Investigating cell cultures with NMR requires high cell densities to provide adequate signal-to-noise, or scans must be summed over long time periods and short-term events are lost. The mixing within a chemostat can be used to shorten the time required to acquire informative in situ NMR spectra from cell cultures. However, performance trade-offs can occur between net signal, spectral resolution...

The role of the rRNA gene copy number as a central component of bacterial life histories was studied by using strains of Escherichia coli in which one or two of the seven rRNA operons (rrnA and/or rrnB) were deleted. The relative fitness of these strains was determined in competition experiments in both batch and chemostat cultures. In batch cultures, the decrease in relative fitness correspond...

Chemostat enrichment is a classical microbiological method that is well suited for use in directed-evolution strategies. We used a two-phase sulfur-limited chemostat to select for gain-of-function mutants with mutations in the biodesulfurization (Dsz) system of Rhodococcus erythropolis IGTS8, enriching for growth in the presence of organosulfur compounds that could not support growth of the wil...

This study presents the metal toxicity as revealed by Chlorella pyrenoidosa using a short-term continuous test and the conventional batch test. Toxicity tests were conducted in a chemostat with a test duration of 1 day. Toxicity data of five different metals (Cd, Pb, Co, Ni, and Zn) derived from the continuous test were compared against results from the conventional batch tests. The batch test ...

Perfusion culture optimization in multiple noninstrumented small-scale flasks allows reduced expense and time associated with process development. These cultures normally use a different process mode because at small scales it is not practical to retain the cells for medium perfusion. In this work, the kinetics of growth, nutrient consumption, metabolite, and product formation were compared in ...

This is a study of high-affinity glucose uptake in Aspergillus niger and the effect of disruption of a high-affinity monosaccharide-transporter gene, mstA. The substrate saturation constant (K(s)) of a reference strain was about 15 microM in glucose-limited chemostat culture. Disruption of mstA resulted in a two- to fivefold reduction in affinity for glucose and led to expression of a low-affin...

The use of chemostat culturing enables investigation of steady-state physiological characteristics and adaptations to nutrient-limited growth, while all other relevant growth conditions are kept constant. We examined and compared the proteomic response of wild-type Saccharomyces cerevisiae CEN.PK113-7D to growth in aerobic chemostat cultures limited for carbon sources being either glucose or et...

The network structure and the metabolic fluxes in central carbon metabolism were characterized in aerobically grown cells of Saccharomyces cerevisiae. The cells were grown under both high and low glucose concentrations, i.e., either in a chemostat at steady state with a specific growth rate of 0.1 h(-1) or in a batch culture with a specific growth rate of 0.37 h(-1). Experiments were carried ou...