Distribution and Function of Marine Bacteria 45 



balances rather than with specific organic substances, and may 

 involve such factors as redox potential, concentration of dis- 

 solved gases, and ionic equilibria. 



Of possible relevance to the foregoing was a paper by Demny 

 and colleagues,* who have made a survey of autil)iotic-producing 

 microorganisms in salt marshes, sea water, shore, bay and deep 

 core habitats. Out of nearly 1500 isolates about ten percent ex- 

 hibited antibiotic activity. The main types were streptomycin 

 and streptothricin which were observed in each of the five areas 

 surveyed. Xanthomycin yielders were also frequently encoimt- 

 ered. There was no evidence to suggest that the marine antibiotic 

 producers are necessarily different from those seen in soils. 



An interesting trio of papers was given on organisms with 

 very special nutrient requirements. Hutner and colleagues (Chap- 

 ter 54) reported on a photosynthetic bacterium, Rhodopseudo- 

 monas, which turned up in a diversity of substrates. All strains 

 so far examined have required para-aminobenzoic acid, the need 

 for which, surprisingly enough, could be satisfied by sulfanila- 

 mide. The significance of this finding for problems of assay will 

 be obvious. 



Yaphe (Chapter 55) discussed the difficulty in classifying 

 those microorganisms which utilize the polysaccharides of sea 

 weeds. There are essentially marine bacteria, since the polysac- 

 charide substrate is characteristic of marine plants. The word 

 agar-agar is used to describe various gelatinous materials and can- 

 not be chemically defined. The author urges that commercial 

 preparations should state the botanical and geographical source 

 of the parent alga. Obviously confusion will arise when attempts 

 are made to classify bacteria on their ability to degrade agar. 

 Yaphe commented on Bergey's classification of the group in ques- 

 tion and proposed modifications to take in forms which utilize 

 carrageenan in addition to or instead of agar and alginic acid. 

 He is not prepared to advocate the creation of a genus on the 

 basis of ability to digest this or that polysaccharide. 



Dealing with another group of chemical specialists, Lear 

 (Chapter 56) discussed bacteria capable of digesting chitin 



* Paper presented. Occurrence of variety of Actinomycetes isolated from marine 

 materials (with I. M. Miller and H. M. Woodruff) . 



