MICROCOCCUS 623 



MICROCOCCUS, SARCINA, RHODOCOCCUS AND LEUCONOSTOC 



In their monograph on the Systematic Relationships of the Coccacece, C.-E. A. 

 Winslow and Anne R. Winslow (1908) emphasize that the white and golden cocci 

 belong to a series of cocci, including the streptococci, which are essentially parasitic 

 in nature and active in fermentative power, whereas the yellow and red forms, 

 including the sarcinse, are geoerally saprophytic in nature and possess a restricted 

 fermentative power. 



Micrococcus 

 Definition. — Micrococcus. 



Spherical or ovoid cells, non-motile, arranged in pairs, tetrads, or groups, but 

 not in grape-like clusters or chains. Generally Grair -positive. Grow freely on 

 ordinary media. Sometimes produce a yellowish pigment. Gelatin liquefaction 

 is not constant, and is usually slow. Fermentative activities weak. Usually 

 non-pathogenic to man or animals. 



Type species is Micrococcus luteus Cohn. 



The term Micrococcus was first used in a generic sense by Cohn (1875), who 

 applied it to small spherical or oval non-motile organisms which occurred in 

 chains or groups. This, it will be observed, was a comprehensive description ; 

 it was not long in fact before certain members, such as the streptococci and the 

 staphylococci, were removed from it, and awarded generic names of their own. 

 The term Micrococcus, as now used, is defined above. 



As with most saproj)hytic organisms, the micrococci have not been studied so 

 fully as the pathogenic cocci — the streptococci and the staphylococci. It must 

 therefore be made clear that, in the following account, we record the characters 

 of certain micrococci which have been from time to time described by different 

 workers, without committing ourselves to any judgment as to their claims to be 

 accorded specific rank. In general, we have been guided in our selection by 

 Hucker (19246, 1928), who uses pigment production, gelatin liquefaction, nitrate 

 reduction, and ability to use ammonium salts as the sole source of nitrogen, as his 

 main differential criteria. To his reports we would refer the reader who requires 

 more detailed information. 



(1) Micrococcus luteus (Schroeter) Cohn. — Isolated by Schroeter (1875) from a potato 

 on which a yellow growth was found ; is a non-motile, Gram-positive coccus, 1 "0-1 -2 fx 

 in diameter, occurring in pairs, tetrads or small groups. It grows well on ordinary media, 

 giving a smooth, lemon-yellow layer. Gelatin is not liquefied, though on this point various 

 workers disagree. Nitrates are not reduced. The optimum temperature of growth is 

 25° C. Its fermentative powers are weak, acid being formed in glucose, not in lactose. 

 It is commonly found in air, water, milk and milk products. The pigment is insoluble in 

 water. 



(2) Micrococcus varians (Dyar) IVIigula (1900) is similar to 31. luteus, but is differentiated 

 from it by its ability to reduce nitrates. 



(3) Micrococcus conglomeratus Fliigge (Migula 1900). Forms large clumps of organisms, 

 often in pairs. Generally Gram-positive. Liquefies gelatin and reduces nitrates. Forms 

 an abundant light yellow growth on agar. Can utilize ammonium salts as the sole source 

 of nitrogen. 



(4) Micrococcus flavus. — Isolated by Prove (1884-87) from human vu-ine. About 0-8 /n 

 in diameter, occurring singly, in pairs or short chains. On gelatin gives colonies 5 mm. 

 in diameter by the 3rd day. Liquefies gelatin about the 12th day. Does not reduce 

 nitrates. Forms a considerable amount of slimy matter. Is said to ferment certain 



