Ji Runzhen,Hua Qijing,Dong Yamin,Zhu Du,Xiao Yiwen,Gao Boliang
Xylanase is the core enzyme responsible for degrading xylan, a major component of lignocellulose, and holds significant application value in fields such as food, feed, and biorefining. In this study, a xylanase gene, Xyn108 , was identified from the genome of the lignocellulose-degrading endophytic fungus Chaetomium globosum DX-THS3 and successfully expressed in Pichia pastoris . The xylanase Xyn108 belongs to glycoside hydrolase family 11 (GH11), with a molecular weight of approximately 38 kDa. The enzyme exhibited optimal activity at pH 6.0 and 40 °C, and demonstrated good stability within pH 3.0–9.0 and at temperatures below 50 °C (retaining > 50% residual activity after 180 min incubation). Xyn108 displayed high enzymatic activity towards beechwood xylan and possessed hydrolytic capacity toward microcrystalline cellulose. Crucially, Xyn108 exhibited significant synergistic effects with the commercial cellulase Cellic CTec2 in hydrolyzing pretreated rice straw. The highest synergistic degrees, reaching 1.34 and 1.24 for NaOH-pretreated and H₂SO₄-pretreated straw, respectively, were achieved at a xylanase/cellulase activity ratio of 1:3. The enzyme’s excellent pH adaptability, low-temperature activity, and remarkable synergistic effects highlight its significant application potential in industrial sectors such as feed processing, paper manufacturing, and biofuel production.
The photocatalytic efficiency of hematite (α-Fe 2 O 3 ) is limited by its photoexcited state lifetime and diffusion length. By adjusting the surface structure, the photogenerated electron pairs can migrate to the surface and the charge recombination can be suppressed, which can effectively solve these problems and improve the photo-Fenton performance. In this study, four kinds different morphologies of α-Fe 2 O 3 - x (truncated hexagonal bipyramidal, cubic, hexagonal shape, and spherical) were synthesized by hydrothermal method , and a photocatalyst (H-α-Fe 2 O 3 - x ) with higher catalytic activity was prepared by hydrogenation. The results of UV–Vis DRS , PL , Raman, and XPS analysis , the oxygen vacancies and Fe (II) species were introduced into the α-Fe 2 O 3 catalyst after the hydrogenation reaction. The H-α-Fe 2 O 3 - x showed good degradation performance for TC and DX as EMPs model pollutants. The results show that the formation of oxygen vacancy and Fe 2+ is the main factor to improve the photocatalytic activity of the reaction system. Furthermore, the reaction mechanism revealed that reactive radicals involved in the H-α-Fe 2 O 3 - x photocatalytic system were •OH, •O 2 − , and h + responsible. This study provides an alternative technology for an easy and effective means for bandgap engineering to improve the photocatalytic performance of photocatalysts and facilitate widening environmental application.
Yannan Chen,Shanshan Tie,Xuedi Zhang,Lijuan Zhang,Mingqian Tan
Novel mitochondria targeting nanocarriers were prepared using triphenylphosphonium bromide (TPP)-modified whey protein isolate (WPI)–dextran (DX) conjugates by self-assembly method for astaxanthin mitochondria targeting delivery. The nanocarriers of astaxanthin-loaded WPI–DX and astaxanthin-loaded TPP–WPI–DX were 135.26 and 193.64 nm, respectively, which exhibited a spherical structure and good dispersibility. The mitochondria targeting nanocarriers had good stability in the stimulated blood fluid. In vitro experiments indicated that the TPP-modified nanocarriers could effectively realize lysosomes escape, and specifically accumulate in the cell mitochondria. Simultaneously, the astaxanthin-loaded nanocarriers could significantly reduce reactive oxygen species generation produced from hydrogen peroxide, protect the normal levels of the mitochondrial membrane potential, and dramatically promote the vitality of leukemia cells in mouse macrophage (RAW 264.7) cells. The present study highlights the promising application of mitochondria targeting nanocarriers for enhanced delivery of astaxanthin.
危险品化学品经营许可证（带存储）