58 MANUAL OF MICROBIOLOGICAL METHODS 



products. Some aspects of this subject have been reviewed by Gale 

 (1951). A few examples are presented below. 



Metabolically active cells. In many studies dealing with the physio- 

 logical activity of cells harvested from culture media, comparatively little 

 attention has been paid to the conditions of growth, a large cell crop being 

 the usual criterion of the adequacy of the medium. Wood and Gunsalus 

 (1942) have pointed out the limitation of this criterion and have studied 

 the effects of the components of the growth medium upon the dehydro- 

 genase activity of suspensions of Streptococcus mastitidis. A suitable and 

 easily prepared medium was described consisting of the following ingredi- 

 ents: 'Hryptone," 10 g; yeast extract, 10 g; K2HPO4, 5 g; glucose, 2 g; 

 water, 1 liter. Metabolically active cells were obtained after incubation 

 at 37°C for 12-15 hr. The final pH was about 6.8. Tsuchiya and 

 Halvorson (1947) made similar studies to obtain suspensions of glyco- 

 lytically-active Lactohacillus casei and L. arahinosus. The significance of 

 this type of study rests upon the knowledge of the effects of each major 

 component of the medium upon the particular physiological activity 

 being studied, and such an analysis should precede biochemical 

 investigation. 



Production of enzyme, toxin, or antibiotic. The report of Bellamy 

 and Gunsalus (1945) on the composition of a pyridoxine-deficient growth 

 medium for Streptococcus faecalis, which yielded cells containing large 

 amounts of tyrosine decarboxylase apoenzyme, will serve as an example 

 of a medium for the production of a bacterial enzyme available in a con- 

 venient form to study coenzyme function. The composition of the 

 medium used is described in the paper cited above; at this point, the 

 major intention is the statement of the availability of a cultural method 

 of great potential advantage in biochemical investigations. 



The production of bacterial toxins has engaged the attention of many 

 bacteriologists. In at least one case {Clostridium perf ring ens) , one of the 

 toxins produced by the organism is an enzyme (lecithinase) . It may be 

 assumed, therefore, that the effect of the constituents of the medium 

 upon toxin production is similar to the situation with respect to the pro- 

 duction of other enzymes and may be studied effectively along parallel 

 lines of investigation. The nutritive requirements for toxin production 

 by the organisms of diphtheria (Mueller and Miller, 1941), botulinus 

 (Lamanna, Eklund, and McElroy, 1946; Lamanna and Glassman, 1947; 

 Lewis and Hill, 1947; Stevenson, Helson and Reed, 1947), tetanus 

 (Mueller and Miller, 1943, 1948), and gas gangrene (Adams and Hendee, 

 1945; Logan et at., 1945) are available. 



The production of antibiotic compounds varies considerably with the 

 nature of the culture medium and other factors. For a discussion of this 

 topic consult Prescott and Dunn (1949). 



