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Updated: Feb 23, 2026

In Situ Chemotaxis Assay to Examine Microbial Behavior in Aquatic Ecosystems
Published on: May 5, 2020
Redefining the sponge-symbiont acquisition paradigm: sponge microbes exhibit chemotaxis towards host-derived
Jessica Tout1, Carmen Astudillo-García2, Michael W Taylor2
1Plant Functional Biology & Climate Change Cluster, University of Technology Sydney, NSW, Australia.
Abstract:
Marine sponges host stable and species-specific microbial symbionts that are thought to be acquired and maintained by the host through a combination of vertical transmission and filtration from the surrounding seawater. To assess whether the microbial symbionts also actively contribute to the establishment of these symbioses, we performed in situ experiments on Orpheus Island, Great Barrier Reef, to quantify the chemotactic responses of natural populations of seawater microorganisms towards cellular extracts of the reef sponge Rhopaloeides odorabile. Flow cytometry analysis revealed significant levels of microbial chemotaxis towards R. odorabile extracts and 16S rRNA gene amplicon sequencing showed enrichment of 'sponge-specific' microbial phylotypes, including a cluster within the Gemmatimonadetes and another within the Actinobacteria. These findings infer a potential mechanism for how sponges can acquire bacterial symbionts from the surrounding environment and suggest an active role of the symbionts in finding their host.
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