Template:Team:Edinburgh/Notebook/Week03

1) Cloning of ccm PCr product into vector

pSB1C3 vector with RFP was used
PCR product was cloned using modified Cfrench:bbcloning protocl
reaction mixture:
water 30 ul
vector pSB1C3 5 ul
PCR ccm 5 ul
buffer 3 5 ul
BSA 1 ul
XbaI 2 ul
PstI 2 ul
components were mixed, pulse-spinned in a centrifuge and incubated for 3 hours in 37 oC

2) Lac promoter characterization

Aim: To test the lacZ promoter by measuring the fluorescence of the RFP gene tied to this promoter. The reason for doing this is because it is not yet known whether our strain of Cf has a lacI gene. If the lacI gene is present on the host’s chromosome, we expect the fluorescence to be much lower in the NO IPTG bottles than in the ones containing IPTG as the promoter will not be on. If there is no lacI gene, we expect the fluorescence in all 3 bottles will fall into a similar range.
Method: In order to characterize the Lac promoter in Cf, 5ml LB bottles were inoculated with colonies from the E. coli/Cf + RFP plates made on Friday. 5 uL of chloramphenicol40 were added to each of the bottles and varying amounts of IPTG were also added, as is shown in the table below. The bottles were then incubated in the warm room on the shaker.

3)Multi-host vector characterization in Cf

Aim: To assess whether the multi-host vector BBa_I742123 is compatible with our strain of Cf, as there was no growth on the relevant Cf plate made on Friday, while there was some growth on the E. coli plate. One reason for this may be that the Cf cells are less resistant to chloramphenicol than E. coli, so we are plating them onto plates with varying concentrations of chloramphenicol to see whether they grow at all.
Method: 500ml of LB was microwaved for 4+4+4+2+1 (15) minutes and then placed in a 55C waterbath to cool. After an hour, 500uL of IPTG90 was added to the bottle and the agar was poured on plates containing varying concentrations of chloramphenicol40, and, after the agar set, loopfulls of the transforms made on Friday were streaked onto the plates, as is shown in the table below. The pSB2K3-containing (and therefore kanamycin, not chloramphenicol resistant) cells were used as controls to test background growth in varying amounts of chloramphenicol. All the plates were then incubated at 37C.

1)Transformation of Citrobacter with various replicons (results)

These results show that all but one of the plasmids have successfully been transformed into both E. coli and Cf, therefore these replicons are compatible with Cf. Cf cells with the multi-host plasmid did not grow at all, and there can be several reasons why: the codon usage in Cf differs from E. coli and Bacillus; the promoter does not work properly in Cf or Cf is less resistant to chloramphenicol. Bacteria transformed with ptg262 will be plated onto plates with differing concentrations of chloramphenicol to assess whether this plasmid is compatible at all with Cf.
The pSB2K3 transforms were plated onto plates containing X-gal in order to assess whether the Cf cells were lacZ positive (had a lacZ gene on their chromosome). Since the colonies turned blue, this means that the Cf cells are lacZ positive (as the plasmid contained no lacZ minigene) whereas the E. coli cells are lacZ negative since the colonies were red. The RFP was expressed in both cells, as evidenced by red fluorescence under a blue light.
2)LA agar plates with different metronidazole and DNBA concentration were examined.
No IPTG was added and no difference was seen between the strains. However, 50 ul (0.1 mg/ml) DNBA/met was chosen as further concentration to use since it did not seem to inhibit growth of the strains substantially.
3)Repeating LA agar plates with metronidazole, nitrofuratoin and DNBA.
50 mg/ml stock of nitrofuratoin ( antibiotic toxic to E.coli) was prepared.
Plates with 0.1 mg/ml DNBA, met or NFT plus and minus IPTG were prepared and inoculated with the four nitroreductase strains.
4)Test if sucrose hydrolase can act as arsenic detector
Chloramphenicol (5 ul out of 40 mg/ml stock), sucrose ( 250 ul out of 20% sucrose stock) and 0/5/25/50 ul As (out of 10 000 pps As stock) were added to LB (5 ml). The four bottles were inoculated with pSBIC3-J33207 CScA blue (4)

5) PCR for MtrCAB and ccmA-H
Stock solutions of primers were prepared by adding water to fresh primers in order to reach 500 pmol/ul concentration.
Working solution was prepared by adding water to stock solution in order to reach 10 pmol/ul concentration.
Cell suspensions of E. coli and S. oneidensis were obtained by inoculating cells in 150 ul water
PCR mixture was prepared according to Cfrench:PfuPCR protocol and PCR was performed for total of 100 minutes.
In the meantime agarose gel was prepared following Cfrench:AGE protocol
PCR product was tested on the gel resulting in clear band of about 6 kb for ccm and no bands for Mtr


ccm PCR product was purified following Cfrench:DNAPurification1 protocol . Purified product was left in freezer for storage [freezer 1 (B grade freezer, the leftmost one), orange rack on top shelf, 1st row, 5ft tube markes KK 9.7.12 ccm PCR E. coli]