Enhanced production of highly methylated brGDGTs linked to anaerobic bacteria from sediments of the Mariana Trench

Zeng，Zhiyu1,2; Xiao，Wenjie1,3; Zheng，Fengfeng1,2; Chen，Yufei1,2; Zhu，Yuanqing2,4; Tian，Jiwei5; Zhang，Chuanlun1,2,4

2023

10.3389/fmars.2023.1233560

Frontiers in Marine Science   Impact Factor & Quartile

2296-7745

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are bacterial membrane lipids that are widely used in terrestrial paleoclimatic reconstructions. Recent studies have reported that brGDGTs can also be produced by marine bacteria. However, the environmental factors influencing marine-derived brGDGTs and their source organisms remain largely unknown. Here, we investigated the distribution and composition of brGDGTs and a suite of their putative derivatives called overly branched GDGTs (obGDGTs) in the Mariana Trench core sediments (water depth 8300 m, core length 320 cm), as well as the composition of bacterial communities. The ratio of the branched over isoprenoid tetraethers (BIT) was 0.03-0.21 (average 0.07; SD = 0.04; n = 21) and the ratio ΣIIIa/ΣIIa of brGDGTs was 0.93-7.47 (average 3.39; SD = 1.73; n = 21), which support the in situ production of brGDGTs. Co-occurrence network analysis revealed that a total of 33 types of bacteria at the order level (e.g., Armatimonadota DG-56, Proteobacteria Rhodospirillales, Chloroflexi SAR202_clade) were closely related to the distribution of brGDGTs and obGDGTs, which could be potential sources for these compounds. The abrupt increase in brGDGT and obGDGT concentrations in deeper oxygen-depleted sediments and their good correlations with anaerobic bacterial abundances suggest that these brGDGTs and obGDGTs may be produced by anaerobic bacteria residing in the anoxic sediments. Considerable variation in the degrees of methylation and cyclization of brGDGTs (obGDGTs) under different redox conditions indicate that sediment oxygen levels may have a profound impact on the presence and abundance of brGDGTs and obGDGTs, which should be considered when applying them for paleo-temperature or pH reconstructions. This study shows that brGDGTs and obGDGTs obtained from the Mariana Trench were probably produced by a variety of bacterial phyla indigenous in the hadal ocean, which are different from Acidobacteria commonly considered to be major terrestrial sources of brGDGTs.

anaerobic bacteria branched GDGTs in situ production Mariana Trench overly branched GDGTs

SCI

English

First ; Corresponding

National Natural Science Foundation of China["42141003","42003063","42206040"] ; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou)[K19313901] ; Stable Support Plan Program of Shenzhen Natural Science Fund[20200925173954005] ; Guangdong-Shenzhen Joint Fund[2021B1515120080] ; Shenzhen Key Laboratory of Marine Archaea Geo-Omics, Southern University of Science and Technology[ZDSYS201802081843490] ; Shanghai Sheshan National Geophysical Observatory[2020Z01]

Environmental Sciences & Ecology ; Marine & Freshwater Biology

Environmental Sciences ; Marine & Freshwater Biology

WOS:001059779600001

FRONTIERS MEDIA SA

2-s2.0-85169664705

Scopus

1.Shenzhen Key Laboratory of Marine Archaea Geo-Omics,Department of Ocean Science and Engineering,Southern University of Science and Technology,Shenzhen,China
2.Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou),Guangzhou,China
3.Department of Biology,HADAL,Nordcee & DIAS,University of Southern Denmark,Odense M,Denmark
4.Shanghai Sheshan National Geophysical Observatory,Shanghai,China
5.Key Laboratory of Physical Oceanography,Ministry of Education,Ocean University of China,Qingdao,China

Zeng，Zhiyu,Xiao，Wenjie,Zheng，Fengfeng,et al. Enhanced production of highly methylated brGDGTs linked to anaerobic bacteria from sediments of the Mariana Trench[J]. Frontiers in Marine Science,2023,10.

Zeng，Zhiyu.,Xiao，Wenjie.,Zheng，Fengfeng.,Chen，Yufei.,Zhu，Yuanqing.,...&Zhang，Chuanlun.(2023).Enhanced production of highly methylated brGDGTs linked to anaerobic bacteria from sediments of the Mariana Trench.Frontiers in Marine Science,10.

Zeng，Zhiyu,et al."Enhanced production of highly methylated brGDGTs linked to anaerobic bacteria from sediments of the Mariana Trench".Frontiers in Marine Science 10(2023).