Extract reporter calibration and salt

Overview: it is common to tune the salt concentration (typically Mg and K) to optimize a given batch of extract. Here we show that optimal fluorescence salt concentration depends on the reporter used. Takeaway: optimize your extract to its specific function.

The above heatmaps show the endpoint fluorescence of 8 hour TX-TL experiments using GFP and mScarlet reporters for four different extracts (two are the same, but with/without dialysis). Experiments were conducted using the echo liquid handling robot. Mg comes from Mg-glutamate and K from K-glutamate. The 'x' in some grid boxes denote experiments with bubbles or other irregularities.