TEE EFFECTS OF ORGANIC ARD INORGANIC KlCRONUTRISNTS OR THE ASSIMILATIOR OF C 

 BY PLARKTORIC COMKURTTISS ARD OR BACTERIAL MULTIPLICATION IR TROPICAL PACIFIC 



SEA WATER 



Galen E. Jones and William H. Thoma6 



lh 



Predatory concepts of life in the sea vere 

 emphasized throughout the early history of 

 marine biology. However, various line of 

 evidence prompted Lucas (l9^7> 19^> 1955) to 

 propose that microorganisms in the sea can 

 interact in a nonpredatory manner by means of 

 external metabolites . In this vay certain 

 organisms might influence the activities of 

 others by producing essential nutrients or by 

 removing or excreting inhibitory substances. 

 Certain marine phytoplankton require growth 

 factors such as thiamin, cyanocobalamin, and 

 biotin (Provasoli and Pintner, 1953; Lewin, 

 195 1 *-; Sweeney, 195^j Droop, 1957; and Johnston, 

 1955) • Requirements for amino acids, purines, 

 pyrimi dines, and other grovth factors have 

 also been shown for some marine bacteria 

 (Ostroff and Henry, 1939; MacLeod et al., 195 1 *-; 

 Jones, 1957) • Some marine algae contain a 

 great diversity of grovth factors (Ericson, 

 1953a and b; Ericson and Carlson, 1953) — -1 

 could presumably supply such factors to other 

 marine organisms. The literature on the exist- 

 ence of such factors in sea vater has been re- 

 viewed by Vallentyne (1957)- 



The present paper reports experiments per- 

 formed at sea on the effects of small con- 

 centrations of added organic substances on bac- 

 terial grovth and C^-^02 assimilation by organ- 

 isms in pelagic sea-vater samples. The effects 

 of additions of certain inorganic substances on 

 these processes were also studied. 



M3TH0DS 



,1^ 



The radioactive C method for measuring 

 organic productivity (Steemann Nielsen, 1951, 

 1952) was utilized to determine the amount of 

 C assimilation by microorganisms in light 

 and dark bottles containing pelagic surface sea 

 vater vhen microquantities of organic and in- 

 organic nutrient pools vere added. Reagent 

 bottles of a 250-ml. capacity vere thoroughly 

 cleaned vith detergent, rinsed vith 10% HC1, 



and finally vith sea vater (five or six times 

 immediately before use). All of the samples 

 vere surface sea vater collected in a clean 

 plastic bucket. After a 220-ml. sample of 

 sea vater vas added to the bottles, the 

 number of marine heterotrophic bacteria in 

 the sample vas determined using the pour- 

 plate method and peptone-yeast extract agar 

 (Oppenheimer and ZoBeli, 1952) . Similar en- 

 umerations vere made at the end of the period 

 of incubation vith C 1 ^. Plates vere poured 

 on a suspended table vhich vas adequate to 

 compensate for the roll of the ship in the 

 moderate seas experienced on this cruise. 

 The bacterial plates vere incubated for three 

 days in the dark at 30 t 1*C before ex- 

 amining for bacterial numbers vith a Quebec 

 colony counter. Appropriate dilutions vere 

 made vith sterile vater blanks vhen high counts 

 vere anticipated. Uninoculated control plates 

 vere maintained in all cases to check the 

 sterility of the medium, the sterility of the 

 disposable plastic petri dishes employed and 

 the incidence of contamination due to handl- 

 ing aboard ship. These uninoculated plates 

 vere sterile in most cases. 



Organic constituents vere added as pools to 

 certain sea-vater samples to give the 

 following final concentrations: 



Vitamin pool 1 (Y-l) ug/100 ml of sample 



folic acid 1.0 



thiamin chloride 1; . ; 



riboflavin 5.0 



pyridoxine hydrochloride 5.0 



calcium pantothenate =:._ 



nicotinamide =:.: 



choline hydrochloride 100.0 



inositol 100.0 



para-aminobenzoic acid 5.0 



biotin 0.05 



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