Cell extracts of 14 species of marine phytoplankters helonging t o six algal classes were tested for antibacterial activity against I) marine isolates and 14 strains of terreseial saprophytes inclr~ding pntential patha~ens. Aparr from iiidividual species differences, some noteworthy differences in antibiotic effectiveness were observed between the algal classes. The Batillariophyceae, Chrysophyceae, and Cq-ptophycrae showed considerably grrnter range and degree of activity than the Chlorophyceae, while the r~ccoid LMyxophycear: showed no deiectabIc-activity. The single spries of Dinophycene examined appe~red to be coinparable in activity to the Cryptophyceae. 'I'he observed spectrum of activity inrlicated selective action against marine isolates and against Gram-positive organisms. In the latter group, three Stophylocorms strains were particularly susceptible to algal antibiotic action. Some ni the algal species showed both ~o w l h inbibitiori and growth stimuktian oi specific test bacteria. The occasional development of an~ibiotic-resistant colo~lies within inhibition zones was noted.
SUMMARYThe acetone-extractable antibacterial components of Zsochrysis galbana have been resolved by paper-chromatography and bioautography. Two pigmented products with similar antibacterial properties were obtained which were tentatively identified from their absorption spectra as chlorophyll a derivatives, probably pheophytin a and an atypical chlorophyllide a.
Investigation of a disease occurring among Rocky mountain whitefish in the Elk river, 1931, and among hybrid Pacific salmon in a retaining pond at Cultus lake, 1932, showed similar pathological features in each epizootic. An easily cultivable bacterium, producing a brown diffusible pigment on nutrient agar, was isolated in pure and in nearly pure culture from lesions of typical cases in each outbreak. Experimental inoculation into goldfish and chub have established the pathogenic nature of the microorganism, and its relationship to the lesions described. No bacterium corresponds in all cultural and biochemical features with Bacillus salmonicida Emmerich and Weibel. The disease in each locality presents the pathological picture typical of "furunculosis."
Summary Prolonged feeding of a Bacterium salmonicida vaccine to groups of cutthroat trout, at temperatures varying between 2.2 C and 14.4 C, resulted in: (a) a mortality of the order of 25 per cent in vaccinated trout, compared to a mortality of the order of 75 per cent in untreated fish, when infection was attained by adding a suspension of the virulent organism to the tank water, at 19 C; (b) a marked increase, in the vaccinated groups, in the numbers of fish showing specific agglutinins, and a tendency in this group toward higher agglutinin-titres. A lesser increase in survival-numbers following the same treatment occurred where trout were infected by intramuscular inoculation.
It is the purpose of this communication to record certain dissociative phenomena in Bacillus salmonicida Emmerich and Weibel (1894). This microorganism, the etiological agent of an epizootic disease ("furunculosis") of salmonid and other fishes, came to the attention of this laboratory through having been identified as a cause of disease amongst the cutthroat trout and Rocky Mountain whitefish in British Columbia (Duff, 1932, Duff and Stewart, 1933). Other work on B. salmonicida is adequately reviewed in the Reports of the Ministry of Agriculture and Fisheries, Great Britain (1929, 1933, 1935). Stock cultures of various British Columbia strains of Bacillus 8almonicida have been carried in this laboratory since August, 1931. Following 6 or more months of artificial culture a marked loss of pathogenicity occurred in all strains. Furthermore a gradual change occurred in the appearance of colonies upon nutrient agar. Immediately after isolation of a strain from an infected fish, the colonies appeared glistening, convex, and translucent. Stock cultures about 6 months after isolation gave rise to colonies more strongly convex, distinctly opaque, and creamcolored. Changes in pathogenicity and colony formation were not accompanied by any change in the ability of the colonies to produce the diffusible brown pigment typical of the species. Occasional loss of pigment-producing ability was noted in some stock cultures, but the ability could be recovered by rapid serial 49
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.