464 Physiology 



presumably qualifies these organisms as symbiotes of their respective hosts. 

 In addition to the Protozoa in which other polysaccharidases have been 

 reported (Table 8. 5), the many species which store and utilize starch 

 and glycogen doubtless have enzymes capable of splitting these reserve 

 foods into simple sugars. However, the utilization of stored polysac- 

 charides may involve phosphorolysis rather than digestive hydrolysis. 

 Starch, for example, would yield a-glucose-1 -phosphate instead of maltose 

 or glucose. This situation raises the possibility that some of the phyto- 

 flagellates which store starch may be unable to use exogenous starch as a 

 substrate. 



The utilization of disaccharides (Table 8. 6) has been reported on the 

 basis of fermentation reactions, the activity of extracts prepared from 

 Protozoa, or the effects of sugars on oxygen consumption. Such abilities 

 also may be inferred for species which digest polysaccharides. 



Digestion of lipids 



Little is known about the utilization of lipids by Protozoa, al- 

 though the production of lipases by many species seems probable in view 



TABLE 8. 6. UTILIZATION OF DISACCHARIDES 



Key: +, utilized; ±, utilized very slowly; — , not utilized; ?, data not reported. 



