Microbial degumming offers an eco-friendly alternative to chemical methods for ramie fiber production, but industrial application is constrained by low efficiency stemming from limited mechanistic insight. This study systematically investigates the process using Pectobacterium carotovorum HG-49. Strain HG-49 showed a lag phase of 0-4 h, a logarithmic phase of 6-10 h, and peak biomass at 12 h. Pectin (97.05%) and water-soluble substances (98.45%) were nearly fully removed, whereas hemicellulose removal was only 73.54%, rendering it the primary residual gum component. Pectinase activity peaked at 120.75 U/mL, while mannanase (35.85 U/mL) and xylanase (30.20 U/mL) reached roughly one-quarter of that level; cellulase activity remained minimal. Scanning electron microscopy (SEM) indicated that 6-12 h constituted the main gum degradation phase. Fourier transform infrared spectroscopy (FTIR) and micro-FTIR showed progressive decreases in pectin, hemicellulose, and lignin absorption peaks with degumming. X-ray diffraction (XRD) revealed increased crystallinity from 72.07% to 80.02%, and thermogravimetric analysis (TGA) showed elevated degradation temperature from 417 °C to 435 °C. Collectively, these data confirm progressive removal of gummy substances and enhanced cellulose purity. Transcriptomic profiling further revealed that low abundance and reduced expression of hemicellulases significantly limited degumming performance. Therefore, enhancing efficiency should focus on: supplementing pectin-rich substrates to accelerate bacterial proliferation and enzyme production, broadening the hemicellulase spectrum and enhancing catalytic activities and establishing effective pretreatment protocols for ramie bast. These findings provide a theoretical foundation for improving microbial degumming efficiency and advancing industrial feasibility.

To address the high pollution burden of chemical degumming for ramie fibers and the low efficiency of microbial methods, this study developed a novel synergistic degumming system employing pectate lyase in conjunction with potassium peroxy(mon)sulfate (PPMS). Based on enzymatic characterization, reducing sugar analysis, and immunofluorescence results, pectate lyase (PcPel1834) was identified as the crucial enzyme in degumming strain Pectobacterium carotovorum HG-49. The enzyme exhibited high catalytic efficiency (4980 U/mg, Kcat/Km = 1588.92 mL·s-1·mg-1), and its degumming performance was comparable to that of commercial pectate lyase. The 6.5 h treatment combining PcPel1834 and PPMS, achieved total gum removal rate of 88.72%, bundle breaking tenacity of 5.10 cN/dtex and whiteness of 52.7, meeting the first-class textile criteria of China. The degumming mechanism of the synergistic system was elucidated via immunofluorescence, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) and gas chromatography-mass spectrometry (GC/MS) analysis. PcPel1834 efficiently degraded pectin and deconstructed the compact bundle structure of ramie bast fibers. This facilitated PPMS in generating a strong oxidative environment rich in oxygen free radicals, which degraded hemicellulose and lignin into small-molecule acids, benzoic acid and aromatic hydrocarbon fragments. This study established an efficient and eco-friendly degumming paradigm for ramie industry.

Bio-degumming is an eco-friendly and energy-efficient method for removing non-cellulosic matrices to extract ramie fiber, while it still requires prolonged processing and remains partial gums with complex side chains. This study demonstrated that, following pectin depolymerization, partial xylan and mannan in the middle lamella and phloem parenchyma could be removed in their non-depolymerized forms. Thus, the bio-degumming process followed by mechanical beating was improved by an alternating approach. Ramie bast was first beaten to loosen the middle lamella and phloem parenchyma, aiding pectinase, xylanase, and mannanase binding to internal gums. These enzymes then partially degraded the gum, weakening gum-fiber connections. Additional beating removed these loosened tissues, accelerating primary wall exposure. This approach reduced the blocking effect of gum laminated junctions, shortening degumming time. Afterward, carbohydrate binding domains further weakened the hindering effect of side chains and enhanced endoxylanase and endomannanase to remove residual hemicellulose on the primary wall. Furthermore, the engineered Pectobacterium carotovorum HG-49 capable of constitutively expressing and secreting the fusion proteins of endoxylanase, endomannanase, and carbohydrate binding domains was built. The alternating treatment with the engineered HG-49 and mechanical beating reduced degumming time from 16 to 12 h, decreased residual gum content from 6.34 to 4.48

Microbial degumming for producing ramie fiber has emerged as mainstream method owing to its eco-friendliness and low energy-consumption, however, its efficiency requires further improvement. This study proposed a synergistic approach to improve degumming efficiency by enhancing xylanase activity in Pectobacterium carotovorum HG-49 and optimizing pretreatment through ammonium oxalate soaking combined with microwave heating for ramie bast fibers. The pretreatment separated and dissolved most pectin, loosened the fiber structure, and provided ammonium oxalate as nitrogen source, thereby promoting HG-49 growth and enhancing its production of degradation enzymes. Therefore, the degumming time shortened by 2 h, the removal ratio of hemicellulose and total gum increased by 10.78% and 5.93%, respectively. The achieved gum removal rate of 87.33% within 14 h represents one of the highest values reported to date. This study demonstrated that synergistic action of enhanced xylanase activity and optimized pretreatment greatly improved the microbial degumming efficiency for ramie bast fibers.

Bio-degumming is more eco-friendly than traditional degumming to produce ramie fiber, while lower efficiency restricts its widespread application. At present, ramie bast structure and its influences on bio-degumming are still unclear, causing a poor understanding of the types of enzymes needed during bio-degumming, as well as their synergistic effects and limiting factors. This study elucidated the ramie bast structure and its obstructive effects. Ramie bast primarily comprised single bundle fibers, middle lamella, and phloem parenchyma. In the middle lamella and phloem parenchyma, pectin comprised lowly-esterified homogalacturonan, while the phloem parenchyma also contained rhamnogalacturonan with araban and galactan branching. Xylan carried acetyl group and arabinofuranose branching, and mannan carried acetyl group and galactose branching, both of which were masked by pectin. These two tissues have respective laminated connections that impede pectinase from removing pectin. The masking by pectin and branched chains further hindered the removal of xylan and mannan. Additionally, the middle lamella and phloem parenchyma covered fiber primary wall, where branched xylan and mannan were present. The covering and branched chains further blocked the removal of hemicellulose from primary wall. Accordingly, the enzymes required, their synergistic effect, and limiting factor were clear. The rhamnogalacturonan-degrading enzymes were used to assist pectate lyase in removing pectin first. Subsequently, corresponding branched-chain degrading enzymes were employed to help the endo-xylanase and endomannanase remove xylan and mannan, including esterase, alpha-galactosidase, alpha-L-arabinofuranosidase, and alpha-glucuronidase. Meanwhile, the steric hindrance caused by the tight connection of ramie bast tissues was an important limiting factor, needing to be weakened.

Janus fabrics are often used for oil/water separation, fog-harvesting, and moisture-wicking clothing due to their unidirectional liquid transport (ULT) ability. However, Janus fabrics are usually mono-functional, and the fabrication process is complex. Moreover, the chemicals used are not green. Herein, a versatile Janus fabric from ramie with ULT, flame retardancy, and moisture-wicking features was fabricated using a facile and sustainable method. Chitosan and phytic acid were rapidly deposited on the surface of fabrics via electrostatic gravitation, and polydivinylbenzene was then used as coating after in situ polymerization. Reverse wettability was achieved on two sides of the Janus ramie fabric after the UV irradiation of one of the sides, which endowed the fabric with ULT ability. Janus ramie fabric exhibited a comparable water vapor transmission rate to that of pristine ramie fabric but a higher water evaporation rate because of its ULT ability, indicating an improved moisture-wicking ability. Furthermore, the Janus ramie fabric displayed a good oil/water mixture separation performance with a separation efficiency of over 98% and good mechanical abrasion and chemical resistance. More importantly, the Janus ramie fabric showed excellent flame retardancy, a self-extinguishing ability, and a high limiting oxygen index of 34.5%, and its heat release rate, heat release capacity, and total heat release rate were significantly lower than those of pristine fabric. Therefore, this versatile Janus ramie fabric demonstrates great potential for various practical applications.

The huge and increasing amount of plastic waste harms wildlife and releases chemical hazards to the environment. Using cellulosic fibers to prepare natural fiber-reinforced plastic composites (NFRPCs) is a promising strategy to decrease plastic wastes and lower their negative impacts because cellulosic fibers are renewable, degradable, and conducive to carbon neutrality. However, the low tensile strength and recycling difficulty of NFRPCs prevent them from substituting nondegradable plastics on an industrial scale. This study prepared high-performance ramie yarn-reinforced polyimine vitrimer composites (RY-PI) that could be recycled both chemically and physically. The polyimine matrix formed a robust bonding interface with ramie yarn via hydrogen bonding. The tensile strength of RY-PI (144 MPa) was superior to that of most NFRPCs available in the market and was the highest amongst the NFRPCs with the same fiber fraction (wt%). RY-PI was also lightweight and had good toughness, self-healing ability, moldability, durability to organic solvents, and moisture barrier resistance. A box prepared by four-layer RY-PI laminates could support more than 3,000 times its own weight. The RY-PI was closed-loop recycled through a chemical strategy without any loss of performance. More importantly, a highly efficient (11 min for each recycling), low-cost, and eco-friendly (without adding any chemicals) physical recycling method of RY-PI was demonstrated. RY-PI could be physically recycled at least 9 times without any loss of performance. The high performance and good recyclability of RY-PI make it a promising environmental-friendly alternative to many conventional plastic products to help achieve zero plastic waste.

In this work, dextrin, an effective and eco-friendly organic compound, was used to separate fluorite from calcite. The depression performance and adsorption mechanism of it on the calcite surface were investigated by flotation experiments, contact angle measurements, Fourier transform infrared spectroscopy (FTIR) measurements, and Xray photoelectron spectroscopy (XPS) analyses. The results showed that fluorite can be selectively separated from calcite with 10 mg/L dextrin and 2 x 10-5 mol/L sodium laurylsulfonate (SLS). Additionally, the contact angle, FTIR and adsorption measurements indicated that the -OH group of dextrin might be adsorbed on Ca sites on the surface of calcite through chemical bonds. The inner electron binding energy of Ca2+ in fluorite is larger than the inner electron binding energy of Ca2+ in calcite, which makes it more difficult to form chemical bonds. Therefore, the chemical adsorption of dextrin on the surface of calcite is stronger than that on the surface of fluorite. Both SLS and dextrin can be adsorbed on the surface of calcite. However, dextrin is a strong hydrophilic compound, the hydrophilicity caused by dextrin is stronger than the hydrophobicity caused by SLS, so dextrin can selectively depress calcite.

Flotation separation of apatite and calcite has always been difficult because of their similar physiochemical properties. To realize the flotation separation of the two minerals, many inorganic depressants are usually used, which contaminate the environment. In this study, the behavior of the polymer molecule gum arabic (GA) as a depressant of calcite in the apatite flotation was investigated by the pure mineral flotation experiments, and the mechanism was discussed by the contact angle measurement, adsorption tests, Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The flotation results showed that GA had a significant depressive effect on calcite but not on apatite. The separation of apatite from calcite was realized by adding 50 mg/L of the depressant GA followed by 0.5 x 10(-4) mol/L of the collector sodium oleate (NaOl) at pH 7-11. The contact angle measurements showed that GA considerably enhanced the hydrophilicity of the calcite surface but had no significant effect on that of the apatite surface. The adsorption tests showed that the amount of GA adsorbed on the calcite surface was obviously greater than that on the apatite surface, indicating that calcite had a stronger affinity for GA. The FTIR and XPS analysis indicated that GA was adsorbed weakly on the apatite surface, but strongly adsorbed on the calcite surface. After GA was strongly adsorbed on the calcite surface, the abundant free -OH and -COOH groups in the GA molecule made the calcite surface more hydrophilic. Subsequently, it was hard for NaOl to be adsorbed on the calcite surface due to the reduction of active site calcium as well as the steric hindrance and electrostatic repulsion effect of GA on the NaOl molecule, which resulted in the selective depression of calcite in the apatite flotation.

Docosahexaenoic acid (DHA) is an important omega-3 polyunsaturated fatty acid (PUFA) that plays a critical physiological role in human health. Schizochytrium sp. is considered an excellent strain for DHA production, but the synthesis of DHA is limited by the availability of nicotinamide adenine dinucleotide phosphate (NADPH). In this study, the endogenous glucose-6-phosphate dehydrogenase (G6PD) gene was overexpressed in Schizochytrium sp. H016. Results demonstrated that G6PD overexpression increased the availability of NADPH, which ultimately altered the fatty acid profile, resulting in a 1.91-fold increase in DHA yield (8.81 g/L) and increased carbon flux by shifting it from carbohydrate and protein synthesis to lipid production. Thus, G6PD played a vital role in primary metabolism. In addition, G6PD significantly increased DHA content and lipid accumulation by 31.47% and 40.29%, respectively. The fed-batch fermentation experiment results showed that DHA production reached 17.01 g/L in the overexpressing G6PD strain. These results elucidated the beneficial effects of NADPH on the synthesis of PUFA in Schizochytrium sp. H016, which may be a potential target for metabolic engineering. Furthermore, this study provides a promising regulatory strategy for the large-scale production of DHA in Schizochytrium sp.

Since the physical and chemical properties of apatite and dolomite can be similar, the separation of these two minerals is difficult. Therefore, when performing this separation using the flotation method, it is necessary to search for selective depressants. An experimental research was performed on the separation behavior of apatite and dolomite using calcium lignosulfonate as a depressant, and the mechanism by which this occurs was analyzed. The results show that calcium lignosulfonate has a depressant effect on both apatite and dolomite, but the depressant effect on dolomite is stronger at the same dosage. Mechanism analysis shows that the adsorptive capacity of calcium lignosulfonate on dolomite is higher than that of apatite, which is due to the strong reaction between calcium lignosulfonate and the Ca sites on dolomite. In addition, there is a hydrogen bond between calcium lignosulfonate and dolomite, which further prevents the adsorption of sodium oleate to dolomite, thus greatly inhibiting the flotation of dolomite.

Flax is an economically important fiber crop, however, it requires degumming to yield usable fibers. The degumming process of flax roving is a key step in flax processing and production. In this study, deep eutectic solvent (DES; choline chloride–urea) pretreatment was combined with microbial treatment to develop an ecofriendly and effective degumming method for flax roving. The optimal conditions for DES pretreatment (100°C for 120 min with 90% DES) were obtained through orthogonal tests. DES combine microbial treatment could effectively remove gum from the flax fibers. The flax roving fibers were characterized by chemical analyses, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffractometry, and thermogravimetric analysis. Compared with fibers treated with microbes alone, flax roving fibers subjected to DES combine microbial treatment showed better breaking tenacity (16.77 cN/tex) and average pectin, hemicellulose, and lignin removal rates of approximately 86.4%, 26.7%, and 55.1%, respectively. NMR revealed that the composition of DES was not damaged during pretreatment, which means the bulk solution could be reused. This research showed that DES combine microbial treatment is feasible and effective method for flax roving degumming.

Through flotation tests and desorption tests, the desorption behavior of methylcellulose from the surface of talc at different temperatures and its influence on the flotation of talc were studied. The results show that the natural floatability of talc is good. The depressive effect on methylcellulose on talc is enhanced with the increase of pulp temperature. Washing can weaken the depressive effect on methylcellulose on talc, increase the flotation recovery of talc, and increase the flotation recovery of talc more at low temperature. The flotation separation of chalcopyrite and talc can be realized by using methylcellulose.

Ramie fiber is known as the “king of natural fibers,” and the key to its wide application is efficient and green manufacturing. Microbial degumming has gradually become a hot area of research due to its environmental protection and mild operating conditions. However, some gummy materials remain after microbial degumming. Xylan is the main component of residual gums; its acetylated branched chains create the space barrier that makes the removal of hemicellulose difficult during ramie degumming. An acetyl xylan esterase (AXE) was obtained from Bacillus pumilus and characterized to solve this problem. Its optimum temperature and pH were 35°C and 8.0, respectively, and it had good temperature and pH stability. These properties were consistent with the conditions of ramie degumming and they laid a foundation for the application of AXE in ramie degumming. Besides, an engineered strain with a high activity of AXE was constructed successfully on the basis of the wild-type degumming strain Pectobacterium carotovorum HG-49 and used for ramie degumming. The removal rate of hemicellulose and total gums by the engineered strain increased by 4.89% and 2.53%, respectively, compared with that of the wild-type strain. Moreover, the role of this AXE in ramie degumming was further proven by X-ray diffraction and scanning electron microscopy. This study showed that AXE played an important role in the removal of hemicellulose in the degumming process of ramie fibers, thus providing a promising degumming strategy for ramie and other bast fiber plants.

Xylanase is the key enzyme responsible for the degradation of hemicellulose and plays an important role in ramie degumming. In this study, an endo-β-1,4-xylanase xyl-1 of GH11 family from Aspergillus terreus HG-52 was cloned and identified for the first time. The protein was heterologously expressed in Escherichia coli BL21, then purified and analyzed for its biochemical properties. The optimal temperature and pH of xyl-1 are 45°C and pH 5, respectively, with a specific activity as high as 1505.11 U/mg. The immunofluorescence staining combined in-situ catalysis of ramie slices revealed that xyl-1 could degrade ramie xylan fraction. The scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy analysis of ramie fibers treated by xyl-1 showed that the treated fibers were more dispersed, the crystallinity was improved, the absorption peak of hemicellulose functional group was reduced. Residual hemicellulose content reduced from 14.93% to 5.75% and whiteness was reached 45.4, indicating xyl-1 had high-efficiency degumming ability for ramie hemicellulose. This work excavated a promising endo-β-1,4-xylanase for ramie fibers degumming applications and has good potential for commercial application.

通过浮选试验、吸附量测试、红外光谱(FTIR)分析和X射线光电子能谱(XPS)分析,研究抑制剂海藻酸钠对磷灰石和方解石浮选的影响,考察海藻酸钠对两种矿物的抑制作用机理.浮选结果表明:pH=9时海藻酸钠可强烈抑制方解石,而对磷灰石浮选的影响较小.海藻酸钠在方解石表面的吸附量大于在磷灰石表面的吸附量.海藻酸钠主要通过氢键吸附在磷灰石表面,而在方解石上的吸附则是氢键结合和化学键合共同作用所致.因此,海藻酸钠在方解石上的吸附强于磷灰石,导致其对方解石的选择性抑制.

Screening of the dominant or core oil resistant bacteria in Aged Oil Sludge (AOS) contaminated soil in Daqing and Shengli oilfields (DQ and SL) in China was investigated through High-Throughput Sequencing method. Enhanced total organic carbon (TOC, 12.53 to 28.35 g/kg in DQ and 3.07 to 4.97 g/kg in SL) and total petroleum hydrocarbons (TPHs, 21 to 2837 mg/mg in DQ and 13 to 1558 mg/kg in SL) were observed. The internal transcribed spacer (ITS) sequencing by Illumine Miseq platform at each taxonomic level revealed the notable toxicological effect of AOS on the diversity and community structure of bacteria. In this study, sequence analyses showed 77–89% and 92–98% reduction of Firmicutes at phylum level in DQ and SL respectively after treated with AOS. Enhanced universal gene location was observed in Proteobacteria, Actinobacteria, Gemmatimonadetes and Bacteroidetes in DQ and SL. The universal dominant family in the two oilfields was anaerolineaceae. At the genus level, Algiphilus in DQ and Pseudomonas in SL were the majority respectively. In total, 3 negligible genera (Perlucidibaca, Alcanivorax and Algiphilus) in DQ and 13 negligible genera (Salinisphaera, Microbulbifer and Idiomarina, et al.,) in SL were significantly enriched after oil treatment indicating their possible role in the attenuation of petroleum hydrocarbons.

The role of hydrogen peroxide (H2O2) and hydroxyethyl cellulose (HEC) in the flotation separation of chalcopyrite and galena has been investigated and the reason why H2O2 can enhance the depression effect of HEC has been explained. The results show that either H2O2 or HEC can depress galena selectively, but the reagent concentration needed is large. A small amount of HEC can completely depress the flotation of galena in the presence of H2O2, but had a little effect on chalcopyrite flotation at the same condition. Therefore, the combined use of H2O2 and HEC can achieve the flotation separation of galena and chalcopyrite. HEC adsorbed on galena surface mainly by chemical reaction with the oxidation products that were generated on galena surface and the addition of H2O2 can generate more oxidation products, which significantly improves the adsorption of HEC.

The influence of oxidizer hydrogen peroxide (H2O2) on the chalcopyrite and galena flotation separation using sodium lignosulfonate as the depressant was studied and the mechanism of H2O2 enhance depression action of sodium lignosulfonate was discussed in this study. The results show that both chalcopyrite and galena have good floatability when using potassium butylxanthate as a collector. The chalcopyrite and galena flotation separation can be realized by using large doses of sodium lignosulfonate. On the premise of using the oxidant H2O2, a small amount of sodium lignosulfonate can depress galena completely, but has a weak depression effect on chalcopyrite. Therefore, the dosage of sodium lignosulfonate can be reduced by using H2O2 and sodium lignosulfonate together. Sodium lignosulfonate adsorbed on galena surface principally by chemical reaction with the oxidates generated on galena and H2O2 promote more oxidation products on galena surface, which causes a small amount of sodium lignosulfonate to depress galena. However, the chalcopyrite has high lattice energy, which makes chalcopyrite very stable, so H2O2 has little effect on it. The depressant has low adsorption capacity on the surface of chalcopyrite, and the flotation separation can be realized.

Tungsten is a crucial rare metal with extensive application in modern industries and scheelite is the major resource for tungsten production. In this work, xanthan gum (XG), a non-toxic, environmentally friendly polysaccharide, was explored as a depressant of apatite during the scheelite flotation. The results of single mineral flotation and artificial mixed minerals flotation showed that XG exhibited efficient selective depressive effect on apatite rather than on scheelite. The Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis indicated that the chelation action between the -COO- groups and the Ca on apatite surface was responsible for XG chelating adsorption. The firm XG chemisorption on apatite surface hindered subsequent sodium oleate (NaOl) chemisorption. Due to fewer available surface Ca sites and intenser anions group electronegativity on scheelite, the XG adsorption on scheelite surface was weak and it exhibited little effect on following NaOl chemisorption. As a result, the flotation separation of scheelite from apatite was achieved using XG as depressant and NaOl as collector.