Production of l-lactic acid by the yeast Candida sonorensis expressing heterologous bacterial and fungal lactate dehydrogenases

Table 1 Extracellular metabolites produced in the presence of CaCO ₃

Strain	Lactate (g/l)	Yield of lactate (g/g)	Ethanol (g/l)	Pyruvate (g/l)
x::BmLDH	85 ± 1.7	0.89 ± 0.02	≤ 0.3	≤ 0.2
pdc1∆::BmLDH	88 ± 1.4	0.90 ± 0.01	1.3 ± 0.4	≤ 0.5
pdc2∆::BmLDH	84 ± 2.6	0.87 ± 0.02	1.2 ± 0.6	≤ 0.6
pdc1∆::BmLDH pdc2∆	84 ± 2.9	0.85 ± 0.03	n.d.	2.1 ± 0.3
pdc1∆::BmLDH pdc2∆::BmLDH	81 ± 3.2	0.80 ± 0.03	n.d.	0.79 ± 0.02
x::LhLDH	83 ± 1.7	0.85 ± 0.02	≤ 0.3	n.a.
pdc1∆::LhLDH	93 ±0.8	0.95 ± 0.01	1.3 ± 0.3	≤ 0.5
pdc1∆::LhLDH pdc2∆	92 ± 1.6	0.94 ± 0.02	n.d.	0.72 ± 0.13
pdc1∆::LhLDH pdc2∆::LhLDH	86 ±1.3	0.88 ± 0.02	n.d.	0.39 ± 0.08
x::RoLDH	78 ± 1.5	0.81 ± 0.02	3.2 ± 0.2	n.a.
pdc1∆::RoLDH	75 ± 0.6	0.77 ± 0.02	7.0 ± 1.2	< 0.5
pdc1∆::RoLDH pdc2∆	78 ± 0.2	0.81 ± 0.01	n.d.	3.2 ± 0.3
wild type C. sonorensis	n.d.	n.d.	17 ± 5.3	n.a.

Maximum concentrations of lactate, ethanol and pyruvate (g/l) and lactate yield on glucose (g/g) produced in YNB-10% (w/v) glucose minimal medium containing non-limiting concentration of CaCO₃. Results are from 6 experiments, each with 4–6 strains. Data are means ± SEM (n= 3–10). n.a. not analyzed. n.d. not detected.

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