ZMT - Leibniz Zentrum für Marine Tropenforschung

Project description

Nitrogen is a key nutrient for phytoplankton, unicellular microorganisms that support marine food webs. Although nitrogen gas (N₂) is abundant in seawater, most marine organisms cannot use it directly. Specialized microorganisms, known as N₂-fixers, convert nitrogen gas into usable forms through the process, known as N₂ fixation, which is the largest source of usable nitrogen in the ocean and helps keep marine ecosystems productive.

Traditionally, photosynthetic cyanobacteria were thought to be the main N₂ fixers in the open ocean. However, recent studies have discovered that other types of bacteria, called heterotrophic N₂-fixers (HNFs), also play a significant role. Despite their importance, very little is known about HNFs. This project aims to understand how these bacteria fix nitrogen, where they are most active, and how they help sustain marine life, especially in tropical and subtropical regions.

Approach

This project will focus on developing mathematical models to understand the role of heterotrophic N₂-fixers in the ocean. These models will simulate the cellular processes inside bacterial cells and examine how environmental factors, such as temperature, nutrient availability, O2 concentration, and organic matter, influence the process of N₂ fixation. The models will also explore how the activity of heterotrophic N₂-fixers varies across different regions and seasons in tropical and subtropical ocean waters.

By running numerical experiments, we aim to understand the role of heterotrophic N₂-fixers in sustaining phytoplankton and the marine food web. This work will help reveal the importance of these bacteria in supporting ocean productivity and resilience, especially in nitrogen-limited regions of the tropics.