Retting has been employed to extract natural fibers from agricultural wastes as a biological and cost-effective approach for centuries.With its global abundance,banana pseudo-stem is a promising agro-waste for lignoce...Retting has been employed to extract natural fibers from agricultural wastes as a biological and cost-effective approach for centuries.With its global abundance,banana pseudo-stem is a promising agro-waste for lignocellulosic fiber extraction.In this study,fibers were extracted from the pseudo-stems after being pre-treated under four conditions using seawater at room temperature for up to 35 d Bacterial isolation from the fresh seawater sample and screening for ligninolytic ability were conducted.Bacterial load as well as laccase and manganese peroxidase enzyme activity profile assay during the retting duration were analyzed.Fourier transform infrared(FT-IR)and X-day diffraction(XRD)analyses were also examined for both pre-treated and untreated extracted fibers.The results shows that six out of the eight bacterial isolates had the ability to degrade lignin.The treatments(Raw stem+Raw seawater)and(Autoclaved stem+Raw seawater)recorded the highest viable bacterial load of 9.24×102 and 4.46×102 CFU,respectively,on the 14th day of the retting process.Additionally,the highest laccase and manganese peroxidase enzymes activity was recorded for(Raw stem+Raw seawater)and(Autoclaved stem+Raw seawater)treatments in the second to the third week.The FT-IR spectra of the pre-treated fibers revealed relative reductions in peaks attributed to polysaccharides and other amorphous substances for all retting conditions.The XRD diffractogram revealed that the crystallinity index(CI)of pre-treated fibers increased in all seawater retting treatment conditions.However,the CI for fibers pre-treated under enzymatic conditions were enhanced even after five weeks.Sequence analysis for selected bacterial isolates showed homology to sequences of Bacillus velezensis,Shewanella sp.L8–5,and Citrobacter amalonaticus and Bacillus subtilis j8 strain.From these findings,it was suggested that physical,biological,and chemical actions were collectively involved in the seawater retting process of banana pseudo-stems.展开更多
Cell-free expression systems have emerged as a versatile and powerful platform for metabolic engineering,biosynthesis and synthetic biology studies.Nevertheless,successful examples of the synthesis of complex natural ...Cell-free expression systems have emerged as a versatile and powerful platform for metabolic engineering,biosynthesis and synthetic biology studies.Nevertheless,successful examples of the synthesis of complex natural products using this system are still limited.Bicyclomycin,a structurally unique and complex diketopiperazine alkaloid,is a clinically promising antibiotic that selectively inhibits the transcription termination factor Rho.Here,we established a modular cell-free expression system with cascade catalysis for the biosynthesis of bicyclomycin from a chemically synthesized cyclodipeptide.The six cell-free expressed biosynthetic enzymes,including five iron-andα-ketoglutarate-dependent dioxygenases and one cytochrome P450 monooxygenase,were active in converting their substrates to the corresponding products.The co-expressed enzymes in the cell-free module were able to complete the related partial pathway.In vitro biosynthesis of bicyclomycin was also achieved by reconstituting the entire biosynthetic pathways(i.e.,six enzymes)using the modular cell-free expression system.This study demonstrates that the modular cell-free expression system can be used as a robust and promising platformforthe biosynthesis of complex antibiotics.展开更多
基金supported by the Science and Technology Development Fund(STDF)project(no.44049)and TICAD7 scholarship from the Egyptian and Japanese governments.We are also grateful to Professor Hiromi Nakanishi from the University of Tokyo,for the analyses with the PCR and TOYOBO for the sequencing.
文摘Retting has been employed to extract natural fibers from agricultural wastes as a biological and cost-effective approach for centuries.With its global abundance,banana pseudo-stem is a promising agro-waste for lignocellulosic fiber extraction.In this study,fibers were extracted from the pseudo-stems after being pre-treated under four conditions using seawater at room temperature for up to 35 d Bacterial isolation from the fresh seawater sample and screening for ligninolytic ability were conducted.Bacterial load as well as laccase and manganese peroxidase enzyme activity profile assay during the retting duration were analyzed.Fourier transform infrared(FT-IR)and X-day diffraction(XRD)analyses were also examined for both pre-treated and untreated extracted fibers.The results shows that six out of the eight bacterial isolates had the ability to degrade lignin.The treatments(Raw stem+Raw seawater)and(Autoclaved stem+Raw seawater)recorded the highest viable bacterial load of 9.24×102 and 4.46×102 CFU,respectively,on the 14th day of the retting process.Additionally,the highest laccase and manganese peroxidase enzymes activity was recorded for(Raw stem+Raw seawater)and(Autoclaved stem+Raw seawater)treatments in the second to the third week.The FT-IR spectra of the pre-treated fibers revealed relative reductions in peaks attributed to polysaccharides and other amorphous substances for all retting conditions.The XRD diffractogram revealed that the crystallinity index(CI)of pre-treated fibers increased in all seawater retting treatment conditions.However,the CI for fibers pre-treated under enzymatic conditions were enhanced even after five weeks.Sequence analysis for selected bacterial isolates showed homology to sequences of Bacillus velezensis,Shewanella sp.L8–5,and Citrobacter amalonaticus and Bacillus subtilis j8 strain.From these findings,it was suggested that physical,biological,and chemical actions were collectively involved in the seawater retting process of banana pseudo-stems.
基金supported in part by grants from the National Key Research and Development Program of China(2022YFC2303100)the National Natural Science Foundation of China(22207117).
文摘Cell-free expression systems have emerged as a versatile and powerful platform for metabolic engineering,biosynthesis and synthetic biology studies.Nevertheless,successful examples of the synthesis of complex natural products using this system are still limited.Bicyclomycin,a structurally unique and complex diketopiperazine alkaloid,is a clinically promising antibiotic that selectively inhibits the transcription termination factor Rho.Here,we established a modular cell-free expression system with cascade catalysis for the biosynthesis of bicyclomycin from a chemically synthesized cyclodipeptide.The six cell-free expressed biosynthetic enzymes,including five iron-andα-ketoglutarate-dependent dioxygenases and one cytochrome P450 monooxygenase,were active in converting their substrates to the corresponding products.The co-expressed enzymes in the cell-free module were able to complete the related partial pathway.In vitro biosynthesis of bicyclomycin was also achieved by reconstituting the entire biosynthetic pathways(i.e.,six enzymes)using the modular cell-free expression system.This study demonstrates that the modular cell-free expression system can be used as a robust and promising platformforthe biosynthesis of complex antibiotics.
