142 CULTURE MEDIA IN RELATION TO METABOLIC PRODUCTS 



QUESTIONS. 



1. How can it be shown whether bacteria in their growth produce a proteo- 

 lytic ferment or not? 



2. What other enzymes are produced by bacteria in their growth? 



3. What is an enzyme? 



4. Describe the preparation of culture media containing starch. 



5. Describe the preparation of a bouillon absolutely free from sugar. 



6. Why is the agar medium not adapted for preparing a sugar-free culture 

 soil? 



7. What is diastase ? 



8. What is its effect upon starch? 



9. What test can be used to demonstrate the presence of amylodextrin, ery- 

 throdextrin, and achroodextrin? What are the color reactions of this test? 



10. What sugar is formed by the action of diastase upon starch? 



11. What is meant by an amylolytic ferment? 



12. What is Fehling's solution? What reaction occurs if sugar is boiled with 

 it? 



13. What is the meaning of the statement that sugar is a reducing substance ? 



14. Describe the determination of the special kind of sugar present in a solu- 

 tion. 



15. What are rennet and "lab" enzymes ? How can they be detected in bacterial 

 growth ? 



16. How is the acid production of bacteria demonstrated ? How is the amount 

 of acid formed determined accurately? 



17. How can alcohol formation be detected? 



18. What apparatus is necessary to determine the formation of gas in bac- 

 terial cultures? 



19. Describe the test to determine whether part of the gas formed is carbon 

 dioxide. 



20. What other gas is usually formed with carbon dioxide from sugar? 



21. What culture media are used to determine whether hydrogen sulphide is 

 formed? What reaction shows the formation of this gas? 



22. What reagent is used to detect the formation of Ammonia? 



23. What is indol? What culture medium is used to demonstrate its forma- 

 tion? 



24. Describe the test for indol. 



25. Describe the test for the detection of carbolic acid. 



26. What kind of a process is the change of nitrates to nitrites? 



27. What culture medium is used to demonstrate the formation of nitrites? 



28. Test for nitrites? 



