Figure 4
From: Bacterioplankton reveal years-long retention of Atlantic deep-ocean water by the Tropic Seamount
Taxonomic and proteomic characterisation of flow sorted bacterioplankton populations sampled from the seamount sheath-water. (a) Characteristic flow cytometric signatures of Hoechst–DNA stained bacterioplankton, sampled at St. 12. Ellipses on the density plot indicate the four main bacterioplankton populations (P1, P2, P3 and P4 with corresponding relative abundances shown as percentages), from which cells were flow sorted for taxonomic and proteomic analyses. The total cell concentration (TCC) is presented for reference. (b) Comparison of average (n = 2) relative taxonomic composition (% of read abundance) of the four main cytometric populations of bacterioplankton (BPL) sampled at the stations 9 (2,653 m), 10 (3,215 m) and 12 (3,030 m). P1 is dominated by the Rhodospirillales, Sphingomonadales and E01-9C-26 group. P2 is reproducibly dominated by the SAR11 and SAR406 groups. P3 is dominated by more diverse Alphaproteobacteria in addition to the SAR406 group. P4 is dominated by the SAR324 group. (c) Functional versus taxonomic classification of the peptides synthesised by cells from P1, focusing on the representative alpha- and gamma- proteobacteria (PB). The limited peptide data reveal the presence of bifunctional aconitate hydratase, 3-hydroxyacyl-CoA dehydrogenase, succinyl-CoA synthetase, isocitrate dehydrogenase, aspartate aminotransferase, aconitate hydratase and malate dehydrogenase enzymes and proteins responsible for core cellular functions such as protein expression, energy conservation, membrane transport or DNA folding.
