Inhibition of anaerobic growth on xylose by pH (Panel A, B), acetate (Panel C, F), bicarbonate (Panel D, F) and citrate (Panel E, F). Panels A-E: Experimental data obtained for IBB10A02 and IBB10B05 are shown as empty and black bars (circles), respectively. Panel B: x-Axis indicates concentration of protons relative to standard pH (= 6.5) conditions, ([H+] = 10-pH – 10-6.5). Panel F: Quantitative representation of Panels C-E. Data obtained in the presence of acetate (full triangles), citrate (empty circles) and bicarbonate (full circles) are shown. Solid lines in Panel B and F represent best fits from linear regression analysis. Framed data were not considered in the analysis. To minimize effects on μ from change in pH over conversion time only the growth phase in which the pH shift was ≤ 0.5 pH units was considered in the calculations. Error bars indicate standard deviations obtained from two individual cultivations.