Chapter Vn — 113 — Activities in Deposits 



adhere to the bacteria. The aggregation of particles of clay, silt, and sand 

 hastens the rate of sedimentation and influences the structures of the 

 resultant bottom deposits. The work of Waksman and Vaktiovaara 

 (1938), RuBENTSCUiK ct dl. (1936), and others has demonstrated that 

 bacteria have a marked affinity for solids. Filamentous cells may weave 

 particles together into intricate meshworks. The extent of the binding 

 action depends primarily upon the types of microorganisms present and 

 the quality of the organic matter (Peele, 1936). The influence of micro- 

 organisms on soil aggregations has been investigated by Martin and 

 Waksman (1940). 



Enzymes in bottom deposits : — In considering the evidence for vari- 

 ous types of biochemical processes which occur in bottom deposits, Keeps 

 (1934) points out that the absence of specific microorganisms does not 

 prove the absence of the corresponding biochemical process because the 

 latter may be effected by organic catalysts or enzymes. He believes that 

 bacterial enzymes are concentrated upon the sea bottom where they con- 

 tinue to function long after the bacteria have disappeared. There are no 

 data available for appraising the part played by buried enzymes or the 

 enzymes of resting cells in the transformation of bottom deposits, but it is 

 possible that such enzymes may be very important catalytic agents. 



Seitz-filtered, germ-free sea water from Murman coast fjords was 

 observed by Bokova et al. (1936) to catalyze changes in the oxygen, 

 phosphate, nitrate, and ammonia content of water samples. Bacterial 

 enzymes, including both oxidases and reductases, were found in greatest 

 concentration in water collected just off the bottom. The observations 

 suggest that marine bottom deposits may be especially rich in various 

 enzymes from the remains of bacteria and other organisms. Certain bac- 

 terial oxidases, in concentrations greater than can be accounted for by 

 the presence of Hving bacteria, have been observed in bottom deposits 

 by ZoBell (1939a). 



