Pyrolysis Gas Chromatography of Pseudomonas and Acinetobacter Species

Low resolution pyrolysis gas chromatography was performed on five species of Pseudomonas and two species of Acinetobacter. Conventional species groups could be differentiated by canonical variates analysis, and visual examination suggested that subspeciation would have been possible with more data.
Carbowax 20M has been used as the stationary phase for the majority of published work on pyrolysis gas chromatography of micro-organisms. However, with this material baseline resolution was poor, analysis times were long and column deterioration was relatively rapid. Peak area reproducibility on a single column averaged 10%, but it proved impossible to achieve quantitatively similar pyrograms on a new column. These serious drawbacks of Carbowax 20M limit the usefulness of this stationary phase for pyrolysis gas chromatography of micro-organisms.     

A Simple, Efficient Technique for Freezing Tetrahymena thermophila

ABSTRACT. We have developed a simple, efficient procedure for the long term freezing of Tetrahymena thermophila in liquid nitrogen. This technique yields excellent recovery of viable cells with all strains tested and does not require the use of a controlled rate low temperature freezer. To optimize the freezing technique, we have examined the effects of varying a number of parameters, including the physiological state of the cells prior to freezing, the time of exposure to cryoprotectant, and the rate of freezing and thawing. the frequency of viable cell recovery following freezing using this technique has been tested for a variety of different cell lines.