Chapter 56 



Occurrence and Significance of Chitinoclastic 

 Bacteria in Pelagic Waters and Zooplankton 



Donald W. Lear^ Jr."^ 



INTRODUCTION 



A 



primary function ascribed to marine microbes is their partici- 

 pation in cycling nutrients in the biological economy of the sea. 

 Much of this concept has been adapted from analogy with 

 terrestrial and limnological studies, as there are few field studies 

 of this cycling in pelagic areas. 



For this study, two indicators of microbial activity were 

 selected: the aerobic heterotrophic marine microorganisms, and 

 chitin-digesting bacteria. 



The properties of chitin make it particularly suitable for the 

 study of microbial participation in the cycling of organic matter. 

 First, chitin is extremely resistant to ordinary chemical or physical 

 degradation under conditions found in the marine environment, 

 requiring the enzyme (or enzymes) chitinase to catalyze its 

 breakdown. Second, few organisms in the sea other than fungi 

 are reported as producing chitinase, and the few reported (20), 

 are not comparable in numbers with the microflora. Third, chitin 

 occurs in the sea in significant amounts in many animals and 

 some plants, and particularly in tlie abundant crustacean zoo- 

 plankton. 



No investigations of pelagic chitinoclastic microflora have 

 been reported in the literature, although there are several papers 

 concerned with nearshore and bentliic marine chitinoclasts (2, 6, 

 11,12, 13,25,27,29,30). 



Since the concept of cycling of organic matter is less compli- 



*Present address: Graduate School of Oceanography, Narragansett Marine Labor- 

 atory, University of Rhode Island, Kingston, R. I. 



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