|Biofluid Dynamics|

Microbial systems represent active states of matter out of thermodynamic equilibrium. A key tenet of such systems is the emergent flow and transport properties at collective scales, generally not observed at the scale of individuals. We develop systematic approaches, combining experiments, theory and simulations, to investigate the emergence of active transport properties in diverse microbial systems, including microalgae, bacteria, and due to microbial interactions with foreign inclusions in their habitats, for instance microplastics or harmful chemicals. Our Biofluid Dynamics research is motivated by the need to understand how microbes adapt and respond under stressful conditions, particularly those imposed by the shifts in climatic patterns and anthropogenic activities.

Nutrient-limited phytoplankton turn predators by generating feeding currents to trap preys (Science Advances 8, 2022)

Bacteria-induced mixing in natural lakes

Bacteria-induced mixing in natural waters

(Geophysical Research Letters 44, 9424, 2017)

Gravitactic, aerotactic or phototactic microorganisms can accumulate locally as a layer, increasing the density of the water. This layer of heavier water on top of lighter water sinks and mixes with the surrounding water, and can be maintained continuously as long as upward swimming is supported by the gravi- aero- or the phototactic cues. Following our 2017 discovery that bioconvection provides fundamental ecological functions to phototrophic bacteria - confirming the role of bioconvection beyond laboratory settings - we started systematic investigations on the microbial traits which regulate bioconvection in natural waters. The SNSF-funded project, in collaboration with key partners at SUPSI and EAWAG (Swizerland), is based at the limnological station of the alpine lake Lago di Cadagno (Tecino). See publications below for details:

Bacteria-induced mixing in natural waters: Geophysical Research Letters 44, 9424, 2017

Dark aerobic sulfide oxidation by anoxygenic phototrophs in anoxic waters: Environmental Microbiology 21, 1611, 2019

Biophysics of mIcrobe-microplastic interactions

The Marie Skłodowska-Curie Actions Individual Fellowship funded project BIOMIMIC (Biophysics of Microbe-Microplastic Interactions & Colonization) initiated a series of studies to capture the dynamic relationships between microplastics (micro-scale pollutants teeming the biosphere) and microbes by leveraging Sengupta Lab's ocean-mimicking experimental set ups. The project has allowed significant mechanistic insights into the encounter and colonization of microbes on microplastics, under both static and dynamic ecologically-relevant settings (manuscripts are currently in preparation).

Microscale biophysics of harmful algal blooms

Despite the well-documented toxic ramifications of Harmful Algal Blooms (HABs) on vertebrates and mammals, including humans, we still lack a biophysical understanding of the mechanisms by which toxins disperse during a bloom event. This HFSP-funded project has allowed us to explore the physico-chemical interplays underlying the release and transport of various molecules (mimicking toxins) at the scale of the microorganism, revealing a central role of the coupling between microbial biophysics, transport phenomena and biochemistry during different stages of HAB lifecycle. The results could be particularly relevant as we encounter rapidly warming climate today (manuscripts are in preparation).

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