Time course of recombinant XynA expression in 50 ml of BMM medium inoculated with the three highest-expressing clones. Cell counts (filled symbols) and xylanase activity (open symbols) were monitored throughout the experiment for clone 5 (•,○), clone 7 (▪,□), and clone 13 (▴,▵). Xylanase activity was measured by the DNS procedure as described in Materials and Methods. The values correspond to the averages of five measurements, and the error was below 10%.