Acetate-detoxification of wood hydrolysates with alkali tolerant Bacillus sp. as a strategy to enhance the lipid production from Rhodosporidium toruloides

Abstract The aim of the current work was to convert an acetate-rich hemicellulose liquid fraction (LF) from hot-water extraction of Betula pendula to oils for biodiesel, with Rhodosporidium toruloides . The toxicity of acetate was circumvented by biological detoxification with an isolated alkali-tolerant and acetate-resistant Bacillus sp. strain. Removal of other lignocellulose-derived inhibitors, such as furfural and phenols, was evaluated by two strategies; an activated carbon (AC) treatment of the undiluted LF, and dilution of the LF by 25% (0.75LF) and 50%. (0.50LF). The bacterium consumed most of the acetic acid in 6–8 days in the treated or diluted media, which were subsequently used for cultivation of the yeast, for conversion of sugars to oils. The oil concentration reached 2.8 and 1.8 g/L, in the AC LF and 0.75LF medium, respectively. In comparison, the oil accumulation in the same media without prior cultivation of Bacillus sp. was 0.86 and 0.03 g/L, respectively.