Self-Assembled Nanoscale Manganese Oxides Enhance Carbon Capture by Diatoms

Abstract

Continuous CO2 emissions from human activities increase atmospheric CO2 concentrations and affect global climate change. The carbon storage capacity of the ocean is 20-fold higher than that of the land, and diatoms contribute to approximately 40% of carbon capture in the ocean. Manganese (Mn) is a major driver of marine phytoplankton growth and the marine carbon pump. Here, we discovered self-assembled manganese oxides (MnO x ) for CO2 fixation in a diatom-based biohybrid system. MnO x shared key features (e.g., di-μ-oxo-bridged Mn–Mn) with the Mn4CaO5 cluster of the biological catalyst in photosystem II and promoted photosynthesis and carbon capture by diatoms/MnO x . The CO2 capture capacity of diatoms/MnO x was 1.5-fold higher than that of diatoms alone. Diatoms/MnO x easily allocated carbon into proteins and lipids instead of carbohydrates. Metabolomics showed that the contents of several metabolites (e.g., lysine and inositol) were positively associated with increased CO2 capture. Diatoms/MnO x upregulated six genes encoding photosynthesis core proteins and a key rate-limiting enzyme (Rubisco, ribulose 1,5-bisphosphate carboxylase–oxygenase) in the Calvin–Benson–Bassham carbon assimilation cycle, revealing the link between MnO x and photosynthesis. These findings provide a route for offsetting anthropogenic CO2 emissions and inspiration for self-assembled biohybrid systems for carbon capture by marine phytoplankton.

Nitrogen Forms Regulate the Response of Microcystis aeruginosa to Nanoplastics at Environmentally Relevant Nitrogen Concentrations

“…Examples include reprogramming carbon and nitrogen metabolism in nitrogen-fixing cyanobacteria by WS 2 and MoS 2 nanosheets, 37,38 promoting nitrate adaptation in diatoms by marine colloids, 39 and enhancing carbon capture in diatoms by nanoscale manganese oxides. 40 This mechanism not only provides insights into the resilience of cyanobacteria but also raises important questions about the broader implications of these "immune mechanisms" on global carbon and nitrogen cycles and the overall health of aquatic ecosystems. Understanding these interactions is crucial for developing strategies to mitigate the environmental impact of nanoplastics and other emerging contaminants.…”

“…aeruginosa to PS-NH 2 are not isolated phenomena but part of a broader pattern that occurs in different algae and nanoparticles, suggesting a possible universal “immune mechanism”. Examples include reprogramming carbon and nitrogen metabolism in nitrogen-fixing cyanobacteria by WS 2 and MoS 2 nanosheets, , promoting nitrate adaptation in diatoms by marine colloids, and enhancing carbon capture in diatoms by nanoscale manganese oxides . This mechanism not only provides insights into the resilience of cyanobacteria but also raises important questions about the broader implications of these “immune mechanisms” on global carbon and nitrogen cycles and the overall health of aquatic ecosystems.…”

Microplastics Weaken the Adaptability of Cyanobacterium Synechococcus sp. to Ocean Warming

“…The chlorophyll fluorescence parameter F v / F m measured by the pulse amplitude modulation (PAM) technique directly reflects the maximum quantum yield of PS II . The maximum quantum yield of PS II was determined on logarithmic phase cultures grown at different temperatures and under different MP conditions with a Water PAM Chlorophyll Fluorometer (WATERPAM, Heinz Walz, Effeltrich, Germany) . Briefly, a 3.5 mL cell suspension was placed in a quartz cuvette, and the minimum fluorescence ( F 0 ) and maximum fluorescence ( F m ) were measured after 10 min dark acclimation.…”

“…52 The maximum quantum yield of PS II was determined on logarithmic phase cultures grown at different temperatures and under different MP conditions with a Water PAM Chlorophyll Fluorometer (WATERPAM, Heinz Walz, Effeltrich, Germany). 53 Briefly, a 3.5 mL cell suspension was placed in a quartz cuvette, and the minimum fluorescence (F 0 ) and maximum fluorescence (F m ) were measured after 10 min dark acclimation. The maximum quantum yield of PS II (represented as the chlorophyll fluorescence parameter F v /F m ) was calculated as…”