Production of lactate by strain LA20Δ lldD (pZSglpKglpD) in a minimal medium containing crude glycerol. A fermentation profile using 60 g/liter glycerol of crude glycerol (40 g/liter in the initial medium followed by a 20 g/liter addition at 48 hours) is shown. Data for concentration of cells (∎), glycerol (♦), lactate (▲), and acetate (●), along with lactate yield (∆), are shown. Coefficients of variation (i.e. standard deviations/average × 100) were below 5% in all cases.