Fluid-based microbial processes modeling in Trichodesmium colonies

In tropical and subtropical ocean gyres, Trichodesmium colonies account for up to half of the total N₂ fixation in the ocean, making it one of the most ecologically significant N₂ fixing cyanobacteria. Trichodesmium trichome colonies and large surface blooms formation have been studied relatively little in laboratory environments. More importantly, the flow motion effect has been ignored in previous studies. As the first step towards small-scale microbial processes associated with Trichodesmium synthesis, we present a shear-related fluid flow-based growth and synthesis model to better understand how fluid dynamics affect bacteria colony formation and growth. Under the assumption that early growth characteristics are strongly dependent on the shear rate, a two-way coupling fluid-structure interaction was developed using the lattice Boltzmann method for a porous colony. The results demonstrate that our model captures the exponential growth trend during the colony formation phase, and both the colony growth and the colony shape are dominated by the flow field.