Nachweis zum Vorkommen von Bakterien und deren physiologischer Aktivitäten auf marinen Partikeln in der Wassersäule

Ten heterotrophic bacterial strains, isolated from particles of the upper water column of the Equatorial Atlantic, taken during a cruise on the R/V METEOR (1997), were investigated concerning their physiological and phylogenetic properties using classical microbiological and modern molecular-biological methods. All isolates are gram-negative rods able to use polymers such as cellulose, chitin or starch as sole carbon source. The phylogeny of the isolates was investigated by fluorescence in situ hybridization (FISH) and 16S rDNA-sequencing. The ten isolated strains belong to the :i:Cytophaga/Flavobacteria:/i:, gamma-Proteobacteria, and alpha-Proteobacteria. In order to study succession during growth with naturally in marine habitats occurring polymers, fluorescence in situ hybridization (FISH) was used as a new instrument to detect cells from different phylogenetic clusters in course of a growth experiment. Mixed cultures consisting of three strains which belong to different phylogenetic groups in equal amounts were incubated with cellulose, chitin, and starch. It could be demonstrated that isolate 4301-10/2, a member of the gamma-Proteobacteria, dominates the mixed cultures with cellulose, chitin, or starch already after 10 days with 55, 60, and 95%, respectively, of cells hybridized with DAPI.