Optimum pH, between 6.8 and 7.2. Growth stops at pH 4.9. Distinctive characters: Mycobacterium- like colonies with coral to vermilion-red chromogenesis on asparagine agar, potato, gelatin and other media; short rods, seldom forms filaments; generally not acid-fast. Comments: Gordon (personal communi- cation, 1954) reports that she finds that a culture isolated and identified by Ford (Textb. of Bact., 1927, 255) as this species is identical with Nocardia corallina Waksman and Henrici. Source: Six cultures were isolated from butter (Grassberger). Several cultures were isolated from soil in Holland (Sohngen) and Australia (Jensen). Two cultures were isolated as contaminants in tuberculin flasks (Hagan and Breed, personal com- munications). Habitat: Probably widely distributed in soil. 17. Nocardia rubra (Krassilnikov, 1938) Waksman and Henrici, 1948. {Proactino- myces ruber Krassilnikov, Bull. Acad. Sci., U.S.S.R., No. ], 1938, 139; also see Krassil- nikov, Guide to the Actinomycetes, Izd. Akad. Nauk, U.S.S.R., Moskau, 1941, 81; Waksman and Henrici, in Manual 6th, ed., 1948, 905.) rub'ra. L. adj. ruber red. Threads at first filamentous, developing into a unicellular mycelium; after a few days, frequent septa are produced and the mycelium breaks up into short, rod-shaped, and later coccoid elements. These grow into a mycelium on a fresh substrate. No aerial mycelium produced in nutrient media. Not acid-fast. Gram-positive. Gelatin: No liquefaction. Colonies usually rough; some are smooth, dry, powdery or of dough-like consistency. Part of mycelium grows into substrate. Colonies bright red. Pigment not dissolved into medium; weakly soluble in ether, alco- hol and acetic acid; well soluble in chloro- form; belongs to the carotenoids. Agar: Poor growth. Synthetic agar: Good, typical growth. Broth: Sediment and surface ring; me- dium clear. Milk: No change. Potato: Good, typical growth. Sucrose not inverted. Starch not hydrolyzed. Cellulose not attacked. Readily assimilates fats, paraffin and, to a less extent, wax. Nitrites not produced from nitrates. Distinctive characters: Grows well in high salt concentrations (5 to 10 per cent NaCl). Various strains of this organism may vary considerably from the type strain. Source: Isolated from soil. Habitat: Soil. 18. Nocardia coeliaca (Gray and Thorn- ton, 1928) Waksman and Henrici, 1948. {Mycobacterium coeliacum Gray and Thorn- ton, Cent. f. Bakt., II Abt., 73, 1928, 88; Proactinomyces coeliacus Reed, in Manual, 5th ed., 1939, 836; Waksman and Henrici, in Manual, 6th ed., 1948, 906.) coe.li'a.ca. Gr. adj. coeliacus suffering in the bowels; L. adj. coeliacus relating to the bowels. Original description supplemented by material taken from Jensen (Proc. Linn. Soc. New So. Wales, 56, 1931, 201). Short, curved, uneven-sided rods, 0.8 by 5 microns with occasional filaments up to 10 to 12 microns long, frequently beaded, occasionally swollen or branched. Coccoid forms 0.8 to 1.2 microns in diameter are common, especially in older cultures. Stain readily. Not acid-fast or occasionally slightly acid-fast. Gram-positive. Gelatin colonies: After 12 days, irregular, raised, white, rugose, dull, entire. Deep colonies: Irregular, smooth or slightly broken. Gelatin stab: Convoluted, buff-white to yellowish, dull; below surface the growth forms many irregular hollow lobes, giving a glistening appearance, to a depth of 3 to 4 mm. Agar colonies: After 11 days, less than 1 mm in diameter, round or irregular, raised, white, resinous, irregular, burred. Deep colonies: Irregularly round or ovoid; edge slightly broken. Agar slant: Filiform, convex, white, ru- gose, resinous, undulate growth.
