Molecular paleontological research for the evolution of symbiosis of chanosynthetic biological community

最近的生物标志物和同位素研究表明，太古宙参与了海洋沉积物中的厌氧甲烷氧化(AOM)。自生碳酸盐沉淀与AOM有关，AOM产生CO_2，降低pH，有利于碳酸盐的溶解而不是沉淀。厌氧氧化甲烷提高了碳酸盐的碱度，有利于自生碳酸盐的沉淀。海底甲烷渗漏和甲烷氧化与碳酸盐沉淀的联系是建立在碳酸盐亏损的基础上的。冷渗型碳酸盐岩中含有厌氧甲烷氧化的生物标志物，在冷渗型碳酸盐沉积过程中起着重要作用。识别AOM最重要的诊断脂质化合物是耗尽的五甲基二十烷(PME)，最有可能的是十氯乙烷。另一种识别甲烷氧化太古代的有用化合物是耗尽的异戊二烯醚脂或降解产物，来源于具有异戊二烯碳骨架的乙醚结合的膜脂。新开发的指示AOM的生物标志物是C13和C18异戊二烯酮。类异戊二烯酮的来源可能是含有甲基肉桂酸的羟基考古醇。本文研究了更新世Koshiba组、Rishiri海峡新近海底和北海道5块白垩纪灰岩中AOM的生物标志物。与AOM相关的原生物质种类繁多，生物标志物是区分地质样品中AMNE-1和ANME-2的有用工具。早白垩世化石化学合成群落以ANME-1为主，早于上白垩世的化石以ANME-2为主。化学合成群落的组合正在进化。

Recent biomarker and isotopic studies indicated the participation of Archea in an anaerobic methane-oxidation (AOM) in the marine sediments. Authigenic carbonate precipitation was related to AOM which produces CO_2 and decreases pH, favoring the dissolution of carbonates rather than precipitation. Anaerobically oxidized methane produces the increase in alkalinity of carbonate and favors the precipitation of authigenic carbonates. The association of methane seepage on the sea floor and an oxidation of methane with carbonate precipitation was established on the basis of carbonate ^<13>C depletion. The cold-seep carbonates contain biomarkers suggesting the anaerobic methane-oxidation which play an important role during cold-seep carbonate precipitation. The most important diagnostic lipid compound for identifying AOM is ^<13>C depleted pentamethyleicosane (PME) and most likely crocetane Another useful compound to identify methane oxidizing Archea is ^<13>C depleted isoprenoid ether lipid or degradation product originated from ether-bound membrane lipids with an isoporenoid carbon skeleton.Newly developed biomarker indicating AOM, especially ANME-2 (group of methanogens), is C13 and C18 isoprenoid ketone. The origin of isoprenoid ketone could be hydroxyarchaeol contained Methanosarcinaceae.Biomarker indicating AOM was investigated from Pleistocene Koshiba formation, Recent sea-floor from Rishiri channel, five Cretaceous limestone from Hokkaido in this study. The Archeal spices related to AOM are multiple, biomarker is useful tool for distinguish AMNE-1 and ANME-2 in geological samples. The fossil chemosynthtic communities at the age of Lower Cretaceous are dominated ANME-1, and the samples from younger than Upper Cretaceous are dominated ANME-2. The combination of chemosynthetic community is evolving.