Development of a co‐culture of Ureibacillus thermosphaericus and Cupriavidus taiwanensis for inhibitors removal from hemicellulose prehydrolysate

For biofuels production, hemicellulose pre-hydrolysate is considered an attractive feedstock rich in fermentable sugars. The lignocellulosic biomass comprises, along with sugars, several inhibitors that can hamper its efficient conversion. In this work, mixed cultures of Ureibacillus thermosphaericus and Cupriavidus taiwanensis were used for the first time to detoxify the pre-hydrolysate. The nutrient source was first optimized in synthetic media with mono-cultures to detoxify phenolic compounds, and a medium containing inorganic salts was selected. Afterwards, the efficiency of phenolic degradation was compared in a single-compound solution and in a mixture. The simultaneous co-culture showed the highest degradation efficiency (90% at 2.8 g/L of phenolic compounds). Finally, the detoxification of a raw pre-hydrolysate was conducted, and a maximum degradation of 14% of the phenolics was obtained using sequential inoculation of Ureibacillus thermosphaericus followed by Cupriavidus taiwanensis addition.