细菌藿多醇的环境指示作用及其在海洋生态环境重建中的应用

Environmental indication of Bacteriohopanepolyols and its application on eco-environmental reconstruction

细菌藿多醇(Bacteriohopanepolyols,BHPs)是细菌细胞膜中高度结构变异的五环三萜类化合物,易保存且受成岩作用影响较小,广泛分布于陆地和海洋环境中。BHPs作为一种新型微生物标志物,由于其细菌来源专属性和环境专属性,近年来已在示踪有机质来源、环境演变过程以及反演古环境方面表现出巨大的应用潜力。本文系统分析了近年来全球土壤、沉积物和海水中BHPs的组成、分布和来源,发现热带和温带区域中BHPs的多样性和含量通常高于寒带区域,且由土壤、河流、近海到外海海域逐渐降低。探讨了土壤标志物BHPs、细菌霍四醇同分异构体(BHT-Ⅱ)和35-氨基霍多醇在有机质来源、缺氧环境、厌氧氨氧化和甲烷氧化活动方面的环境指示作用及在海洋生态环境重建中的应用,以期为示踪海洋生态环境变化提供新指标和新途径。

Objectives:Bacteriohopanepolyols(BHPs)are pentacyclic triterpenoids with high structural variation in bacterial cell membranes.They are easy to preserve and less affected by diagenesis,and widely distribute in terrestrial and marine environments.In recent years,as a novel microbial biomarker,BHPs have shown great application potential in tracking organic matter source,environmental evolution and reconstructing paleoenvironment due to their specificity in bacterial origin and environmental response.It is expected to provide new indicators and new approaches for tracking the changes of the marine eco-environment.Methods:In this paper,we comprehensively analyzed the composition,distribution,and source of BHPs in soils,sediments,and seawaters according to the recent studies.We also evaluated the environmental indication of BHPs to organic matter sources,anoxic environment,anammox and aerobic methane oxidation processes and their application on marine eco-environmental reconstruction based on the characteristics of BHP composition.Results and Conclusions:The main compositions of BHPs in soils were aminotriol,BHT cyclitol ether,BHT and adenosylhopane,and while that in seawaters and sediments were BHT、BHT-Ⅱand 2-MethylBHT.At spatial distribution,the diversity and content of BHPs in tropical and temperate regions are generally higher than those in frigid zone,and they also displayed a decreasing order from soils,rivers,coastal waters to open waters.An vertical distribution,BHPs have relatively high values at the hypoxic bottom waters of the coastal waters and minimum oxygen zone of the open areas.Soil marker BHPs in rivers and oceans were closely related to land-derived input and could be used to indicate the terrestrial organic matter inputs to the marine environment.BHT-Ⅱwas closely related to hypoxic/anoxic environment and anammox,which could not only trace the marine hypoxic/anoxic condition,but also indicate the intensity of the important nitrogen removal pathway,i.e.,anammox.35-amino-BHPs,in particular aminotetrol and aminopentol,are highly specific to the source of aerobic methanotroph and their contents increased with increasing abundance and activity of aerobic methanotroph.Thus 35-amino-BHPs could be used to indicate aerobic methane oxidation activity.