上海海洋大学王旭东及其课题组在研究西伯达管蠕虫微生物氮利用的钼同位素特征中取得新进展。2023年5月26日，国际知名学术期刊《地质学》发表了这一成果。

在这项研究中，课题组发现，南海被套动物Paraescarpia echinospica 的 δ⁹⁸Mo 值为-4.59‰(-1.13‰±1.75‰, 1SD, n =19)，这是迄今为止被报道的所有天然物质中最低的 δ⁹⁸Mo 值。研究表明，这种极端负的钼同位素组成是由西伯达虫的内共生体或附生体在硝酸盐还原过程中优先利用同位素轻钼造成的。这种钼同位素标记可以提供一种识别西伯达管蠕虫的方法，西伯达管蠕虫是一种以前由于缺乏矿化骨架而在岩石记录中未被明确识别的环节动物。

据悉，许多在深海环境中繁荣的化学合成群落依赖于硫化物氧化细菌的代谢活动。以被套动物西伯达管蠕虫为例，它们对营养的需求主要由其体内的共生细菌来满足，这些细菌隐藏在一种被称为营养体的特殊器官中。这种化学共生导致营养体的氮同位素组成比其他类型的软组织低得多。然而，西伯达虫利用氮的具体过程仍然还不清楚。作为相关酶（固氮酶和硝酸还原酶）的关键元素，钼(Mo)在氮的生物地球化学循环中是必不可少的。

附：英文原文

Title: Molybdenum isotope signature of microbial nitrogen utilization in siboglinid tubeworms

Author: Xudong Wang, Ting Xu, Jrn Peckmann, Germain Bayon, Zice Jia, Shanggui Gong, Jie Li, Erik Cordes, Yanan Sun, Jun Tao, Duofu Chen, Dong Feng

Issue&Volume: 2023-05-26

Abstract: Many chemosynthesis-based communities prospering in deep-sea environments rely on the metabolic activity of sulfide-oxidizing bacteria. This is the case for vestimentiferan siboglinid tubeworms, whose demand for nutrition is satisfied predominantly by their endosymbiotic bacteria harbored in a specialized organ called the trophosome. Such chemosymbiosis leads to a significantly lower nitrogen isotope composition of the trophosome than in other types of soft tissue. However, the specific process of nitrogen utilization by siboglinids remains unclear. As a key element in the relevant enzymes (nitrogenase and nitrate reductase), molybdenum (Mo) is indispensable in the biogeochemical cycling of nitrogen. The Mo isotope composition (δ⁹⁸Mo) of siboglinids is thus a potential proxy for decoding the processes involved in nitrogen metabolism. In this study, we found δ⁹⁸Mo values along the chitinous tube of the vestimentiferan siboglinid Paraescarpia echinospica from the Haima seeps of the South China Sea as negative as -4.59‰ (-1.13‰ ± 1.75‰, 1SD, n = 19)—the lowest δ⁹⁸Mo value ever reported for any kind of natural material. It is suggested that this extremely negative Mo isotope composition is caused by preferential utilization of isotopically light Mo by the tubeworm's endosymbionts or epibionts during nitrate reduction. Such Mo isotope signature could provide a means for identifying siboglinid tubeworms, a group of annelids that has previously escaped unambiguous identification due to the lack of mineralized skeleton, in the rock record.

DOI: 10.1130/G51077.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G51077.1/623710/Molybdenum-isotope-signature-of-microbial-nitrogen