Experiments in microbial genetics / edited by R.C. Clowes and W. Hayes.

Date:
[1968], ©1968
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Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Experiments in microbial genetics / edited by R.C. Clowes and W. Hayes. Source: Wellcome Collection.

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    Experiment i Ultraviolet irradiation survival curve Wacker A. (1963) In: Progress in Nucleic Acid Research, Eds. J.N. Davidson and W.Cohen, vol. i, pp.369-399. Academic Press: London and New York. WiTKiN E.M. (1947) Genetics 32, 221. Intention The purpose of this experiment is two-fold : 1. to demonstrate and measure the sensitivity of Escherichia coli K12 to ultraviolet radiation, 2. to provide experience in dilution and plating techniques. Requirements Part i 50 ml of an o/n broth culture of Escherichia coli K12, non-lysogenic for phage Л (EMGio or 14. See Appendix B) 24 nutrient agar (NA) plates. 300 ml buffer 6 glass petri dishes, selected with flat bottoms (see below). 19 large tubes. 1 X 100 ml bottle. 2 X 25 ml bottles. u.V. lamp. A 15 watt low-pressure Hanovia 'Bacteri¬ cidal' lamp is suitable. But any lamp which gives a uniform beam of u.v. having about 90% of the emission at 2600 Â will suffice. The output of a new lamp may be calibrated in erg/mm^/sec using a u.v. intensity meter, or it can be calibrated biologically by measuring the u.v.-inactivation of bacteriophage T2 or E.coli. [60 erg/mm^ inactivates approx. 90% of T2 parti¬ cles. 100 erg/mm^ inactivates approx. 99% of T2 particles. 500 erg/mm^ inactivates approx. 99% of a A-lysogenic strain of E.coli K12, e.g. EMG2.] 15