Plasmid Isolation – pCR2.1/OsHv-1_ORF117 Miniprep

Grew up 5mL of culture from re-streaked colony #1 in 1xLB + 100ug/mL of ampicillin @ 37C on a rocking platform in a 15mL conical over night (~18hrs).

Isolated plasmid DNA from the entire 5mL of culture (repeated pelleting of bacteria in the same 1.5mL snap cap tube) using the QIAprep Spin Miniprep Kit, according to their protocol.

Eluted DNA with 50uL of EB Buffer.

Quantified on the Roberts Lab Qubit 3.0 using the dsDNA BR Kit (broad range) and 1uL of sample.


The results are not good. Using 1uL of the sample, I received an error message that the concentration was out of range – too low!

Repeated, but used 10uL of sample. Concentration was displayed as 1.13ng/uL!!

This is insufficient yield/concentration for sequencing.

It’s possible that the kit is too old (no receipt date marked on the box…)? The reagents shouldn’t go bad, but can the columns? I feel like the resins in the columns are pretty stable, just like the various buffers.

The ridiculously low yields could also possibly indicate that the bacteria don’t actually have the plasmid, but PCRs from yesterday suggest otherwise.

Maybe the column was overloaded? I’ll repeat this next week, but using smaller culture size and/or not using the column and perform an isopropanol precipitation instead…

And/or make fresh stock of ampicillin (current stock is many years old, but has been frozen).

2 thoughts on “Plasmid Isolation – pCR2.1/OsHv-1_ORF117 Miniprep

  1. Pingback: Plasmid Isolation – pCR2.1/OsHv-1_ORF117 Miniprep | Sam's Notebook

  2. Pingback: Transformation – pCR2.1/OsHV-1_ORF117 into One Shot Top10 Chemically Competent Cells | Sam's Notebook

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