in the dark. Thus, while the presence of 

 vitamins depressed C^-^Og uptake by the phyto- 

 plankton in the light, bacterial multiplica- 

 tion was enhanced. This may he due to the ac- 

 tion of the vitamins on the bacteria directly 

 or to the release of organic substances from 

 the phytoplankton. 



The various methods for preparing the bottles 

 in the otherwise untreated samples had no 

 appreciable affect on the C^-^j assimilation 

 by light -incubated phytoplankton in the 

 samples, although the autoclaved bottles show- 

 ed a slightly increased C^^C^ uptake and about 

 one-third fewer bacteria. 



An experiment of the same type was prepared to 

 determine the effect of the individual pools 

 and other complexes on C^^Do fixation and bac- 

 terial populations. Surface sea water was 

 collected at 09*0k' N latitude, 89°13' W 

 longitude (Station BT - 9 - 2k), dispensed in 

 250-ml glass stoppered reagent bottles, and 

 treated as follows: no treatment (control), 

 combination of all that follows, vitamin pool 

 1 (V-l), vitamin pool 2 (V-2), vitamin pool 3 

 (V-3)j purines and pyrimidines (pp), essential 

 amino acids (EAA), nonessential amino acids 

 (NEAA), yeast extract (0.001*/ o ), soil extract 

 (1.0°/.), and Tween 80 (0.001°/.). The temp- 

 erature of the surface sea water was 2k-.~j'C. 

 The bottles were incubated at 25 1 1° C in the 

 illuminated water bath for four hours before 

 1,21*6,300 counts/minute of NaHC 1 ^ were added. 

 The bottles were returned to the water bath 

 and incubated for a total of eight hours. 

 Owing to lack of space in the water bath, dark 

 bottles were not included in this experiment. 

 The results of the bacterial increases per ml 

 and the Cl^s assimilation in the light appear 

 in Table 17 . 



None of the vitamin pools stimulated either 

 {jl* uptake or bacterial development to any 

 extent. Vitamin pool 3 (Y-3) decreased the 

 C^ fixation by more than 1/3 of the untreated 

 control. The surface active agent, Tween 80, 

 ( a complex mixture of polyoxyethylene ethers 

 of mixed partial oleic ethers of sorbitol anhy- 

 drides) increased C 1 ^ fixation by a factor of 



three over the untreated sample, the most 

 pronounced stimulation of C^ assimilation in 

 any of the treatments. The bacterial increase 

 was also appreciable for this treatment 

 (Table 17) . 



The amino acid pools stimulated C^^* fixa- 

 tion in the light by a factor of about 1.5, 

 and the essential amino acids promoted a 

 slightly greater increase. These amino acid 

 pools also stimulated bacterial development; 

 the essential amino acids proved about 1.3 

 times as effective as the nonessential amino 

 acid pool (Table 17). 



The purine and pyrimidine pool enhanced ClV>2 

 fixation only slightly hut stimulated the 

 bacterial numbers by a factor of thirteen 

 compared to the untreated controls . These re- 

 sults appear consistent with those of previous 

 experiments. 



ill 

 The soil extract had no effect on C uptake 



but increased the bacterial numbers by seven- 

 fold. The treatment containing yeast extract 

 was so cloudy and turbid by the end of the 

 eight-hour incubation period that, it could not 

 be filtered. Consequently, no C O2 fixation 

 data exist for this treatment. The bacteria 

 increased by a factor of 36 compared to the 

 untreated control which was by far the great- 

 est increase in the bacterial population ex- 

 cept where yeast extract was present in the 

 combined treatment. Although the combined 

 pools showed considerable stimulation compared 

 to the untreated controls, the values for 

 C^-^Oo fixation and bacterial increases were 

 lower than some of the individual treatments 

 (Table 17 ) . This effect was attributed to 

 the inhibitory properties of the vitamin pools. 



Finally, an experiment was conducted to deter- 

 mine the effects of selected individual 

 substances from the pools on C^ O2 fixation 

 and bacterial development. Surface sea water 

 at 25.7°C was collected at 09*38' N latitude, 

 89*35 ' W longitude (Station BT - 9 - 36) and 

 dispensed in the 250-ml glass-stoppered rea- 

 gent bottles as in the other experiment. The 

 following additions were made to paired bottles 



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