Global diversity and distribution of aerobic anoxygenic phototrophs in the tropical and subtropical oceans

Special issue Microbial Ecology of Aquatic Systems.-- 17 pages, 5 figures, 1 table, supporting information https://doi.org/10.1111/1462-2920.15835The aerobic anoxygenic phototrophic (AAP) bacteria are common in most marine environments but their global diversity and biogeography remain poorly characterized. Here, we analyzed AAP communities across 113 globally-distributed surface ocean stations sampled during the Malaspina Expedition in the tropical and subtropical ocean. By means of amplicon sequencing of the pufM gene, a genetic marker for this functional group, we show that AAP communities along the surface ocean were mainly composed of members of the Halieaceae (Gammaproteobacteria), which were adapted to a large range of environmental conditions, and of different clades of the Alphaproteobacteria, which seemed to dominate under particular circumstances, such as in the oligotrophic gyres. AAP taxa were spatially structured within each of the studied oceans, with communities from adjacent stations sharing more taxonomic similarities. AAP communities were composed of a large pool of rare members and several habitat specialists. When compared to the surface ocean prokaryotic and picoeukaryotic communities, it appears that AAP communities display an idiosyncratic global biogeographical pattern, dominated by selection processes and less influenced by dispersal limitation. Our study contributes to the understanding of how AAP communities are distributed in the horizontal dimension and the mechanisms underlying their distribution across the global surface oceanThis work was funded by the Spanish Ministry of Economy and Competitiveness (MINECO) through the Consolider-Ingenio program (Malaspina 2010 Expedition, CSD2008-00077), with contributions from grants ECLIPSE (PID2019-110128RB-I00) funded to IF, MIAU (RTI2018-101025-B-I00) to JMG and OS, and GRAMMI (RTI2018-099740-J-I00) to Clara RG, all from the Spanish Ministry of Science and Innovation (MICIN). Carlota RG was supported with a contract for research staff training from the Universitat Autònoma de Barcelona. Authors affiliated to the Institut de Ciències del Mar had the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), and IF received the support of the BBVA Foundation through the ‘Becas Leonardo a Investigadores y Creadores Culturales’ 2019 Program. The Foundation takes no responsibility for the contents of this publication, which are entirely the responsibility of its authors. PCJ was supported by São Paulo Research Foundation–FAPESP (PhD grants #2017/26786-1 and #2020/02517-4