Contribution of Heterotrophic Diazotrophs to N₂ Fixation in a Eutrophic River: Free-Living vs. Aggregate-Associated.

ABSTRACT: Recent studies have indicated that heterotrophic diazotrophs are highly diverse and fix N₂ in aquatic environments with potentially adverse conditions for diazotrophy, such as oxic and rich in total nitrogen. In this study, we compared the activity and diversity of heterotrophic diazotrophs associated with aggregates (>12 μm) to free-living cells in the eutrophic Qishon River during the winter and summer seasons. Overall, measured heterotrophic N₂ fixation rates in the Qishon River ranged between 2.6-3.5 nmol N L^-1 d^-1. Heterotrophic N₂ fixation was mainly associated with aggregates in the summer samples (74 ± 24%), whereas during the winter the bulk diazotrophic activity was mostly ascribed to the free-living fraction (90 ± 6%)

SUBMITTER: Geisler E 

PROVIDER: S-EPMC8882987 | biostudies-literature | 2022

REPOSITORIES: biostudies-literature