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Kanna et al. AMB Express 2011, 1:15 http://www.amb-express.com/content/1/1/15

Page 6 of 8

Figure 3 Activity of b-xylosidase was measured 1, 3, and 7 days after culture grown in 4% solca flock. Closed column; Y-94, Open column; YKX1. Standard deviations are calculated from triplicate experiments.

Because there was no evidence of any titration effect in YKX1, it is appropriate to use the cbh1 promoter to enhance hemicellulase activity in the strain A. cellu- lolyticus Y-94.

Expression of the xylanolytic gene, bxl1, is induced by xylobiose in T. reesei (Margolles-Clark et al. 1997). In A. nidluns, D-xylose induces xylanolytic enzymes via the regulatory gene, xlnR (Tamayo et al. 2008).

Although D-xylose and xylobiose can induce xylanolytic enzymes, another report indicates that the activity of b-xylosidase depends on the concentration of D-xylose in T. reesei (Mach-Aigner et al. 2010). b-xylosidase activity of YKX1 might have no effect in the presence of D-xylose because YKX1 used cbh1 promoter.

YKX1 grew faster than Y-94 in the same medium measured by ATP amount (Figure 2). In a previous

Y94 (U/ml)

YKX1 (U/ml)

b-xylanase

56.68 ± 4.13

59.59 ± 2.96

b-mannanase

4.21 ± 0.29

3.76 ± 0.21

b-mannnosidase

0.0071 ± 0.00042

0.0063 ± 0.00042

Y94

YKX1

b-xylosidase

0.02 ± 0.004

3.3 ± 0.509

Cellobiohydrolase I

15.78 ± 3.316 *

11.16 ± 2.321 *

Table 1 Gene expression in Y94 and YKX1 was analyzed one day after the cultures were started.

Number showed expression relative to an internal control (gene/b-actin) *P < 0.01

Table 2 Enzyme activity 3 days after the cultures were started.

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