A rapid, sensitive and effective method for screening of the fungi excreting extracellular cellulases

Abstract:

[Objective] To establish a rapid, sensitive and effective method for screening of the fungi producing extracellular cellulases with high β-glucosidase activity. [Methods] Iodine vapor staining was used to replace Congo red or iodine dip dyeing in the screening methods of extracellular cellulase producing fungi by agarose plates complemented with avicel or CMC in order to reduce the consumption and pollution of gram’s iodine, and the screening method of β-glucosidase producing fungi by the agarose plates complemented with 4-Nitrophenyl-β-D-glucopyranoside (pNPG) was established. Finally, these two methods were used successively to screening the fungi producing extracellular cellulases with high β-glucosidase activity. [Results] The screening methods of both the avicel or CMC agarose plates with iodine vapor staining and the pNPG agarose plates were established successfully, and used successively to screening 8 strains of extracellular cellulase producing fungi with level ++++ cellulase activity out of 56 fungus strains, and from which 4 strains of extracellular cellulase producing fungi with high β-glucosidase activity were screening out. [Conclusion] It could be concluded that the method of avicel or CMC agarose plate with iodine vapor staining integrated with pNPG agarose plate assay would be a rapid, sensitive and effective method for screening of the fungi producing extracellular cellulases with high β-glucosidase activity.