ZoBell — 184 — Marine Microbiology 



a Seitz filter rendered Black Sea water less bactericidal for adventitious 

 organisms. Krassilnikov stressed the importance of the organic content 

 of water as a factor which affects the survival of bacteria. 



Colif orm bacteria surveys : — The sanitary significance of Escherichia 

 coli, Aerohacter aerogenes, and other colif orm bacteria in the sea is con- 

 tingent upon two important considerations. First, do the intestinal tracts 

 of marine animals normally harbor such organisms, and secondly, how 

 long do coliform bacteria of fecal origin survive in the sea? 



Large numbers of coliform bacteria are introduced in the sea by land 

 drainage, particularly in raw and partially treated sewage. It is estimated 

 from data given by Warren and Rawn (1938) that enough coliform bac- 

 teria are discharged by sewage efiiuents along the west coast of the United 

 States each day to give over a hundred for every liter of water in the 

 North Pacific Ocean, if evenly distributed. However, such organisms are 

 found only in tide water, harbors, and bays, which are often badly pol- 

 luted. Comparable sanitary conditions were found by Weston (1938) on 

 the east coast of the United States. 



Extensive surveys around the Hyperion outfall shows the rapidity 

 with which coliform bacteria succumb in the sea. This outfall carries raw 

 sewage from nearly two million inhabitants of Los Angeles a mile into the 

 ocean. As may be expected, millions of coliform bacteria per ml. are often 

 found near the sewer outlet. The number decreases with distance from 

 the outlet much more rapidly than can be accounted for by dilution. 

 Surveys, summarized by Knowlton (1929), indicate that even during 

 onshore winds and currents the count is often less than 10 coliform bac- 

 teria per ml. in the surf. As many or more Escherichia coli may be intro- 

 duced by bathers on the beach. Under no conditions were coliform bac- 

 teria traced more than a mile or two from sewer outfalls in the open ocean. 

 The effect of air currents, water movements, composition of the sewage, 

 and other factors which influence the distribution of E. coli were consid- 

 ered by a commission appointed by the California State Bureau of Sani- 

 tary Engineering (1943). Only in solids or greases were coliform bacteria 

 found to be able to survive for long periods of time in the sea. 



Similar observations were made in Europe by Dienert and Guillerd 

 (1940) who concluded that, while sea water is neither antiseptic nor inimi- 

 cal to E. coli, sewage discharged into the sea is rapidly purified by sedi- 

 mentation, predatory organisms, and dilution. Lloyd (1930) was im- 

 pressed by the virtual freedom of Clyde Sea water from coliform bacteria 

 of fecal origin. 



ZoBell (19416) failed to find coliform bacteria in any of 961 samples 

 of sea water collected at stations remote from possibilities of terrigenous 

 contamination, although large numbers were found in polluted bays and 

 estuaries. Positive presumptive tests were obtained from the intestinal 

 contents of 203 of the 387 marine fishes examined. The coliform bacteria 

 isolated from the fishes were identified as follows using the "IMVIC" 

 tests: 



Escherichia coli 6 per cent 



Aerobacier species 73 per cent 



Citrobacter species 21 per cent 



Imvic is a mnemonic which fixes in order the four tests commonly used in 

 classifying coliform bacteria: (I) indol formation, (M) methyl-red reac- 



