Morphology, Physiology, and Serology of a Pasteurella Species Pathogenic for White Perch ( Roccus americanus )

Abstract

The Pasteurella species implicated as the etiologic agent of a massive white perch mortality in the Chesapeake Bay and first described by S. F. Snieszko et al. has been characterized further in our laboratory. The general morphology and physiology of this organism is similar to that of the pasteurellae and several known fish pathogens. There are enough dissimilarities, however, to rule out its identification with any established species. The organism is obligately halophilic and grows in a temperature range between 17 and 31 C on ordinary media containing 1% NaCl. It has a relatively narrow range of p H, temperature, and salinity tolerance, and a very short survival time in spent media or brackish water, in contrast to Pasteurella pestis and P. pseudotuberculosis . Serological tests also indicate that this organism is distinct from other species which it resembles. On the basis of classic morphological and physiological criteria, this organism fits best in the genus Pasteurella ; the species name piscicida (L. noun piscis , a fish; L.v.L.adj. suffix- cidus , to kill; M.L. noun piscicida , fish killer) is proposed.