ABSTRACT
Objective To investigate the genetic diversity and genetic differentiation of different geographical isolates of Gohieria fusca.. Methods G. fusca isolates were sampled from Wuhu (WH), Bengbu (BB) and Bozhou cities (BZ) of Anhui Province and Jiaxing City of Zhejiang Province (JX). Mitochondrial cytochrome b (Cytb) and ribosomal internal transcribed spacer (ITS) genes were amplified in WH, BB, BZ and JX isolates of G. fusca using PCR assay. The gene sequences were edited and aligned using the software Chromas 2 and DNASTAR 1.00, and the haplotype, haplotype diversity (Hd) and nucleotide polymorphism (Pi) of each isolate were calculated using the software DnaSP 5.10.00. The genetic differentiation among isolates (Fst) and gene flow value (Nm) were estimated using the software MEGA 10.2, and a phylogenetic tree was built. Tests of neutrality and analysis of molecular variance (AMOVA) were performed using the software Arlequin 3.1 and a haplotype network was built based on the Median-Joining network using the software Network 10.2. Results PCR assay showed that the sizes of the Cytb and ITS genes were 372 bp and 1 301 to 1 320 bp, respectively. All four isolates of G. fusca presented high genetic diversity based on mitochondrial Cytb and ITS genes (Hd = 0.804, Pi = 0.006 91). AMOVA showed genetic differentiation among geographical isolates of G. fusca (Fst = 0.202 40, P < 0.05), and the genetic variation was mainly caused by intra-population variations (79.76%). Gene flow analysis showed a high level of gene flow among G. fusca isolates (Nm > 1). Tests of neutrality based on Cytb gene measured a Tajima’s D value of −1.796 31 (P < 0.05) and a Fu’s FS value of −3.293 98 (P < 0.05) in WH isolate of G. fusca, indicating population expansion in WH isolate of G. fusca. Haplotype network analysis and phylogenetic analysis revealed no remarkable geographical distribution pattern among different geographical isolates of G. fusca. All four isolates of G. fusca presented high genetic diversity (Hd = 0.985, Pi = 0.011 97). AMOVA showed moderate level of genetic differentiation between four isolates (Fst = 0.104 62, P < 0.05). The tests of neutrality based on ITS genes measured a Tajima’s D value of −6.088 20 and a Fu’s FS value of −1.935 99 (both P > 0.05) in the whole isolate of G. fusca, indicating no obviously population expansion. Conclusions The four geographical isolates of G. fusca have high genetic diversity and remarkable genetic differentiation. Since a high level of gene flow is detected among different geographical isolates of G. fusca, no obvious geographical distribution pattern of G. fusca is found.
ABSTRACT
White-rot fungus manganese peroxidase (MnP) that has great potential in degrading azo dyes is one of the extracellular glycolsylated heme proteins. MnP from Schizophyllum sp. F17 was isolated and purified by Sephadex G-75 gel filtration chromatography followed by DEAE-cellulose anion exchange chromatography. The molecular weight of the puried enzyme was 49.2 kDa, while the half-life of the MnP in the presence of 0.1 mmol/L H2O2 was 5-6 min. The efficiency of MnP-catalyzed reactions were determined by three key factors: the concentrations of Mn2+, H2O2, and the amount of MnP. Using single factor analysis, an optimized concentration of Mn2+, H2O2 and enzyme were optimized to be 1.2 mmol/L, 0.1 mmol/L, and 0.4 mL, respectively. A response surface methodology (RSM) employing two-level-three-factor full factorial central composite design was used to optimize the catalytic conditions. The result showed that the concentration of H2O2 and the interaction between H2O2 and MnP mostly affect the MnP catalytic efficiency. Finally, we show that the azo dyes could be efficiently decolorized by the purified MnP under optimized conditions.