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Advisor(s)
Abstract(s)
The mechanical behavior of living cells, during planktonic growth, has been thoroughly explored combining common biological techniques with rheology and rheo-imaging measurements. Under a shear flow, bacterial cultures of Staphylococcus aureus revealed a complex and rich rheological behavior not usually accessed in biological studies. In particular, in stationary shear flow, the viscosity increased during the exponential phase and returned close to its initial value at the late phase of growth, accompanied by the stabilization of the bacterial population. In oscillatory flow, the elastic and viscous moduli exhibited power-law behaviors whose exponents are dependent on the bacteria growth stage, and can be associated to a Soft Glassy Material behavior. These behaviors were framed in a microscopic model that suggests the formation of a dynamic web-like structure, where specific aggregation phenomena may occur, depending on growth stage and cell density. Furthermore, systematic measurements combining optical density and dry weight techniques presented new evidences, which confirmed that the observed cell aggregation patterns developed during growth, under shear, can not only be cell density dependent.
Description
Keywords
Rheology Staphylococcus aureus Biological studies Oscillatory flow Soft Glassy Material Specific aggregation phenomena Growth stage Cell density
Citation
PORTELA, R. – Rheology of living cells. In 6th IEEE Portuguese Meeting on Bioengineering (ENBENG 2019). Lisbon, Portugal: IEEE, 2019. ISBN 978-1-5386-8507-5. Pp. 1-4