© 2005 International Council for the Exploration of the Sea
Bacteria in the gut of juvenile cod Gadus morhua fed live feed enriched with four different commercial diets
a Institute of Marine Research PO Box 1870, Nordnes, N-5817 Bergen, Norway
b Bodø Regional University N-8049 Bodø, Norway
c Nordland Research Institute N-8049 Bodø, Norway
*Correspondence to Ø. Bergh: tel: +47 5523 6370; fax: +47 5523 8586. e-mail: oivind.bergh{at}imr.no.
Atlantic cod, Gadus morhua L., larvae were fed rotifers, Brachionus plicatilis and Artemia franciscana enriched on four different commercial media, using the manufacturers' protocols. Pooled samples of 20 cod larvae were homogenized, diluted, and plated out on Petri dishes. The number of colony-forming units per larva was estimated, and the dominant strains subsequently sampled for sequencing of 16S rDNA. Bacteria showing high sequence similarity to a pathogen characteristic of cod and other fish species, Listonella anguillarum, were present in all four groups. Other taxa present among the dominating bacterial colonies were Pseudoalteromonas sp., and Vibrio sp. However, these bacteria could be assigned to genera only. The different enrichments probably affected the number of colony-forming bacteria per millilitre in the enrichment cultures as well as in the larval gastrointestinal (GI) tract. Also, the composition of the microbiota associated with the larval GI tract was probably affected by the enrichment media.
Keywords: Atlantic cod larvae, bacteria, enrichment, live feed
Received 22 September 2004; accepted 28 October 2005.