4.1. Strains, Media and Culture Conditions

The strains used in this study are shown in Table 3. All of the strains belonged to the Department of Biotechnology and Food Microbiology at Wrocław University of Environmental and Life Sciences, Poland.

Strains of E. coli and Y. lipolytica used in this study.

Escherichia coli strains were grown in a Luria–Bertani medium at 37 °C. A supplementation of ampicillin (100 mg/L) was necessary to screen the transformants on media plates. The Y. lipolytica strains were grown at 28 °C in a YPD medium containing 1% (w/v) yeast extract, 1% (w/v) peptone and 2% (w/v) glucose. The YPD medium was used for the preparation of inoculation for the bioreactor studies. During the shake flask experiments, the yeast cultures were grown in 0.25 L baffled flasks containing 0.03 L of the medium on a rotary shaker. The parameters were set at 28 °C and 200 rpm. Erythritol synthesis was carried out in an erythritol synthesis medium containing 100 g/L of glycerol as described by Mirończuk et al. (2017).