SYRUPS 205 



sistant of all bacterial spores. They are further characterized by 

 their ability to form gummy products on potato, on bread and in 

 sugars. 



Bacillus mesentericus niger and B. granulaius mesentericus 

 are also members of the potato group and may be found in sugars 

 and syrups. Leuconostoc mesenteroides and Bacterium gelatinosum 

 beta, which are frequently found in sugar beet juice, are evidently 

 related to the potato group. Bacillus gummosus, also a gum 

 former, is frequently found in digitalis infusions. This latter 

 bacillus is comparatively large, feebly motile, forms spores and 

 produces lactic and butyric acids. Another organism which is 

 probably closely related to the potato group is the Bacterium 

 mesentericus panis viscosum, the cause of stringy or slimy bread. 

 All of the organisms named are Gram positive, are spore formers, 

 liquefy gelatin and are motile, having flagellse. The principal 

 biologic characteristics of the group may be given as follows: 



1. They form gums (levan) from sugars. 



2. The spores are very resistant to heat. 



3. They have a very low nutrient requirement. 



Very minute quantities of sugar are sufficient to induce them 

 to grow and multiply, resulting in the transformation of some of 

 the sugar into a gum known as levan. 



From the above general characteristics of the sugar bacteria 

 it is almost self-evident how they may cause very serious harm to 

 solutions of all kinds containing sugar. The highly resistant 

 spores make thorough sterilization difficult and, since high tem- 

 peratures cause inversion of sugars, the use of the autoclave and 

 repeated and prolonged heating at the boiling temperature are 

 frequently not permissible. In cases where the use of the autoclave 

 is permissible, a single exposure at a temperature of 120° C. 

 for a period of 30 min. is sufficient to kill the spores. More 

 generally the fractional method of heat sterilization must be 

 employed. 



It is a noteworthy fact that after the gum formers have 



