(A) Sucrose is hydrolyzed into glucose and fructose by invertase located in the cell wall. The glucose and fructose are imported into the cell by hexose transporters or escape into the medium by diffusion. (B) The glucose and fructose monosaccharides diffuse away from the cell wall and are more easily shared between cells when the cells are clustered in a clump (right) than when the cells are spaced apart (left).

The simulated local glucose concentration and glucose uptake of a cell inoculated at the center of a 150 µl sphere of 8 mM sucrose in two environments: at the center of a clump of 30 cells and at the center of a total of 30 cells uniformly dispersed throughout the volume. (A) Glucose concentration as a function of radial distance from the center of the cell after 30 h of incubation. Note the logarithmic scale on the x-axis. (B) Glucose intake rate of the cell as a function of time after inoculation. Note the logarithmic scale on the y-axis. See Supporting Information for details of code and parameters.

60 SUC2 cells and 60 suc2Δ cells or three 15–25 cell SUC2 clumps and three 15–25 cell suc2Δ clumps were sorted into 150 µl wells at the given sugar concentration and allowed to grow for 72 h at 30°C. During incubation, the 96-well plates were either shaken at 1,000 RPM (left column) or left still (right column). (A) Cellular yield of SUC2 strains in competition with suc2Δ strains. Optical density (OD) values were converted to cell population by measuring the optical density of dilutions of a culture with known cell densities. (B) The growth advantage of various SUC2 strains over a suc2Δ strain. ln( SUC2 cells/suc2Δ cells) is proportional to the difference in the mean growth rate, assuming both strains start with an equal number of cells. The population frequencies were counted using a FACS machine: in half the samples SUC2 strains expressed mCitrine from the ACT1 promoter and suc2Δ strains expressed mCherry from the ACT1 promoter, and in the other half of the samples, the colors were reversed. Single cells expressed the amn1-W303 allele and clumps expressed the AMN1-RM11 allele. SUC2 strains yJHK401 (cell) and yJHK390 (clump) express mCitrine, and SUC2 strains yJHK410 (cell) and yJHK391 (clump) express mCherry. suc2Δ strains yJHK302 (cell) and yJHK433 (clump) express mCitrine, and suc2Δ strains yJHK437 (cell) and yJHK435 (clump) express mCherry. 24 samples were counted in each color combination. Error bars refer to the 95% confidence interval calculated using the one-sample Student's t test.

Cells were sorted into microtiter wells, each containing 150 µl of medium, at the given cell density and sugar concentration and allowed to grow for 85 h without shaking at 30°C. (A) Typical fluorescent scan of a plate containing 4 mM glucose plus 4 mM fructose inoculated with the indicated number of cells. (B) The fraction of wells with growth using strain yJHK111 (W303 genetic background). Results shown are totals of three experiments; each experiment used one plate per sugar concentration. Error bars refer to 95% binomial confidence interval using the adjusted Wald method. See Figure S2 for results using a strain with the S288C background.

(A) A 40× confocal image of W303 yeast cells showing the clumpiness phenotype of two different alleles of AMN1. The amn1-W303 (non-clumpy) strain yJHK112 constitutively expressed mCherry driven by the ACT1 promoter and is shown in red. The AMN1-RM11 (clumpy) strain yJHK223 constitutively expressed mCitrine driven by the ACT1 promoter and is shown in green. (B) FACS inoculation. All cells expressed mCitrine driven by the ACT1 promoter. By gating on pulse width and fluorescence, clumps of 15 to 30 cells were differentiated from single cells. The number of cells and the gating for each well was set on the FACS software. After 85 h of growth without shaking at 30°C, plates were read on a fluorescent scanner and growth was scored by manually counting colonies. (C) Comparison of growth between inoculations of clumps of 15–30 cells and 30 individual cells using clumpy, AMN1-RM11 strains yJHK223 (SUC2) and yJHK224 (suc2Δ). Results shown are totals of three experiments; each experiment used one plate for each sugar concentration, which represents 24 wells for each combination of genotype and clumpiness. Error bars refer to 95% binomial confidence interval using adjusted Wald method. The suc2-1cyt (cytoplasmic-invertase only) strain yJHK259 was also tested and did not grow in any well in 2, 4, 8, or 16 mM sucrose media and grew in 100% of the wells in 4 mM glucose+4 mM fructose media (not shown).