125 



h. Investigations on the natural group of hutyric acid and butyl alcohol 

 bacteria. 



A second natural group of bacteria which became the subject of a 

 thorough investigation by Beijerinck is that of the anaerobic, spore- 

 forming, sugar-fermenting bacteria, generally known by their com- 

 mon names of butyric acid and butyl alcohol bacteria. 



Beijerinck's first publication on the bacteria of this group was of 

 an astonishingly exhaustive character i). Judging from the title, "Sur 

 la fermentation et Ie ferment butyliques", one might expect that this 

 publication would be restricted to the butyl alcohol fermentation and 

 its causative organism. In reality, however, Beijerinck gave a 

 critical ^urvey of the whole group of anaerobic, spore-forming, sugar- 

 fermenting bacteria. The discussion is obviously based on extensive 

 personal experiences with the main representatives of this group. 



The introduction opens with the remark that the author already in 

 1886, i.e., seven years before, had found that certain cereal grains — 

 more especially barley — after having been ground and soaked with 

 boiling water, readily enter into a. gassy fermentation, amongst the 

 products of which butyl alcohol is easily detected. Starting from 

 other samples, however, in many cases butyric acid is the most 

 characteristic fermentation product. 



At first sight it is a little surprising that Beijerinck postponed the 

 publication of his studies on the butyl alcohol fermentation so long. 

 His statement that in 1885, after the death of Fitz, he received the 

 strains of Bacillus butylicus described some years earlier by this 

 pioneer in the fermentation field, supplies evidence that Beijerinck 

 had already thoroughly studied that bacterial group at the very 

 beginning of his microbiological career. 



Obviously, at that time, other problems took his attention before 

 he found the time necessary for concluding his investigations by a 

 publication. 



In the introductory remarks to his 1896 paper Beijerinck emphas- 

 izes that normal butyl alcohol frequently occurs in the fermentation 

 of sugars by various bacterial species. Yet he added that, as a rule, 

 this alcohol has only the character of a minor product accompanying 

 larger amounts of butyric acid. This holds, for example, for the ferm- 

 entation caused by Bacillus butylicus Fitz. Beijerinck also referred 

 to the fermentation caused by Grimbert's Bacillus orthobutylicus as 

 being of the butyric acid type. Beijerinck, therefore, expressed as 

 his opinion that the butyl alcohol fermentation described by him in 

 such profuse detail differs in principle from all so-called "butyl alcohol 

 fermentations" reported up to that time. 



>) Verhandelingen Kon. Akad. v. Wet. Amsterdam, 2de Sectie, 1, No. ^0, 1893. A 

 French, somewhat extended, version of this memoir was published three years later 

 Arch. néerl. d. sciences exactes et naturelles 29, 1, 1896. 



