Genus: Betabacterium (Abbr. Bhm.). 



The betabacteria (Table XXXI) are in most respects so closely allied lo the beta- 

 cocci that they may be regarded as the analogous rod forms, and they can^like the beta- 

 cocci, be divided into those which ferment arabinose (Nos. 1—20) and those which do 

 not (Nos. 21 — 33). The Bacterium casei y and 8^) formerly described by me are typical 

 representatives of these groups, and as they also difler in morpiiological respects, — 

 the arabinose-fermenting rods being generally shorter than the others — we consider 

 ourselves justified in eslal)lishing the species Betabaclerium breve and Betabaclerium Ion- 

 gum. Besides occurring in vegetable matter, they are also found in cheese, fæces and 

 kefir grains. The rods forming the tissue of the kefir grains (Nos. 1 and 2) are, however, 

 so different -from the remaining betabacteria that they must undoubtedly be reckoned 

 as a distinct species which we will call Betabaclerium caucasicum, as the kelir rods are 

 now for the most part known under the name of Bacterium caucasicum. This last name 

 is also erroneously used for streptobacteria, which are likewise also found in kefir (though 

 not as a rule in the grains themselves), and which are considerably easier to obtain in 

 pure cultures. 



Most of the betabacteria are not altogether killed by heating until 75°. They form 

 inactive lactic acid, at times with a surplus of dextro-lactic acid. The great majority of 

 strains develop gas (carbonic acid and more or less hydrogen). When the development 

 of gas is strong, succinic acid is also formed. The power to form any considerable quantity 

 of gas, and thus succinic acid, is, however, soon lost in artificial nutritive substrates, 

 and in most of our strains, gas development could only be observed by sowing out closely 

 in sugar agar tubes. From lævulose, some few strains can form a small amount of man- 

 nite, and as the mannite-forming mash bacterium Lactobacillus fermentatum-), whicii lias 

 been closely studied by Jan Smit, has the greatest resemblance to the betabacterium 

 (judging from its fermentation of sugar, with Sbm. longum) it should doubtless be reckoned 

 under this head. Possibly the mannite bacteria^) so dreaded in the making of wine also 

 belong here. Some of these form, like the betacocci, sUme from cane sugar, which the beta- 

 bacteria investigated by us never do. 



The betabacteria grow poorly in milk, and do not as a rule attack casein at all. When 

 cultivated at optimal temperature, however, some few strains, in a freshly isolated state, 

 were able to curdle milk, and even with a slight development of gas, but this power 

 was soon lost. The frequent occurrence of these bacteria in cheese is due to the fact that 

 they are better able to utilise lactate of lime as a source of carbon than arc most other 

 lactic acid bacteria. 



A characteristic feature in the betabacteria is their lack of ability to ferment salicin 

 and alcohols, and, with the exception of the Bbm. longum forms, their preference for 



') Studien über die flüchtigen Fettsäuren im Käse etc. Centraiblatt f. Bakteriologie II. Abt. 19Ü4, 

 XIII, p. 604. 



-) Zeitschrift für Gärungsphysiologie 1915, Bd. V, p. 273. 



^) In Müller-Thurgan and Osterwalder's big work: "Die Bakterien im Wein und Obstwein und 

 die dadurch verursacliten Veränderungen" (Centralblatt f. Bakt. II. Abt. 1913, Bd. 36i there is also a list 

 of works on this subject. 



n. K. U. Vidensk. Selsk. Skr., natuivldensk. og maUieni. Aid., 8. Række. V. 2. — ' 



