Screening of high xylanase-producing Chaetomium globosum strain by microwave mutagenesis

Objective To screen a high xylanase-producing Chaetomium globosum strain with genetic stability by microwave mutagenesis.Methods C.globosum strain was activated and prepared into spore suspension,then subjected to radiation at various powers for 60 s.The strain was subjected to microwave mutagenesis for various seconds at the selected radiation power with a lethal rate of about 80% and,after preliminary and repeat screenings,determined for xylanase activity by DNS method,based on which a high xylanase-producing strain was screened and analyzed for genetic stability.Results The lethal rate of spores of C.globosum was 89.5% after microwave radiation at a power of 240 W for 80 s.High xylanase-producing C.globosum W80-8 strain was obtained after mutagenesis and screening,of which the xylanase activity was 7 520 U / ml and increased by 124% as compared with that of original strain.Neither decrease of xylanase activity nor in situ back mutation was observed in W80-8 strain after subculture for 6 passages.Conclusion A high xylanase-producing C.globosum strain with genetic stability was successfully screened.