Symbol Definition Value Range (Experimental) Time of the end of residual growth 10 h 10

Transcription

1 Table 1. Definitions and experimental values of parameters Symbol Definition Value ange (Experimental) T I Time of the end of residual growth 10 h 10 T D D D ate s s G max V max c-fed c-fed Delay in Death rate of Death rate of Death rate of s entry into death phase after the onset of starvation h 70 denine supplied per ysine supplied per Maximum growth rate of in the absence of ade after time T Value* /h 0.01 in the absence of lys averaged from time T I to T 0.054/h in the absence of lys after time T Maximum lysine uptake rate per de consumed to produce a fed ys consumed to produce a fed 0.02/h 0.02 cell upon death 3 fmole per cell 3 cell upon death 15 fmole per cell 15 I Fold-increase in cell density during residual growth of when lysine is in excess 0.31/h 0.31 cell when lysine is in excess 2.4 fmole per cell/h 2.4 cell when ade is in excess 1 fmole per cell cell when lys is in excess 5.4 fmole per cell I Fold-increase in cell density during residual growth of c ** c ** de consumed in order to produce a starving ys consumed in order to produce a starving cell fmole per cell 1 cell fmole per cell K m Michaelis-Menten half-saturation constant of lysine transporter µm (1, 2) 50 2 *Values used in calculations. Data from Fig 2. Death rates were measured during the specified time windows and were found to be density-dependent. D = 0.01 is the average of 0.007, 0.009, and per h, respectively, obtained over a range of initial cell densities varying from 0.05 to cells per ml. D and D ate were obtained at initial cell densities ranging from 0.28 to cells per ml. The kinetics of metabolite release approximately coincided with that of cell death (Fig. 2B). Thus, we assume that a starving cell releases a fixed amount of the overproduced metabolite into the medium on

2 death. Metabolite supplied per dead cell was estimated from Fig. 2B by dividing the final concentration of released metabolite by the final population density of dead cells. See SI Fig. 10. When adenine was present in excess, the maximum uptake rate of adenine V max was 0.5 fmole per cell/h, and the maximum growth rate of cells was G max = 0.37/h (methods of measurement similar to those in Fig. 10). Thus, it took c-fed = V max (ln2/ G max ) ~1 fmole adenine to produce a fed ln2/ G max was the doubling time of lysine to produce a fed **Because one fed cell. cell, where. Similarly, it took c-fed = V max (ln2/ G max ) = 5.4 fmole cell gave rise to I lysine-starved c-fed /I amount of lysine to produce a starving adenine to produce an adenine-starved cell. cells during residual growth, it took c= cell. Similarly, it took c = c-fed /I amount of 1. Sychrova H, Chevallier M (1993) east 9: Garcia JC, Kotyk (1988) Folia Microbiol (Praha) 33:

3 Fig. 6. Viability of CoSMO requires both adenine- and lysine-overproduction mutations. Monocultures of two strains with indicated genotypes were washed free of adenine and lysine and mixed at time 0. Plots show the dynamics of live (red), live (green), dead (gray), and total (black) cell densities of the coculture. Fig. 7. Stabilization of CoSMO partner ratio. Duplicate CoSMO cultures, in which partners were mixed at : = (magenta), 1 (cyan), and 10-3 (blue) to OD 600 of 0.01, were initiated at time 0. Whenever the cultures reached the near-saturation set point of OD 600 = 0.4-1, they were diluted to OD 600 of [dsim] t various time points, population densities of Dsed-positive and FP-positive cells were measured twice by flow cytometry. The average : ratio is shown with a vertical bar indicating the range. Triangles mark points of dilution. Fig. 8. schematic diagram of the experimental protocol for Fig. 5B. near-saturation ound-0 culture was subjected to 10-fold serial dilutions with three replicate cultures at a fixed volume per dilution so that density requirement of the culture, expressed in the number of cultures (out of 3) that are viable at various dilutions, could be measured. Out of diluted cultures that were able to grow, one near-saturation culture was chosen and subjected to 10-fold serial dilutions. This procedure was repeated 10 times, spanning a total of 70 generations. The last near-saturation culture chosen was the ound-10 culture, and its density requirement was similarly determined. Fig. 9. Characterization of CoSMO components using flow cytometry. Exponentially growing (eft) and (ight) cells were washed free of supplements at time 0. Percentages of red-fluorescent (), yellow-fluorescent (), and dark (dark) cells were measured at 0 h (Upper) and 97 h (ower), and their values are indicated. Fig. 10. Measurements of G max and V max. cells were grown in SD supplemented with lysine. Time 0 was arbitrarily chosen in early exponential phase. Plots show the

4 population density of (eft, green circles) and the concentration of lysine remaining in the medium (ight, brown circles) over time. The least-squares-fitting equation for the Gmax t left panel is = 0e (dotted line) and yields the initial population density 0 and the maximum growth rate G max. The least-squares-fitting equation for the right panel is = + V (1- e ) / G Gmax t 0 max 0 max (dotted line), which is the solution to the differential d Gmax t = Vmax = Vmax 0e equation dt, and yields the initial lysine concentration 0 and the maximum lysine uptake rate per cell V max.

5 Population Density (cells/ml) Time (hours)

6 : Time (hours)

7 inocula w/ various : ound-0 #1 #2 #10 ound Fold-Dilution 10 7

8 Dark Dark 1.7 Dsed Fluorescence Dark Dark hour 97 hour FP Fluorescence

9 Population Density (x10 6 cells/ml) [ys] (mm) Time (hours) Time (hours)