Culture of A. niger

For cultures of A. niger AB4.1, ΔxlnR, ΔclrA and ΔclrB strains, spores were washed with 0.01 % (v/v) Tween-80 solution and 10⁸ spore, in suspension were inoculated into 250 ml sterile Erlenmeyer flasks containing 100 ml AMM (Delmas et al. 2012) containing 1 % (w/v) glucose or ball-milled wheat straw (1 % w/v) (Delmas et al. 2012) and incubated for 48 h at 28 °C on a shaker (New Brunswick Scientific, St Albans, UK) set to 150 rpm. Media were autoclaved at 117 °C instead of 121 °C to limit the caramelising of sugars. For studies involving time-points, the A. niger strain used was grown in 1 % (w/v) glucose for 48 h before being washed and transferred to AMM supplemented with 1 % (w/v) of the carbon source and incubated further for 24 or 48 h. Supernatants were collected at each time point for enzymatic analysis.