M.L. neut.n. arabinosum arabinose, a pen- tose sugar derived from gum arable. Cells in neutral lactate media spherical, 0.8 micron in diameter, occurring in pairs and short chains. In acid media swollen spheres and ellipsoidal cells occur, mostly 2.0 by 3.0 to 3.5 microns, often in pairs and short chains. Non-motile. Show metachro- matic granules. Gram-positive. Yeast-gelatin-lactate-stab: No liquefac- tion. Yeast-agar-lactate-stab : Cream-colored growth in stab with distinct orange-yellow surface growth. Liquid cultures: Turbid in early stages; cream-colored, smooth sediment. Litmus milk: No coagulation. Indole not produced. Ferments lactic and pyruvic acids, glyc- erol, dihydroxyacetone, d- and 1-arabinose, glucose, galactose, fructose, mannose, cello- biose, maltose, sucrose, raffinose and man- nitol with the production of propionic and acetic acids and carbon dioxide. Acid from sorbitol. No acid from dulcitol, xylose, rhamnose, salicin or inulin. Pantothenic acid and biotin, but not para-aminobenzoic acid, are required for growth; thiamine, although not required, is growth-stimulating (Delwiche, Jour. Bact., 58, 1949, 396). Nitrite production not recorded. Very slightly catalase-positive. Anaerobic, but less so than Propionibac- terium freudenreichii. Distinctive characters: The development of spherical involution forms in acid media, the almost complete absence of catalase and the ability to ferment both d- and 1-arabinose but not xylose or rhamnose. Note : The strain obtained from Dr. E. B. Fred produced only minute amounts of acid from lactose and starch; it is questionable whether these carbohydrates are fermented. Source: Not definitely stated. Habitat: Dairy products. 11. Propionibacterium pentosaceum van Niel, 1928. {Bacillus acidi propioriici von Freudenreich and Orla- Jensen, Cent. f. Bakt., II Abt., 17, 1906, 532; van Niel, The Propionic Acid Bacteria, Haarlem, 1928, 163.) pen.to.sa'ce.um. Gr. pi. adj. pente five; M.L. neut.n. pentosum a pentose sugar; M.L. adj. pentosaceus relating to a pentose. Description taken from van Niel {loc. cit.) and from Werkman and Brown (Jour. Bact., 26, 1933, 408). In neutral lactate media cells spherical, 0.8 micron in diameter, occurring in pairs and short chains. In media developing acid- ity, long, irregular rods, swollen and branched, 3 to 4 microns in length, occur. Aerobic growth occurs as irregular, swollen and branched, long rods. Non-motile. Show metachromatic granules. Gram-positive. Yeast-gelatin-lactate stab: No liquefac- tion. Yeast-agar-lactate stab: Cream-colored development in stab with abundant, cream- colored surface growth. Liquid media: Turbid in early stages; smooth, creamy sediment; ropy. Litmus milk: Coagulated, acid. Indole not produced. Ferments lactic and pyruvic acids, glyc- erol, dihydroxyacetone, d- and 1-arabinose, xylose, rhamnose, glucose, galactose, fruc- tose, mannose, cellobiose, lactose, maltose, sucrose, raffinose, mannitol and sorbitol with the production of propionic and acetic acids and carbon dioxide. Acid from adonitol, arabitol, erythritol, esculin, inositol, salicin and trehalose. No acid from dextrin, dulcitol, glycogen, inulin, perseitol or pectin. Pantothenic acid and biotin, but not para-aminobenzoic acid, are growth re- quirements; although thiamine is not re- quired, it is stimulating for growth (Del- wiche, Jour. Bact., 58, 1949, 396). Nitrites and free nitrogen produced from nitrates. Slightly catalase-positive. Anaerobic, but less so than any of the other species of the genus. Distinctive characters: The formation of long, rod-shaped involution forms in acid media, the absence of pigment production, and the ability to ferment d- and 1-arabi- nose, rhamnose and xylose. Source: Isolated from Emmental cheese. Habitat: Dairy products.
