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In situ interactions between photosynthetic picoeukaryotes and bacterioplankton in the A tlantic O cean: evidence for mixotrophy
Author(s) -
Hartmann Manuela,
Zubkov Mikhail V.,
Scanlan Dave J.,
Lepère Cécile
Publication year - 2013
Publication title -
environmental microbiology reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.229
H-Index - 69
ISSN - 1758-2229
DOI - 10.1111/1758-2229.12084
Subject(s) - bacterioplankton , prochlorococcus , phototroph , cyanobacteria , biology , ecology , plankton , synechococcus , botany , photosynthesis , phytoplankton , bacteria , nutrient , paleontology
Summary Heterotrophic bacterioplankton, cyanobacteria and phototrophic picoeukaryotes (< 5 μm in size) numerically dominate planktonic oceanic communities. While feeding on bacterioplankton is often attributed to aplastidic protists, recent evidence suggests that phototrophic picoeukaryotes could be important bacterivores. Here, we present direct visual evidence from the surface mixed layer of the A tlantic O cean that bacterioplankton are internalized by phototrophic picoeukaryotes. In situ interactions of phototrophic picoeukaryotes and bacterioplankton (specifically P rochlorococcus cyanobacteria and the SAR11 clade) were investigated using a combination of flow cytometric cell sorting and dual tyramide signal amplification fluorescence in situ hybridization. Using this method, we observed plastidic P rymnesiophyceae and C hrysophyceae cells containing P rochlorococcus , and to a lesser extent SAR11 cells. These microscopic observations of in situ microbial trophic interactions demonstrate the frequency and likely selectivity of phototrophic picoeukaryote bacterivory in the surface mixed layer of both the N orth and S outh A tlantic subtropical gyres and adjacent equatorial region, broadening our views on the ecological role of the smallest oceanic plastidic protists.