Electron micrographs of cell-wall fraction of B. polymyxa shadowed with gold-palladium: (a) wall from 31 hr. culture; (b) walls from 18hr. culture; (c) and (d) material extracted with urea, dialysed and freeze-dried. The scale marks represent 0-2o t.
A simple, inexpensive, battery-powered, portable luminometer which is based on a silicon photodiode is described. The instrument is intended to measure the light produced by chemiluminescent and bioluminescent reactions. The device shows a good detection limit and, in a bioluminescent reaction for adenosine 5'-triphosphate (ATP), detected 0.5 pmol in 1 ml of aqueous solution. The instrument measures irradiance from 10(-13) to 10(-11) W cm-2 at the sensor, within the range 300 to 900 nm.
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