Skip to main content
ARS Home » Southeast Area » Auburn, Alabama » Aquatic Animal Health Research » Research » Publications at this Location » Publication #417170
Research Project: Integrated Research to Improve Aquatic Animal Health in Warmwater Aquaculture

Location: Aquatic Animal Health Research

Title: Indole-3-acetic acid promotes growth in bloom-forming Microcystis via an antioxidant response

Author
item BAYLOUS, HUNTER - James Madison University
item GLADFELTER, MATTHEW - Auburn University
item GARDNER, MALIA - James Madison University
item FOLEY, MADALYNN - James Madison University
item WILSON, ALAN - Auburn University
item STEFFEN, MORGAN - James Madison University

Submitted to: Harmful Algae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2024
Publication Date: 2/6/2024
Citation: Baylous, H.R., Gladfelter, M.F., Gardner, M.I., Foley, M., Wilson, A.E., Steffen, M.M. 2024. Indole-3-acetic acid promotes growth in bloom-forming Microcystis via an antioxidant response. Harmful Algae. 133:102575. https://doi.org/10.1016/j.hal.2024.102575.
DOI: https://doi.org/10.1016/j.hal.2024.102575

Interpretive Summary: Cyanobacterial harmful algal blooms pose a serious threat to aquatic ecosystem health and water security worldwide. Despite decades of research on these destructive organisms, we still have little insight on the impact of biotic interactions on bloom development and success.This study reveals the molecular mechanisms that underlie the growth promoting activity of the auxin indole-3-acetic acid, a common chemical currency exchanged within bloom bacterial populations. Additionally, we show that the complex interactions between bacteria within bloom communities exhibit a clear division of labor, where individual taxa contribute unique supportive functions to bloom-forming Microcystis.

Technical Abstract: Interactions between bacteria and phytoplankton in the phycosphere facilitate and constrain biogeochemical cycling in aquatic ecosystems. Indole-3-acetic acid (IAA) is a bacterially produced chemical signal that promotes growth of phytoplankton and plants. Here, we explored the impact of IAA on bloom-forming cyanobacteria and their associated bacteria. Exposure to IAA and its precursor, tryptophan, resulted in a strong growth response in a bloom of the freshwater cyanobacterium, Microcystis. Metatranscriptome analysis revealed the induction of an antioxidant response in Microcystis upon exposure to IAA, potentially allowing populations to increase photosynthetic rate and overcome internally generated reactive oxygen. Our data reveal that co-occurring bacteria within the phycosphere microbiome exhibit a division of labor for supportive functions, such as nutrient mineralization and transport, vitamin synthesis, and reactive oxygen neutralization. These complex dynamics within the Microcystis phycosphere microbiome are an example of interactions within a microenvironment that can have ecosystem-scale consequences.