ZoBell — 140 — Marine Microbiology 



also widely distributed in aquatic environments. The decomposition of 

 cellulose by these organisms was unimpaired by a salt concentration as 

 high as 15 per cent NaCl. Rubentschik (1928&) related that from the 

 salt lake Ssaky in Crimea he isolated Bacterium cellulosae album and Bac- 

 terium cellulosae flavum which digest cellulose. 



Cellulose is decomposed primarily to CO2 and water in the presence of 

 oxygen. Under anaerobic conditions appreciable quantities of methane 

 and hydrogen are produced from the decomposition of cellulose. Accord- 

 ing to several theories of petroleum formation, cellulose may also be con- 

 verted into higher hydrocarbons. Theoretically, cellulose could be re- 

 duced by either hydrogen or hydrogen sulfide to hydrocarbons. In view 

 of the possible significance of the reaction, this question merits thorough 

 investigation. 



From marine materials, Stanier (1941) isolated and described Vibrio 

 fuscus, Pseudomonas iridescens, Cytophaga krzemieniewskae, and Cytophaga 

 difuens, all being new species which digest cellulose and agar. He also 

 described Vibrio beijerinckii which digests agar but not cellulose. Accord- 

 ing to Stanier (1941), Vibrio granii and Pseudomonas droebachense, two 

 species previously named by Lundestad (1928), digest both agar and 

 cellulose. About half of the agar digesters studied by Stanier utilized 

 alginic acid, and most of them attacked starch and simpler carbohy- 

 drates. 



Agar is the principal carbohydrate constituent of many marine algae, 

 particularly certain Rhodophyceae. Although not attacked by most bac- 

 teria, agar is digested by several marine species and a few terrestrial ones. 

 Indicative of the abundance of agar digesters in the sea is the report of 

 Bavendamm (1932) that marine muds from the Bahama Islands contain 

 from 50,000 to 200,000 agar digesters per gram. It is estimated that be- 

 tween one and two per cent of the bacteria occurring in the sea are able 

 to digest agar. 



Agar-digesting bacteria were more commonly found in the sea than 

 were cellulose decomposers by Waksman et al. (1933a), especially in 

 diatom tows and around larger marine algae or their residues. In i.o ml. 

 of diatom tow, from 2,100 to 2,500 cells of bacteria capable of hquefying 

 agar were found. Agar digesters made up 5.7 to 6.7 per cent of the total 

 number of colonies developing on plates inoculated with the diatom tow. 

 Starch, cellulose, inulin, galactan, and mannite were decomposed by most 

 of the agar digesters. 



Gran (1902) was the first to isolate a pure culture of agar-digesting 

 bacteria from the sea. His Bacillus gelaticus is now known as Pseudo- 

 monas gelatica. In a careful search for agar digesters in sea water off the 

 Norwegian coast, Lundestad (1928) found and described Achromobacter 

 {Vibrio) granii, Flavobacterium rhodomelae, Fl. polysiphoniae, Fl. {Pseu- 

 domonas) droebachense, Fl. delesseriae, Fl. boreale, and Fl. ceramicola. Most 

 of the cultures studied by Lundestad were able to grow at 0° C, although 

 their optimum temperatures ranged from 20° to 30° C. Some were killed 

 by prolonged exposure at 31° C. 



Van der Lek (1929) demonstrated the occurrence in the sea of Vibrio 

 agarliquefaciens, an organism which is capable of attacking cellulose and 

 agar. 



Angst (1929) found the following new species of agar digesters associ- 

 ated with marine algae: Agarbacterium aurantiacum, A. bufo, A. cyanoideSy 

 A. mesentericus, A. reducans, A. viscosum, and seven others which he 

 described but failed to name. 



