Abstract 3-Hydroxy fatty acids (3-OH-FAs), derived from Gram-negative bacterial outer membranes, have received recent attention for their potential as new terrestrial pH and temperature proxies for palaeoclimate studies. However, it is not known whether 3-OH-FA based proxies can be developed and applied to the marine environment. Here we analyze 3-OH-FAs from a latitudinal transect of marine surface sediments from the North Pacific Ocean (12°N to 61°N with a annual mean sea surface temperature (SST) range of 28.1–1.3 °C). The results show that distributions of 3-OH-FAs in marine sediments yield overall higher abundances of anteiso 3-OH-FA homologues compared to soils. Furthermore, 16S rRNA gene sequencing of the marine sediments and soils shows the Gram-negative bacterial community is dominated by Proteobacteria (ca. 94%) at the phylum level. In contrast, in regional soils the Gram-negative bacterial community is more diverse with significant contributions from Proteobacteria (ca. 50%), Acidobacteria (ca. 24%), Verrucomicrobia (6%), Bacteroidetes (6%) and other phyla. These distinct genomic and molecular differences suggest distinctly different aggregate compositions of bacteria that produce 3-OH-FAs in the marine realm vs soils. Moreover, we find that the ratio of anteiso to normal C13 3-OH-FA (RAN13) measured in surface sediments is highly correlated with annual mean SST throughout the temperature transect. When applied to a short sediment core from the East China Sea, the SST changes reconstructed by the RAN13 proxy are comparable to instrumental SST data. These findings demonstrate that RAN13 and potentially other, so far undiscovered, proxies based on 3-OH-FAs have potential for environmental and palaeoclimate applications in marine environments.

中文翻译：

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基于细菌 3-羟基脂肪酸的新海面温度代理

摘要 源自革兰氏阴性细菌外膜的 3-羟基脂肪酸 (3-OH-FAs) 最近因其作为古气候研究的新陆地 pH 和温度代理的潜力而受到关注。然而，尚不清楚基于 3-OH-FA 的代理是否可以开发并应用于海洋环境。在这里，我们分析了来自北太平洋（12°N 至 61°N，年平均海面温度 (SST) 范围为 28.1–1.3 °C）的海洋表层沉积物纬度横断面的 3-OH-FA。结果表明，与土壤相比，海洋沉积物中 3-OH-FA 的分布产生了总体上更高丰度的反异 3-OH-FA 同系物。此外，海洋沉积物和土壤的 16S rRNA 基因测序显示，革兰氏阴性细菌群落在门水平上以变形杆菌（约 94%）为主。相比之下，在区域土壤中，革兰氏阴性细菌群落更加多样化，其中变形杆菌（约 50%）、酸杆菌（约 24%）、疣微菌（6%）、拟杆菌（6%）和其他门类的贡献显着。这些明显的基因组和分子差异表明，在海洋和土壤中产生 3-OH-FA 的细菌的聚集体组成明显不同。此外，我们发现在表层沉积物中测量的反异与正常 C13 3-OH-FA (RAN13) 的比率与整个温度断面的年平均海温高度相关。当应用于来自东海的短沉积岩心时，由 RAN13 代理重建的 SST 变化与仪器 SST 数据相当。这些发现表明 RAN13 和潜在的其他迄今为止尚未发现的