Serin Mangel som Signalstof for Aftagende Kromosom Initiering af Escherichia coli i Luria-Bertani Medie

Sara Furbo Pedersen, Anne Fogh Kristensen, Rasmus Nygaard Ibsen & Emil Kildesø Ottosen

Student thesis: Basic Project

Abstract

When Escherichia coli grows in a Luria-Bertani medium its growth raises to an exponential state,
after which the growth will decrease to a steady state. This work has examined the period between the exponential and steady state growth, referred to as the late exponential state, which occurs at an OD600 of approximately 0,3. It is assumed that the bacteria E. coli at this point will receive a signal, which forces the bacteria to reduce the initiation rate of oriC. This project hypothesizes that the signal received, might be due to the depletion of L-serin in its medium, as previous work carried out by Zhang et al. has shown, that this amino acid is depleted well before other amino acids. The hypothesis was analyzed using flow cytometry, to investigate the amount of oriC in cells at different OD’s in a growth medium. In addition, the amount of serine left in the medium was examined at the same OD’s, using chloroform to sterilize the medium and measuring the growth of a serine auxotroph E. coli. The results showed that around an OD600 of 0,3, the amount of oriC in each cell decreases, indicating that the cells had received a signal at this point, forcing the cell to subside growth. However, it has not been able to determine when or whether L-serin was depleted from the medium, using this method of analysis. Further study is therefor needed to validate a correlation between serin depletion and decreasing growth of E. coli.

EducationsMolecular Biology, (Bachelor/Graduate Programme) Bachelor
LanguageDanish
Publication date26 May 2016
Number of pages32
SupervisorsOle Skovgaard

Keywords

  • Serin
  • E. coli
  • oriC
  • Kromosom Replikation
  • Luria-Bertani
  • Escherichia coli
  • Flow Cytometry
  • LB
  • Restmedie