In situ interactions between photosynthetic picoeukaryotes and bacterioplankton in the Atlantic Ocean: evidence for mixotrophy. Issue 6 (22nd July 2013)

• Record Type: Journal Article
• Authors: Hartmann, Manuela; Zubkov, Mikhail V.; Scanlan, Dave J.; Lepère, Cécile
• Is Part Of: Environmental microbiology reports. Volume 5:Issue 6(2013:Dec.)
• Page Start: 835
• Page End: 840
• Publication Date: 2013-07-22
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; Electronic journals; 579.17
• DOI: 10.1111/1758-2229.12084
• Languages: English
• ISSNs: 1758-2229

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>Heterotrophic bacterioplankton, cyanobacteria and phototrophic picoeukaryotes (&lt; 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 Atlantic Ocean that bacterioplankton are internalized by phototrophic picoeukaryotes. <italic>In situ</italic> interactions of phototrophic picoeukaryotes and bacterioplankton (specifically <italic>Prochlorococcus</italic> cyanobacteria and the SAR11 clade) were investigated using a combination of flow cytometric cell sorting and dual tyramide signal amplification fluorescence <italic>in situ</italic> hybridization. Using this method, we observed plastidic Prymnesiophyceae and Chrysophyceae cells containing <italic>Prochlorococcus</italic>, and to a lesser extent SAR11 cells. These microscopic observations of <italic>in situ</italic> microbial trophic interactions demonstrate the frequency and likely selectivity of phototrophic picoeukaryote bacterivory in the surface mixed layer of both the North and South Atlantic subtropical gyres and adjacent equatorial region, broadening our views on the ecological role of the smallest oceanic plastidic protists.</p> </abstract>