RT Journal Article SR Electronic T1 The action of light on culture media JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 273 OP 277 DO 10.1136/jcp.22.3.273 VO 22 IS 3 A1 Pamela M. Waterworth YR 1969 UL http://jcp.bmj.com/content/22/3/273.abstract AB Failure of growth of staphylococci on nutrient agar plates was shown to be due to previous exposure to sunlight in an exceptionally well lit laboratory. Such plates inhibited the growth of Staph. aureus, Staph. albus, some Proteus species and Providence, but not that of various other bacteria. The affected species are found to be more susceptible to the action of hydrogen eroxide added to the medium. The effect was produced in plates of five different nutrient agars, but not in two others which contained casein. Plates awaiting inoculation should be protected from light; a white fabric blind was found not to be fully protective.