NTT Corporation (Headquarters: Chiyoda Ward, Tokyo; Representative Member of the Board and President: Akira Shimada, hereinafter “NTT”) and Euglena Co., Ltd. (Headquarters: Minato Ward, Tokyo; Founder and President CEO: Mitsuru Izumo, hereinafter “Euglena Co.”) have successfully developed the world’s first algal breeding technology using neutron beam irradiation for mutagenesis. This groundbreaking achievement is expected to provide a fundamental technology to address climate change by enhancing algae’s CO2 absorption and producing algae with various beneficial applications.
The research results were published in the scientific journal Scientific Reports on July 3, 2024.
Background
The Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report unequivocally states that human activities have warmed the atmosphere, ocean, and land. Consequently, there is an urgent need to reduce greenhouse gases such as CO2. Algae, which photosynthesize like plants and have a fast growth rate, are being considered as a viable solution to the climate crisis. Effective algal breeding technology is essential to maximize the desired traits of algae.
Previously, algal breeding methods using electromagnetic waves and heavy particle beams were ineffective due to their low permeability in water-containing substances like culture mediums. In response, NTT and Euglena Co. focused on neutron beams, which are highly permeable to such substances. Since 2022, they have been conducting joint research to establish algal breeding technology using high-energy neutron beams and thermal neutron beams.=
Key Points of Technology and Experiment Overview
- Optimization of Neutron Beam Irradiation Conditions For the first time, the relationship between the type of neutron beam (high-energy or thermal) and the absorbed dose and mutagenesis efficiency of algal genes was clarified. Mutagenesis was evaluated using the unicellular alga Cyanidioschyzon merolae (Cyzon), with findings indicating optimal mutations at 20 Gy irradiation for high-energy neutron beams and 13 Gy for thermal neutron beams.
- Elucidation of Mutation Patterns The mutation patterns caused by optimized irradiation conditions were analyzed. Approximately 90% of the mutations were single nucleotide substitutions, deletions, or insertions, while about 10% involved changes in two or more nucleotide sequences. This differs from the mutation pattern caused by gamma rays, where changes of two or more nucleotide sequences account for about 30%.
- Isolation of Algae with Improved Oil Production By applying the optimal neutron beam irradiation conditions to Euglena gracilis (Euglena), strains producing up to 1.2 to 1.3 times more oil than the wild type were bred. Fluorescent dye staining was used to select cells with enhanced oil production, resulting in the successful acquisition of four high-oil-producing strains.
- NTT: Leveraged expertise in neutron beam irradiation from semiconductor research to elucidate the relationship between neutron beam type, absorbed dose, mutagenesis efficiency, and mutation patterns.
- Euglena Co.: Applied technology to evaluate and acquire high-oil-producing algal strains suitable for biofuel production from irradiated algae.
This collaborative effort marks a significant milestone in algal biotechnology, promising to advance solutions for climate change and biofuel production.
