Figure 5.
Niche Creation through Nitrogen Overflow and Emergence of Mutualism
(A) Amino acid secretion by yeast is proportional to total nitrogen load. Shown are relative secretion levels at different degrees of total nitrogen content. See Table S7 for amino acid composition.
(B) Secreted amino acids have the lowest cost of biosynthesis. Stacked bars represent different cost metrics: unitless costs based on flux balanced changes in uptakes (Barton et al., 2010, top), respiratory energetic cost (Wagner, 2005, middle), and energetic cost of biosynthesis, including biosynthesis of precursors (Akashi and Gojobori, 2002, bottom).
(C) S. cerevisiae S90 shows positive effect on L. plantarum growth when co-cultured in grape juice. Note: grape juice pH did not affect yeast-LAB interaction (Figure S9).
(D) Amino acid uptake/secretion by yeast in grape juice in response to rapamycin and NCR/TORC1 pathway mutations. Inset: glutamine secretion by different yeast strains in CDM35 versus grape juice. See also Figures S8 and S10.
(E) Mutualistic growth of yeast and L. lactis kefir isolate in CDM35-Lactose. OD600 values refer to the seed cultures.
(F) Mutualistic relation between yeast and L. lactis (kefir) is also evident in liquid cultures. The inset shows residual lactose in mono and co-cultures. L. lactis (kefir) cell counts are based on flow cytometry (STAR Methods).
(G) Amino acid concentration in yeast monocultures and co-cultures with L. lactis (kefir) in CDM35-lactose. Data shown as mean ± SD of three independent replicates in (A, C, D, F, and G).