Photoheterotrophic organisms play a significant role in the carbon flow of marine environments. Among them, aerobic anoxygenic phototrophic (AAP) bacteria stand out due to their ability to harvest light using bacteriochlorophyll a. In spite of their relatively low abundances, they are a dynamic group that exhibits faster growth rates than other bacterioplankton groups. Many studies have focused on their temporal patterns and spatial distribution in the surface ocean; however, little is known about their distribution along the water column. We hypothesized that AAP bacteria will follow a strong vertical gradient related to the deep chlorophyll maximum (DCM) structure and, to test it, we analyzed a total of 171 samples along the DCM profile in contrasting trophic zones of the Atlantic Ocean. We combined epifluorescence microscopy for abundance, high-pressure liquid chromatography for pigment analysis, and high-throughput sequencing of the pufM gene, to describe the diversity and abundance distribution of AAP communities. These bacteria follow a marked horizontal and vertical gradient, as seen by differences in the diversity and taxonomic composition of their communities, dominated by different uncultured assemblages that have been barely described previously. Bacteriochlorophyll a and AAP abundances follow the vertical chlorophyll variation, with contrasting changes along the different trophic regimes. The structure of AAP communities is highly dependent on the phytoplankton communities pointing to a strong coupling between both groups.    

Primary Presenter: Carlota Gazulla, Universitat Autònoma de Barcelona (lotaruiz@gmail.com)

Authors:

Isabel Ferrera, Spanish Institute of Oceanography (IEO-CSIC)  (isabel.ferrera@ieo.csic.es)

Michal Koblížek, Institute of Microbiology CAS, Center Algatech  (koblizek@alga.cz)

Vanessa Balagué, Institut de Cièncias del Mar (ICM-CSIC)  (vbalague@icm.csic.es)

Carolina Marín-Vindas,  Institut de Cièncias del Mar (ICM-CSIC) & Laboratorio de Microbiología Marina, Escuela de Ciencias Biológicas, Universidad Nacional, Costa Rica  (carimvi@gmail.com)

Aleix Obiol, Institut de Cièncias del Mar (ICM-CSIC)  (obiol@icm.csic.es)

Ramón Massana, Institut de Cièncias del Mar (ICM-CSIC)  (ramonm@icm.csic.es)

Alba González-Vega, Universidad de Las Palmas de Gran Canaria  (alba.gonzalez@ulpgc.es)

José Escánez-Pérez, Canary Islands Oceanographic Center, Spanish Institute of Oceanography (IEO-CSIC)  (jose.escanez@ieo.csic.es)

Eugenio Fraile-Nuez, Canary Islands Oceanographic Center, Spanish Institute of Oceanography (IEO-CSIC)  (eugenio.fraile@ieo.csic.es)

Jesus M. Arrieta, Canary Islands Oceanographic Center, Spanish Institute of Oceanography (IEO-CSIC)  (jesus.arrieta@ieo.csic.es)

Josep M. Gasol, Institut de Cièncias del Mar (ICM-CSIC)  (pepgasol@icm.csic.es)

Olga Sánchez, Universitat Autònoma de Barcelona (UAB)  (olga.sanchez@uab.cat)