Inhibition of Heterogeneous Ice Nucleation in Genetic Resources based on Biogenic Magnetitee

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K04304
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: Kochi University (2023); Tokyo Institute of Technology (2020)
• Principal Investigator: KOBAYASHI ATSUKO 高知大学, 海洋コア国際研究所, 特任教授 (50557212)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 過冷却操作可能な氷晶因子 / 生体由来のマグネタイト / 長期低温貯蔵技術 / 歳差磁場下

Outline of Final Research Achievements

When suitable surfaces are present, ice crystals will nucleate from supercooled water in plant tissues, causing frost damage. These ice nucleating particles (INPs) limit the ability of supercooling to preserve food without harm. Recent studies have shown that magnetite (Fe3O4) nanoparticles are powerful INPs for heterogeneous ice nucleation, and that they are present at trace levels in many tissues. In particular, cloves of garlic (Allium sativum) are known to remain supercooled down to temperatures as low as -13℃, yet superconducting magnetometry indicates that large numbers of magnetite nanoparticles are present that should have initiated freezing at higher temperature. By developing a temperature-dependent survivability analysis, combined with the use of oscillating magnetic fields designed to disturb the ice nucleating process on magnetite nanoparticles, we found that weak oscillations raise the freezing temperature, but stronger oscillations reduce it.

Free Research Field

顕微鏡科学

Academic Significance and Societal Importance of the Research Achievements

農産物種の資源保護・安定供給に向けて、胚芽・種など遺伝資源を管理君間で超低温保存する方法が研究されている。しかし植物には細胞膜の外側に硬い細胞壁があるため、凍結保存では間隙の水分膨張が細胞膜を損傷するので、個体再生が不能である。そこで本研究は、歳差磁場下で植物細胞内に過冷却を促進し、耐寒温度を下げた状態を長時間持続させて、かつ植物株の成長点が再生したことが確認された。またこの過冷却操作可能な氷晶核因子が磁性体微粒子マグネタイトであることを同定した。この学術的知見は、今後の長期低温貯蔵技術の発展に大いに貢献する。