206 



BACTERIA IN THE DEEP SEA 



The hydraulic pump, by means 

 of which the bacteria in the 

 steel cylinder on the right can 

 be subjected to a pressure of 

 i,ooo atmospheres, correspon- 

 ding to the pressure of the 

 surroundings at a depth of 

 10,000 metres. 



first proof of growth and activity of organisms at such a high pressure ! 

 P'urther evidence of microbial activity in the sediment was indicated by 

 decreases in the ratio of organic carbon to nitrogen. 



That the bacteria were actually from the deep sea and not adventitious 

 contaminants was indicated by the fact that they grew in nutrient medi- 

 ums when incubated at 1,000 atmospheres but not in similar mediums 

 incubated at one atmosphere. Since the deep-sea forms seem to require 

 high pressure, they have been described as barophilic, a term that means 

 pressure-loving. 



Additional observations on samples subsequently collected from other 

 stations in the Philippine Trench, Java Deep, Weber Deep, New Britain 

 Trench, and Kermadec-Tonga Trench established the occurrence of an 

 abundant barophilic bacterial flora on the sea floor at depths ranging 

 from 7,000 to 10,000 metres. The topmost layers of bottom deposits at 

 the mud-water interface were found to contain from several hundred 

 thousand to a few million living bacteria per mililitre (cc). The total 

 weight of bacteria is estimated to be a minimum of 0.002 grams per square 



