i'3 LABORATOBT BACTERIOLOGY. 



EXERCISE XXXI. 



THE TEANSFOKMATION OF NITRATE NITROGEN INTO PROTEIN. 



1. Measure off eight 100 cc. portions of "nitrate-nitrogen 

 transformation" solution into Erlenmeyer flasks. 



2. Plug and sterilize in the autoclave. 



3. Inoculate thus: 



1 & 2 — 1 cc. vigorous culture B. subtilis. 



3 & 4 — 1 cc. vigorous culture B. mycoides. 



5 & 6 — 20 cc. ( = 10 gm. soil) filtered, 5-minute infusion Soil 1. 



7 & 8 — 20 cc. (=10 gm. soil) filtered, 5-minute infusion Soil 2. 



4. Incubate 10-14 days at 20° C. 



5. Precipitate the protein present by means of basic lead 

 acetate. 



6. Filter, wash and digest the residue by the regular Kjel- 

 dahl method for total IST. 



7. The results obtained show the power of the pure cul- 

 tures and the soils to transform nitrate nitrogen into pro- 

 tein. 



