BACTERIA FROM PALEOZOIC SALT DEPOSITS 



Heinz Dombrowski 



Justus-Liebig University, Giessen, Germany 



Stimulated by the bacteriological tindings in the mineral springs of Bad 

 Nauheim, which carry salts from Permian deposits, I investigated from a bac- 

 teriological point of view the Zechstein salts, obtained by means of mining and 

 drilling. Mliller and Schwartz (1953), Rippel (1945), and Strong (1956) only 

 achieved the isolation of dead bacteria from Zechstein salts. Reiser and Tasch 

 (1960) reported the living isolation of a diplococcus from Permian salts. We 

 now succeeded in isolating living bacteria. Yet, this achievement seemed rather 

 improbable; for if we had actually extracted living bacteria from Zechstein 

 salts, then we have to assume that we found creatures of the highest individual 

 age ever registered. 



The following is a description of the isolating technique we used. 



In bacteriological work it is obviously very easy to get unwanted secondary 

 infection. To be sure that this secondary effect would not spoil our results, 

 we used extraordinary precautions. (1) We chose a small research laboratory 

 in which an ultraviolet sterilization lamp was kept burning for four days before 

 the experiment. No one entered this room during these four days. (2) The 

 two researchers entered the laboratory in sterile clothes and sterile rubber gloves 

 after thorough disinfection of their hands and arms. (3) The table and neces- 

 sary tripods were covered with sterile towels. (4) All necessary instruments, 

 glassware, and apparatus were thoroughly sterilized. (5) The research ma- 

 terial, i.e., the piece of salt under consideration, was suspended on thin, sterilized 

 wire from the tripod. (6) This suspended piece of salt was then flamed for one 

 minute with a hot bunsen flame. (7) Immediately afterwards a glass with a 

 culture solution was brought under the piece of salt, so that it was suspended 

 in the solution. (8) The supporting wire was then cut and the glass was closed 

 after sterilizing the rim and the stopper also with the bunsen flame. (9) The 

 cultivation was carried out at a temperature of 40° C. (10) As soon as the cul- 

 ture began to grow, the elaboration to the pure culture proceeded in the usual 

 bacteriological manner. 



To working procedure 6, I must add that the necessary time for the surface 

 treatment of the salt with the bunsen flame was ascertained in preliminary 

 experiments. Salt-pieces, which were brought into a fresh suspension of living 

 Pyocyaneus — about 80,000 per cm.^ — could be sterilized in 45 seconds. 



Because salt is a poor heat conductor, the temperature fell rapidly toward the 

 center of the crystal. We heated the surface for 45 seconds. Then 3 cm. from 

 the surface, the temperature rose only by 6.2° C. Thus, we achieved a sterility 

 of the surface and regions close to the surface without producing sterilizing 

 temperatures in deeper layers. Of course, the crystals must be large enough; 

 they must have a diameter of at least 6 cm. Such specimens have a weight of 

 about 250 to 300 gm. A crystal this large saturates about 1 liter of culture 

 solution; a saturated solution is necessary for the cultivation of halophil and 

 halotolerant organisms. 



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