Nutritional Patterns in Marine Bacterial Populations 691 



RESULTS 



Results showing the relative ineidence oi the different nu- 

 tritional groups of organisms within populations derived from 

 the \ arious sources are summarized in Table 1. 



DISCUSSION 



Results indicate that organisms isolated on sea water mud 

 extract show considerable diversity in their nutritional require- 

 ments for maximum growth. Further, there is some correspon- 

 dence in the relative distribution of "nutritional groups" of or- 

 ganisms between the two surface water populations and similarly 

 between those originating from sediments. On the other hand out- 

 standing differences between surface water and sediment bac- 

 teria are apparent in the comparatively liigher proportion of sea 

 water organisms that showed a requirement for amino acids, and 

 the incidence among bacteria indigenous to sediments of a group 

 dependent, under the experimental conditions, upon nutrients 

 provided by sea water mud extract. In contrast to surface water 

 forms, bacteria from deep waters showed little or no growth 

 on the simpler media (B and BA) and demanded complex ad- 

 denda of vitamins, yeast extract or mud extract for maximum 

 growth. While estimated absolute numbers (per unit volume) of 

 bacteria of any one nutritional group are highest in the sediments, 

 nevertheless outstanding qualitatixe differences (expressed by 

 changes in the relative proportion of different groups) are dis- 

 cernible among the sampled populations. 



Previous studies have shown amino acids are a class of com- 

 pounds which satisfy the growth requirements of many bacteria 

 of marine origin ( 16 ) . Nearly all of fifteen "representative" marine 

 bacteria studied by Ostroff and Henry (17) utilized amino acids 

 which also supported growth of many of the strains isolated from 

 sea water and fish by MacLeod et al. ( 15) either with or without 

 non-amino sources of carbon and energy. There is thus some 

 agreement between earlier observations and the present finding 

 that isolates from surface waters include a high percentage of 

 amino acid-requiring bacteria. If this high percentage of this 

 group of organisms is also characteristic of indigenous bacterial 

 populations in situ, it raises speculation as to the relationship of 



