Habitat: Undoubtedly widely distril)uted in milk or milk products. 3. Lactobacillus helveliciis (Orla-Jen- sen, 1916) Holland, 1920. (Bacillus e, von Freudenreich, Cent. f. Bakt., II Abt., /, 1895, 173; also see Landw. Jahrb. d. Schweiz, 1895, 211; Bacillus casei e, von P'reudenreich and Thoni, Landw. Jahrb. d. Schweiz, 1904, 526; Thermobacterium helveticiun Orla-Jen- sen, Maelkeri-Bakteriologie, 1916, 35; also see The Lactic Acid Bacteria, 1919, 164; Holland, Jour. Bact., 5, 1920, 223.) hel.ve'ti.cus. L. adj. Helveiicus Swiss. Rods, 0.7 to 0.9 by 2.0 to 6.0 microns, oc- curring singly and in chains. Non-motile. Gram-positive. Whey gelatin colonies: Does not grow readily at temperatures required for incu- bation of gelatin. Lactose agar colonies: Small, grayish, viscid. Milk: Acid, with coagulation; may be- come slimy. Acid from glucose, fructose, galactose, mannose, maltose and lactose; smaller amounts are produced from dextrin. The lactic acid produced is optically inactive. Nitrites not produced from nitrates. Microaerophilic. Temperature relations: Optimum, be- tween 40° and 42° C. Minimum, between 20° and 22° C. Maximum, 50° C. Source: Isolated from sour milk and cheese. Habitat: Widely distributed in dairy products. 4. Lactobacillus acidophilus (Moro, 1900) Holland, 1920. (Bacillus acidophilus Moro, Wiener klin. Wochnschr., 13, 1900, 114; also see Jahrb. f. Kinderheilkunde, 52, 1900, 38; Holland, Jour. Bact., 5, 1920, 215.) a.ci.do'phi.lus. L. adj. acidus sour; M.L. neut.n. acidum acid; Gr. adj. philus loving; M.L. adj. acidophilus acid-loving. Description of Moro supplemented by material from Kulp and Rettger (Jour. Bact., 9, 1924, 357), Curran, Rogers and Whittier (Jour. Bact., 25, 1933, 595) and Rettger, Levy, Weinstein and Weiss (Lacto- bacillus acidophilus, Yale Univ. Press, New Haven, 1935). Rods, 0.6 to 0.9 by 1.5 to 6.0 microns, oc- curring singly, in pairs and in short chains with rounded ends. Non-motile. Dimensions variable (Kulp and Rettger), (Curran, Rogers and Whittier). Gram-positive; old cultures often Gram-negative (Moro). Gelatin: No growth at 20° C. No lique- faction. Wort-agar (Moro) or tomato agar (Kulp and Rettger) plates. Surface colonies: pe- ripheries a capilliform maze of long, deli- cate, twisted, fuzzy projections; center appears as a thick, dark, felt-like mass. Deep colonies: small, irregularly shaped, with fine radiate or ramified projections. Wort-agar slants: Growth scant, limited, dry, veil-like. Wort-broth: After 48 hours, fine, floccu- lent sediment. Other acid broths sediment whitish, slight turbidity. Milk: Slow growth with small inoculum. Coagulates from the bottom up. Potato: No growth. Acid but no gas from glucose, sucrose and lactose (Moro). Acid from glucose, fructose, galactose, mannose, maltose, lactose and sucrose. Some cultures ferment raffinose and trehalose and have slight action on dextrin. Xylose, arabinose, rhamnose, glyc- erol, mannitol, sorbitol, dulcitol and inosi- tol not fermented (Kulp and Rettger). Op- tically inactive lactic acid and volatile acids formed from sugars (Curran, Rogers and Whittier). No visible growth in carbohydrate-free media (Rettger, Levy, Weinstein and Weiss). Microaerophilic. Temperature relations: Optimum, 37° C. No growth between 20° and 22° C. (Moro). Maximum, between 43° and 48° C. (Curran, Rogers and Whittier). Not pathogenic for laboratory animals. Distinctive characters: Grows in acid media. Unless frequent transfers are made, organism may become Gram-negative and rapidly develop characteristic degeneration forms (Moro). The so-called original strains of Bacilhts acidophilus from the Krdl col- lection, described and called Microbaclerium lacticum by Orla-Jensen, do not have the characteristics given by Moro. Comments: Crecelius and Rettger (Jour.
