Coombs A M, Moss S H
Int J Radiat Biol Relat Stud Phys Chem Med. 1987 Mar;51(3):493-503. doi: 10.1080/09553008714550971.
The role of peroxide and catalase on NUV radiation sensitivity was examined in two repair competent E. coli strains, AB1157 and B/r. Exponential phase B/r is considerably more sensitive to NUV radiation than exponential phase AB1157. However, resistance to 5 mmol dm-3 H2O2 was induced in both AB1157 and B/r by pretreating growing cells with 30 mumol dm-3 H2O2. Pretreatment also induced resistance to broad-band NUV radiation in these strains. The addition of catalase to the post-irradiation plating medium increased survival to the same extent as that provided by pretreatment with 30 mumol dm-3 H2O2, in both strains. The NUV radiation sensitivity seen in B/r does not appear to be due to a deficiency in enzymes that scavenge H2O2, as a catalase deficient mutant, E. coli UM1, is more resistant to NUV radiation than B/r. Also, assays for H2O2 scavenging ability show little difference between AB1157 and B/r in this respect. Two hypotheses are put forward to account for the sensitivity of exponential phase B/r. Whilst it is apparent that peroxides and catalase do have a role in NUV radiation damage, it is clear that other factors also influence survival under certain conditions.
在两种具有修复能力的大肠杆菌菌株AB1157和B/r中，研究了过氧化物和过氧化氢酶对近紫外线（NUV）辐射敏感性的作用。对数期的B/r对NUV辐射的敏感性明显高于对数期的AB1157。然而，通过用30μmol dm⁻³ 的过氧化氢预处理生长中的细胞，AB1157和B/r对5 mmol dm⁻³ 的过氧化氢的抗性均得以诱导。预处理还诱导了这些菌株对宽带NUV辐射的抗性。在两种菌株中，向辐照后平板培养基中添加过氧化氢酶，使存活率提高到与用30μmol dm⁻³ 的过氧化氢预处理相同的程度。B/r中观察到的NUV辐射敏感性似乎并非由于清除过氧化氢的酶缺乏，因为过氧化氢酶缺陷型突变体大肠杆菌UM1对NUV辐射的抗性比B/r更强。此外，在这方面，对过氧化氢清除能力的测定表明AB1157和B/r之间几乎没有差异。针对对数期B/r的敏感性提出了两种假说。虽然很明显过氧化物和过氧化氢酶在NUV辐射损伤中确实起作用，但很明显在某些条件下其他因素也会影响存活率。
