Long-Term Monitoring of Bacteria Undergoing Programmed Population Control in a Microchemostat - PowerPoint PPT Presentation

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Long-Term Monitoring of Bacteria Undergoing Programmed Population Control in a Microchemostat

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  1. Long-Term Monitoring of Bacteria Undergoing Programmed Population Control in a Microchemostat Frederick K. Balagaddé, Lingchong You, Carl L. Hansen, Frances H. Arnold, Stephen R. Quake Science, 309:137-140 (2005) Article critique presented by Véronique Lecault January 10, 2006 EECE 491c

  2. Cell sorting and analysis DNA microarrays Protein crystallization DNA amplification Immunoassays Electrophoresis Microfluidics: A Small World with Large Applications… (Thorsen et al., 2002) Balagaddé et al. (2005) Science 309:137-140

  3. Advantages: • Reduced reagent costs • High-throughput experiments • Cell tracking • Reduced waste • Increased speed of experiments Scaling Bioreactors Down to Nanoliters… Liters 1x109 1 1x106 1x10-6 1x10-3 1x103 1x10-9 Balagaddé et al. (2005) Science 309:137-140

  4. Batch • Fed-batch (semi continuous) • Chemostat (continuous) How do we culture cells? Number of bacteria Time Balagaddé et al. (2005) Science 309:137-140

  5. Bacteria and biofilms (www.medicdirect.co.uk) Balagaddé et al. (2005) Science 309:137-140

  6. Bacteria and biofilms Balagaddé et al. (2005) Science 309:137-140

  7. The Microchemostat Balagaddé et al. (2005) Science 309:137-140

  8. The Microchemostat Balagaddé et al. (2005) Science 309:137-140

  9. The Microchemostat Balagaddé et al. (2005) Science 309:137-140

  10. The Microchemostat 3 g/L 0.5 g/L 0.1 g/L Balagaddé et al. (2005) Science 309:137-140

  11. Quorum Sensing Balagaddé et al. (2005) Science 309:137-140

  12. Quorum Sensing Balagaddé et al. (2005) Science 309:137-140

  13. Quorum Sensing Balagaddé et al. (2005) Science 309:137-140

  14. Quorum Sensing IPTG - Balagaddé et al. (2005) Science 309:137-140

  15. Quorum Sensing IPTG + Balagaddé et al. (2005) Science 309:137-140

  16. MC4100Z1 Cells Balagaddé et al. (2005) Science 309:137-140

  17. Top10F’ Cells Balagaddé et al. (2005) Science 309:137-140

  18. Loss of Regulation MC4100Z1 Top10F’ Balagaddé et al. (2005) Science 309:137-140

  19. Population dynamics Balagaddé et al. (2005) Science 309:137-140

  20. Population dynamics Balagaddé et al. (2005) Science 309:137-140

  21. Conclusions • Operation of a miniaturized bioreactor 300 times smaller than the previous microfermentor. • Automatic culturing and monitoring of populations of 100 to 10000 bacteria with instantaneous cell resolution. • In theory, the mutation rate should be reduced by a factor of 105and prolong monitoring of homogeneous populations. • Monitoring the programmed behavior of bacterial population for hundred of hours despite strong selection pressure. Balagaddé et al. (2005) Science 309:137-140

  22. Critique Summary • Experiments missing to explain what causes the loss of regulation • Could fit the model to data in order to estimate the true constants • Could put more emphasis on the absence of biofilm formation and on the limitations of the chemostat • Should compare mutation rates to a macroscale chemostat instead of a microscale batch • Very novel technology • Attempt to show a possible application • Honesty of the authors Major points • Clear representation of the microchemostat technology • Some figures are not very intuitive to read • Explanation missing for the morphological behavior • Incomplete Material and methods section leading to hardly reproducible experiments Minor points Balagaddé et al. (2005) Science 309:137-140