| The xylanase gene xylN from Neocallimastix patriciarum was research subject in this paper.We performed bioinformatics analysis of gene xylN,We heterologously expressed it in Pichia pastoris.The production was effectively increased with the multicopy Pichia pastoris xylanase gene strategy.It encoded a total of 225 amino acids.The molecular weight of this protein was 24.39 kD.Its theoretical isoelectric point was 5.77.The XYLN did not contain signal peptide.The results of secondary structure and tertiary structure analysis showed that XYLN was composed of 9.78%α helix,36.00%extended strand,6.67%β turn and 47.56%random coil.XYLN was a hydrophilic protein.The GS115-pPIC9K-xylN was that the pPIC9K-xylN was transferred into Pichia pastoris.The GS115-pPIC9K-xylN-pPlCZaA-xylN was that the pPICZaA-xylN was transferred into the GS115-pPIC9K-xylN.The maximal xylanase activity of GS115-pPIC9K-xylN-pPICZaA-xylN was 154023.4 U/mL in 15 L of bioreactor,which was 2.08 times more than the maximal xylanase activity of GS115-pPIC9K-xylN.The optimum pH of XYLN expressed in Pichia pastoris was 7.0.The optimum temperature was 65℃.The retain xylanase activity was 80.6%after keeping it for 5 min at 80℃.The recombinant xylanase XYLN is good thermostability,and it is promising for industrial application. |
