Occurrence and Significance of Chitinoclastic Bacteria 607 



Lingappa and Lockwood ( 18 ) have shown, in soils, that a chitin 

 mineral agar supported actinomycetes well, but not bacteria. 

 Chitin agar, with organic additives, on the other hand, supported 

 chitinoclastic bacteria better than actinomycetes or fungi. 



In the environmental situations examined, chitinoclasts 

 seemed definitely aerobic in preference, although Aleshina (1) 

 and Steiner (26) report anaerobic chitin degradation from bottom 

 sediments. 



An appreciable delay between the appearance of colonies 

 on plates and tlie first appearance of clearing zones around them 

 was noted in these studies. This delay may indicate these chitin- 

 ases are endoenzymes and are released to the surrounding me- 

 dium after autolysis, or that these enzymes are adaptive in na- 

 ture. The differences in response of several pure cultures of pela- 

 gic chitinoclastic bacteria on the chitin-0.1 per cent yeast extract- 

 sea water medium, shown in Figure 2, indicate this medium is 

 not optimal for many strains, and possibly that different chitinase 

 systems may be represented by the different organisms. This lag 

 in chitinoclastic activity in vitro has been noted by other investi- 

 gators (16). 



Nature of the Microflora of Pelagic Zooplankton 



The microflora of pelagic zooplankters seems to be similar to 

 the pelagic microflora described by many authors {cf. ZoBell 

 (28) for summary). Few or no fungi were encountered on plates 

 from pelagic areas, and no actinomycetes. Of the microflora of 

 zooplankters. Gram negative asporogenous rods were the most 

 numerous (69%), Gram positive cocci next most abundant 

 (23.5%), Gram positive rods amounted to 5.5 per cent and yeasts, 

 2 per cent. These figures are based on a random examination of 

 55 colonies. Approximately 50% of the colonies were chromogenic. 

 These results will be reported in detail in a later paper. 



Microbial Participation in the Bioeconomy of the Sea 



In striking contrast to the relatively sparse microbial popu- 

 lations found in sea water samples, are the large, active popula- 

 tions found associated with zooplankters. The population levels 

 of aerobic heterotrophs from water samples were generally less 



