nl^ sroLoov 



133 



DAYS 



Figure 65. Effect of glucose on streptomycin production; key same as in Fig. 64. (Reproduced 

 from: X. A. Krassilnikov, 1950, p. 206). 



grow only above a certain temperature, al- 

 though they may remain alive, without 

 multiplication, at much lower temperatures. 

 When the temperature reaches a point which 

 is specific for each organism, growth begins. 

 The rates of reproduction and of the meta- 

 bolic reactions increase rapidly with a fur- 

 ther rise in temperature up to a certain 

 point, which is again specific for each or- 

 ganism. A still further rise in temperature 

 leads to a drop in the rate of growth, until 

 finally a point is reached at which growth 

 stops. 



According to Haines (1932), the ordinary 

 saprophytic actinomycetes found in cold 

 stores and in soil fall into two groups: 1. 

 Those organisms that have their optimum 

 temperature for growth at 37° C, their range 

 of growth extending from 40 to 5° C, with a 

 lower limit at just about 0° C. 2. Those that 



have a less sharply defined optimum tem- 

 perature, growth being rapid at 20 to 30° C; 

 corresponding to a lower optimum tempera- 

 ture is also a lower minimvmi temperature, 

 growth being slow but good at 0° C, with a 

 minimum between and — 5° C. The con- 

 clusion was reached that actinomycetes are 

 probably of greater practical significance in 

 modern trade practice in chilled meat, eggs, 

 and possibly fruit than in well-frozen meat. 

 The presence of active cultures is sufhcient, 

 without actual grow'th, to cause a "musty" 

 taste in the stored product. 



Three points are thus established in the 

 temperature range for every organism: (a) a 

 minimum or lower limit of growth; (b) a 

 maximum or upper limit; and (c) an opti- 

 mum at which growth is at its best. The 

 optimmn temperature may not be a sharp 

 point, but may cover a comparatively wide 



