Determination of dipicolinic acid in bacterial spores by ultraviolet spectrometry of the calcium chelate

✍ Scribed by J.C. Lewis

• Publisher: Elsevier Science
• Year: 1967
• Tongue: English
• Weight: 627 KB
• Volume: 19
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(67)90168-6

✦ Synopsis

The occurrence of substantial amounts of dipicolinic acid (DPA) in bacterial spores, the idea that DPA is related in some yet-to-be-explained way to the extraordinary heat stability of these cells, and the lack of knowledge of any function for this biologically unusual compound make a rapid accurate determination of DPA useful. The sensitivity and the convenience of the absorbance near 270 rnp has been used for comparative assays of crude extracts (l-3). Conditions for quantitative extraction of DPA from spores (1) and for spectrometry as the acid (4) have been reported. This communication ,presents a more specific extraction procedure, a more specific spectrum for measurement, and a method of calculation that largely eliminates the effects of moderate blanks. The method is about 5 times more sensitive than the widely used Fe(D) complex absorbance at 440 rnp (5).

EXPERIMENTAT, Apparatus Spectra were recorded with a Cary model 14 spectrophotometer. Photometric accuracy was verified with alkaline potassium chromate solutions 16). Mercury and cadmium emission lines were used for wavelength calibration. Matched fused-quartz stoppered cells were used. The optical path usually was 1.000 -C 0.001 cm. The temperature was 25.0°C except as noted. Spectra were recorded, usually from 390 to 220 rnp. For the more precise data, the maxima and minima at about 278, 274, 270, and 265 rnp were scanned repeatedly at 0.05 m&ec with a 5 set period until the absorbances at the peaks could be estimated to 0.001.

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