和氮降解和转化进行代谢网络分析,发现高原微生物缺乏全面高效的降解有机碳的酶系统,氮,和其他生物大分子,说明高山植被的短期退化对土壤微生物群落的基本组成没有影响。相关分析发现,高含水率草甸固氮能力强,它们的关键固氮酶与鞘氨醇单胞菌显著相关。在缺水的栖息地中,反硝化代谢得到了增强,和关键的酶,一氧化二氮还原酶,与藻球菌显着相关,并加速了氮的流失。此外,芽孢杆菌含有大量的淀粉酶(GH13和GH15)和蛋白酶(S8,S11,S26和M24),可能会促进人工修复草地中有机碳和氮的有效降解。
■这项研究说明了草甸退化的不可恢复性,并为改变微生物群落以恢复高山生态系统提供了基本信息。
UNASSIGNED: The Three-River Source Nature Reserve is located in the core area of the Qinghai-Tibetan Plateau, with the alpine swamp, meadow and steppe as the main ecosystem types. However, the microbial communities in these alpine ecosystems, and their carbon and nitrogen degrading metabolic networks and limiting factors remain unclear.
UNASSIGNED: We sequenced the diversity of bacteria and fungi in alpine swamps, meadows, steppes, and their degraded and artificially restored ecosystems and analyzed soil environmental conditions.
UNASSIGNED: The results indicated that moisture content had a greater influence on soil microbial community structure compared to degradation and restoration. Proteobacteria dominated in high moisture alpine swamps and alpine meadows, while Actinobacteria dominated in low moisture alpine steppes and artificial grasslands. A metabolic network analysis of carbon and nitrogen degradation and transformation using metagenomic sequencing revealed that plateau microorganisms lacked comprehensive and efficient enzyme systems to degrade organic carbon, nitrogen, and other biological macromolecules, so that the short-term degradation of alpine vegetation had no effect on the basic composition of soil microbial community. Correlation analysis found that nitrogen fixation was strong in meadows with high moisture content, and their key nitrogen-fixing enzymes were significantly related to Sphingomonas. Denitrification metabolism was enhanced in water-deficient habitats, and the key enzyme, nitrous oxide reductase, was significantly related to Phycicoccus and accelerated the loss of nitrogen. Furthermore, Bacillus contained a large number of amylases (GH13 and GH15) and proteases (S8, S11, S26, and M24) which may promote the efficient degradation of organic carbon and nitrogen in artificially restored grasslands.
UNASSIGNED: This
study illustrated the irrecoverability of meadow degradation and offered fundamental information for altering microbial communities to restore alpine ecosystems.