検索対象:     
報告書番号:
※ 半角英数字
 年 ~ 
 年

Effect of water activity on the mechanical glass transition and dynamical transition of bacteria

微生物の機械的ガラス転移と動力学転移に対する水分活性の影響

曽我部 知史*; 中川 洋   ; 山田 武*; 小関 成樹*; 川井 清司*

Sogabe, Tomochika*; Nakagawa, Hiroshi; Yamada, Takeshi*; Koseki, Shigenobu*; Kawai, Kiyoshi*

本研究の目的は、バクテリア($$Cronobacter sakazakii$$)のガラス転移挙動を水分活性($$a_{rm w}$$)の関数として明らかにすることである。298Kでの機械的緩和を調べ、機械的$$a_{rm wc}$$(298Kで機械的ガラス転移が起こる$$a_{rm w}$$)を0.667と決定した。平均二乗変位の温度依存性は、中性子非弾性散乱により調べた。フィッティングにより、2つの動的転移温度(low $$T_{rm ds}$$とhigh $$T_{rm ds}$$)が決定された。乾燥試料を除いて、低Tdに対する$$a_{rm w}$$の影響はわずかであった。高$$T_{rm d}$$$$a_{rm w}$$の減少に伴い大きく上昇した。高$$T_{rm d}$$で決定された動的$$a_{rm wc}$$(0.688)は、測定時間スケールが異なるため、機械的$$a_{rm wc}$$よりもわずかに高い値であった。高$$T_{rm d}$$をガラス転移温度($$T_{rm g}$$)に変換し、無水$$T_{rm g}$$は411Kと推定された。

The purpose of this study was to clarify the glass transition behavior of bacteria ($$Cronobacter sakazakii$$) as a function of water activity ($$a_{rm w}$$). Mechanical relaxation was investigated at 298 K, and the mechanical $$a_{rm wc}$$ ($$a_{rm w}$$ at which mechanical glass transition occurs at 298 K) was determined to be 0.667. Temperature-dependency of mean square displacement was investigated by inelastic neutron scattering. From the linear fitting, two dynamical transition temperatures (low and high-$$T_{rm ds}$$) were determined. There was a minor effect of $$a_{rm w}$$ on the low-$$T_{rm ds}$$ except for the anhydrous sample. The high-$$T_{rm ds}$$ largely increased with the decrease in $$a_{rm w}$$. The dynamical $$a_{rm wc}$$determined by high-$$T_{rm ds}$$ (0.688) was slightly higher than the mechanical $$a_{rm wc}$$ because of the difference in the measurement time-scale. The high-$$T_{rm ds}$$ was converted to the glass transition temperature ($$T_{rm g}$$), and anhydrous $$T_{rm g}$$ was estimated to be 411 K. Bacterial inactive-active transition was discussed according to the glass transition behavior.

Access

:

- Accesses

InCites™

:

パーセンタイル:23.43

分野:Biophysics

Altmetrics

:

[CLARIVATE ANALYTICS], [WEB OF SCIENCE], [HIGHLY CITED PAPER & CUP LOGO] and [HOT PAPER & FIRE LOGO] are trademarks of Clarivate Analytics, and/or its affiliated company or companies, and used herein by permission and/or license.