ZoBell — 82 — Marine Microbiology 



After noting that bacteria survived longer and were more active in 

 heat-sterilized sea water or in artificial sea water, Waksman and Hotch- 

 Kiss (1937) concluded that the antagonistic effects of microorganisms 

 including nannoplankton help to explain the low numbers of bacteria 

 usually found in natural sea water. 



Another manifestation of microbial antagonism is the progressive de- 

 crease in the number of species of bacteria found in sea water during its 

 incubation in the laboratory (ZoBell and Anderson, 1936a). As a rule, 

 the larger the bacterial population which develops in stored sea water, the 

 fewer the species which survive. After several months storage, only two 

 or three species of bacteria were found in samples of sea water which 

 contained thirty to forty species when collected from the sea. 



Taylor (1940) directs attention to the commonly observed fact that 

 the denser the bacterial population in natural waters, the smaller the num- 

 ber of species. In Lake Windermere, which normally contains only a few 

 thousand bacteria per ml., Taylor (1942) found scores of bacterial types, 

 contrasted with only a few types found in polluted river water entering the 

 lake. 



Besides contributing to the rapid destruction of adventitious species, 

 the accumulation of hetero-antagonistic substances in the sea may help to 

 explain the specificity of marine bacteria. In spite of the interchange of 

 bacteria between the land and sea through the intermediaries of wind and 

 water, most of the bacteria occurring in the sea at places remote from pos- 

 sibilities of recent terrigenous contamination are quite unlike bacterial 

 species occurring in soil or fresh-water environments. 



Bacteriophage in sea water: — Bacteriophage is a lytic, filter-passing, 

 self -propagating principle which causes the destruction of susceptible bac- 

 teria. It has been credited with contributing to the self-purification of 

 polluted water. According to d'Herelle (1926), the first record of bac- 

 teriophage action was the observation of Hankin in 1896 that unsterilized 

 waters of certain rivers in India have a tendency to destroy bacteria. For 

 example, just below Agra more than 100,000 bacteria per ml. were found 

 in the Jumna River, while 5 kilometers farther down the river fewer than 

 100 bacteria were found in the water. The antiseptic property of the 

 water was destroyed by boiling. 



Our knowledge of the occurrence and activity of bacteriophage in sea 

 water is rather fragmentary. Bacteriophage is relatively resistant to ad- 

 verse chemical and physical conditions, occupying a position in this re- 

 spect intermediate between vegetative forms and spores of Bacillus sub- 

 tilis (d'Herelle, 1926). A high concentration of salt is not injurious to 

 bacteriophage, Brutsaert (1924) having shown that the bacteriophage 

 for Staphylococcus aureus and Staph, albus is active in broth containing as 

 much as 14.5 per cent NaCl. 



After noting the occurrence of bacteriophage in rivers, soil, sewage, 

 and in nearly all environments harboring large bacterial populations, 

 d'Herelle (1926) remarked, "It is everywhere present, one might say." 

 d'Herelle found bacteriophage active against dysentery bacilli in sea 

 water at the mouths of rivers. He found the bacteriophage for Escherichia 

 coli in the estuary of Mekong, French Indo-China. Although bacterio- 

 phage is often present in sea water along the coast and particularly near 

 the mouths of rivers, d'Herelle was unable to find it in water collected 

 from the Indian Ocean at approximately 60° E. Long, and 10° N. Lat. 



