Quiescence and transient growth dynamics in chemostat models

A chemostat model for microbial growth taking into account that cells can exist in two states, active and quiescent, is proposed and analyzed. Cells adapt to environmental (nutrient supply) fluctuations by changing from one state to another with asymmetric thresholds. Depending on the growth conditions, steady-state growth is attained with either a homogeneous population of active cells or a heterogeneous population of both active and quiescent cells. Transient oscillatory growth that has been observed in bacterial and algal chemostat cultures can be a result of such an adaptation mechanism.