A turbidostat is a continuous microbiological culture device, similar to a chemostat or an auxostat, which has feedback between the turbidity of the culture vessel and the dilution rate.[1][2] The theoretical relationship between growth in a chemostat and growth in a turbidostat is somewhat complex, in part because they are similar. A chemostat has a fixed volume and flow rate, and thus a fixed dilution rate. A turbidostat dynamically adjusts the flow rate (and therefore the dilution rate) to make the turbidity constant. At steady state, operation of both the chemostat and turbidostat are identical. It is only when classical chemostat assumptions are violated (for instance, out of equilibrium; or the cells are mutating) that a turbidostat is functionally different. One case may be while cells are growing at their maximum growth rate, in which case it is difficult to set a chemostat to the appropriate constant dilution rate.[3]

While most turbidostats use a spectrophotometer/turbidimeter to measure the optical density for control purposes, there exist other methods, such as dielectric permittivity.[4]

The morbidostat is a similar device built to study the evolution of antimicrobial resistance. The aim is also to maintain constant turbidity levels, but this is controlled using the addition of antimicrobials.[5]

References

  1. ↑ Bryson V, Szybalski W (1952). "Microbial selection". Science. 116 (115): 45–51. doi:10.1126/science.116.3003.45. PMID 14950177.
  2. ↑ Sorgeloos P, Van Outryve E, Persoone G, Cattoir-Reynaerts A (1976). "New Type of Turbidostat with Intermittent Determination of Cell Density Outside the Culture Vessel". Applied and Environmental Microbiology. 31 (3): 327–331. PMC 169774. PMID 16345153.
  3. ↑ Watson TG (1972). "The Present Status and Future Prospect of the Turbidostat". Journal of Applied Chemistry and Biotechnology. 22 (2): 229–243. doi:10.1002/jctb.5020220206.
  4. ↑ Markx GH, Davey CL, Kell DB (1991). "The Permittistat: A novel type of turbidostat". Journal of General Microbiology. 137 (4): 735–743. doi:10.1099/00221287-137-4-735.
  5. ↑ Toprak E, Veres A, Michel JB, Chait R, Hartl DL, Kishony R (2012). "Evolutionary paths to antibiotic resistance under dynamically sustained drug selection". Nature Genetics. 44 (1): 101–105. doi:10.1038/ng.1034. PMC 3534735. PMID 22179135.


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