Bacteria associated with sardine (Sardina pilchardus) eggs in a natural environment (Ría de Vigo, Galicia, northwestern Spain).

Abstract The present study was undertaken to describe the epiflora of the eggs of an important fishing species collected in a coastal zone. Microflora associated with sardine (Sardina pilchardus) eggs collected in the Ría de Vigo was examined from January to June 2000. The count was carried out in three different ways: a total direct count by epifluorescence, a heterotrophic bacteria count on marine agar (MA) and a total vibrio count on thiosulfate citrate bile sucrose (TCBS). It was observed that the counts of total bacteria by epifluorescence were always higher by 2-3 logarithms than the bacterial counts on MA, and by 3-4 logarithms than the count of vibrios on TCBS. In both cases the differences were statistically significant. Throughout the sampling period only a slight variation was observed in the counts undertaken, and in the measured physicochemical parameters. For the qualitative study, 250 strains isolated from MA and 81 strains recovered on TCBS were identified. Members of the genera Vibrio, Pseudoalteromonas, Pseudomonas and Moraxella were found to dominate on the culturable adherent microflora of sardine eggs and Aeromonas, Tenacibaculum (Flexibacter), Flavobacterium and Cytophaga spp. were present in minor amounts. Vibrio anguillarum and Vibrio fischeri, pathogens of fish larvae, as well as Tenacibaculum ovolyticum, a pathogen of fish eggs, were detected.