A Simple Method for Aseptic Grinding of Bacteria

Abstract

For the mechanical disintegration of bacteria Macfadyen and Rowland 1 employed a highly-complicated machine in which the organisms are pulverized in a frozen condition between a rapidly rotating metal pestle and a stationary metal receptacle immersed in liquid air. The bacteria are rendered very brittle by this intense chilling and are rapidly disintegrated by the grinding process. The amount of bacteria dealt with is not large, varying from 0.5 to 1 gm. of the washed organism. Barnard and Hewlett 2 introduced a ball mill capable of grinding bacteria in a moist pasty condition. Thomson⁸ devised a vaccine churn that is capable of smashing bacteria in emulsion form with some success. Recently, Krueger 4 described a type of ball mill for disintegrating bacteria and tissues under aseptic conditions.

The grinding machines above described are generally very costly to construct, and are not all uniformly successful. For grinding small quantities of bacteria it appears that an inexpensive and equally efficient apparatus may be used with advantage. A simple method in which bacteria may be disintegrated in a moist condition is here described.

The grinding chamber consists of a large-size pyrex test tube measuring approximately 20 cm. long and 3 cm. wide. Into this are placed a number of rustless steel balls, 8 mm. in diameter, sufficient to fill one-third of the test tube. The tube is tightly closed, plugged by means of a rubber cork and inserted into an outer metal tube 23 cm. long and 3.2 cm. wide. The test tube is held firmly in position inside the metal tube by means of a rubber cork as shown in Fig. 1. The test tube will now move with the metal tube when the latter is rotated. The outer rubber cork so effectually seals up the metal tube that in case of breakage (which practically never happens) the bacterial contents cannot escape.