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Table 1 Biological saccharification using glycoside hydrolase family-1 β-glucosidases from C. thermocellum and T. thermosaccharolyticum

From: Direct glucose production from lignocellulose using Clostridium thermocellum cultures supplemented with a thermostable β-glucosidase

  Specific activity (U/mg) Thermal stability (%)a Optimum temperature (°C)b Optimum pHb Glucose inhibition (mM)c Biological saccharification
       Cellobiose concentration (mM)d Glucose concentration (mM)d
CglT (T. brockii) 26.0 ± 0.05 97 60 to 75 6.0 to 7.0 450 ± 10.2 5.9 ± 0.7 425.9 ± 24.7
BglA (C. thermocellum ATCC) 19.4 ± 0.05 10 50 to 60 6.0 to 7.0 400 ± 5.1 22.1 ± 1.3 240.7 ± 18.5
Bgl (T. thermosaccharolyticum NOI-1) 28.8 ± 0.05 10 60 to 70 6.0 to 7.0 650 ± 3.2 36.4 ± 0.7 304.3 ± 18.5
  1. aThermal stability is indicated as the percentage of remaining β-glucosidase activity after incubation for 24 hours at 60°C; brange reported represents where >90% of the maximal activity was maintained; cglucose inhibition was calculated as the glucose concentration required to inhibit 50% of initial β-glucosidase activity; dbiological saccharification was carried out by culturing C. thermocellum with each β-glucosidase using 100 g/L crystalline cellulose as described in the Methods section. To allow comparison with glucose production, cellobiose concentration was indicated in mM glucose equivalents. Values are the means of triplicate experiments ± SD.