Nan Zhang,Junaid Haider,Maxine Yew,Jianhua Yang,Leilei Zhu
Lytic polysaccharide monooxygenases (LPMOs) play a unique role in biomass saccharification as they catalyze oxidative cleavage of recalcitrant polysaccharides. Here, four new starch-active AA13 LPMOs were identified via phylogenetic analysis and functionally expressed in Pichia pastoris , followed by the investigation of oxidative activity towards different starch substrates. The four purified AA13 LPMOs were capable of oxidizing amylose, amylopectin and corn starch, generating soluble products. Among the four, Fv AA13, which exhibited the best oxidative activity, was further studied. Its yield of oxidized products was 1.9-fold, 1.4-fold, and 1.3-fold higher than the previously reported Nc AA13 when applied to starch substrates amylose, amylopectin, and corn starch, respectively. Furthermore, the oxidized product yield of Fv AA13 was enhanced by 2-fold when supplemented with 100 μM H 2 O 2 . Fv AA13 also enhanced the amylose degradation catalyzed by α-amylase and glucoamylase at 50 °C with an increment of the product by 1.4-fold and 1.9-fold, respectively. When combined with glucoamylase at a mass concentration ratio of 0.5:1 to 2:1, the reducing sugars released from the enzymatic degradation of amylopectin were improved by 4.5 to 9.7-fold compared to using glucoamylase alone. These findings underscored the substantial promoting effect of the supplementary Fv AA13 in amylolytic cocktails for starch saccharification.
Utilizing biological resources facilitates alleviating energy shortage and environmental pollution problems, but high-value utilization of these resources requires breaking the biomass structure. This study realized the clean and efficient separation of cellulose, hemicellulose, and lignin from tobacco stems using a sustainable H 2 O 2 -enhanced alkaline pretreatment combined with acid and ethanol precipitation. The purity and thermal stability of the separated cellulose increased from 32.49% to 92.41% and 261 °C to 369 °C, respectively. Changes in the cellulose crystal form and the solubilization mechanisms of hemicellulose and lignin were elucidated. In addition, a food-preservation film was prepared from the obtained biocellulose using the solution-casting method. After adding glycerol and sorbitol as plasticizers , the tensile strength and water-contact angle (a hydrophobicity indicator) of the biocellulose composite film increased from 125 MPa to 154 MPa and from 50.48° to 73.16°, respectively. This study provides a platform for lignocellulosic biomass separation, renewable utilization, and a practical route toward functional biomaterial production.
危险品化学品经营许可证（带存储）