Fig. 4

Relative selectivity of the formed n-butyrate (n-C4), iso-butyrate (i-C4), n-valerate (n-C5), iso-valerate (i-C5), n-caproate (n-C6), carbon dioxide (CO₂) and methane (CH₄) of continuous methanol-based propionate and acetate elongation in an anaerobic open-culture reactor at 36 °C at the steady-state with 250 mM methanol in the influent (a) (day 64–71) and at the last days with 400 mM methanol in the influent (b) (day 111–120). The values are calculated based on the production rates in g/L/day; the total production rates were 1.37 ± 0.26 (a) and 2.12 ± 0.18 (b) g/L/day