Cellobiose is abundant in partial hydrolysis of lignocellulosic hydrolysates for the weak activity of β-glucosidase, the rate-limiting step in the enzymatic hydrolysis. Thermoanaerobacterium aotearoense SCUT27 termed SCUT27 has broad substrate spectrums and can co-utilize glucose and xylose, xylose and cellobiose. However, SCUT27 can’t co-utilize glucose and cellobiose due to carbon catabolite repression (CCR), which couldn’t be eliminated after ccpA knockout. The ability of co-utilizing glucose and cellobiose is a desirable feature of SCUT27 for industrial application. Four operons related to cellobiose utilization had been explored in SCUT27, named as Cel1, Cel2, Cel3 and Cel4. RT-PCR results showed that Cel2 operon is the only intact operon including integral cellobiose PTS transport elements and glycoside hydrolase, which is very important for cellobiose utilization. The transcription of Cel2 was regulated by σ⁵⁴-dependent transcription activator CelR^cel2 (V518_2450). With sigma factor 54 (σ⁵⁴) deletion, the transcription strength of Cel2 decreased significantly. By replacing the σ⁵⁴-dependent promoter with the strong promoter of gene adhE (V518_0444), gene cluster bglp^cel2EIIABC^cel2 (V518_2444−2449) could be easily overexpressed and SCUT27/ΔcelR^cel2/padhE obtained the ability to co-utilize glucose and cellobiose, which was a potential candidate for ethanol or lactic acid fermentation from partial hydrolysis of lignocellulosic hydrolysates.

纤维二糖在木质纤维素水解产物的部分水解中含量很高，这是因为β-葡萄糖苷酶的弱活性是酶水解的限速步骤。称为SCUT27的嗜热厌氧嗜热厌氧杆菌SCUT27具有较宽的底物谱，可以共同利用葡萄糖和木糖，木糖和纤维二糖。但是，由于碳分解代谢物阻抑（CCR），SCUT27无法同时利用葡萄糖和纤维二糖，而ccpA后无法消除昏死。葡萄糖和纤维二糖共同利用的能力是SCUT27在工业应用中的理想功能。与纤维二糖利用有关的四个操纵子已在SCUT27中进行了探索，分别命名为Cel1，Cel2，Cel3和Cel4。RT-PCR结果显示，Cel2操纵子是唯一完整的操纵子，包括完整的纤维二糖PTS转运元件和糖苷水解酶，这对纤维二糖的利用非常重要。CEL2的转录物通过σ调节⁵⁴依赖性转录激活子CelR ^CEL2（V518_2450）。与σ因子54（σ ⁵⁴）的缺失，CEL2的转录强度显著降低。通过更换σ ⁵⁴与基因的强启动子依赖性启动子的adhE（V518_0444），基因簇bglp ^cel2 EIIABC ^cel2（V518_2444-2449）可能容易过表达，并且SCUT27 / ΔcelR ^{cel 2} / padhE获得了共同利用葡萄糖和纤维二糖的能力，这是乙醇或乳酸发酵的潜在候选者来自木质纤维素水解产物的部分水解。