Recent studies shed light on how cyanobacteria facilitate nitrogen removal in aquatic environments through a fascinating hydrogen cycle within cyanobacterial aggregates (CA). This process holds significant implications for managing nitrogen levels in both natural and engineered water systems.
Researchers have observed that cyanobacteria generate hydrogen during the dark phase of their daily cycle. This hydrogen then acts as a fuel for denitrifying bacteria, which are responsible for removing nitrate from the water. A study published on May 31, 2025, indicates that this process achieves a nitrogen removal rate of 3.47 ± 0.42 mmol l-1 day-1.
Metagenomic analysis confirms the presence and activity of both hydrogen-producing cyanobacteria and hydrogen-consuming denitrifying bacteria within these aggregates. This process occurs in various natural settings, including eutrophic lakes, marine aggregates, hot spring mats, and glacier cryoconites, highlighting its global significance in nitrogen cycling.