A new study sheds light on oceanic dark matter

The new findings suggest that marine microbes use photosynthesis.

Photosynthesis is used by marine bacteria to absorb carbon dioxide.

Scientists may be able to determine whether or not oceanic bacteria are involved in the global carbon cycle by determining whether or not marine microbes use

Using a Raman spectroscopy technique, scientists at the Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT) of the Chinese Academy of Sciences (CAS) have directly identified cells that fix carbon dioxide or cells that absorb CO2 from sea. This finding suggests that bacteria engage in photosynthesis.

Their findings were recently published in the journal Biodesign research.

Bacteria that fix CO2 in the ocean

Not yet cultured CO2-fixing bacteria are sorted by Raman-activated Gravity-driven Encapsulation (RAGE) technology at single-cell resolution according to Raman shifts, and subsequent single-cell sequencing uncovered a driven proton by pumping rhodopsin-based light into target cells. Credit: Liu Yang

Chlorophyll-based photosynthesis is a well-known light harvesting system for CO2 fixation. Photosynthesis based on a type of protein known as proteorhodopsin, or PR, has been reported to fix CO2 in the presence of light. Subsequently, some types of CO2 fixation in marine bacteria have been reported.

“PR-containing bacteria could be the most abundant, and microbial rhodopsins, another type of protein, could contribute a large part to solar energy harvesting in the oceans. However, it is still unclear whether PR-containing bacteria under natural conditions can repair CO2,” said co-first author Jing Xiaoyan, senior engineer at QIBEBT’s Single-Cell Center.

The researchers first identified the CO2-fixing cells from seawater taken from the euphotic zone — or uppermost part of the ocean, which is exposed to sunlight — of China’s Yellow Sea by monitoring the uptake of a compound C-bicarbonate . The researchers did this using single cell Raman spectra (SCRS), a technique used to study molecules.

“Then we used a technique called Raman-activated Gravity-driven Encapsulation, or RAGE, to isolate target cells of Pelagibacter, the bacterium we studied, which is a member of the SAR11 group of bacteria,” said co-first author. Xu Teng, postdoctoral fellow at the Single Cell Center of QIBEBT. The researchers amplified the genomes of these individual isolated Pelagibacter cells and sequenced each cell.

“Using an improved Raman-activated cell sorting technique that sorts and sequences the microbiome with precisely one-cell resolution, we reveal that Pelagibacter spp. and thus contribute to the global carbon cycle,” said co-first author GongYanhai, research assistant at the Single-Cell Center of QIBEBT.

“This study demonstrates that RAGE-mediated analysis of a single cell genome can establish a reliable link between the phenotype and genotype of non-ocean-cultured bacteria, which solves an underlying problem and paves the way for based dissection. on the function of ‘biological dark matter’ in the environment,” said corresponding author Prof. HUANG Wei from the

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