A novel heat survival mechanism in deinococcal bacteria

• Main Authors: Chung, Su Fang, 鍾素芳
• Other Authors: Tan, Shieh Te
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/39731592249016006959

碩士 === 國立清華大學 === 輻射生物研究所 === 81 === A highly radiation resistant bacterium, Deinococcus radiodurans, has a higher resistance to lethal thermal stress than other mesophile bacteria,In 1982, Tan & Maxcy have reported that there was a unusual heat survival curve : when the cells of D. radiodurans were treated at lethal temperature, 60 C , for 20 min, the survivors could preseve their activities more than 3 hours. So there was a novel tailing in the survival curve after the first log killing. We called this special phenomenon as "thermo-tailing " which only induced by thermal stress. To compare the survivors at the thermo- tailing state ( TT cells : 60 C 60 min ) and at the first exponential killing state ( EK cells : 60 C 10 min ), we found that the salt-tolerance of TT cells was higher than the EK cells. The lag time of TT cells was shorter than that of EK cells after reculture at the fresh growth medium. These results suggested that the TT cells suffered less heat injury than EK cell. Our results suggested : If the cells of D. radiodurans were resuspended in phosphate buffer or distiled water, or in medium containing EDTA, heat survival curve had no thermo-tailing. It indicated that the formation of thermo- Thermo-tailing could be found in 55 C and 60 C treatment. The TT cells ( 60 C, 60 min, or 55 C 120 min) after shifted to room temperature ( 25 C ) for 10 min for the duration of thermo-tailing were disturbed and the survivors become more sensitive to heat. In addition, shifting the TT cells of 55 C and 60 C to 60 C and 55 C respectively, the thermo-tailing were also disturbed.