1915] 



DAVIS ENZYME ACTION IN MARINE ALGAE 821 



THE AMIDASES 



The tissues from the several algae were tested for their 

 ability to split NH3 from such amino and amido compounds 

 as urea, acetamid, asparagin, and methyl amine. These com- 

 pounds were used in 1 per cent concentrations. Series were 

 set up in which 50 cc. of the substrate to be tested were placed 

 in flasks together with 2 grams of the powdered tissue and 

 chloroform-thymol as an antiseptic. Checks were used with 

 the nitrogen compounds alone and with the algal tissue in 

 distilled water. The flasks of duplicate series were kept at 

 room temperature and at 35° C. respectively, for 30 days, at 

 the end of which time Folin's method was employed for the 

 determination of any NH3 that might have been split off. In 

 the collection of the NH3, Friedrich's improved gas washing 

 bottles containing 250 cc. of N/50 HC1 were used. Air was 

 bubbled through by means of a suction pump for two hours, 

 then 25 cc. portions of the collection acid were removed and 

 titrated against N/50 NaOH, with alizarin red as an indicator. 

 In no case was there any action over that evidenced by the 

 checks. 



These results are extremely interesting, in the case of Ulva 

 especially. This form, as has been shown, thrives in waters 

 where the organic nitrogen content is high. The question 

 would at once arise whether this increased growth were due 

 to the ability of the Ulva to break down the protein molecule 

 and thus obtain an increased supply of nitrogen as NH3, or 

 whether it were due to the activities of the denitrifying bac- 

 teria rendering available a larger assimilable supply. That 

 such bacteria are relatively abundant in sewage-contaminated 

 water has been shown in the review of literature. We can 

 conceive of another factor entering in — that of selective for- 

 mation of enzymes. It might well be that with plenty of the 

 amino-nitrogen available through the activity of bacteria, no 

 amidases would be formed. The possibility of shedding some 

 light on this point led to the experiments following. 



Experiments on amidase formation by Chlamydomonas. 

 Chlamydomonas was grown in pure culture upon two differ- 

 ent media; one (with one or two modifications, that used by 



