Nutritional Patterns in Marine Bacterial Populations 687 



antagonistic reactions may complicate tlie relationship, the in- 

 cidence of any group of organisms at any one time will depend 

 largely upon the availability of appropriate nutrients, and infor- 

 mation on the spectrum of nutritional requirements within a given 

 population mav promote understanding of the nature of such re- 

 relationships as those between heterotrophs and their organic 

 milieu. 



A unique approach to the study of bacterial activity in soils 

 by Lochhead and co-workers (13) culminated in a series of val- 

 uable articles on nutritional relationships of the soil microflora. 

 By developing a method of characterizing bacteria according to 

 their nutritional needs, they utilized fundamental nutritional dif- 

 ferences as a basis for comparing both qualitatively and quanti- 

 tatively the bacterial microfloras representative of different soils 

 and soil habitats. Changes in the relative incidence of different nu- 

 tritional groups or organisms were related to effects on the soil 

 populations of seasons and soil treatment (10), of the growing 

 plant ( 14 ) , and other studies yielded data on the utilization and 

 biosynthesis of amino acids and growth factors by certain groups 

 of soil bacteria. 



The present study was undertaken to explore the possibilities 

 of applying similar nutritional criteria in the examination of bac- 

 terial activity and relationships in marine environments. For 

 these purposes it was planned to compare qualitative characteris- 

 tics of representative marine bacteria from populations of a selec- 

 ted number of widely differing habitats, viz. neritic and oceanic 

 surface waters, deep ocean waters, sublittoral and deep sea sedi- 

 ments. 



Cultivation of Marine Bacteria 



Many cultural studies of marine bacteria have been primarily 

 directed towards devising complex media to provide maximum 

 plate counts ( 25 ) and it has commonly been stated that so diverse 

 are the nutritional requirements of marine bacteria that no one 

 medium can suffice for the growth of all ( 2 ) . The problem of ob- 

 taining random samples of isolates representative of indigenous 

 soil populations was approached by Lochhead by choosing an 

 isolation medium of soil extract agar with no added energy ma- 



