Team:Osaka/Protocols

Protocols

• Preparation of Competent cells and Heat-shock Transformation
  • Preparation

1. SOB medium 1L (-> final conc.)
   • Bacto Tryptone 20g (-> 2.0%)
   • Bacto Yeast Extract 5g (-> 0.5%)
   • 5M NaCl 2ml (-> 10mM)
   • 2M KCl 1.25ml (-> 2.5mM)
   • Add miliQ water 990ml to all miture and sterilize by autoclave. Before using, add sterilized Mg2 solution (1M MgSO4, MgCl2) 10 ml.
2. SOC medium
   • Add sterilized 2M glucose 1 / 100 volume to SOB medium, and sterilize by filtration using 0.22 um microfilter. Store at 4℃.
3. Tranformation buffer, TB 1L (-> final conc.)
   • PIPES 3.0g (-> 10mM)
   • CaCl2 2H2O 2.2g (-> 15mM)
   • KCl 18.6g (-> 250mM)
   • After this mixture is suspended in about 950ml sterilized water, control the pH to 6.7-6.8 by 5N KOH (5M KOH). In low pH, this mixture cannot dissolve. Next, add MnCl2 4H2O (10.9g) to the solution, so as to be final concentration 55mM. Ajust it to 1L and sterilize by filtration using 0.22 um microfilter. Store at 4℃.
4. Liquid nitrogen
5. DMSO (dimethyl sulfoxide)

• • Preparation of competent cell

1. Streak E. coli appropriate strain on LB plate. Incuabte at 37℃ overnight.
2. Inoculate single colony (1-3mm in diameter) into 1ml SOB medium and incubate at 37℃ overnight. After that, inoculate overight culture into SOB 250ml provided in 3L conical flask.
3. Incubate at 18℃ for 19-50 hour with shaking (>200rpm).
4. If OD600 reach at 0.4-1.5 (anyphase may be possible to use), immediately put cell culture flask onto ice water for 10min.
5. Decant cell culture to 500ml centrifuge tube (or 250ml tube X2) and centrifuge in 3000rpm for 15min at 4℃.
6. Remove soup, suspend ppt by ice-cold TB 80ml, put it onto ice water for 10min.
7. Centrifuge in 3000rpm for 15min at 4℃.
8. Suspend ppt by 20ml ice-cold TB and add 1.5ml DMSO (final conc. 7%). Moreover, put on ice water for 10min.
9. Dispence 0.1-0.5ml each to 1.5ml tube and immediately transfer all tubes into liquid nitrogen. Cold shock is needed for competent cell.
10. Store at -80℃ until to use.

• • Transfomation method

1. Melt competent cell taken from freezer in hand and put on ice.
2. After dispencing 10-50μl each competent cell, add 1-20μl DNA. Put on ice for 30min.
3. Heat shock at 42℃ in water bath for 30sec and immediately put onto ice for 2min.
4. Add 40-200μl SOC medium and incubate at 37℃ for 1hour with shaking.
5. Plate the culture onto LB with appropriate antibiotics, for example ampicillin, kanamycin,chloramphenicol, etc. Incubate at 37℃ overnight.

• Plasmid DNA miniprep
• 3A BioBrick assembly
• PCR cloning
• PCR site-directed mutagenesis

• Extraction of genome DNA for PCR cloning

1. E. coli or S. cerevisiae are cultured overnigt.
2. Suspend about 10⁵ cells into sterilized miliQ-water and place in boiling water for 5 min. When treating S. cerevisiae, wash cells once by PBS buffer. PBS buffer is 25mM sodium phosphate pH 7.0-7.2, 125mM NaCl₂.
3. Chill on ice for 2 min, then spin down for 3 min by microcentrifuge at 13,000 g.
4. Transfer the supernatant to a fresh tube. Use 2.5-10ul in one PCR.
   • Reference: M. J. McPherson et al., PCR: a practical approach, 1991.