Xylose and Maltose Uptake Assay

The uptake of d-[¹⁴C] xylose or [¹⁴C] maltose (CAMPRO Scientific GmbH, Veenendaal, the Netherlands) was performed as described earlier with minor modifications (Shin et al. 2017 (link)). Cells were collected by centrifugation (3000 rpm, 3 min, 20°C), washed and resuspended into mineral medium. [¹⁴C] xylose stocks were added to the cells supplemented with different concentrations of glucose or maltose. For [¹⁴C] maltose uptake, 1.1 mM [¹⁴C] maltose was used. The uptake reactions were stopped at various time intervals by addition of 5 ml of 0.1 M lithium chloride, and the suspension was filtered (0.45 mm HV membrane filter, Millipore, France). Filters were washed with another 5 ml of lithium chloride and counted with the emulsifier scintillator plus (Perkin-Elmer).