NTT and RFI to start demonstration experiment with the aim of reducing carbon dioxide in the ocean
-The world's first application of genome editing to the carbon cycle of algae and fish and shellfish with containment measures-

Nippon Telegraph and Telephone Corporation (NTT, President & CEO: Jun Sawada) and Regional Fish Institute, Ltd. (RFI, President & CEO: Tadanori Umekawa) have started a demonstration experiment of carbon dioxide conversion technology that can reduce the amount of carbon dioxide dissolved in the ocean by applying genome editing technology^*1 to algae and fish and shellfish. This is one of the trials to achieve the new environmental energy vision "NTT Green Innovation toward 2040"^*2 that realizes zero environmental load and economic growth at the same time.
 This technology is applied to an environmental load reduction in the ocean by using genome editing technology to accelerate carbon dioxide fixation in marine organisms consisted of algae which absorb carbon dioxide and fish and shellfish which eat the algae. By utilizing the land-based aquaculture platform, it is expected to provide the world with carbon dioxide reduction effect without spreading the genome-edited organisms. Our aim is to contribute to virtually zero greenhouse gas emissions through the demonstration of this technology.
 This technology will be introduced in the "NTT R & D Forum-Road to IOWN 2021"^*3 scheduled to be held from November 16th to 19th, 2021.

1．Background

According to the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report, carbon dioxide emissions from the ocean account for 33.7% (286 billion tons CO2/year) of the total carbon dioxide emissions into the atmosphere (848.47 billion tons CO2/year). The emissions from the ocean are about seven times higher than those from human activities (4.8%, 40.33 billion tons CO2/year) (Fig. 1). In addition, the ocean accounts for 34.6% (293.33 billion tons CO2/year) of the absorption of carbon dioxide from the atmosphere. Most of the absorption by the ocean is achieved by marine life in wetlands and seaweed forests. Therefore, technologies that reduce carbon dioxide emissions and increase absorption in the ocean can be an effective method for reducing the total amount of carbon dioxide in the atmosphere.

2．Technology features and demonstration models

Even in the normal marine food chain, carbon dioxide in the atmosphere is absorbed into the ocean. However, it is not possible to reduce the amount of carbon dioxide that stays in the atmosphere more than at present since the amount of carbon dioxide emitted into the atmosphere is increasing year by year due to human activities. Therefore, NTT will work on research and development of genome editing technologies that increases the amount of carbon dioxide fixation^*4 in algae, and RFI will work on research and development of genome editing technologies that increases the amount of carbon stored in the body of fish and shellfish. By applying these two technologies to the marine food chain, we aim to establish a carbon dioxide conversion technology that synergistically increases the amount of carbon fixation in the ocean.
 The Cartagena Act^*5 sets forth regulatory measures to prevent adverse effects on biodiversity when using genetically modified organisms. Although genome-edited organisms are not subject to the Cartagena Act, we will utilize a land-based aquaculture platform that can prevent the release of genome-edited organisms into the environment (Fig. 2).
 In this demonstration experiment, we will clarify the target genes for genome editing to maximize the amount of carbon dioxide fixed by algae and the culture conditions suitable for feeding fish and shellfish. For fish and shellfish, we will also clarify the target genes and breeding methods to maximize the amount of carbon dioxide fixation in soft tissues such as muscles and hard tissues such as bones and shells. In addition, we will proceed with research on establishing a method for quantitative evaluation of carbon dioxide fixation in algae and fish and shellfish.

3．Future perspective

We are planning to conduct demonstration tests to realize this technology for reducing carbon dioxide in the ocean. We consider the application of this technology to increase the production volume and quality of fish and agricultural products in the future.
 As mentioned in the IPCC's Sixth Assessment Report, soil accounts for 61.3% of carbon dioxide emissions into the atmosphere, and forests account for 57.7% of carbon dioxide absorption. Therefore, we will also engage in technology development to reduce the carbon dioxide emissions from soil and to increase carbon dioxide absorption by forests. By combining these technologies, we aim to contribute to the realization of zero environmental impact and to eliminate the global food shortage and protein crisis^*6 that may occur due to the population explosion.

^*1Genome editing technology is a technology to modify DNA sequences of desired target genes by using a site-specific nuclease. The sequence changes will result in a change of the organism's traits.

^*2NTT group defined its Environmental Vision "NTT Green Innovation toward 2040" on Sep 2021. Under this vision, NTT group aims to reduce 80% of greenhouse gas emitted by NTT group by FY2030 and achieve carbon neutrality by FY2040. NTT group contributes to the goal of Japanese government that aims to reduce greenhouse gas emission by 46% compared to FY2013 by 2030 and achieve carbon neutrality by 2050 through introduction of NTT's activity and technology to society.

^*3NTT R&D FORUM ― Road to IOWN 2021
URL: https://www.rd.ntt/e/forum/

^*4Carbon dioxide fixation is the process of converting inorganic carbon such as carbon dioxide into organic carbon such as sugar and taking it into the body.

^*5Cartagena Act is a law to regulate the use of Living Modified Organisms (LMOs) produced by biotechnology such as genetic recombination. This law provides for rules to assess the effect of LMOs on biological diversity and the way to use appropriately LMOs (official name: Law Concerning the Conservation and Sustainable Use of Biological Diversity through Regulations on the Use of Living Modified Organisms).

^*6Protein crisis is an alarm bell that the supply for protein will not be able to keep up with the demand　due to the increase in living standards due to population growth and economic development in emerging countries.