Elucidation of acetic acid stress response mechanism by budding yeast Haa1 and application to acetic acid resistant yeast breeding technology

• Project/Area Number: 16K00655
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Design and evaluation of sustainable and environmental conscious system
• Research Institution: Okayama Prefectural University
• Principal Investigator: TANAKA Koichi 岡山県立大学, 保健福祉学部, 教授 (90282615)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000); Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2017: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2016: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
• Keywords: 酵母 / バイオエタノール / 酢酸 / ストレス / グリセロール / HAA1 / 応用微生物学 / 発酵 / バイオマス

Outline of Final Research Achievements

Budding yeast Haa1 is a transcription factor that plays an important role for resistance to acetic acid stress, but its mechanism was unclear. I revealed that Haa1 transiently accumulates intracellular glycerol, which protects yeast cells from acetic acid stress and enables their survival and growth. Haa1 increases intracellular glycerol concentration by activating transcription of the GPP2 gene encoding an enzyme involved in glycerol biosynthesis, and by inducing the degradation of Fps1 protein that has a role to export glycerol to the outside of cells. These results can be applied to the development of a novel breeding technology for "acetic acid-tolerant yeast" that contributes to more efficient bioethanol production.

Academic Significance and Societal Importance of the Research Achievements

再生可能エネルギーであるバイオ燃料の効率生産は、低炭素社会の構築に必要不可欠な基盤技術となる。セルロース系バイオマスを原料としたバイオエタノールの生産では、発酵を強力に阻害する酢酸が糖化液に残存することが大きな問題である。本研究成果をもとにして、酢酸存在下でも増殖や発酵が阻害されない「酢酸耐性化酵母」を開発することで、糖化液から酢酸を除去する必要が無くなるだけでなく、酢酸が持つ強い抗菌作用により培地の滅菌という高コスト工程も省くことが可能になる。従って、本研究成果はバイオエタノール製造の大幅な高効率化・低コスト化に繋がることが期待される。

Research Products

• [Journal Article] A silkworm infection model to investigate Vibrio vulnificus virulence genes (2016)
  • Author(s): Yamamoto, M., Kashimoto, T., Yoshimura, Y., Tachibana, N., Kuroda, S., Miki, Y., Kitabayashi, S., Tong, P., Xiao, J., Tanaka, K., Hamamoto, H., Sekimizu, K., and Yamamoto, K.
  • Journal Title: Mol Med Rep Volume: 14 Issue: 5 Pages: 4243
  • DOI: 10.3892/mmr.2016.5782
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] 切れないハサミも使いよう (2016)
  • Author(s): 田中晃一
  • Journal Title: 生物工学会誌 Volume: 94 Pages: 345-345
• [Presentation] 微生物の力で生活を豊かに (2017)
  • Author(s): 田中晃一
  • Organizer: おかやまバイオアクティブ研究会