Collected reprints: Abstract 2913
Collected reprints
Abstract
Verdonck, L.; Dehasque, M.; Swings, J.; Sorgeloos, P.; Léger, P. (1993). The microbial environment of rotifer (Brachionus plicatilis) and Artemia production systems. Spec. Publ. Eur. Aquacult. Soc. 15: 398-398
In many cases, disease problems in larval rearing seem to be related to bacterial infections. As the live food is suspected to be a source of contamination, it was our aim to look into the microbial population in algae, rotifer and Artemia production systems. Samplings were organized in three marine fish hatcheries. Samples were taken at different steps in the production process of the live feeds. Bacterial numbers were determined on marine agar, BTB, and TCBS media. They ranged from 10³ to 107 in the live feeds, depending on the sampling site and sampling time. During hatching of the Artemia cysts, bacterial numbers increased a 10³ to a 105 fold compared to the initial population before the breaking of the cysts. This bacterial population remained well established and could not be removed from the nauplii by rinsing with seawater and freshwater. During the nutritional enrichment of the rotifers and the Artemia, the number of bacteria did not increase. Some 300 dominant colony types were isolated for further characterization. The isolates were compared to each other and to reference strains of Listonella, Photobacterium, Vibrio and Alteromonas, using fatty acid and API20E profiles. Fatty acid profiles of the isolates were grouped using principal component analysis. The isolates fell into at least ten major groups, of which two respectively correspond to the genera Vibrio-Listonella and to Alteromonas. Some groups seem to be restricted to one type of live feeds or to one isolation site. Although 43% of the isolates belong to Vibrio-Listonella, only a minority of them could be readily assigned to known species.
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