2.7. Mutagenesis by N-methyl-N-nitro-N-nitrosoguanidine
(NTG)
The wide type cell grown in CMC medium at 50 C for 24 h
was harvested at logarithmic phase by centrifugation
(10,000g, 20 min) at 4 C and washed twice with McIlvaine’s
buffer (containing 0.1 M citric acid and 0.2 M phosphate buffer)
pH 5.0. The cell was resuspended in buffer at a concentration
of 5.8 · 108 cell/ml. and NTG (1 mg/ml) was added into
the cell suspension. After incubation for 1 h at 37 C in incubation
shaker at 100 rpm, the cell was centrifuged and washed
immediately with buffer. The treated sample was transferred
into CMC plates (Xu et al., 2011) and incubated at 50 C for
48 h. The cellulolytic activity was assayed