Putrefactive Bacteria. 163 



They are rod-shaped bacteria, motile, non-spore bearing, and Gram-negative. The 

 forms of colonies and characteristics are quite variable, sometimes showing root-like 

 extensions, and at other times branching outshoots. 



The most important spore-forming proteolytes originate from forage, hay, stable 

 dust and the stable air, and are collected, under the name of potato bacilli, hay bacilli 

 and root bacilli. 



They are small rods up to the size of the anthrax bacillus, with central or terminal 

 spores, and are Gram-positive. 



They grow best under aerobic conditions. 



Gelatin is liquefied, milk is precipitated as if by rennet, and is then dissolved. 

 In these instances the rennet action is at times more prominent, at other times the action, 

 of the caaease appears more prominently. 



On solid media the colonies have either a wrinkled, slimy appearance, or they are 

 dry, with a fine map-like drawing on their surface; again they may appear like dull 

 glass, gray, grayish-white, yellowish to brownish, delicate and profuse. On the borders 

 of the culture branch-like shoots or ' ' forms of Medusa heads ' ' similar to the cc lonies of 

 anthrax (anthracoid varieties) may be seen. 



The more important forms are: 



The Bacillus mesentcricus vulgatus; the potato bacillus (fuscus, graveolens, ruber) ; 

 Bacillus liodermes; Bacillus subtills (hay bacillus) ; the mycoid varieties; the anthracoid 

 varieties, Bacillus ramosus, implexus, radicosus, tumescens, megatherium, tyrotJirix, etc. 



In fluid media they generally form prolific wrinkled membranes; at times they 

 cloud the bouillon or they may grow in long, stringy filamentous masses. 



Some of the varieties also form butyric acid ; thus for instance the Bacillus 

 mesentericus changes lactic acid into butyric acid. To this class some of the mycoid 

 varieties belong, for instance the Bacillus butyricus Hueppe and the Clostridium polymyxa. 



Through the growth of these and similar forms, the formation 

 of albumose and peptones develops, and the further decomposi- 

 tion of the proteid substances is carried out, if possible, with the 

 production of end products such as leucin, tyrosin, ammonia, car- 

 bonic acid, indol, skatol, methylmerkaptan, sulphureted hydrogen, 

 toxic toxalbumins, and ptomaines. 



For the judgment of milk which is considerably contaminated 

 with bacteria from litter and forage the increased presence of such 

 bacteria is of special importance, since most of them form spores 

 which are not always destroyed at the temperature of 100 deg. C. 

 and higher. 



The Bacillus prodigiosus, Bacillus fluorescens liquefaciens, 

 Bacillus amylobacter, and Bacillus putrificus Bienstock, may also 

 split up proteins. Their products vary. 



The bacterial substances which dissolve proteins and split 

 them up, exert their action especially in neutral and alkaline ma- 

 terial, and they are therefore hindered in their action by the pro- 

 ducts of the third phase, the second decomposing phase. 



The lactic acid producers, however, proliferate only after 

 the necessary requirements for their propagation have been created 

 by the activity of the peptonizing bacteria. 



Through the activity of the lactic acid bacteria the milk sugar 

 and other varieties of sugar are fermented to dextro-rotary (ro- 

 tates plane of polarization to right) lactic acid, inactive lactic acid, 

 and levo-rotary (rotates plane of polarization to left) lactic acid, 

 depending on the species of bacteria or the conditions under which 

 the special species prevail. 



The splitting of lactose C^H^O,, is accomplished by an inverting bacterial enzyme, 

 the lactase, through the introduction of water whereby it is converted into 2C 6 H 12 O 6 

 known as D-glucose and D-galaetose, which by further splitting break up into 4C 3 H 6 O 3 . 



