Microbial interactions influence the productivity and biogeochemistry of the ocean, yet they occur in miniscule volumes that cannot be sampled by traditional oceanographic techniques. To investigate the behaviours of marine microorganisms at spatially relevant scales, we engineered an in situ chemotaxis assay (ISCA) based on microfluidic technology. Here, we describe the fabrication, testing and first field results of the ISCA, demonstrating its value in accessing the microbial behaviours that shape marine ecosystems.
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The authors thank A. Gavish and A. Vardi for supplying V. coralliilyticus YB2, A. Stahl and M. Ullrich for supplying M. adhaerens (HP15 ΔfliC) and C. Gao and F. Moser for assistance generating the fluorescent E. coli strain used in this study. This work was supported by the Gordon and Betty Moore Foundation through a grant (GBMF3801) to J.S., G.T., P.H. and R.S. J.B.R. was supported by Australian Research Council fellowship DE160100636.
Electronic supplementary material
Supplementary Notes 1–3 (incl. Supplementary Figures N1 and N2), Supplementary Figures 1–12 and Supplementary References.
Computer-aided design (CAD) file for the ISCA mold; CAD file for the laboratory ISCA microcosm; CAD file for the ISCA field deployment enclosure.
Mathematical model of chemotaxis into an ISCA well implemented in COMSOL.
Evolution of the chemoattractant concentration field as it diffuses from the ISCA well, as predicted by the mathematical model.
Accumulation of bacteria into an ISCA well predicted by the mathematical model.
Fluorescently labelled Vibrio coralliilyticus cells at middepth in an ISCA well containing 10% marine broth.
Fluorescently labelled Vibrio coralliilyticus cells at middepth in an ISCA well containing filtered artificial seawater.
Example of cell enumeration through image analysis in laboratory ISCA experiments, for Vibrio coralliilyticus.
Example of cell enumeration through image analysis in laboratory ISCA experiments, for Escherichia coli.
Example of cell enumeration through image analysis in laboratory ISCA experiments, for Marinobacter adhaerens.