Polysaccharide Content Research Articles

Impact of Conditioning Agent Addition Sequence on Dewatering Performance of Advanced Anaerobic Digested Sludge

The advanced anaerobic digestion process enhances sludge resource utilization. However, thermal hydrolysis pretreatment of anaerobically digested sludge reduces dewatering efficiency due to excessive organic matter decomposition. This necessitates significant time and effort for sludge conditioning in wastewater treatment plants. Using conditioning agents can achieve high dewatering efficiency. This study investigates how the order of adding coagulants and flocculants impacts the dewatering performance of digested sludge. The results indicate that, compared to the flocculation–coagulation process with the same dosage, the coagulation–flocculation process leads to a 15–20% increase in the average particle size of digested sludge. The content of polysaccharides and proteins in S-EPS decreases by 28.8–30.8% and 10.1–11.3%, respectively. The filter cake solids content increases by 8.5%, and there is an increase in surface water channels within the flocs. This is because initially adding coagulants efficiently adsorbs small particles, forming larger aggregates that settle effectively. This promotes the breakdown of extracellular polymeric substances, releasing more bound water. Adding flocculants later bridges the aggregates, further enhancing settling and filtration performance, thereby improving sludge dewatering efficiency. These research findings contribute to a better understanding of the mechanisms of coagulant and flocculant co-conditioning for digested sludge and provide recommendations for optimizing sludge conditioning steps.

Nanoplastics increase algal absorption and toxicity of Cd through alterations in cell wall structure and composition

Nanoplastics (NPs) may act as carriers of heavy metals and cause complex toxicity to aquatic organisms, while the exact role of NPs in the joint toxicity remains unclear. Here, we investigated the joint toxicity of polystyrene NPs (PS-NPs) and Cd to freshwater algae (Chlorella vulgaris). It was found that PS-NPs (1 mg L−1) could hardly enter algal cells and slightly inhibit algal growth (p < 0.01). The effect of PS-NPs as carriers on the joint toxicity of PS-NPs and heavy metals could be neglected because of the limited adsorption of Cd by PS-NPs, while the PS-NPs altered the cell wall structure and composition, which resulted in the increased algal absorption and toxicity of Cd. Compared to the low dose Cd (0.4 mg L−1) treatment alone, the extracellular and intracellular Cd contents in the cotreatment were significantly increased by 27.3 % and 18.0 %, respectively, due to the increased contents of cell wall polysaccharides (pectin and hemicellulose in particular) by the PS-NPs. Furthermore, after the high dose Cd (2 mg L−1) exposure, the inhibited polysaccharide biosynthesis and the loosen cell wall structure weakened the tolerance of cell wall to abiotic stress, facilitating the entry of PS-NPs into the algal cells and inducing the higher toxicity. These results elucidate the mechanism by which NPs enhance heavy metal toxicity to algae, providing a novel insight into environmental risks of NPs.

Combining thermal–alkaline hydrolysis pretreatment with catalytic supercritical water gasification for hydrogen production from sewage sludge

An integrated process consisting of a thermal–alkaline hydrolysis pretreatment (TAHP) combined with catalytic supercritical water gasification (CSCWG) was developed to treat sewage sludge to produce H2. TAHP facilitated the transfer of organics from sludge into liquid products for subsequent CSCWG to produce H2. Upon increasing the hydrolysis temperature, time, and alkali dosage, the continuous transfer of organics to liquid products was observed, wherein the hydrolysis temperature had the greatest effect. Under the optimal pretreatment conditions (180 °C, 1 h, and mNaOH/mOM = 25 %), approximately 70 % of proteins, carbohydrates, and 50 % of humus in sludge, i.e., easily gasified organic species, were transferred. Using this process, the TOC concentration in the liquid products reached about 17,000 mg/L, and the polysaccharide and soluble protein concentrations reached 2400 and 15,000 mg/L, respectively. With this integrated process, the H2 yield and selectivity increased by 3.7–7.6 times and 5.94–52.92 times, respectively, compared with the directly catalyzed gasification of sludge. This improvement occurred because TAHP promoted the transfer of easily gasified organic species into the liquid products, while the difficult-to-gasify organics and inorganics in ash remained in the solid phase, which prevented them from inhibiting the catalyst.

Rheological and mechanical behavior of soy protein-polysaccharide composite paste for extrusion-based 3D food printing: Effects of type and concentration of polysaccharides

Soy protein isolate (SPI)-based pastes are widely employed for 3D printing of food materials. However, their rheological properties often do not meet the 3D printing requirements. To enhance the 3D printing characteristics of SPI pastes, this study combined SPI with carrageenan and sodium alginate to form composite materials. The effect of polysaccharide type and concentration on the rheological and textural properties of the ink was investigated to elucidate the mechanism of interaction between proteins and polysaccharides. The results demonstrated that the addition of carrageenan (1.5%, wt %) and sodium alginate (1.5%, wt %) effectively improved the mechanical properties of the paste, such as hardness and adhesiveness, enhanced thus the quality of 3D printed products. With the increase of polysaccharide proportion, the apparent viscosity and storage modulus (G′) of the composite paste increased significantly. Fourier-transform infrared spectroscopy (FT-IR), protein solubility measurement, X-ray diffraction (XRD), and differential scanning calorimetry (DSC) were employed and the results revealed notable interactions among SPI and two kinds of polysaccharides, with electrostatic interactions and hydrophobic interactions being the primary driving forces. The addition of polysaccharides induced changes in the paste crystalline state and improved its thermal stability. Scanning electron microscopy (SEM) confirmed a uniform and compact microstructure due to the incorporation of polysaccharides. Consequently, the SPI-polysaccharide paste can be considered as novel material for 3D printing food materials, and the results of this study provides a theoretical foundation for its application in the field of plant-based food products.

Unraveling the significance of calcium as a biofilm promotion signal for Bacillus licheniformis strains isolated from dairy products

Bacillus licheniformis, a quick and strong biofilm former, is served as a persistent microbial contamination in the dairy industry. Its biofilm formation process is usually regulated by environmental factors including the divalent cation Ca2+. This work aims to investigate how different concentrations of Ca2+ change biofilm-related phenotypes (bacterial motility, biofilm-forming capacity, biofilm structures, and EPS production) of dairy B. licheniformis strains. The Ca2+ ions dependent regulation mechanism for B. licheniformis biofilm formation was further investigated by RNA-sequencing analysis. Results revealed that supplementation of Ca2+ increased B. licheniformis biofilm formation in a dose-dependent way, and enhanced average coverage and thickness of biofilms with complex structures were observed by confocal laser scanning microscopy. Bacterial mobility of B. licheniformis was increased by the supplementation of Ca2+ except the swarming ability at 20 mM of Ca2+. The addition of Ca2+ decreased the contents of polysaccharides but promoted proteins production in EPS, and the ratio of proteins/polysaccharides content was significantly enhanced with increasing Ca2+ concentrations. RNA-sequencing results clearly indicated the variation in regulating biofilm formation under different Ca2+ concentrations, as 939 (671 upregulated and 268 downregulated) and 951 genes (581 upregulated and 370 downregulated) in B. licheniformis BL2-11 were induced by 10 and 20 mM of Ca2+, respectively. Differential genes were annotated in various KEGG pathways, including flagellar assembly, two-component system, quorum sensing, ABC transporters, and related carbohydrate and amino acid metabolism pathways. Collectively, the results unravel the significance of Ca2+ as a biofilm-promoting signal for B. licheniformis in the dairy industry.

Antimicrobial Activities of Polysaccharides Isolated from Some Plant Seeds

The present investigation is about the measurement of antimicrobial activity (AMA) of polysaccharides isolated from the seeds of pumpkin (Cucurbita pepo), purslane (Portulaca oleracea), safflower (Carthamu stinctorius),coriander (Coriandrum sativum) and rapeseed (Brassica napus) against Staphylococcus aureus (S.aureus), Escherichia coli (E.coli), Bacillus subtilis (B.subtilis) and (MRSA) at different concentrations using agar diffusion method In vitro. Polysaccharides (PSs) were extracted, isolated and purified from different seeds separately. Paper chromatographic analysis of the purified PSs, revealed the presence of different percentages of monosaccharides constituents per each seed PS. In vitro study was performed to evaluate the obtained PSs activities against 4 microbial strains (S. aureus, E. coli, B subtilis and MRSA) using agar diffusion method. PSs showed AMA against S. aureus and E. coli more than that of B subtilis and MRSA at 10% concentration and inhibition zones were estimated. Minimal inhibitory concentrations (MIC) of PSs against S. aureus, E. coli, B subtilis and MRS were found in the range of 1-5 mg/ml. The result demonstrates the killing effect of PSs against S. aureus, E. coli, B subtilis and MRSA at 10% PS within 24 hours. Inhibition zone diameters exhibited different levels of decreases with the PSs concentrations decreases against S. aureus, E. coli, B. subtilis and MRSA. Inhibition effects of PSs against different microbial strains were found to be depending on PSs concentration. However, the lowest concentration of PSs produced lower inhibitory activity against S. aureus B. subtilis E. coli and MRSA. The results obtained with all PSs showed best AMA against S. aureus and E. coli than the other two microbial strains used in the present study. Results indicated these PSs have AMA against Gram-positive and Gram-negative bacterium at 10% concentration. The common PSs consider important sources of antimicrobial agents with minimal inhibitory concentrations of 100-500µg/ml for treatment some infectious diseases.

New reports on the association between eggs and sclerotium-forming fungi in Neotropical termites with insights into this mutualistic interaction

Abstract Over many years of co-evolution, termites and fungi have developed varied interactions. Sclerotia, termed termite balls, are fungal resting structures often mixed with termite eggs, with many reports in temperate areas. Here, we show that this interaction is more widespread than suggested, by reporting the occurrence of fungal sclerotia harboured in the nests of four Neotropical termitids: Cornitermes cumulans, Silvestritermes euamignathus (Syntermitinae), Velocitermes heteropterus, and Nasutitermes corniger (Nasutitermitinae). We performed termite–fungus recognition bioassays and carried out morphometrical, histological, and histochemical analyses on the sclerotia, assuming that they vary in their stored materials according to the maturation stage. Morphometrical and morphological features varied among the sclerotia associated with the different termite species. Moreover, workers preferentially carried related sclerotia, suggesting a species-specific interaction, and did not mistake them for eggs. Immature and mature sclerotia varied in the concentration of stored proteins, polysaccharides, and melanin. This facultative mutualism is advantageous for the sclerotia because they are kept in a competitor-free environment and, in turn, are likely to serve as an additional source of termite digestive enzymes. We provide new findings concerning the geographical distribution, termite species, and nesting habits related to this termite–fungus association, reinforcing its parallel evolution.

Detection and characterization of the Pichia manshurica biofilm on the traditionally produced homemade apple vinegar.

Pichia yeasts are capable of forming biofilms during vinegar production and causing spoilage in various beverages. In addition, there exists a significant likelihood of encountering yeast contamination which can prevent vinegar production. The present study investigates the detection and characterization of the Pichia manshurica (P. manshurica) biofilm on traditionally produced homemade apple vinegar. The unique characteristics of vinegar were analyzed with a focus on the constituent, known as the "mother of vinegar", whose composition is comprised of cellulosic biofilm and acetic acid bacteria, including Gluconobacter oxydans (G. oxydans) Briefly, P. manshurica was isolated from apple vinegar and characterized in terms of the effect of biofilm formation on the surface of the cellulosic film on vinegar production. Microbial identification of vinegar with/without contamination by P. manshurica was analyzed through MALDI-TOF mass spectrometry (MS), and biofilm was characterized by Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), and crystal violet staining. Accordingly, MS spectrum of isolates was identified as G. oxydans and P. manshurica with a ratio of 2.01 and 1.94, respectively. The FTIR analysis indicated that the peaks within the range of 1150-900 cm-1 revealed a high content of polysaccharide in P. manchuria-contaminated biofilm, which is attributed to the stretching vibration of C-C and C-O bonds. The spectral region from 2921.51 to 2853.71 cm-1 exhibited the characteristic of lipids in bacterial cell walls and membranes. SEM images of bacterial biofilms revealed a three-dimensional network composed of ultrafine fibers with a ribbon-like shape; however, the condensed reticulated structure was observed in contaminated biofilms. The presence of two microbial populations was detected regarding the morphological analysis. Crystal violet staining of contaminated-cellulosic biofilms visualized bacterial and yeast colonization. Concisely, this study emphasizes that the proliferation of Pichia during apple fermentation has the potential to adversely affect the quality of the homemade vinegar, due to its distinct biofilm characteristics.

Transcriptomic analysis reveals ozone treatment delays kiwifruit postharvest softening by modulating cell wall metabolism.

Kiwifruit ripening and senescence after harvesting are closely related to its economic value. Transcriptome analysis and biochemical parameters were used to investigate the differences in gene expression levels and the potential regulation of cell wall metabolism in kiwifruit treated with ozone, thereby regulating fruit softening and prolonging postharvest life. Compared to the control group, the activities of the cell wall modification enzyme were lower under ozone treatment, the content of polysaccharide in the cell wall of primary pectin and cellulose was higher, and the content of soluble pectin was lower. Meanwhile, ozone treatment delayed the degradation of the cell wall mesosphere during storage. A total of 20 pectinesterase (PE)-related genes were identified by sequencing analysis. The data analysis and quantitative polymerase chain reaction results confirmed that cell wall modifying enzyme genes played an important role in softening and senescence after harvesting, which may reduce or induce the expression of certain genes affecting cell wall metabolism. Ozone treatment not only regulates active genes such as xyloglucan endo glycosyltransferase/hydrolase, cellulose synthase, polygalacturonase, and PE to maintain the quality of fruit after harvest but also acts synergically with cell wall modifying enzymes to inhibit the degradation of cell wall, resulting in changes in the ultrastructure of cell wall, thereby reducing the hardness of kiwifruit. In addition, according to the results of cis-acting elements, cell wall degradation is also related to downstream hormone signaling, especially PE-related genes. These results provide a theoretical basis for studying the mechanism of firmness and cell wall metabolism difference of kiwifruit and also lay a good foundation for further research.

Effects and Underlying Mechanisms of Rice-Paddy-Upland Rotation Combined with Bacterial Fertilizer for the Abatement of Radix pseudostellariae Continuous Cropping Obstacles

Radix pseudostellariae is one of the well-known genuine medicinal herbs in Fujian province, China. However, the continuous cropping obstacles with respect to R. pseudostellariae have seriously affected the sustainable utilization of medicinal resources and the development of related industrial systems. The occurrence of continuous cropping obstacles is a comprehensive effect of multiple deteriorating biological and abiotic factors in the rhizosphere soil. Therefore, intensive ecological methods have been the key to abating such obstacles. In this study, four treatments were set up, i.e., fallow (RP-F), fallow + bacterial fertilizer (RP-F-BF), rice-paddy-upland rotation (RP-R), and rice-paddy-upland rotation + bacterial fertilizer (RP-R-BF), during the interval between two plantings of R. pseudostellariae, with a newly planted (NP) treatment as the control. The results show that the yield of R. pseudostellariae under the RP-F treatment decreased by 46.25% compared to the NP treatment. Compared with the RP-F treatment, the yields of the RP-F-BF, RP-R, and RP-R-BF treatments significantly increased by 14.11%, 27.79%, and 62.51%, respectively. The medicinal quality of R. pseudostellariae treated with RP-R-BF was superior to that achieved with the other treatments, with the total saponin and polysaccharide contents increasing by 8.54% and 27.23%, respectively, compared to the RP-F treatment. The ecological intensive treatment of RP-R-BF significantly increased the soil pH, content of organic matter, abundance of beneficial microbial populations, and soil enzyme activity, thus remediating the deteriorating environment of continuous cropping soil. On this basis, the ecological intensive treatment RP-R-BF significantly increased the activity of protective enzymes and the expression levels of genes related to disease and stress resistance in leaves and root tubers. Redundancy and Pearson correlation analyses indicated that rice-paddy-upland rotation improved the soil structure, promoted the growth of eutrophic r-strategy bacterial communities, enhanced compound oxidation and reduction, broke the relationship between the deteriorating environment and harmful biological factors, and eventually weakened the intensity of harmful factors. The subsequent application of bacterial fertilizer improved the beneficial biological and abiotic factors, activated various ecological functions of the soil, enhanced the ecological relationship between various biological and abiotic factors, and reduced the stress intensity of R. pseudostellariae, thereby improving its disease and stress resistance, and ultimately reflecting the recovery of yield and quality. The results indirectly prove that the intensive ecological amelioration of the soil environment was the main factor for the yield recovery of R. pseudostellariae under continuous cropping.

Structure of KOH-soluble polysaccharides from сoniferous greens of Norway spruce (Picea abies): The pectin-xylan-AGPs complex. Part 1

Using 7 % KOH, the polysaccharide PAK has been isolated from the coniferous greens of Norway spruce. PAK was found to contain predominantly arabinoglucuronoxylan, xyloglucan and arabinan, but also pectic polysaccharides, glucomannan and arabinogalactan proteins (AGPs), as determined by 1D/2D NMR analysis. It was found that fractionation of PAK on DEAE-cellulose resulted in simultaneous elution of pectins, arabinoglucuronoxylans and AGPs. It was evident that the content of 4-OMe-α-D-GlcpA and xylose, 1,4-β-D-GlcpA, and T-β-D-GlcpA increased with an increase in NaCl concentration. However, 1,4-α-D-GalpA content was almost independent of NaCl concentration, indicating unchanged pectic polysaccharide concentration. Interestingly, pectins extracted with 0.1–0.3 M NaCl solutions were richer in rhamnogalacturonan-I (RG-I) than those extracted with water and 0.01 M NaCl. Conclusion: The content of RG-I, AGPs and arabinoglucuronoxylan rises with rising NaCl concentration. An intense signal indicating an intermolecular linkage between the xylan and RG-I domains, i.e. that part of the arabinoglucuronoxylan is covalently bound to RG-I, is observed in the HMBC spectra of the polysaccharides obtained. The discovery here of a new relationship between rhamnogalacturonan I and xylan contradicts the prevailing cell wall model.

Effect of defatted flaxseed gum powder addition on the quality of sesame paste

The study explored the influence of defatted flaxseed gum powder (DFGP) on the stability and quality of sesame paste by measuring and analyzing its composition, color, texture, particle size, centrifugal oil separation rate, rheological properties, and microstructure. The results showed that the moisture and polysaccharide content of sesame paste was increased as the DFGP increased. Additionally, the hardness, gumminess, and chewiness of the sesame paste was improved, while the presence of particles with small particle size (1–100 ​μm) was decreased. The rate of oil precipitation was reduced by 28.99% when the amount of DFGP was 6%. The sesame paste samples exhibited pseudoplastic behavior, demonstrating shear thinning. As the shear rate increased, the apparent viscosity of sesame paste gradually decreased. Both the storage modulus (G′) and the loss modulus (G″) increased as the shear frequency increased. The microstructure observation revealed that protein and oil were evenly distributed in the sesame paste system, and the addition of DFGP enhanced the bonding between oil and protein. This study can provide valuable references for high-quality sesame paste products in the food industry.

A comprehensive investigation on the chemical changes of traditional Chinese medicine with classic processing technology: Polygonum multiflorum under nine cycles of steaming and sunning as a case study.

The processing of traditional Chinese medicine (TCM) plays an important role in the clinical application, which usually has the function of "increasing efficiency and reducing toxicity". Polygonum multiflorum (PM) has been reported to induce hepatotoxicity, while it is believed that the toxicity is reduced after processing. Studies have shown that the hepatotoxicity of PM is closely related to the changes in chemical components before and after processing. However, there is no comprehensive investigation on the chemical changes of PM during the processing progress. In this research, we established a comprehensive method to profile both small molecule compounds and polysaccharides from raw and different processed PM samples. In detail, an online two-dimensional liquid chromatography coupled with quadrupole-orbitrap mass spectrometry (2D-LC/Q-Orbitrap MS) was utilized to investigate the small molecules, and a total of 150 compounds were characterized successfully. After multivariate statistical analysis, 49 differential compounds between raw and processed products were screened out. Furthermore, an accurate and comprehensive method for quantification of differential compounds in PM samples was established based on ultra-high performance liquid chromatography/Q-Orbitrap-MS (UHPLC/Q-Orbitrap-MS) within 16 min. In addition, the changes of polysaccharides in different PM samples were analyzed, and it was found that the addition of black beans and steaming times would affect the content and composition of polysaccharides in PM significantly. Our work provided a reference basis for revealing the scientific connotation of the processing technology and increasing the quality control and safety of PM.

Characterization of Changes in Active Ingredients and Mining of Key Metabolites in Bletilla striata under Shading and Drought Stresses

Shading and drought are considered crucial abiotic stress factors that limit the normal growth of plants. Under natural conditions, the quality of Bletilla striata pseudobulbs (BP), a Chinese traditional medicinal crop, is often affected by the dual stresses of shading and drought. However, the relationship and mechanism of the interaction between the two stress factors in B. striata remain unclear. In this study, we examined the changes in photosynthetic properties and active ingredients of B. striata under shading (L), drought (W), and shading-drought dual stresses (LW). We aimed to explore the metabolite mechanism that led to these changes using GC-MS-based non-targeted metabolomics techniques. The results indicated a significant reduction in the polysaccharide content of BP under W and LW treatments compared to the control (CK). The total phenol content was significantly reduced under L treatment, while the total flavonoid content did not change significantly under the three stresses. The significant increase in militarine content under all three stresses implies that B. striata may modulate its biosynthesis in response to different environmental stresses. Transpiration rate and stomatal conductance were reduced, amino acid expression was up-regulated, and carbohydrate expression was down-regulated in B. striata under L treatment. The net photosynthesis rate, stomatal conductance, and transpiration rate exhibited significant reductions, and the tuber metabolic disorder marker Homocysteine increased and organic acid content as well under W treatment. The net photosynthetic rate, transpiration rate, stomatal conductance, and water use efficiency of B. striata were further reduced under LW compared with single stress, which is in agreement with the “trade-off theory”. Pseudobulb metabolite changes, in combination with the results of the two single stresses, showed an up-regulation of amino acids and disaccharide compounds and a down-regulation of monosaccharide compounds. A support vector machine model (SVM) was used to screen 10 marker metabolites and accurately predict the changes in active ingredient content through an artificial neural network model (ANN). The results suggest that an appropriate stress environment can enhance the content of the target active ingredients based on cultivation goals.

Effect of electrolytic zero-valent iron activated sodium hypochlorite on sludge dewatering performance.

Using electrolytic zero-valent iron-activated sodium hypochlorite (EZVI-NaClO) to pretreat sludge, the capillary suction time (CST) was utilized to evaluate sludge dewaterability. Ammonia nitrogen (NH4-N), dissolved phosphorus, and total phosphorus in the supernatant were used to analyze sludge disintegration. This approach aimed to evaluate the effectiveness of the pretreatment process and its impact on the sludge composition. The migration and transformation of extracellular polymeric substances (EPS), including dissolved EPS (S-EPS), loosely boundEPS, and tightly bound-EPS (TB-EPS), were analyzed by detecting protein and polysaccharide concentrations and three-dimensional fluorescence excitation-emission spectroscopy (3D-EEM). The sludge particle properties, including sludge viscosity and particle size, were also analyzed. The results suggested that the optimal pH value, NaClO dosage, current, and reaction time were 2, 100 mg/gDS (dry sludge), 0.2A, and 30 min, respectively, with a CST reduction of 43%. Protein and polysaccharide contents in TB-EPS were significantly reduced in the EZVI-NaClO group. Conversely, protein and polysaccharides contents in S-EPS increased, suggesting that EZVI-NaClO treatment could disrupt the EPS. Besides, the viscosity of the treated sludge decreased from 195.4 to 54.9 mPa·S, indicating that sludge fluidity became better. ZEVI-NaClO could enhance sludge dewaterability by destructing protein and polysaccharide structure and improving sludge hydrophobicity.

Antibacterial Activity and Mechanism of Three Root Exudates from Mulberry Seedlings against Ralstonia pseudosolanacearum.

Bacterial wilt is a significant soil-borne disease that poses a threat to mulberry production yield and quality of agricultural production worldwide. However, the disease resistance mechanisms dependent on root exudates are not well understood. In this present study, we investigated the antibacterial mechanisms of the main active substances (erucamide, oleamide, and camphor bromide) present in mulberry root exudates (MRE) against Ralstonia pseudosolanacearum (Rp), the causal agent of bacterial wilt. Our findings revealed that these three active substances inhibited the growth activity of Rp by affecting the cell morphology and extracellular polysaccharide content, as well as triggering a burst of reactive oxygen species. The active substances induced oxidative stress, leading to a decrease in Rp growth. Additionally, the expression levels of key genes in the hrp gene cluster (hrpB, hrpX, and hrpF) and other virulence-related genes (such as ripAW, ripAE, Rs5-4819, Rs5-4374, ace, egl3, and pehB) were significantly reduced upon treatment with the active substances. Further pathogenicity experiments demonstrated that root exudates (at a concentration of 1.5 mg·mL-1) delayed or slowed down the occurrence of bacterial wilt in mulberry. These findings provide valuable insight into the antimicrobial mechanisms of MRE against Rp and lay a theoretical foundation for the development and application of biocontrol agents to control mulberry bacterial wilt.

Effect of linear anionic surfactant (sodium dodecyl sulfate) dosage on nitrogen removal performance of an anammox reactor

AbstractThe impact of sodium dodecyl sulfate (SDS, as model linear anionic surfactant) dosage on overall nitrogen removal performance of anammox reactor alongside its microbial population and sludge properties was investigated. In this study (day 136), an anmmox sequencing batch biofilm reactor was subjected to gradual dosage of SDS from 0 to 20 mg L−1. Intriguingly, results revealed that SDS at ≥7.5 mg L−1 prompted sludge disintegration, evidenced by increased protein and polysaccharide content in the effluent. Nevertheless, reactor's average total nitrogen removal efficiency slightly improved from 83.12% (0 mg L−1) to 86.3% (20 mg L−1). The 16S rRNA gene sequencing revealed that SDS dosing significantly suppressed the unwanted and unavoidable nitrite oxidizing bacteria (NOBs) in the reactor as the abundance of genus Nitrospira declined from 40.68% (day 1) to 19.15% (day 136). The abundance of anammox genus Candidatus Kuenenia significantly improved from 1.86% (day 1) to 40.02% (day 136) as a result of NOB suppression. This study revealed that low concentration of surfactants in wastewater does not affect the anammox bacteria in a biofilm reactor. Furthermore, adding low concentrations of SDS (≥7.5 to 20 mg L−1) to wastewater may effectively suppress notorious NOBs in biofilm‐based anammox systems.

Comprehensive analysis of metabolites in the mycelium of Cordyceps fumosorosea cultured on Periplaneta americana

Abstract Background Cordyceps fumosorosea is one of the common species within the Cordyceps genus, which are cultured on Periplaneta americana. This study aimed to determine the composition of bioactive compounds, including β-glucans, polysaccharides, cordycepic acid, flavonoids, ergosterol, and nitrogenous compounds (specifically nucleosides: adenosine, guanosine, adenine, and hypoxanthine), present in the mixture and mycelium at various time incubation. Methods Different bioactive compounds, including β-1,3-glucan, polysaccharides, cordycepic acid, flavonoids, ergosterol, and nitrogenous compounds (specifically nucleosides: adenosine, guanosine, adenine, and hypoxanthine) are detected from C. fumosorosea which cultured on P. americana by UV and HPLC. Results Mycelia of C. fumosorosea were cultivated in P. americana (medium). The highest total β-1,3-glucan content was observed in the mixture (C. fumosorosea + P. americana) after 25 days (69.21 ± 0.07 mg/g) and in the mycelium after 25 days (56.32 ± 0.39 mg/g) using different solvents. The highest β-1,3-glucan content was attained at specific time incubation in other solvents. The content of cordycepic acid peaked at 52.28 ± 0.11 mg/g in the mixture after 25 days and at 46.96 ± 0.13 mg/g in the mycelium after 25 days. The polysaccharide content reached its highest level in the mixture after 20 days (16.68 ± 0.38 mg/g) and in the mycelium after 20 days (14.85 ± 0.10 mg/g). The peak flavonoid content was observed in the mixture after 25 days (4.65 ± 0.24 mg/g) and in the mycelium after 25 days (4.04 ± 0.07 mg/g). Nucleosides, including adenine, adenosine, hypoxanthine, and guanosine, exhibited their highest levels after 25 days in the mixture and mycelium. Ergosterol content peaks at 25 days (2.25 ± 0.04 mg/g). Conclusion Cordyceps fumosorosea mixture and time incubation of 20 and 25 days are optimal for detecting a diverse array of bioactive compounds, including β-1,3-glucan, polysaccharides, cordycepic acid, flavonoids, ergosterol, and nucleosides.

Impact of κ-Carrageenan on the Cold-Set Pea Protein Isolate Emulsion-Filled Gels: Mechanical Property, Microstructure, and In Vitro Digestive Behavior

More understanding of the relationship among the microstructure, mechanical property, and digestive behavior is essential for the application of emulsion gels in the food industry. In this study, heat-denatured pea protein isolate particles and κ-carrageenan were used to fabricate cold-set emulsion gels induced by CaCl2, and the effect of κ-carrageenan concentration on the gel formation mechanism, microstructure, texture, and digestive properties was investigated. Microstructure analysis obtained by confocal microscopy and scanning electron microscopy revealed that pea protein/κ-carrageenan coupled gel networks formed at the polysaccharide concentration ranged from 0.25% to 0.75%, while the higher κ-carrageenan concentration resulted in the formation of continuous and homogenous κ-carrageenan gel networks comprised of protein enriched microdomains. The hydrophobic interactions and hydrogen bonds played an important role in maintaining the gel structure. The water holding capacity and gel hardness of pea protein emulsion gels increased by 37% and 75 fold, respectively, through increasing κ-carrageenan concentration up to 1.5%. Moreover, in vitro digestion experiments based on the INFOGEST guidelines suggested that the presence of 0.25% κ-carrageenan could promote the digestion of lipids, but the increased κ-carrageenan concentration could delay the lipid and protein hydrolysis under gastrointestinal conditions. These results may provide theoretical guidance for the development of innovative pea protein isolate-based emulsion gel formulations with diverse textures and digestive properties.

BolA promotes the generation of multicellular behavior in S. typhimurium by regulating the c-di-GMP pathway genes yeaJ and yhjH

The generation of multicellular behavior enhances the stress adaptability, antibiotic resistance, and pathogenic potential of Salmonella enterica serovar Typhimurium (S. typhimurium), which is challenging for its prevention and control. Therefore, determination of the mechanism of multicellular behavior development is urgently required. Accordingly, this study investigated BolA, a transcription factor that promotes bacterial survival under different stresses. We found that BolA promoted the generation of multicellular behavior. Furthermore, transcriptome analysis revealed that BolA affected the expression of numerous genes, including biofilm formation and motility-related genes. In terms of biofilm formation, compared with the wild-type strain, bolA overexpression (269BolA+) increased the extracellular matrix content (extracellular polysaccharide, extracellular protein, and extracellular DNA (eDNA) by upregulating gene expression, ultimately increasing the biofilm formation ability by 2.56 times. For motility, bolA overexpression inhibited the expression of flagella synthesis genes, resulting in a 91.15 % decrease in motility compared with the wild-type (6 h). Further mechanistic analysis demonstrated that BolA affected the expression of the C-di-GMP pathway genes yeaJ and yhjH, which influenced the generation of multicellular behavior. In terms of biofilms, the extracellular polysaccharide content of 269BolA + ∆Yeaj (bolA overexpression and yeaJ deletion) was reduced by 89.91 % compared with 269BolA+, resulting in a 71.1 % reduction in biofilm forming ability. The motility of the 269∆BolA∆Yhjh (bolA/yhjH double deletion) strain was significantly decreased compared with that of 269∆BolA. Finally, the LacZ gene reporting showed that BolA promoted and inhibited the expression of yeaJ and yhjH, respectively. In conclusion, BolA mainly improves the content of extracellular polysaccharide by promoting the expression of yeaJ, thus enhancing the formation of biofilms. BolA also restricts flagellar synthesis by inhibiting yhjH expression, therefore reducing motility, ultimately promoting multicellular behavior arises. These findings lay a theoretical foundation for the prevention and control of S. typhimurium.