Natural and Cultivated Marine Algae Have Substantially Different Metabolites

The Science                                  

Nitrogen is essential for all life, but most organisms can't use nitrogen gas directly from air to meet their needs. Special microbes called nitrogen fixers convert this gas into usable forms like ammonia. Trichodesmium, a type of cyanobacteria, is one of the most abundant nitrogen fixers in the world. These bacteria form colonies with different shapes (morphologies), but scientists have not understood how these shapes relate to their function. A new study used cutting-edge technology to analyze individual natural colonies of Trichodesmium. By identifying the unique chemicals produced by each colony type, researchers discovered how Trichodesmium colony types contribute different nutrients to their environments.

The Impact

Although Trichodesmium species are globally abundant, they are difficult to study because most species cannot easily be grown in the laboratory. This study demonstrated that natural colonies collected from spring blooms in the Red Sea differ from each other and also differ from laboratory-grown colonies. The approach was developed by a multi-institutional team, and can be used to understand how natural colonies of different types and from diverse environments produce different forms of nitrogen that ultimately control environmental productivity and community composition.

Summary

Trichodesmium is a vital marine bacteria that converts atmospheric nitrogen into usable forms, fueling life in nutrient-poor environments. It forms diverse colonies with distinct morphologies, where each type of colony plays a unique role in global nutrient cycles. Trichodesmium colonies are often sparsely distributed in the vast ocean, making it difficult to collect enough for traditional analyses. It remains unclear how representative laboratory-based strains are to different morphotypes of Trichodesmium found in marine environments. As part of a multi-institutional study, researchers investigated the chemical diversity within and between three Trichodesmium morphotypes collected from the Red Sea, comparing them to a laboratory-grown strain. In collaboration with scientists and using capabilities at EMSL, the Environmental Molecular Sciences Laboratory, a Department of Energy Office of Science user facility at Pacific Northwest National Laboratory, researchers applied advanced microscale matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) capabilities to identify and map a wide range of small molecules within individual colonies. They found 80 unique metabolites shared across morphotypes, with 57 showing significant variation in abundance between them. Interestingly, the laboratory-grown strain showed the most distinct chemical profile, differing significantly from its wild counterparts. This research highlights the chemical diversity within Trichodesmium colonies and emphasizes the differences between laboratory-grown and natural populations. These findings provide a foundation for future studies exploring the roles of these metabolites and Trichodesmium colony morphopogy across environments.

Contacts 

Rene Boiteau
University of Minnesota
rboiteau@umn.edu 

Karl Romanowicz
University of Oregon
krom@uoregon.edu

Yeala Shaked
Interuniversity Institute for Marine Sciences, Eilat
yeala.shaked@mail.huji.ac.il

Futing Zhang
Interuniversity Institute for Marine Sciences, Eilat
futing.zhang@mail.huji.ac.il 

Dusan Velickovic
EMSL | Pacific Northwest National Laboratory
dusan.velickovic@pnnl.gov 

Funding

This research was performed under the Facilities Integrating Collaborations for User Science (FICUS) program and used resources at the Environmental Molecular Sciences Laboratory, a Department of Energy Office of Science user facility at Pacific Northwest National Laboratory sponsored by the Biological and Environmental Research program. This research was also supported by a United States-Israel Binational Science Foundation grant and a Simons Foundation grant.

Publication

Z. Romanowicz, et al. 2024. “Single-colony MALDI mass spectrometry imaging reveals spatial differences in metabolite abundance between natural and cultured Trichodesmium morphotypes.” mSystems 9, 10. [DOI: 10.1128/msystems.01152-24]