Secretory perturbations increase oxygen and ATP consumption. (a) Flux balance analysis of strains. TCA cycle is suppressed in high glucose. Bar graphs show flux in mmol/gDCW/h. Complete fluxes in Additional file 4. FBA calculations were performed using n = 3 measurements with errors noted in Additional file 1 (Tables S1 and S2). The average coefficient of variance for these measurements is 11%. (b) Oxygen required for growth. The amount of oxygen consumed for each gram of cells (DCW) formed. Oxygen measurements are mean +/- s.e.m. (n = 3). (c) Specific maintenance ATP consumption as calculated by flux balance analysis (see Materials and Methods for details of calculation). FBA calculations were performed using n = 3 measurements with errors noted in Additional file 1 (Table S1 and S2). The average coefficient of variance for these measurements is 11%. Wild-type, no protein secretion (WN), wild-type insulin precursor secretion (WI), wild-type α-amylase secretion (WA), Δhac1 no protein secretion (dN), Δhac1 insulin precursor secretion (dI), Δhac1 α-amylase secretion (dA). Gram dry cell weight (gDCW). acetyl-CoA (Ac-CoA); fructose-6-phosphate (F6P); glyceraldehyde-3-phosphate (G3P); glucose-6-phosphate (G6P); pyruvate (PYR).