salt): Filiform, slightly raised, smooth, glistening, butyrous, bright red (Lochhead, loc. cit). Broth (5 to 35 per cent salt) : No growth. Good growth when grown according to di- rections of Katznelson and Lochhead {op. cit., 1952,97). Codfish broth (25 per cent salt): Turbid, dense, pink sediment; imperfect, pink pel- licle. Potato immersed in brine: No growth. Indole not produced. Hj'drogen sulfide is produced. No indication of action on carbohydrates. Starch not hydrolyzed. Cannot utilize inorganic nitrogen as a sole source of nitrogen. Tests (Warburg respir- ometer) show active oxidation of amino acids (such as serine, glutamic acid and as- partic acid); also active oxidation of glj'c- erol. Nitrites not produced from nitrates (Lochhead, op. cit., 1934, 275). Aerobic. Optimum temperature, 37° C. Grows at 22° C. Optimum salinity, 28 to 32 per cent (Loch- head, loc. cit.). When the salt concentration is reduced to 8 per cent, cells are ruptured. Distinctive characters: See Halobacterium cutirubrum. Source: Isolated from cured codfish (Harrison and Kennedy, op. cit., 1922, 121) and salted fish (Browne, Absts. Bact., 6, 1922, 25, and Proc. Soc. Exp. Biol, and Med., 19, 1922, 321) ; also from salted hides (Loch- head, op. cit., 1934, 275). Habitat: Produces a reddening of salted fish and hides where untreated solar salt is used. Abundant in tidal pools along shores of tropical seas. Reddens the water in the pools where solar salt is produced as soon as the brine is concentrated to 18 per cent salt. Common on untreated solar salt.
2. Halobacterium cutirubrum (Loch- head, 1934) Elazari-Volcani, 1940. {Serratia cutirubra Lochhead, Can. Jour. Research, 10, 1934, 275; Flavobacterium {Halobacterium) cutirubrum Elazari-Volcani, Studies on the Microflora of the Dead Sea. Thesis, Hebrew Univ., Jerusalem, 1940, 59.) cu.ti.ru'brum. L. nonn cutis the skin; L. adj . ruber red; M.L. adj . cutirubrus skin-red. Occurs as spheres and rods. The spheres are 1.0 to 2.0 microns in diameter, and the rods measure 0.7 to 4.0 by 1.5 to 8.0 microns. Age of culture and nature of medium influ- ence the size and shape of cells. Rod forms are motile with a single polar flagellum; coccoid forms are motile when young. Gram- negative. No growth on ordinary media. Milk agar (20 per cent salt to saturation; optimum 28 to 32 per cent) colonies : 3 to 4 mm in diameter, round and slightly convex, pink to dark red (rose dorde, Ridgway chart) . Milk agar slants: Growth filiform, slightly spreading, rather flat with smooth, glisten- ing surface and membranous consistency. Proteolytic action. Liquid media: No or slight growth. Good growth when grown according to directions of Katznelson and Lochhead (Jour. Bact., 64, 1952, 97). Gelatin (salt): Pronounced liquefaction. Indole not produced (Lochhead, op cit., 1934, 275) ; faint positive (Gibbons, Jour. Biol. Board Canada, 3, 1936, 75). Hydrogen sulfide is produced. Tests (Warburg respirometer) show slow oxidation of amino acids (such as serine, glutamic acid and aspartic acid) ; also slow oxidation of glycerol. Nitrites not produced from nitrates. Diastatic action negative. No carbohydrate fermentation. Aerobic. Optimum temperature, 37°C. Salt tolerance: Halophilic, obligate. No rupturing of cells occurs when the salt con- centration is reduced to 8 per cent; rup- turing occurs when the salt concentration is 4 per cent. Distinctive characters: Resembles Halo- bacterium salinarium. Differs from it in mor- phology and cultural characters, particu- larly as regards color and consistency. More actively proteolytic. Slower oxidative ac- tion on amino acids and glycerol. Ruptur- ing of cells does not occur as rapidly when the salt concentration is reduced.
