Pretreatment of the corn stover powder by dilute sulphuric acid （solid-liquid ratio 1 ： 20） at 130 for 30 min was carried out with 89.09% of the hemicellulose removed. After filtration, the xylose-rich corn stover ...Pretreatment of the corn stover powder by dilute sulphuric acid （solid-liquid ratio 1 ： 20） at 130 for 30 min was carried out with 89.09% of the hemicellulose removed. After filtration, the xylose-rich corn stover pretreatment liquid, whose fermentable sugar was from hemicellulose hydrolysis only, consisting of 81.16% xylose and 15.27% glucose, was used to cultivate genetic recombinant Escherichia coli BL21 with human-like collagen （HLC） expression enhanced by 50.00% and 63.71% xylose consumption.展开更多
Vitamin B_(2)is an essential water-soluble vitamin.For most prokaryotes,a bifunctional enzyme called FAD synthase catalyzes the successive conversion of riboflavin to FMN and FAD.In this study,the plasmid pNEW-AZ cont...Vitamin B_(2)is an essential water-soluble vitamin.For most prokaryotes,a bifunctional enzyme called FAD synthase catalyzes the successive conversion of riboflavin to FMN and FAD.In this study,the plasmid pNEW-AZ containing six key genes for the riboflavin synthesis was transformed into strain R2 with the deleted FMN riboswitch,yielding strain R5.The R5 strain could produce 540.23±5.40 mg/L riboflavin,which was 10.61%higher than the R4 strain containing plasmids pET-AE and pAC-Z harboring six key genes.To further enhance the production of riboflavin,homology matching and molecular docking were performed to identify key amino acid residues of FAD synthase.Nine point mutation sites were identified.By comparing riboflavin kinase activity,mutations of T203D and N210D,which respectively decreased by 29.90%and 89.32%compared to wild-type FAD synthase,were selected for CRISPR/Cas9 gene editing of the genome,generating engineered strains R203 and R210.pNEW-AZ was transformed into R203,generating R6.R6 produced 657.38±47.48 mg/L riboflavin,a 21.69%increase compared to R5.This study contributes to the high production of riboflavin in recombinant E.coli BL21.展开更多
基金Supported by the Agriculture Application Investigation and Improvement Item of New Countryside Construction and Promotion Project of the Bureau of Science and Technology in Xi’an (NC08005)
文摘Pretreatment of the corn stover powder by dilute sulphuric acid （solid-liquid ratio 1 ： 20） at 130 for 30 min was carried out with 89.09% of the hemicellulose removed. After filtration, the xylose-rich corn stover pretreatment liquid, whose fermentable sugar was from hemicellulose hydrolysis only, consisting of 81.16% xylose and 15.27% glucose, was used to cultivate genetic recombinant Escherichia coli BL21 with human-like collagen （HLC） expression enhanced by 50.00% and 63.71% xylose consumption.
基金the Natural Science Foundation of Zhejiang Province,China(No.LY21C200006)。
文摘Vitamin B_(2)is an essential water-soluble vitamin.For most prokaryotes,a bifunctional enzyme called FAD synthase catalyzes the successive conversion of riboflavin to FMN and FAD.In this study,the plasmid pNEW-AZ containing six key genes for the riboflavin synthesis was transformed into strain R2 with the deleted FMN riboswitch,yielding strain R5.The R5 strain could produce 540.23±5.40 mg/L riboflavin,which was 10.61%higher than the R4 strain containing plasmids pET-AE and pAC-Z harboring six key genes.To further enhance the production of riboflavin,homology matching and molecular docking were performed to identify key amino acid residues of FAD synthase.Nine point mutation sites were identified.By comparing riboflavin kinase activity,mutations of T203D and N210D,which respectively decreased by 29.90%and 89.32%compared to wild-type FAD synthase,were selected for CRISPR/Cas9 gene editing of the genome,generating engineered strains R203 and R210.pNEW-AZ was transformed into R203,generating R6.R6 produced 657.38±47.48 mg/L riboflavin,a 21.69%increase compared to R5.This study contributes to the high production of riboflavin in recombinant E.coli BL21.
