STUDIES OF FLAVOBACTERIUM PISCICIDA BEIN: I. Growth, Toxicity, and Ecological Considerations.

Species of Flavobacterium are abundant in marine environments, occurring in sea water and sediments as well as in the slime and feces of various fish. The activity of flavobacteria in fish spoilage is not uncommon (Castell and Mapplebeck, 1952). Other than the studies of these latter workers, only the investigations of MacLeod and his associates (MacLeod et al., 1954, 1958) deal, to any extent, with the physiology and nutrition of marine flavobacteria. In the latest treatment of Flavobacterium in Bergey's Manual of Determinative Bacteriology (Breed et al., 1957) 26 species are recognized, 13 of which occur in marine habitats. Eight species have been described originally from marine material, although only one, Flavobacterium piscicida Bein, has been diagnosed as toxic to fish. F. piscicida was collected in 1951 from Whitewater Bay on the southwest coast of Florida, during an outbreak of mass mortality of fishes, commonly known as "red tide." Bein (1954) described the bacterium as a new species, and demonstrated its toxicity in laboratory tests. Since 1952, in conjunction with field investigations of marine fish mortalities, personnel of The Marine Laboratory have collected numerous flavobacteria from sea water and marine muds at areas along the west coast of Florida as far north as Apalachicola. The majority of the collections were made in inshore localities over an extensive geographic range, in phytoplankton blooms, with and without accompanying fish mortality; and in routine bacteriological analyses. This present paper reports preliminary studies undertaken during the past year to investigate