Extended Data Fig. 4: Auxotroph growth strictly depended on cross-feeding.
From: De novo biosynthesis of plant lignans by synthetic yeast consortia
a, The final OD600 values of 55 paired cocultures. Three strongest cooperative pairings with desired final biomass (OD600) were highlighted with red triangles. b, Growth curves of eleven auxotrophs. All mutants (his3Δ, thr4Δ, ilv1Δ, ser2Δ, pro2Δ, arg4Δ, trp1Δ, lys2Δ, leu2Δ, met15Δ, and ade2Δ) were constructed from the parent strain CEN. PK 113-11C. c, Schematics of three experiments used to confirm the obligate mutualism between met15Δ and ade2Δ deletion mutants in the consortia. A single clone was inoculated in 5 ml of YPD medium and cultured at 30 °C for 16 hours to generate a yeast seed cell suspension. Before co-inoculation, the cells of two auxotrophs were washed three times with isovolumetric ultrapure water and resuspended to obtain an aqueous cell suspension. The aqueous cell suspension is disrupted by oscillation with glass beads at 1600 rpm for 10 min, followed by centrifugation at 5000 rpm for 5 min and filtration through a 0.22 μm filter membrane to obtain the supernatant. The experimental setup included three treatments: 1:1 inoculation of two aqueous cell suspensions (the inoculum OD600 of 0.05 for each strain); inoculation of met15Δ aqueous cell suspension at an OD600 of 0.05 with the filtered ade2Δ lysate supernatant (the supernatant volume equivalent to an inoculum OD600 of 0.05); inoculation of ade2Δ aqueous cell suspension at an OD600 of 0.05 with the filtered met15Δ lysate supernatant (the supernatant volume equivalent to an inoculum OD600 of 0.05). d, Proposed model depicting the mechanism of cross-feeding in the met15Δ-ade2Δ coculture system. The export and import of exchanged methionine- and adenosine-related metabolites support the auxotroph growth of yeast consortia. All the strains were grown at 30 °C in 20 ml of Delft-D medium without histidine, uracil and additional additions. All the data are presented as the means of n=3 independent biological samples, and the error bars show the SDs.
