Figure S1 from Migration promotes plasmid stability under spatially heterogeneous positive selection

Rate of Hg(II) detoxification by bacteria carrying the mer mercury resistance operon measured as MIC of supernatant following growth with plasmid containing bacteria. KB media microcosms were initiated with 40µM HgCl2 and either inoculated with bacteria carrying the plasmid pQBR103 (black) or with no bacteria (grey). 3x bacteria and control microcosms were destructively sampled after 0, 2, 4, 6 and 8 hrs of incubation at 28oC and media was filtered to remove bacteria. Media was then diluted with mercury free KB along a gradient of dilution factors from 1 (100% spent mercury supernatant) to 0 (100% mercury-free supernatant) in increments of 0.1 in a 96 well plate. 1 plate was established for each biological replicate per time point with 8x replicate wells per dilution factor. Mercury susceptible bacteria were then inoculated into 7 wells per dilution factor with one left as a control for carry over plasmid containing bacteria. Positive (fresh mercury free media) and negative (fresh mercury containing media) growth controls were included on each plate. After 24hrs of growth at 28oC the minimum inhibitory concentration was recorded.