High hydrostatic pressure inactivation of Escherichia coli under molecular crowding conditions

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05887
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 38050:Food sciences-related
• Research Institution: National Agriculture and Food Research Organization
• Principal Investigator: YAMAMOTO Kazutaka 国立研究開発法人農業・食品産業技術総合研究機構, 食品研究部門, グループ長補佐 (00353954)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 分子クラウディング / 大腸菌 / 高圧 / 不活性化 / Ficoll / エチレングリコール / ポリエチレングリコール / 損傷

Outline of Final Research Achievements

High pressure tolerance of high order structure in biopolymers has been reported under molecular crowding conditions (solute conc., 300-400 mg/ml). Therefore, it was assumed that high pressure inactivation of bacteria might be less effective in foods such as meat than in dilute food systems due to their enhanced tolerance possibly caused by high solute concentrations at 30-40 %. Ethylene glycol, polyethylene glycol, and Ficoll as molecular crowding agents (MCAs) were added at a max. concentration of 40 %w/w to phosphate-buffered saline where Escherichia coli cells were suspended. The suspension was treated with high hydrostatic pressures (HHPs) of 400-600 MPa at 25 °C for 10 min and then spread on selective and nonselective media to detect healthy cells and healthy/injured cells, respectively. There was a trend where HHP-induced injury of the cells was suppressed by the addition of MCAs, and healthy population was highly detected under some conditions.

Free Research Field

食品高圧科学

Academic Significance and Societal Importance of the Research Achievements

非熱的殺菌技術としてジュース、肉加工品への利用が進む食品高圧加工ではあるが、高圧損傷菌の知見は限定的であり、各種高圧加工食品における損傷菌発生への影響因子解明が不可欠である。本研究では、分子クラウディング環境が、大腸菌を高圧ストレスから保護し、損傷を抑制し、健常菌を生残させ得ることをモデル系にて示した。これにより、分子クラウディングが新影響因子であることを見出して学術に貢献した。更に、ジュース等の希薄系よりも肉加工品等の濃厚系では高圧殺菌効果が低下し、損傷菌または健常菌が増加する可能性を示したことで、高圧殺菌において実用的にも有用な知見が得られた。