Presentation Information
[3EMT-02]Symbiosis with Growth-Promoting Bacteria Enhances Biomass Production in Chlamydomonas reinhardtii
○Tadashi Toyama1, Yuge Bai1, Kazuhiro Mori1 (1. University of Yamanashi (Japan))
Keywords:
Microalgae,Growth-promoting bacteria,Symbiosis,Chlamydomonas reinhardtii,Biomass production
Co-cultivation with microalgae growth-promoting bacteria (MGPB) has emerged as a promising strategy to enhance microalgal biomass production and bioproduct yields. However, the molecular mechanisms governing MGPB–microalgae interactions remain poorly understood, limiting the rational design of efficient co-culture systems.
In this study, we investigated the effects of two MGPBs, Emticicia sp. JSL2 and Sediminibacterium sp. SCP3, on the growth and metabolic responses of Chlamydomonas reinhardtii.
Co-cultivation with both strains significantly increased cell density and biomass productivity of C. reinhardtii, with SCP3 exhibiting a stronger promotive effect. Scanning electron microscopy revealed distinct interaction modes: JSL2 remained free-living, whereas SCP3 tightly adhered to algal cell surfaces via extracellular polymeric substances, suggesting different symbiotic strategies. Biochemical analyses demonstrated that JSL2 enhanced lipid and hydrocarbon production, while SCP3 promoted lipid, hydrocarbon, and protein accumulation. Furthermore, reverse transcription quantitative PCR analyses showed significant upregulation of key metabolic genes, including rbcL, PGM1, and DAGAT, indicating enhanced carbon fixation and biosynthetic activity, particularly in SCP3 co-cultures.
These results provide quantitative evidence linking MGPB-induced phenotypic enhancements with transcriptional regulation in C. reinhardtii. This study advances our understanding of the molecular basis of microalgal–bacterial symbiosis and provides a foundation for the rational design of high-efficiency microalgal production systems.
In this study, we investigated the effects of two MGPBs, Emticicia sp. JSL2 and Sediminibacterium sp. SCP3, on the growth and metabolic responses of Chlamydomonas reinhardtii.
Co-cultivation with both strains significantly increased cell density and biomass productivity of C. reinhardtii, with SCP3 exhibiting a stronger promotive effect. Scanning electron microscopy revealed distinct interaction modes: JSL2 remained free-living, whereas SCP3 tightly adhered to algal cell surfaces via extracellular polymeric substances, suggesting different symbiotic strategies. Biochemical analyses demonstrated that JSL2 enhanced lipid and hydrocarbon production, while SCP3 promoted lipid, hydrocarbon, and protein accumulation. Furthermore, reverse transcription quantitative PCR analyses showed significant upregulation of key metabolic genes, including rbcL, PGM1, and DAGAT, indicating enhanced carbon fixation and biosynthetic activity, particularly in SCP3 co-cultures.
These results provide quantitative evidence linking MGPB-induced phenotypic enhancements with transcriptional regulation in C. reinhardtii. This study advances our understanding of the molecular basis of microalgal–bacterial symbiosis and provides a foundation for the rational design of high-efficiency microalgal production systems.
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