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14 results on '"Song, Jianxiao"'

12. Direct Preparation of Cellulose Nanofibers from Bamboo by Nitric Acid and Hydrogen Peroxide Enables Fibrillation via a Cooperative Mechanism

Author

Shuangfei Wang, Xue Yichun, Xusheng Li, Wu Kunze, Jinlong Wang, Yiting Wu, and Song Jianxiao

Subjects
Aqueous solution, biomass, General Chemical Engineering, hydrogen peroxide, Article, lcsh:Chemistry, nitric acid, chemistry.chemical_compound, Crystallinity, lcsh:QD1-999, chemistry, Chemical engineering, Nitric acid, Nanofiber, General Materials Science, Thermal stability, Cellulose, Selectivity, Hydrogen peroxide, cellulose nanofibers
Abstract

Separating the fibers, deconstructing both the interlamellar structures and the intermicrofibrils structures in the cell wall, and cleaving the amorphous regions of cellulose (all reached in one bath chemical-assisted treatment), then extracting cellulose nanofibers (CNFs) from biomass, is both challenging and imperative. A simple, cost-effective and green strategy for extracting CNFs from bamboo using nitric acid and hydrogen peroxide (NCHP), to enable fibrillation via a cooperative mechanism, is demonstrated herein. NCHP-CNFs 13.1 &plusmn, 2.0 nm wide, with a high aspect ratio, 74% crystallinity, excellent UV resistance and high thermal stability, were successfully extracted by treatment in HNO3 aqueous solution, at a concentration of 3.2 mol/L, and treatment with 60.00 mmol/g H2O2 at 50 &deg, C for 48 h. The yields of NCHP-CNFs reached 73% and 99% based on biomass and cellulose, respectively, due to the high delignification selectivity of OH+ and the mild aqueous conditions during the NCHP treatment. These NCHP-CNFs with excellent UV resistance can potentially be applied in the field of UV-resistant coatings, to replace organic and inorganic materials.

Published
2020

14. Tryptophan transport gene inactivation promotes the development of antibiotic resistance in Escherichia coli.

Author

Hou B, Song J, Wang H, Ye N, and Wang RW

Subjects
Membrane Transport Proteins genetics, Membrane Transport Proteins metabolism, Gene Deletion, Drug Resistance, Multiple, Bacterial genetics, Biological Transport, Drug Resistance, Bacterial genetics, Reactive Oxygen Species metabolism, Ampicillin pharmacology, Gene Silencing, Kanamycin pharmacology, Amino Acid Transport Systems genetics, Amino Acid Transport Systems metabolism, Gene Expression Regulation, Bacterial, Carrier Proteins, Escherichia coli genetics, Escherichia coli drug effects, Escherichia coli metabolism, Tryptophan metabolism, Escherichia coli Proteins genetics, Escherichia coli Proteins metabolism, Anti-Bacterial Agents pharmacology, Microbial Sensitivity Tests
Abstract

Indole serves as a signaling molecule that could regulate different bacterial physiological processes, including antibiotic resistance through biofilm formation and drug efflux pump activity. In Escherichia coli, indole is produced through the tryptophan pathway, which involves three permeases (Mtr, AroP, and TnaB) that can transport the amino acid tryptophan. Although these permeases play distinct roles in the secretion of indole biosynthesis, their impact on multidrug resistance mediated by indole remaines unclear. This study was designed to investigate the connection between the tryptophan transport system and antibiotic resistance by constructing seven gene deletion mutants from E. coli MG1655 (wild type). Our result showed that deletion of the aroP or tnaB gene led to increased antibiotic resistance as evaluated by MICs for different antibiotics. Efflux activity test results revealed that the increased antibiotic resistance was related with the AcrAB-Tolc drug efflux pump in the mutants. The transcriptome analysis further demonstrated that decreased susceptibility to kanamycin and ampicillin in E. coli was accompanied by reduced accumulation of reactive oxygen species and decreased motility. These findings highlight the substantial influence of the tryptophan transport system on antibiotic resistance in E. coli, which is crucial for developing strategies against antibiotic resistance in bacterial infections., (© The Author(s) 2024. Published by Oxford University Press on behalf of FEMS.)

Published
2024
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