Dendrobium nobile Lindl. polysaccharide (DNP1) showed good anti-inflammatory activity in our previous study. In this study, the structural characterization of DNP1 and its mode of action on TLR4 were investigated. Structural characterization suggested that DNP1 was a linear glucomannan composed of (1 â 4)-ß-Manp and (1 â 4)-ß-Glcp residues, and the acetyl group was linked to the C-2 of Manp. The possible repeating structural units of DNP1 were [â4)-2-OAc-ß-Manp-(1â]3 â4)-ß-Glcp-(1â. Surface plasmon resonance (SPR) binding test results showed that DNP1 did not bind directly to TLR4. The TLR4 and MD2 receptor blocking tests confirmed that DNP1 needs MD2 and TLR4 to participate in its anti-inflammatory effect. The binding energy of DNP1 to TLR4-MD2 was -7.9 kcal/mol, indicating that DNP1 could bind to the TLR4-MD2 complex stably. Therefore, it is concluded that DNP1 may play an immunomodulatory role by binding to the TLR4-MD2 complex and inhibiting the TLR4-MD2-mediated signaling pathway.
The development of stable and efficient heterojunction photocatalysts for wastewater environmental purification exhibits a significant challenge. Herien, a promising binary heterojunction complex comprising boron subphthalocyanine bromide/bismuth oxychloride (SubPc-Br/BiOCl) was successfully synthesized using the hydrothermal method, which involved the self-assembled of SubPc-Br on the surface of BiOCl via intermolecular π-π stacking interactions to compose an electron-transporting layer. The photocatalytic efficiency of SubPc-Br/BiOCl for the degradation of tetracycline and the minocycline exhibited a substantial improvement of 29.14% and 53.72%, respectively, compared to the original BiOCl. Experimental characterization and theoretical calculations elucidated that the enhanced photocatalytic performance of the SubPc-Br/BiOCl composite photocatalysts stemmed from the S-scheme electron transport mechanism at the interface between BiOCl and SubPc-Br supramolecules, which broadened the visible light absorption range, increased the carrier molecular efficiency, and accelerated the carriers. Furthermore, molecular dynamic (MD) simulations provided insights into the action trajectories of the two semiconductors, revealing that the presence of SubPc-Br enhances the water and organic pollutant adsorption capabilities of the BiOCl surface within the supramolecular array system. In conclusion, the synthesis and analysis of the binary heterojunction complex SubPc-Br/BiOCl yield valuable insights into the efficient photocatalytic degradation of antibiotics, holding great promise for diverse environmental applications.
Biogas production via anaerobic digestion is highly attractive for microalgae. The technology of microalgae cultivation has profound impacts on biogas production system as it is the most energy-consuming process. However, a comprehensive evaluation of the environmental and economic benefits of different cultivation systems has yet to be sufficiently conducted. Here, life-cycle and economic assessments of open raceway ponds, photobioreactors and biofilm systems were investigated. Results showed greenhouse gas emissions of all systems were positive because more than two-thirds of carbon in fuel gas was lost and the fixed carbon in product gas and solid fertilizer was less than the emitted carbon during energy input. Particularly, biofilm system achieved the least greenhouse gas emissions (9.3 g CO2-eq/MJ), net energy ratio (0.7) and levelized cost of energy (0.9 $/kWh), indicating the optimum cultivation system. Open raceway ponds and photobioreactors failed to achieve positive benefits because of low harvesting efficiency and biomass concentration.
Greenhouse Gases , Microalgae , Biofuels/analysis , Carbon Dioxide/analysis , Biomass , Biofilms , Carbon
Constructing heterojunction of supramolecular arrays self-assembled on metal-organic frameworks (MOFs) with elaborate charge transfer mechanisms is a promising strategy for the photocatalytic oxidation of organic pollutants. Herein, H12 SubPcB-Br (SubPc-Br) and UiO-66 are used to obtain the step-scheme (S-scheme) heterojunction SubPc-Br/UiO-66 for the first time, which is then applied in the photocatalytic oxidation of minocycline. Atomic-level B-O-Zr charge-transfer channels and van der Waals force connections synergistically accelerated the charge transfer at the interface of the SubPc-Br/UiO-66 heterojunction, while the establishment of the B-O-Zr bonds also led to the directional transfer of charge from SubPc-Br to UiO-66. The synergy is the key to improving the photocatalytic activity and stability of SubPc-Br/UiO-66, which is also verified by various characterization methods and theoretical calculations. The minocycline degradation efficiency of supramolecular SubPc-Br/UiO-66 arrays reach 90.9% within 30 min under visible light irradiation. The molecular dynamics simulations indicate that B-O-Zr bonds and van der Waals force contribute significantly to the stability of the SubPc-Br/UiO-66 heterojunction. This work reveals an approach for the rational design of semiconducting MOF-based heterojunctions with improved properties.
The industrial robot-based polisher has wide applications in the field of optical manufacturing due to the advantages of low cost, high degrees of freedom, and high dynamic performance. However, the large positioning error of the industrial robot can lead to surface ripple and seriously restrict the system performance, but this error can only be inefficiently compensated for by measurement before each processing at present. To address this problem, we discovered the period-phase evolution law of the positioning error and established a double sine function compensation model. In the self-developed robotic polishing platform, the results show that the Z-axis error in the whole workspace after compensation can be reduced to ±0.06m m, which reaches the robot repetitive positioning error level; the Spearman correlation coefficients between the measurement and modeling errors are all above 0.88. In the practical polishing experiments, for both figuring and uniform polishing, the ripple error introduced by the positioning error is significantly suppressed by the proposed model under different conditions. Besides, the power spectral density (PSD) analysis has shown a significant suppression in the corresponding frequency error. This model gives an efficient plug-and-play compensation model for the robotic polisher, which provides possibilities for further improving robotic processing accuracy and efficiency.
Laser ablation is widely used as a flexible and non-contact processing technology for the fabrication of fused silica. However, the introduction of thermal stress inevitably leads to crack growth and reduces the lifetime of fused silica. Due to the complicated coupling interaction and properties of fused silica, the unclear thermal stress formation is the bottleneck restricting further development of laser ablation. In this article, a three-dimensional multi-physics thermo-mechanical model was developed to reveal the evolution mechanism, and experiments were performed to validate the simulated results. The surface morphology evolution was elaborated during process cycles, with recoil pressure identified as the key factor in determining surface morphology. Moreover, thermal stress was quantified utilizing optical retardance and stress birefringence, effectively distinguishing between non-thermal and thermal stress induced by laser ablation. The theoretical simulations fit well with experimental measurements. Meanwhile, stress distribution and evolution behaviors were revealed under different processing parameters by this model. This work not only contributes to a profound understanding of the laser ablation process but also establishes a theoretical foundation for achieving high surface quality and non-thermal stress laser ablation.
Laser beam figuring (LBF), as a processing technology for ultra-precision figuring, is expected to be a key technology for further improving optics performance. To the best of our knowledge, we firstly demonstrated CO2 LBF for full-spatial-frequency error convergence at negligible stress. We found that controlling the subsidence and surface smoothing caused by material densification and melt under specific parameters range is an effective way to ensure both form error and roughness. Besides, an innovative "densi-melting" effect is further proposed to reveal the physical mechanism and guide the nano-precision figuring control, and the simulated results at different pulse durations fit well with the experiment results. Plus, to suppress the laser scanning ripples (mid-spatial-frequency (MSF) error) and reduce the control data volume, a clustered overlapping processing technology is proposed, where the laser processing in each sub-region is regarded as tool influence function (TIF). Through the overlapping control of TIF figuring depth, we achieved LBF experiments for the form error root mean square (RMS) reduced from 0.009λ to 0.003λ (λ=632.8â nm) without destroying microscale roughness (0.447â nm to 0.453â nm) and nanoscale roughness (0.290â nm to 0.269â nm). The establishment of the densi-melting effect and the clustered overlapping processing technology prove that LBF provides a new high-precision, low-cost manufacturing method for optics.
Rice, supplemented with Dendrobium officinale, was subjected to cofermentation using Saccharomyces cerevisiae FBKL2.8022 (Sc) and Wickerhamomyces anomalus FBKL2.8023 (Wa). The alcohol content was determined with a biosensor, total sugars with the phenol-sulfuric acid method, reducing sugars with the DNS method, total acids and total phenols with the colorimetric method, and metabolites were analyzed using LC-MS/MS combined with multivariate statistics, while metabolic pathways were constructed using metaboAnalyst 5.0. It was found that the quality of rice wine was higher with the addition of D. officinale. A total of 127 major active substances, mainly phenols, flavonoids, terpenoids, alkaloids, and phenylpropanoids, were identified. Among them, 26 substances might have been mainly metabolized by the mixed-yeasts fermentation itself, and 10 substances might have originated either from D. officinale itself or from microbial metabolism on the newly supplemented substrate. In addition, significant differences in metabolite could be attributed to amino acid metabolic pathways, such as phenylalanine metabolism and alanine, aspartate, and glutamate metabolism. The characteristic microbial metabolism of D. officinale produces metabolites, which are α-dihydroartemisinin, alantolactone, neohesperidin dihydrochalcone, and occidentoside. This study showed that mixed-yeasts cofermentation and fermentation with D. officinale both could increase the content of active substances in rice wine and significantly improve the quality of rice wine. The results of this study provide a reference for the mixed fermentation of brewer's yeast and non-yeast yeasts in rice wine brewing.
Intelligent manufacturing of ultra-precision optical surfaces is urgently desired but rather difficult to achieve due to the complex physical interactions involved. The development of data-oriented neural networks provides a new pathway, but existing networks cannot be adapted for optical fabrication with a high number of feature dimensions and a small specific dataset. In this Letter, for the first time to the best of our knowledge, a novel Fourier convolution-parallel neural network (FCPNN) framework with library matching was proposed to realize multi-tool processing decision-making, including basically all combination processing parameters (tool size and material, slurry type and removal rate). The number of feature dimensions required to achieve supervised learning with a hundred-level dataset is reduced by 3-5 orders of magnitude. Under the guidance of the proposed network model, a 260 mm × 260 mm off-axis parabolic (OAP) fused silica mirror successfully achieved error convergence after a multi-process involving grinding, figuring, and smoothing. The peak valley (PV) of the form error for the OAP fused silica mirror decreased from 15.153λ to 0.42λ and the root mean square (RMS) decreased from 2.944λ to 0.064λ in only 25.34 hours. This network framework has the potential to push the intelligence level of optical manufacturing to a new extreme.
Microbial community in natural or artificial environments playes critical roles in substance cycles, products synthesis and species evolution. Although microbial community structures have been revealed via culture-dependent and culture-independent approaches, the hidden forces driving the microbial community are rarely systematically discussed. As a mode of cell-to-cell communication that modifies microbial interactions, quorum sensing can regulate biofilm formation, public goods secretion, and antimicrobial substances synthesis, directly or indirectly influencing microbial community to adapt to the changing environment. Therefore, the current review focuses on microbial community in the different habitats from the quorum sensing perspective. Firstly, the definition and classification of quorum sensing were simply introduced. Subsequently, the relationships between quorum sensing and microbial interactions were deeply explored. The latest progressives regarding the applications of quorum sensing in wastewater treatment, human health, food fermentation, and synthetic biology were summarized in detail. Finally, the bottlenecks and outlooks of quorum sensing driving microbial community were adequately discussed. To our knowledge, this current review is the first to reveal the driving force of microbial community from the quorum sensing perspective. Hopefully, this review provides a theoretical basis for developing effective and convenient approaches to control the microbial community with quorum sensing approaches.
Anti-Infective Agents , Microbiota , Humans , Quorum Sensing/physiology , Bacteria/genetics , Microbial Interactions , Anti-Infective Agents/pharmacology , Biofilms
In ultra-precision optical processing, the sub-aperture polishing is prone to produce a mid-spatial-frequency (MSF) error. However, the generation mechanism of the MSF error is still not fully clarified, which seriously affects the further improvement of optical component performance. In this paper, it is proved that the actual contact pressure distribution between the workpiece and tool is a crucial source which affects the MSF error characteristics. A rotational periodic convolution (RPC) model is proposed to reveal the quantitative relationship among the contact pressure distribution, speed ratio (spin velocity/feed speed) and MSF error distribution. In-depth analyses show that the MSF error is linearly related to the symmetry level of contact pressure distribution and inversely proportional to the speed ratio, where the symmetry level is effectively evaluated by the proposed method based on Zernike polynomials. In the experiments, according to the actual contact pressure distribution obtained from the pressure-sensitive paper, the error rate of modeling results under different processing conditions is around 15%, which proves the validity of the proposed model. The influence of contact pressure distribution on the MSF error is further clarified through the establishment of RPC model, which can further promote the development of sub-aperture polishing.
Bioaccumulation through diet is the predominant source of metal(loid)s in fishes; however, the trophic transfer of metal(loid)s from the diet to aquatic organisms remains largely unclear. In this study, aquatic organisms and five potential food sources (leaf litter, coarse and fine particulate organic matter (CPOM and FPOM, respectively), epilithon and fish) were collected around the Shimen Realgar Mine of China. Stomach content analysis and stable nitrogen and carbon isotope analysis, combined with a new Bayesian mixing model (MixSIAR), were used to quantify diet compositions of aquatic organisms. The δ13C and δ15N values varied among fish sizes and sampling sites and were probably related to the diet shift of aquatic organisms. The MixSIAR modelling results showed that the aquatic organisms' food sources were mainly composed of FPOM (9%-68%) and epilithon (15%-65%), with leaf litter, CPOM and fish accounting for smaller proportions (2%-30%). Concentrations ranged from 0.91 to 1298 mg/kg for As, 0.01-1.30 mg/kg for Cd, 0.12-37.79 mg/kg for Pb, 0.63-1158 mg/kg for Cr, 1.22-411 mg/kg for Cu, 0.82-1772 mg/kg for Mn, 0.31-542 mg/kg for Ni and 21.84-1414 mg/kg for Zn in all the collected samples, including the aquatic organisms and the relevant food sources. The metal(loid) concentrations in the CPOM, FPOM and epilithon were significantly higher than those in aquatic organisms and leaf litter. In addition, the biomagnification factors were all less than 1, indicating a biodilution from diet to freshwater organisms. The predominant As species were organic As in aquatic organisms, while inorganic As was common in their food sources, indicating that As biotransformation occurred within the freshwater food chain.
Arsenic , Animals , Arsenic/analysis , Aquatic Organisms/metabolism , Bayes Theorem , Metals/metabolism , Fishes/metabolism , Fresh Water , Diet
Heap leaching ionic rare earth tailings might be prone to nourish sulfate reducing bacteria (SRB), but the SRB community in terrestrial ecosystems, such as tailings, has never been studied. This work was conducted to investigate the SRB communities in revegetated and bare tailings in Dingnan county, Jiangxi province, China, incorporating with indoor experiments to isolate SRB strain in bioremediation of Cd contamination. Significant increases in richness, accompanied by reductions in evenness and diversity, were found in the SRB community in revegetated tailings compared to bare tailings. At genus taxonomic level, two distinct dominant SRB were observed in samples from bare and revegetated tailings, with Desulfovibrio dominating in the former and Streptomyces dominating in the latter, respectively. A single SRB strain was screened out from the bare tailings (REO-01). The cell of REO-01 was rod-shaped and belonged to family Desulfuricans and genus Desulfovibrio. The Cd resistance of the strain was further examined, no changes in cell morphology were observed at 0.05 mM Cd, additionally, the atomic ratios of S, Cd, and Fe changed with the increase in Cd dosages, indicating FeS and CdS were produced simultaneously, XRD results further confirmed the production changed gradually from FeS to CdS with increasing Cd dosages from 0.05 to 0.2 mM. FT-IR analysis showed that functional groups containing amide, polysaccharide glycosidic linkage, hydroxyl, carboxy, methyl, phosphodiesters and sulfhydryl groups in extracellular polymeric substances (EPS) of REO-01 might have affinity with Cd. This study demonstrated the potential of a single SRB strain isolated from ionic rare earth tailings in bioremediation of Cd contamination.
Desulfovibrio , Metals, Rare Earth , Cadmium/analysis , Biodegradation, Environmental , Ecosystem , Spectroscopy, Fourier Transform Infrared , Sulfates/analysis
Subaperture polishing is a key technique for fabricating ultra-precision optics. However, the error source complexity in the polishing process creates large fabrication errors with chaotic characteristics that are difficult to predict using physical modelling. In this study, we first proved that the chaotic error is statistically predictable and developed a statistical chaotic-error perception (SCP) model. We confirmed that the coupling between the randomness characteristics of chaotic error (expectation and variance) and the polishing results follows an approximately linear relationship. Accordingly, the convolution fabrication formula based on the Preston equation was improved, and the form error evolution in each polishing cycle for various tools was quantitatively predicted. On this basis, a self-adaptive decision model that considers the chaotic-error influence was developed using the proposed mid- and low-spatial-frequency error criteria, which realises the automatic decision of the tool and processing parameters. An ultra-precision surface with equivalent accuracy can be stably realised via proper tool influence function (TIF) selection and modification, even for low-deterministic level tools. Experimental results indicated that the average prediction error in each convergence cycle was reduced to 6.14%. Without manual participation, the root mean square(RMS) of the surface figure of a Ï100-mm flat mirror was converged to 1.788â nm with only robotic small-tool polishing, and that of a Ï300-mm high-gradient ellipsoid mirror was converged to 0.008 λ. Additionally, the polishing efficiency was increased by 30% compared with that of manual polishing. The proposed SCP model offers insights that will help achieve advancement in the subaperture polishing process.
Biofilm plays an important role in resisting the adverse environment, improving the taste and texture, and promoting the synthesis of flavor substances. However, to date, the findings on the effect of biofilm and dominating bacteria Bacillus on the ester synthesis in the Baijiu field have been largely lacked. Therefore, the objectives of the present study were to primarily isolate biofilm-producing microbes in the fermented grains, evaluate the stress tolerance capacity, and unveil the effect of biofilm and co-culture with Bacillus on the ester synthesis in the strong flavor Baijiu. Results indicated that after isolation and evaluation of stress-tolerance capacity, bacterial strain BG-5 and yeast strains YM-21 and YL-10 were demonstrated as mediate or strong biofilm-producing microbes and were identified as Bacillus velezensis, Saccharomycopsis fibuligera, and Zygosaccharomyces bailii, respectively. Solid phase microextraction/gas chromatography-mass spectrometer indicated that biofilm could enhance the diversity of esters while reduce the contents of ester. The scanning electron microscopy showed an inhibitory effect of B. velezensis on the growth of S. fibuligera, further restraining the production of esters. Taken together, both biofilm and B. velezensis influence the ester synthesis process. The present study is the first to reveal the biofilm-producing microorganisms in fermented grains and to preliminarily investigate the effect of biofilm on the ester synthesis in the Baijiu field.
Bacillus , Esters , Coculture Techniques , Bacteria , Biofilms , Saccharomyces cerevisiae
The exploitation of ionic rare earth ore using ammonium sulfate extractant in China caused serious soil degradation and nitrogen compounds pollution in surrounding water. It was critical to improve soil properties and eliminate the nitrogen compounds and prevent their diffusion from the rare earth tailings. Here, we addressed this issue by conducting a field experiment for six months through four different treatments including control (CK), denitrifying bacteria agent mainly consisted of Bacillus (DBA), composite materials (CM) and denitrifying bacteria agent together with composite materials (DBA+CM). Besides, the treatments except CK were also amended with basic soil conditioners. DBA+CM could significantly increase soil pH from 5.01 to 6.84 (p ≤ 0.05). Cation exchange capacity in DBA+CM increased from below detection limit to 2.79 cmol+/kg. DBA+CM possessed the highest removal rate of soil NH4+ (95.14 %) and soil NO3- (66.46 %). Compared to CK, DBA+CM significantly increased the absolute abundance of nirS genes and relative abundance of denitrification, nitrate respiration, and nitrite respiration the most (p ≤ 0.05). Denitrification, nitrate respiration and nirS genes were negatively correlated with soil NO3- (p ≤ 0.05). This study demonstrates denitrifying bacteria agent together with composite materials can be a promising approach to control the pollution of nitrogen compounds in ionic rare earth tailings.
Metals, Rare Earth , Soil , Soil/chemistry , Nitrates/analysis , Nitrites , Soil Microbiology , Bacteria/genetics , Denitrification , Nitrogen
Ionic rare earth mining has resulted in large amounts of bare soils, and revegetation success plays an important role in mine site rehabilitation and environmental management. However, the mining soils still maintain high NH4+ concentrations that inhibit plant growth and NH4+ toxicity thresholds for restoration plants have not been established. Here we investigated the NH4+ toxicological effects and provided toxicity thresholds for grasses (Lolium perenne L. and Medicago sativa L.) commonly used in restoration. The results show that high NH4+ concentration not only reduces the plant biomass and soluble sugars in leaves but also increases the H2O2 and MDA content, and SOD, POD, and GPX activities in roots. The SOD activities and root biomass can be adopted as the most NH4+ sensitive biomarkers. Six ecotoxicological endpoints (root biomass, soluble sugars, proline, H2O2, MDA, and GSH) of ryegrass, eight ecotoxicological endpoints (root biomass, soluble sugars, proline, MDA, SOD, POD, GPX, and GSH) of alfalfa were selected to determine the threshold concentrations. The toxicity thresholds of NH4+ concentrations were proposed as 171.9 (EC5), 207.8 (EC10), 286.6 (EC25), 382.3 (EC50) mg kg-1 for ryegrass and 171.9 (EC5), 193.2 (EC10), 234.7 (EC25), 289.6 (EC50) mg kg-1 for alfalfa. The toxicity thresholds and the relation between plant physiological indicators and NH4+ concentrations can be used to assess the suitability of the investigated plants for ecological restoration strategies.
Ammonium Compounds , Lolium , Soil Pollutants , Poaceae , Soil , Ammonium Compounds/toxicity , Hydrogen Peroxide , Soil Pollutants/toxicity , Soil Pollutants/analysis , Plants , Sugars , Proline , Superoxide Dismutase
The structure and the effect of polysaccharide from peach gum (DPG2) on ameliorating DSS-induced acute colitis in mice were investigated in the present study. The results showed that DPG2 was identified as an AG II arabinogalactan with the backbone of ß-D-(1 â 6)-galactan, which consisted of mannose, glucuronic acid, galactose, xylose and arabinose with a molar ratio of 4.64:1.02:2.61:39.82:3.89:48.02. Moreover, DPG2 behaved as a flexible chain conformation with a coil-like structure with a molecular weight (Mw) of 5.21 × 105 g/mol. Furthermore, the worm-like chain model parameters for DPG2 were estimated as follows: ML = 379 nm-1, q = 0.74 nm and d = 0.82 nm. The results of the animal assay showed that the intake of DPG2 not only effectively improved the phenotypes of DSS-induced colitis in mice, but also significantly improved the oxidative stress status of mice, such as regulating NO content and T-SOD and MPO levels and repairing oxidative damage to the colonic mucosa. Moreover, DPG2 improved the inflammation of DSS-induced colitis in mice by inhibiting the secretion of the proinflammatory cytokines TNF-α, IFN-γ, IL-1ß, IL-6 and IL-17. Therefore, these results suggested that peach gum polysaccharide showed protective effects against colitis, and has great potential for the application of functional components in the food industry.
Colitis , Prunus persica , Animals , Mice , Colitis/chemically induced , Colitis/drug therapy , Colon , Inflammation , Cytokines , Polysaccharides/chemistry , Dextran Sulfate/adverse effects , Mice, Inbred C57BL , Disease Models, Animal
Mining activities can result in severe heavy metal contamination in freshwater ecosystems and lead to significant health risks. In this study, eight heavy metal concentrations in the water, sediments and aquatic organisms, including eighteen fish species, two shrimp species, one crab species and one amphibian frog species of the abandoned Shimen Realgar Mine area, were analysed. The results showed that most of the heavy metals detected in water, sediments and fish from the mine area were at relatively high levels, and historical realgar mining activities were a major source of arsenic (As) contamination in this area. We concluded that heavy metal bioaccumulation is species- and tissue-specific and is different for each element and sampling site. The concentration of heavy metals in fish was generally lower than that of the other aquatic organism species; these concentrations varied among different species with different feeding habits and habitats. The study showed that heavy metal concentrations were lower in muscle tissue than in other tissues (e.g. liver, skin, exoskeleton). A significant positive correlation between the As concentrations in sediment and fish was observed, indicating that sediment is an important factor affecting As accumulation in fish; thus, for fish protection, controlling the sources of water and sediment contamination is essential. Furthermore, the estimated daily intake (EDI) of all metals was acceptable, and the corresponding target hazard quotient (THQ) and total target hazard quotient (TTHQ) values were less than 1; hence, there was no serious health risk through fish consumption in this area.
Arsenic , Metals, Heavy , Water Pollutants, Chemical , Animals , Aquatic Organisms , Water/analysis , Ecosystem , Environmental Monitoring/methods , Metals, Heavy/analysis , Arsenic/analysis , Fishes , Water Pollutants, Chemical/analysis , Risk Assessment , Geologic Sediments
In the present study, we investigated the in vitro digestion and fermentation characteristics of three peach gum polysaccharides (PGPs) of different molecular weights; i.e., AEPG2 (1.64 × 107 g/mol), DPG2 (5.21 × 105 g/mol), and LP100R (8.50 × 104 g/mol). We observed that PGPs were indigestible during the oral, gastrointestinal, and intestinal stages. However, they were utilized by the gut microbiota with utilization rates in the order of DPG2 > AEPG2 > LP100R. Furthermore, arabinose in PGPs was preferentially utilized by the gut microbiota followed by galactose and xylose. Fermentation of peach gum polysaccharides could significantly increase the production of short-chain fatty acids (SCFAs), especially n-butyric acid. In addition, PGPs with different molecular weights values were predominantly fermented by different bacterial species. AEPG2 and DPG2 were fermented by the Bacteroidetes bacteria Bacteroides, while the dominant n-butyrate-producing bacteria was Faecalibacterium. While the LP100R was fermented by Bacteroides, Parabacteroides, Phascolarctobacterium, Dialister, Lachnospiraceae, and Blautia, the dominant n-butyrate-producing bacteria was Megamonas. These results indicated that PGPs are potential prebiotics for the food industry.
