Host and Habitat Relationships 619 



from the north Pacific, but the latter attack glucose more fre- 

 quently. Somewhat paradoxically, a slightly larger percentage of 

 southern Pacific Pseudomonas sp. were able to utilize citrate as 

 sole carbon source. Differences seemed less between tlie Achro- 

 mobacter groups, though northern Pacific strains were apparently 

 more saccharolytic and greater numbers utilized citrate as sole 

 carbon source than did those strains from the southern Pacific. 



The most clear-cut difference between commensal bacteria 

 of the northern and the southern Pacific Ocean areas was in tem- 

 perature growth range. As can be seen from Table 4, in the nor- 

 thern waters psychrophilic bacteria predominated; in the southern 

 areas the mesophils were the ascendant types. In both areas, a 

 significant and consistent number of eurythermic bacteria ( those 

 able to grow at both temperature extremes) persisted. Thus, 

 temperature, a long recognized determinant factor in bacterial 

 growth, has a definite efi^ect on the populations of bacteria found 

 associated with marine animals from different climatological 

 habitats. 



TABLE 4 



Habitat and Temperature Range Relationships for Bacteria 

 FROM Marine Animals 



Puget Washington Eniwetok Rongelap 

 Sound Coast Atoll Lagoon 



Per cent showing growth at C* 77.0 60.6 30.9 14.3 



Per cent showing growth at 37 C* 24.0 59.0 92.4 97.1 



Per cent showing growth at C 23.0 30.8 30.4 12.8 



and 37 C* 



* Expressed as per cent of total sample tested. 



Figure 4 presents data obtained from studies of the biochem- 

 ical and physiological activities of bacteria taken from vertebrates 

 and from invertebrates. There are no explicit differences in the 

 metabolic activities of the bacteria isolated from the two animal 

 groups. However, bacteria isolated from vertebrates demonstra- 

 ted greater reductive capacity, and, a greater tendency to produce 

 acid in litmus milk and aerobic dissimilation of sugars possibly 

 indicates a more active carbohydrate metabolism. This hypothesis 

 is furtlier supported by the greater preponderance of citrate 



