Exploring the Influence of Altered Nutrient Stoichiometry on Cyanopeptide Production and its Effects on Phytoplankton Community Structure and Dynamics: A Mesocosm Study

• Grant number: 25/08223-6
• Support Opportunities: Scholarships in Brazil - Master
• Start date: July 01, 2025
• End date: January 31, 2027
• Field of knowledge: Biological Sciences - Ecology - Ecosystems Ecology
• Principal Investigator: Mathias Ahii Chia
• Grantee: Besna Armando Daniel
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 23/00798-4 - Elucidating and predicting the ecological roles of cyanopeptides in four Sao Paulo State Public water supply reservoirs, AP.JP

Abstract

Is there a consistency in cyanopeptide profiles produced by strains of Microcystis aeruginosa under changing forms of nitrogen? Background Cyanobacteria, also known as blue-green algae, are photosynthetic microorganisms in various aquatic ecosystems. Among the cyanobacterial genera, Microcystis aeruginosa is well-known for its ability to form harmful algal blooms (HABs) under favourable environmental conditions (Harke et al. 2016). These blooms can produce potent cyanotoxins, including microcystins, cylindrospermopsins, anabaenopeptins, and over a thousand other linear and cyclic peptides collectively called cyanopeptides. Cyanopeptides are bioactive compounds that have raised significant interest due to their potential applications in medicine, pharmaceuticals, and biotechnology (Janssen 2019). The ecological implications and human health risks associated with cyanopeptides have sparked widespread concern. Microcystins, for instance, are potent hepatotoxins that pose a severe threat to the health of humans and aquatic organisms if ingested or exposed to contaminated water at high concentrations (Jochimsen et al. 1998). Understanding the factors influencing cyanopeptide production and their consistency among different strains of Microcystis aeruginosa is essential to assess and manage the risks associated with cyanobacterial blooms in water bodies. Despite their significance, the production of cyanopeptides by cyanobacteria remains understudied. Previous research has predominantly focused on toxicological aspects, and more is needed about the diversity and consistency of cyanopeptide profiles among different strains of Microcystis aeruginosa. Investigating the variations in cyanopeptide production and their stability under changing physicochemical conditions, particularly when different forms of nitrogen are available, will shed light on the adaptability of these strains to varying nutrient environments. Nitrogen is a crucial nutrient that plays a vital role in the growth and metabolism of cyanobacteria. It exists in various forms, including nitrate, ammonium, and urea, and its availability can significantly influence the development and physiology of cyanobacterial populations. Understanding how different forms of nitrogen affect cyanopeptide production in Microcystis aeruginosa strains is paramount to predicting the occurrence and intensity of harmful algal blooms and devise effective strategies for bloom management and water quality control. This project holds great promise for advancing our knowledge of cyanobacterial bioactive compounds and their response to changing environmental factors. The outcomes of this study can potentially inform strategies for mitigating cyanobacterial bloom occurrences and managing the risks associated with cyanopeptides in aquatic ecosystems. This proposed research aims to address the gap in knowledge by investigating the consistency of cyanopeptide profiles produced by different strains of Microcystis aeruginosa and their response to changing forms of nitrogen. By gaining insights into the diversity and stability of cyanopeptide production under various conditions, this study will contribute to the broader understanding of cyanobacterial ecology, bioactive compounds, and their potential implications for human health and environmental management. (AU)