Estimation of indigoidine titer using a colorimetric assay
Harvest 250uL from your timepoint. Store collected samples at -20C until ready for processing
Spin down the culture (max speed, 3 min) and discard the supernatant
Resuspend cell pellet in 500uL DMSO. Mix briefly to resuspend the cells.
Place all samples on the TOMY mixer (or your favorite vortexer) for ~10 minutes and vortex at max speed.
Once all the indigoidine has dissolved, spin down the samples for 3 min at max speed to remove any insouble cell debris
Take out 100uL of DMSO resuspension and place into a clear bottomed 96 well plate.
Quantitate the absorbance at OD612, using an in-house generated indigoidine standard curve. Generally the linear range of indigoidine in DMSO is 0.1 to 3.0 units. If the samples are very blue, apply another dilution to get things in the linear range (0.1 to 3 OD612 units). Apply your standard curve to convert OD612 to g/L indigoidine.