Discovering the diversity and functionality of diazotrophs in the East Mediterranean Sea (DIAZOGENE)

Ibello, Valeria
Karahan, Arzu
Küçükavşar, Selin
Biological nitrogen fixation (NF) is the process transferring nitrogen (N) from atmosphere to ocean interior. Primary production in the sea, often limited by the scarcity of N, benefits by the activity of marine diazotrophs, able to convert N2 gas into organic form. N2 can be fixed following two main pathways: i) autotrophic process, in the euphotic layer and ii) heterotrophic process all over the water column. Although, occurrence of marine autotrophic NF is largely documented, a proper understanding of its ecological role, limiting and triggering factors is still missing. On the other side, heterotrophic NF in surface and deep ocean, has just been recently reported. Investigating gene diversity and gene expression can provide important information about role and functioning of these organisms.In the current study, we aim to analyze the diversity, functionality and abundance of both autotrophic and heterotrophic N2-fixing community in the East Mediterranean Sea. Metatranscriptomic analysis, revealing gene expression of the bacterial community will be carried out, in the surface and deep layers. Sampling will continue for one year, in four seasons at Erdemli Time Series site (ETS).Metatranscriptomic data will be coupled to a large dataset of parameters (metagenomic, NF rates, biogeochemical and physical measures) collected during a parallel project focusing on marine microbial community (TUBITAK, 116Y629), which will also provide logistics support for the field activities.