Efficient whole-cell-catalyzing cellulose saccharification using engineered Clostridium thermocellum

Table 1 Enzymatic properties of selected BGLs

Protein	Optimal temp (°C)/pH^a	Specific activity (U/mg)	Thermal stability at 60/80 °C (%)^b	Glucose inhibition (mM)^c
CaBglA	75–80/5.0–5.6 [23]	346.0 ± 3.7	99.3/91.4	314
CtBglA	65/5.5	208.2 ± 4.8	116.9/4.8	205
CglT	60–75/6.0–7.0 [25]	79.3 ± 5.9	104.0/10.5	450
Td2f2	75/5.5 [31]	9.2 ± 0.3	71.1/40.9	None^d

All experiments were performed in triplicate to calculate the averages and standard errors with pNPG as a substrate, and the reaction conditions were at pH 5.5 and 55 °C
^a The optimal temperature and pH of CaBglA and CtBglA were also determined in this study as shown in Additional file 1
^b The thermal stability was shown as percentage of remaining BGL activity after incubating at 60 or 80 °C for 24 h
^c The glucose inhibition of BGLs was determined by adding glucose at different concentrations (0–600 mM) to the standard reaction mixture, and calculated as the glucose concentration required to inhibit 50% of initial BGL activity (Additional file 1)
^d Instead of inhibition, Td2f2 could be stimulated by 29.2–72.0% with the addition of 100–600 mM glucose, which was consistent with previous report [31]

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