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Updated: Jan 10, 2026

Author Spotlight: Scaling Microalgal Biotechnology for Enhanced Biomethane Production
Published on: March 22, 2024
Biomass ratio regulates methane conversion and carbon fixation in a methanotrophs-microalgae symbiotic system:
Xiaoqian Li1, Xiao Lin2, Ziyi Dong1
1School of Environmental Science and Engineering, China-America CRC for Environment & Health of Shandong Province, Shandong University, Qingdao, Shandong, 266237, China; Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, Shandong University, Qingdao, Shandong, 266237, China.
Abstract:
The methanotrophs-microalgae symbiotic system for greenhouse gas treatment is a novel biological carbon fixation technology. However, practical applications are limited by low conversion efficiency, which arises from metabolic heterogeneity in growth rates and carbon-nitrogen resource utilization within the system. To improve metabolic stability of such symbiotic systems, this study systematically assessed CH4 metabolic fluxes by regulating the methanotrophs-microalgae biomass ratio, and further revealed synergistic mechanisms that enhance system stability. Experimental results indicated that at a methanotrophs to microalgae ratio of 1:5, the CH4 consumption rate peaked at 1.1 L CH4/d/g biomass. The extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory and the laser confocal revealed that the co-aggregation force of methanotrophs and microalgae was significantly enhanced at the optimal ratio. This enhancement was crucial for regulating the spatial mutualistic growth and metabolic interactions within the methanotrophs-microalgae symbiotic community. Structural equation modeling (SEM) indicated that poly-β-hydroxybutyrate (PHB) exerts a significant negative effect on methane consumption (-0.68***). Metagenomics results indicated that at the optimal methanotrophs-microalgae ratio, the relative abundance of genes associated with the methane oxidation center metabolic pathway increased by 1.38 times. This significantly enriched Type I methanotrophs (1.89 times) and Type II methanotrophs (1.51 times), while the relative abundance of genes involved in the PHB production pathway decreased by 16 %. This change accelerated the conversion and assimilation of methane carbon, ultimately improving the carbon fixation efficiency by 16 %. This study provided theoretical foundations and technical support for advancing the engineering application of methanotrophs and microalgae symbionts to achieve efficient, stable methane conversion and simultaneous carbon sequestration.
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