Lipid-accumulating fungi may be able to produce biodiesel precursors from agricultural wastes. As a first step in understanding and evaluating their potential, a mathematical model was developed to describe growth, lipid accumulation and substrate consumption of the oleaginous fungus Umbelopsis isabellina (also known as Mortierella isabellina) in submerged chemostat cultures. Key points of the ...

Two of the central problems in biology are determining the molecular basis of adaptive evolution and understanding how cells regulate their growth. The chemostat is a device for culturing cells that provides great utility in tackling both of these problems: it enables precise control of the selective pressure under which organisms evolve and it facilitates experimental control of cell growth ra...

The adaptation of the tubercle bacillus to the host environment is likely to involve a complex set of gene regulatory events and physiological switches in response to environmental signals. In order to deconstruct the physiological state of Mycobacterium tuberculosis in vivo, we used a chemostat model to study a single aspect of the organism's in vivo state, slow growth. Mycobacterium bovis BCG...

We study the chemostat model for one species competing for one nutrient using a Lyapunov-type analysis. We design the dilution rate function so that all solutions of the chemostat converge to a prescribed periodic solution. In terms of chemostat biology, this means that no matter what positive initial levels for the species concentration and nutrient are selected, the long-term species concentr...

The complexity of biofilm communities like dental plaque suggests that laboratory model biofilm growth systems may help to understand their structure and function. This study describes the use of a constant-depth film fermenter (CDFF) to investigate biofilm formation by a nine-membered community of oral bacteria. The community was grown to steady state in a chemostat incubated anaerobically. Th...

This paper develops a novel characterization of uniform input-to-state stability (UISS) in terms of vector Lyapunov functions. The motivation is coming from the problem of robust global stabilization of the chemostat and in particular from anaerobic digestion processes, which are characterized by narrow stability regions and extreme sensitivity to external perturbations, if operated under optim...

In the continuous mode of cell culture, a constant flow carrying fresh media replaces culture fluid, cells, nutrients and secreted metabolites. Here we present a model for continuous cell culture coupling intra-cellular metabolism to extracellular variables describing the state of the bioreactor, taking into account the growth capacity of the cell and the impact of toxic byproduct accumulation....

Chemostat cultivation is a powerful tool for physiological studies of microorganisms. We report the construction and application of a set of eight parallel small-scale bioreactors with a working volume of 10 mL for continuous cultivation. Hungate tubes were used as culture vessels connected to multichannel-peristaltic pumps for feeding fresh media and removal of culture broth and off-gas. Water...