Erythritol production by Yarrowia lipolytica from okara pretreated with the in-house enzyme pools of fungi

[Display omitted] •In-house hydrolysis was taken place in okara during primary fermentation with fungi.•Fungal-fermented okara was used as alternative feedstock for erythritol production.•No mineral and nitrogen supplementation was needed in this erythritol fermentation.•An erythritol titer of 14.7g/L with yield of 0.49g/g substrate was obtained.•This study suggests a low-cost erythritol production from the easily available okara. Okara (soybean residue) is an ideal erythritol feedstock due to its low price and high-nutrient content. Fungal-fermentations were carried out in okara using in-house enzyme pools generated by Mucor flavus or Trichoderma reesei to make okara more accessibility in the subsequent erythritol production using Yarrowia lipolytica. Mucor-fermented okara produced a high erythritol yield because of its special component and micromorphology. Five days is the optimal period for Mucor fermentation. Different fermentation modes were compared in terms of erythritol production and yield. The concentration of Mucor-fermented okara in erythritol fermentation medium was optimal at 30.0g/L. Moreover, 40.0g/L NaCl was added as the osmotic regulator. No extra ingredient was needed during this process. Results of 5-L fermentations showed that an erythritol titer of 14.7g/L, with a yield of 0.49g/g okara was obtained. These findings indicated that Mucor-fermented okara was an economically alternative feedstock for low-cost erythritol production.