600 



ORDER IV. EUBACTERIALES 



oped colonies are transparent with a bluish 

 sheen by reflected light, circular and entire. 



Tellurite agar colonies: Grayish and pin- 

 point in 24 hours, later increasing in size 

 and becoming jet black. 



Broth: Slight turbidity with scant, gray- 

 ish sediment. 



Litmus milk: No change. 



Indole not produced. 



Hj^drogen sulfide produced. 



Blood serum shows scant growth. 



No gas from carbohydrates. 



Acid from glucose, galactose, fructose 

 and lactose. When the basic medium is very 

 favorable, acid may be produced from xy- 

 lose, arabinose, mannose, maltose, cello- 

 biose and melibiose. Usually no acid from 

 glycerol, sorbitol, mannitol, inositol, rham- 

 nose, sucrose, trehalose, melezitose, raffi- 

 nose, starch, inulin or salicin. The addition 

 of yeast autolysate to media for fermenta- 

 tion studies is recommended. 



Esculin not hydrolyzed. 



Final pH in yeast extract trj^pticase-glu- 

 cose broth usually about 6. 



Blood agar: On prolonged incubation 

 there is at first a greening and then a slight 

 but definite clearing around the colonies. 



Nitrites not produced from nitrates. 



Catalase-negative. 



Facultatively anaerobic. 



Temperature range of growth, 16° to 

 41° C. The fastest growth rate is at about 

 37° C. The maximum cell crop is obtained 

 near 33° C. 



Optimum pH, between 7.4 and 7.8. 



Tolerates phenol in concentrations to 0.2 

 per cent and potassium tellurite in concen- 

 trations to 0.05 per cent. 



Source: Isolated from cases of swine ery- 

 sipelas, human erysipeloid and mouse sep- 

 ticemia; also isolated from infections in 

 birds, e.g. turkeys and ducks. Transmissible 

 to a large number of experimental animals : 

 pigeons and mice are susceptible to experi- 

 mental infection, but rabbits are less sus- 

 ceptible, and guinea pigs are quite resist- 

 ant; inoculation in man has been successful; 

 susceptibility of swine is very variable. Fish 

 handlers are especially subject to erysipe- 

 loid infections derived from fish (Bedford 

 and Leeds, Brit. Jour. Dermat. and Syph., 

 U, 1932, 368; Niewiarowski, see Biol. Abst., 

 ;g7, 1953, No. 17069). 



Habitat : This organism is widely distrib- 

 uted in nature as indicated above. 



Genus IV. Microbacterium Orla-Jensen, 1919.* 

 (The Lactic Acid Bacteria, 1919, 179.) 



Micro. bac.te'ri.um. Gr. adj. micrus small; Gr. neut.dim.n. hactcrium a small rod; M.L. 

 neut.n. Microbacterium a small rodlet. 



Small rods with rounded ends; vary in length from 0.5 to 30 microns. Non-motile. Gran- 

 ulations demonstrable with methylene blue stain. Gram-positive. Good surface growth 

 on media supplemented with milk or yeast extract. Acid production weak with principally 

 L (+)- lactic acid produced from fermented carbohydrates. Catalase-positive. Optimum 

 temperature, 32° C. Thermoduric saprophytes found chiefly in dairy products and on 

 utensils. 



The type species is Microbacterium lacticum Orla-Jensen. 



Key to the species of genus Microbacterium. 



I. Hydrolyzes starch; produces acid from maltose. 



1. Microbacterium lacticum. 

 II. Does not hydrolj^ze starch; acid not produced from maltose. 



2. Microbacterium flavum. 



1. Microbacterium lacticum Orla-Jen- 

 sen, 1919. (The Lactic Acid Bacteria, 1919, 

 179.) 



lac'ti.cum. L. mas.n. lac, lactis milk; M.L. 

 adj. lacticxis pertaining to milk, lactic. 

 Small, diphtheroid rods, 0.4 to 0.7 by 1.0 



Revised by Dr. R. N. Doetsch, University of Maryland, College Park, Maryland, April, 



1953. 



