Microbial Interactions in the Phycosphere

Dear Colleagues,

The phycosphere represents one of the most dynamic and ecologically critical microenvironments in aquatic ecosystems. As primary producers, algae form the base of aquatic food webs, and their interactions with co-occurring associated microbes (including bacteria, archaea, viruses, fungi, and protozoa) shape diverse processes, ranging from global biogeochemical cycling to phytoplankton bloom dynamics, as well as the ecological health of marine and freshwater habitats. Despite decades of research, the complex nature of these interactions—their molecular mechanisms, ecological consequences, and responses to environmental changes—remains incompletely resolved. It is within this context that we are launching this Special Issue, “Microbial Interactions in the Phycosphere”.

Aims:

The primary aims of this Special Issue are as follows:

1. Advance Mechanistic Understanding: To synthesize and publish research that uncovers the molecular, physiological, and ecological mechanisms driving interactions in the phycosphere. This can include, but is not limited to, nutrient exchange, signaling pathways, and symbiotic or antagonistic relationships.
2. Bridge Scales of Inquiry: To connect microscale interactions (e.g., cell-to-cell signaling) to macroscale ecological outcomes (e.g., bloom formation, carbon export to the deep ocean). By integrating studies across spatial (from nanometers to ecosystems) and temporal (from hours to seasonal) scales, this Special Issue aims to resolve gaps in how phycosphere dynamics can be scaled up to influence aquatic biogeochemistry and food web structures.
3. Address Global Change Impacts: To highlight research exploring how anthropogenic stressors—such as ocean warming, acidification, eutrophication, and pollution—alter phycosphere interactions. Understanding these responses is critical in predicting shifts in aquatic ecosystem function (e.g., changes in primary productivity, increased harmful algal blooms) under a changing climate.

Scope:

To achieve these aims, this Special Issue will encompass a broad range of topics, approaches, and aquatic systems, including the following:

• Key Organism Interactions: Studies investigating pairwise or multi-species interactions involving phytoplankton (e.g., diatoms, dinoflagellates, cyanobacteria) and associated microbes (e.g., heterotrophic bacteria of the Roseobacter clade, viruses, protozoan grazers). We will consider work on both beneficial interactions (e.g., mutualistic nutrient cycling) and detrimental ones (e.g., viral lysis, algicidal bacterial activity).
• Methodological Advancements: Contributions showcasing innovative techniques to study the phycosphere, such as meta-omics (metagenomics, metatranscriptomics, metabolomics), single-cell imaging (e.g., fluorescence in situ hybridization, atomic force microscopy), microfluidic systems (to mimic phycosphere microenvironments), and stable isotope probing (to trace nutrient flow).
• Aquatic Ecosystem Diversity: Research conducted in diverse aquatic habitats, including marine (coastal, open ocean), freshwater (lake, river), and brackish (estuary) systems. This breadth reflects the universality of the phycosphere while highlighting ecosystem-specific variations in interaction dynamics (e.g., nutrient limitation in oligotrophic oceans vs. eutrophic lakes).
• Theoretical and Applied Perspectives: In addition to empirical research, this Special Issue will include review articles synthesizing current knowledge, perspective pieces proposing new hypotheses (e.g., "the phycosphere as a hub for horizontal gene transfer"), and applied studies (e.g., leveraging phycosphere interactions for bioremediation, sustainable aquaculture, or the mitigation of harmful algal blooms).

By bringing together these diverse perspectives, this Special Issue will serve as a definitive resource for researchers, students, and practitioners in phycosphere microbial ecology, aquatic biology, biogeochemistry, and climate science, ultimately advancing our collective understanding of the phycosphere as a driver of aquatic ecosystem health and global biogeochemical cycles.

Dr. Qiao Yang
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 250 words) can be sent to the Editorial Office for assessment.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Phycology is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• phycosphere
• algae–bacteria interactions
• interaction between bacteria and algae
• relationship between bacteria and algae
• interaction between diatoms and bacteria
• microbial interactions
• phytoplankton–bacteria relationships
• phytoplankton–bacteria interactions
• host–microbe interactions
• phycosphere microbiology
• mutualistic interactions
• symbiotic interactions
• bacteria–dinoflagellate interactions
• interaction between microalgae and phycosphere bacteria
• diatom–bacterium interactions
• phycosphere microbes
• phycosphere microbiota
• phycosphere bacteria
• algal–bacteria consortia
• phycosphere microbial diversity
• algae–bacteria symbiotic system
• bacteria–algae symbiotic system
• quorum sensing
• algicidal bacteria
• microalgae growth-promoting bacteria
• phycosphere holobiont
• chemotaxis
• auxin signaling
• aquatic ecosystems
• biogeochemical cycling
• molecular mechanisms
• harmful algal blooms
• phytoplankton bloom
• phycoremediation
• wastewater treatment
• extracellular polymeric substances
• aquatic ecosystems
• marine food web
• microbial loop
• exopolysaccharide
• indole-3-acetic acid