Part:BBa_J45999:Design

E. coli strain YYC912; Odor-free chassis

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]

Design Notes

A key challenge in our work to reprogram bacterial odor was to ensure that the natural, fecal odor of E. coli did not overpower our engineered wintergreen and banana odors. Indole was suggested to be the primary component of the fecal odor of E. coli (E Pichersky, personal communication, 2008). We confirmed that indole was the primary odor produced by E. coli by smelling LB Lennox medium supplemented with indole at a concentration comparable to that of LB cultures of E. coli strain MG1655 (~300 μM) Wang-2001. In nature, E. coli uses indole for intercellular signaling in biofilm formation Martino2003. Since indole is not essential for cell viability, we could reprogram bacterial odor by modifying cellular metabolism for decreased indole production.

Indole is a product of the tryptophanase enzyme encoded by the tnaA gene of the tna operon in E. coli Snell-1975. Mutations to the tna operon can reduce indole levels Rezwan-2004. We tested four E. coli strains as potential odor-free chassis for our engineered system: YYC912, JC12337, MEB61, and MB408 (CGSC 7602, CGSC 6373, CGSC 6836, and CGSC 7152, respectively) Chang-1994, Ream-1980, Edwards-1982. The four strains all carry mutations in the tnaA gene. By smelling overnight liquid LB cultures of each strain, we selected E. coli strain YYC912 as an odor free chassis for our engineered system. We confirmed via gas chromatography analysis that E. coli strain YYC912 produced no measurable indole in comparison to E. coli strain TOP10.

Source

We thank Mary Berlyn for useful advice regarding tna operon mutants and [http://cgsc.biology.yale.edu/ The Coli Genetic Stock Center] for E. coli strains [http://cgsc2.biology.yale.edu/Strain.php?ID=64826 YYC912 (CGSC 7602)], JC123337 (CGSC 6373), MEB61 (CGSC 6836), and MB408 (CGSC 7152).

References

<biblio>

1. Wang-2001 pmid=11418561
2. Snell-1975 pmid=236639
3. Rezwan-2004 pmid=15489459
4. Chang-1994 pmid=8022274
5. Ream-1980 pmid=6255290
6. Edwards-1982 pmid=7052072
7. Martino-2003 pmid=14569285

</biblio> Chang, Y.-Y., A.Y. Wang, J.E. Cronan 1994. Expression of Escherichia coli pyruvate oxidase (PoxB) depends on the sigma factor encoded by the rpoS(katF) gene. Mol.Microbiol. 11:1019-1028