CHAPTER 31 

 LACTOBACILLUS 



Definition. — Lactobacillus. 



Rods, often long and slender, sometimes pleomorphic. Gram-positive. Non- 

 motile and non-sporing. Growth on surface media poor. Some members grow 

 best at 40°-44° C. Usually produce acid from carbohydrates, as a rule lactic ; 

 some members form gas in addition. Little or no proteolytic activity. Most 

 members are microaerophihc and facultative anaerobes ; some members are strict 

 anaerobes. Readily destroyed by heat, but imusuaUy resistant to acid. Not 

 known to be pathogenic to man or animals. Widely distributed in fermenting 

 vegetable and animal products. 



Type species is Lactobacillus caucasicus, Beijerinck. 



History. — The first organism of this group was isolated by Kern in 1881 

 from the fermented milk of the Caucasus, known as Kefir. The name he gave it 

 was Dispora Kaukasica, but later it was called Bacillus Kaukasicus, and 

 is now known as Lactobacillus caucasicus. As Kern did not give a complete 

 description of the organism, and as it is impossible to be certain of its identity, 

 it is somewhat unfortunate that it has been adopted as the type species. A similar 

 bacillus was observed by Doderlein in 1892 in the acid vaginal secretion of preg- 

 nant \fomen ; this is usually known as Doderlein's bacillus, but is also known 

 as B. vaginalis and B. crassus. Slender Gram-positive bacilli were observed 

 microscopically in the stomach contents of patients with gastric carcinoma by 

 Oppler in 1895, working in the clinic of Dr. Boas at Berlin ; this organism, which 

 was not cultivated, is generally known as the Boas-Oppler bacillus. In 1900 

 Moro (1900a, b) cultivated a similar bacillus from the faeces of breast-fed infants ; 

 this organism he called B. acidophilus ; his findings were confirmed in the same 

 year by Finkelstein (1900). Tissier, also in 1900, isolated two new organisms of 

 the same group from the faeces of infants, to which he gave the names B. bifidus 

 and B. exilis. In 1905 GrigoroS, working in Massol's laboratory, isolated from 

 Kisselo-mleko, better known as Yoghurt, the fermented milk of Bulgaria, three 

 organisms to which he gave the names A, B, and C ; the first of these is now known 

 as Lactobacillus bulgaricus or Massol's bacillus. Similar bacilli have been found 

 by other workers in a number of fermented milks, chiefly the Armenian Mazun, 

 the Sardinian Gioddu, and the Egyptian Leben raib (Cohendy 1906, White and 

 Avery 1910) ; they have also been isolated from ordinary market milk and from 

 human milk (Moro 1900a, Heinemann and Hefferan 1909, Sherman and Stark 

 1927). Bacilli of this group have been cultivated by Mereshkowsky and his pupils 

 (Mereshkowsky 1905, 1906, Petrow 1907) from the faeces of a large series of inverte- 

 brates, fishes, and mammals ; by Heinemann and Hefieran (1909) from human 

 saliva and gastric juice, from soil, and from a number of different foods, such as 



760 



