456 STATE BOARD OF AGRICULTURE 



tions were made at the end of several months' incubation, results of which 

 will be found in Table 4, Part II, of this bulletin. 



In appearance the 55° cultures from these cans were identical with 

 those isolated originally from string beans and from some silage. Also the 

 rapid growth was characteristic. If cultures for cultivating at 55°-65° C. 

 are made in hot agar (temperature within growing limits of thermophiles) 

 and this agar is allowed to cool only sufficiently for solidification to start, 

 then covered with sterile paraffin and placed at the incubating temperature 

 the growth will be hastened much more than when the agar is allowed to 

 become cold and wholly solid before incubating. It is necessary, however, 

 that the agar be cooled until it starts to harden, before incubating, otherwise 

 it will remain liquid and colony formation will not be seen. 



In a recent study made of some experimental silage, plates made from 

 it in acid whey and litmus dextrose agar plated and incubated at 55° showed 

 active gas production but no visible growth just as in the case of the organism 

 isolated from canned string beans. Isolations from these plates showed the 

 same "ghosthke" colonies producing gas anaerobically. Although this coin- 

 cidence has not been deemed of sufficient importance to determine whether 

 the bacterium isolated from the silage and that from the string beans are the 

 same organism, it does serve to show that an organism or organisms (anaerobic 

 thermophiles having the peculiarities described) are not uncommon and are 

 probably fairly well distributed in nature. The finding of organisms pro- 

 ducing colonies of low visibility suggests that they may be common and not 

 confined to anaerobic thermophiles. It is possible that ultra-microscopic 

 organisms may produce this type of colony. Attention is called to the 

 desirability of selecting the proper medium for this type of organism. 



Since thermophiles are not infrequently found in canned foods and because 

 of the discovery of this peculiarly growing anaerobic thermophile, it seems 

 desirable (1) that the microbiologists in food research laboratories should 

 make a practice of culturing all spoiled foods, canned or otherwise, both 

 aerobically and anaerobically not only at room and body temperatures but 

 also at a temperature sufficiently high to demonstrate the possible presence 

 of thermophiles; (2) it seems that attention should be directed to the im- 

 provement of technic designed to overcome the difficulty of demonstrating 

 organisms of low visibility of the type described or ultra-microscopic 

 organisms. 



