Pectate lyase (PL) holds significant potential for applications in various industries. However, the existing PL was unable to adapt to thermo-alkaline industrial environments. In this work, a PL from Caldicellulosiruptor bescii DSM 6725 (hereafter, CbPelD) was studied to disclose its structural and biochemical properties. CbPelD consisted of a putative signal peptide sequence, a short linker region, and a catalytic domain (PelD-II), along with an exoacting β-fructofuranosidase domain (PelD-I). In molecular dynamics simulation, PelD-II demonstrated significantly higher activity and thermal stability compared to other truncated enzymes of CbPelD. The optimal pH and temperature for PelD-II were 10.0 and 60 °C, respectively, with the specific activity increasing by 164–223% in the presence of Ca2+ or Ni2+. The exotype PelD-II exhibited efficient degradation of polygalacturonic acid (PGA) into unsaturated galacturonic acid (uG1), digalacturonic acid (uG2), and trigalacturonic acid (uG3). In the bioscouring assay, PelD-II exhibited a significant increase in the wetted fabric area to 6.072 ± 0.684 cm2, which was about 7.9 times higher than untreated fabric. Scanning electron microscopy further revealed that treatment with PelD-II resulted in a smoother fiber surface, providing direct visual confirmation of the enzyme’s action. These results highlight the potential of PelD-II for applications in the textile industries.
Guotao Mao,Fangyuan Wang,Jie Wang,Pengyu Chen,Xiaodong Zhang,Hongsen Zhang,Zhimin Wang,Andong Song
Laccases are green biocatalysts that are advantageous in the bioremediation of the triphenylmethane dye malachite green (MG). Here, Cblac from Caldicellulosiruptor bescii was characterized to be a novel DUF152 laccase. Cblac mutant Mut8 was designed with enhanced thermostability, which was demonstrated by the Thermofluor assay, circular dichroism spectrum, and structural analyses. MG bioremediation by Mut8 at high temperatures was performed and examined for its potential to degrade and detoxify the high-temperature MG effluent. Approximately 100% of 100 mg/L of MG was degraded by 40 U/L of Mut8 within 2 h at 75 °C. Mut8 initiated the degradation via oxidative cleavage of the central C–C bond and N-demethylation of MG, and the intermediates were further demethylated, hydroxylated and oxidized. Moreover, the systematic toxicity assessment of the MG degradation products using bacteria, Zea mays , and zebrafish demonstrated that Mut8 thoroughly eliminated MG toxicity. Taken together, Mut8 could effectively decolorize and detoxify MG at high temperatures, showing great promise as an environmental friendly and effective approach to remediate MG effluent immediately released from the dyeing process, thus avoiding the cooling process and lowering the cost simultaneously.
危险品化学品经营许可证（带存储）