Streptococci which Grow at High Temperatures

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Abstract
A study was made of 294 cultures of streptococci from milk and other sources which grow actively at 45[degree]C. The most prevalent types encountered are discussed below. Strep. thermophilus does not hemolyze blood; reduces litmus milk slightly after coagulation; does not produce NH3 from peptone; grows at 50[degree] but not at 10[degree]C; grows slowly at room temp.; ferments glucose, lactose, and sucrose; does not ferment maltose, inulin, mannitol, glycerol or salicin; and may or may not ferment ramnose and arabinose. Its resistance to pasteurization is greater than that of the other types studied. When grown in milk, long chains are formed. Strep. bovis does not hemolyze blood, reduce litmus before coagulation of milk, or grow at 10[degree] or at 50[degree]; but it does grow at 45[degree]C; ferments arabinose, glucose, maltose, lactose, sucrose, raffinose and salicin; hydrolyzes starch; does not ferment glycerol; and may or may not ferment inulin and man nitol. Strep. inulinaceus differs from Strep. bovis in that it always ferments inulin, but does not ferment arabinose, while starch is hydrolyzed only faintly. Strep. fecalis does not hemolyze blood; reduces litmus before curdling milk; grows at 10, 45[degree], and often slowly at 50[degree]; produces NH3 from peptone; ferments arabinose, glucose, maltose, lactose, and salicin; does not ferment raffinose, inulin, and glycerol; does not hydrolyze starch; may or may not ferment sucrose and mannitol; and does not digest casein or liquefy gelatin. Strep. glycerinaceus differs from Strep. fecalis in that it ferments glycerol and always ferments sucrose. Strep. glycerinaceus usually does not curdle milk as rapidly as Strep. fecalis Strep. liquefaciens does not hemolyze blood; reduces litmus before curdling milk; grows at 10[degree], 45[degree], and may or may not grow at 50[degree]; produces NH3 from peptone; ferments glucose, maltose, lactose, sucrose, raffinose, glycerol, mannitol and salicin; does not ferment arabi nose and inulin; does not hydrolyze starch; but liquefies gelatin and digests casein. Strep. zymogenes differs from Strep. liquefaciens in that it is beta-hemolytic and ferments arabinose. In view of the present state of our knowledge it might be better to consider Strep. inulina-ceus, Strep. glycerinaceus, and Strep. zymogenes as only varieties of Strep. bovis, Strep. fecalis, and Strep. lique- faciens, respectively. This, however, is a matter of opinion which should be left to specialists in taxonomy. All of the spp. described in this study survive heating for 30 min. at 62.8[degree] in milk.

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