Psychrotrophic bacteria from a coastal station in the Ross Sea (Terra NovaBay, Antarctica)

Seawater samples were collected from a fixed, coastal station in the Terra Nova Bay at different depths during the Xth Oceanographic Cruise in the 199 4-95 Antarctic summer. Picoplanktonic abundance, estimated by direct counts in epifluorescence microscopy, ranged from 2.2x10(7) to 1.6x10(8)cells.1(- 1). The heterotrophic bacterial densities, evaluated on Marine Agar 2216 (D ifco) after incubation at +4 degrees C for 21 days, ranged from 2x10(3) to 4.5x10(6) CFU.1(-1). The qualitative composition of the heterotrophic bacte rial community was studied on 64 morphological and biochemical characters o f the 125 strains isolated. Heterotrophic, psychrotrophic isolates were ten tatively identified at genus level as Pseudomonas, Vibrio, Acinetobacter, a nd Flavobacterium/Cytophaga. In order to compare the characteristics of the isolates with those previous ly studied during 1989/90, the synthetical indices of the structure and the metabolic potentiality of the heterotrophic bacterial community were proce ssed. Results showed that the bacterial community was metabolically more ac tive and more homogenous than that previously studied.