Predictive value of serum alanine aminotransferase for fatty liver associated with metabolic dysfunction.

In this editorial, we offer commentary on the article published by Chen et al in a recent issue of the World Journal of Gastroenterology (2024; 30: 1346-1357). The study highlights a noteworthy association between persistently elevated, yet high-normal levels of alanine transaminase (ALT) and an escalated cumulative risk of developing metabolic dysfunction-associated fatty liver disease (MAFLD). MAFLD has emerged as a globally prevalent chronic liver condition, whose incidence is steadily rising in parallel with improvements in living standards. Left unchecked, MAFLD can progress from hepatic steatosis to liver fibrosis, cirrhosis, and even hepatocellular carcinoma, underscoring the importance of early screening and diagnosis. ALT is widely recognized as a reliable biomarker for assessing the extent of hepatocellular damage. While ALT levels demonstrate a significant correlation with the severity of fatty liver disease, they lack specificity. The article by Chen et al contributes to our understanding of the development of MAFLD by investigating the long-term implications of high-normal ALT levels. Their findings suggest that sustained elevation within the normal range is linked to an increased likelihood of developing MAFLD, emphasizing the need for closer monitoring and potential intervention in such cases.

Long-term liver-related outcomes and liver stiffness progression of statin usage in steatotic liver disease.

BACKGROUND: Statins have multiple benefits in patients with metabolic-associated steatotic liver disease (MASLD). AIM: To explore the effects of statins on the long-term risk of all-cause mortality, liver-related clinical events (LREs) and liver stiffness progression in patients with MASLD. METHODS: This cohort study collected data on patients with MASLD undergoing at least two vibration-controlled transient elastography examinations at 16 tertiary referral centres. Cox regression analysis was performed to examine the association between statin usage and long-term risk of all-cause mortality and LREs stratified by compensated advanced chronic liver disease (cACLD): baseline liver stiffness measurement (LSM) of ≥10 kPa. Liver stiffness progression was defined as an LSM increase of ≥20% for cACLD and from <10 kPa to ≥10 or LSM for non-cACLD. Liver stiffness regression was defined as LSM reduction from ≥10 kPa to <10 or LSM decrease of ≥20% for cACLD. RESULTS: We followed up 7988 patients with baseline LSM 5.9 kPa (IQR 4.6-8.2) for a median of 4.6 years. At baseline, 40.5% of patients used statins, and cACLD was present in 17%. Statin usage was significantly associated with a lower risk of all-cause mortality (adjusted HR=0.233; 95% CI 0.127 to 0.426) and LREs (adjusted HR=0.380; 95% CI 0.268 to 0.539). Statin usage was also associated with lower liver stiffness progression rates in cACLD (HR=0.542; 95% CI 0.389 to 0.755) and non-cACLD (adjusted HR=0.450; 95% CI 0.342 to 0.592), but not with liver stiffness regression (adjusted HR=0.914; 95% CI 0.778 to 1.074). CONCLUSIONS: Statin usage was associated with a relatively lower long-term risk of all-cause mortality, LREs and liver stiffness progression in patients with MASLD.

Lipopolysaccharide-induced bacterial infection model: microRNA-370-3p participates in the anti-infection response by targeting the macrophage TLR4-NLRP3 caspase-1 cellular pyroptosis pathway.

OBJECTIVE: To explore the effect of miR-370-3p on LPS triggering, in particular its involvement in disease progression by targeting the TLR4-NLRP3-caspase-1 cellular pyroptosis pathway in macrophages. METHODS: Human macrophage RAW264.7 was divided into 6 groups: control, LPS, LPS + inhibitor-NC, LPS + miR-370-3p inhibitor, LPS + mimics-NC and LPS + miR-370-3p mimics. RT-qPCR was used to detect the expression level of miR-370-3p and analyzed comparatively. CCK-8 and flow cytometry assays were used to detect cell viability and apoptosis. ELISA assay was used to detect the levels of IL-1ß and TNF-α in the supernatant of the cells. The WB assay was used to detect TLR4, NLRP3, Caspase-1 and GSDMD levels. RESULTS: After LPS induction, macrophage miR-370-3p levels decreased, cell viability decreased, and apoptosis increased. At the same time, the levels of TLR4, NLRP3, Caspase-1 and GSDMD increased in the cells, and the levels of IL-1ß and TNF-α increased in the cell supernatant. Compared with the LPS group, the significantly higher expression level of miR-370-3p in the cells of the LPS + miR-370-3p mimics group was accompanied by significantly higher cell viability, significantly lower apoptosis rate, significantly lower levels of TLR4, NLRP3, Caspase-1, and GSDMD in the cells, and significantly lower levels of IL-1ß and TNF-α in the cell supernatant. CONCLUSION: MiR-370-3p may be involved in anti-infective immune responses by targeting and inhibiting the macrophage TLR4-NLRP3-caspase-1 cellular pyroptosis pathway.

Rhizosphere microbial community construction during the latitudinal spread of the invader Chromolaena odorata.

The colonization of alien plants in new habitats is typically facilitated by microorganisms present in the soil environment. However, the diversity and structure of the archaeal, bacterial, and fungal communities in the latitudinal spread of alien plants remain unclear. In this study, the rhizosphere and bulk soil of Chromolaena odorata were collected from five latitudes in Pu' er city, Yunnan Province, followed by amplicon sequencing of the soil archaeal, bacterial, and fungal communities. Alpha and beta diversity results revealed that the richness indices and the structures of the archaeal, bacterial, and fungal communities significantly differed along the latitudinal gradient. Additionally, significant differences were observed in the bacterial Shannon index, as well as in the structures of the bacterial and fungal communities between the rhizosphere and bulk soils. Due to the small spatial scale, trends of latitudinal variation in the archaeal, bacterial, and fungal communities were not pronounced. Total potassium, total phosphorus, available nitrogen, available potassium and total nitrogen were the important driving factors affecting the soil microbial community structure. Compared with those in bulk soil, co-occurrence networks in rhizosphere microbial networks presented lower complexity but greater modularity and positive connections. Among the main functional fungi, arbuscular mycorrhizae and soil saprotrophs were more abundant in the bulk soil. The significant differences in the soil microbes between rhizosphere and bulk soils further underscore the impact of C. odorata invasion on soil environments. The significant differences in the soil microbiota along latitudinal gradients, along with specific driving factors, demonstrate distinct nutrient preferences among archaea, bacteria, and fungi and indicate complex microbial responses to soil nutrient elements following the invasion of C. odorata.

Clinical implications of linking microstructure, spatial biochemical, spatial biomechanical, and radiological features in ligamentum flavum degeneration.

Background: The ligamentum flavum (LF) degeneration is a critical factor in spinal stenosis, leading to nerve compression and pain. Even with new treatment options becoming available, it is vital to have a better understanding of LF degeneration to ensure the effectiveness of these treatments. Objective: This study aimed to provide insight into LF degeneration by examining the connections between various aspects of LF degeneration, including histology, microstructure, chemical composition, and biomechanics. Method: We analyzed 30 LF samples from 27 patients with lumbar vertebrae, employing magnetic resonance imaging (MRI) to link lumbar disc degeneration grades with fibrosis levels in the tissue. X-ray diffraction (XRD) analysis assessed microstructural alterations in the LF matrix component due to degeneration progression. Instrumented nanoindentation combined with Raman spectroscopy explored the spatial microbiomechanical and biochemical characteristics of the LF's ventral and dorsal regions. Results: Our outcomes revealed a clear association between the severity of LF fibrosis grades and increasing LF thickness. XRD analysis showed a rise in crystalline components and hydroxyapatite molecules with progressing degeneration. Raman spectroscopy detected changes in the ratio of phosphate, proteoglycan, and proline/hydroxyproline over the amide I band, indicating alterations in the extracellular matrix composition. Biomechanical testing demonstrated that LF tissue becomes stiffer and less extensible with increasing fibrosis. Discussion: Notably, the micro-spatial assessment revealed the dorsal side of the LF experiencing more significant mechanical stress, alongside more pronounced biochemical and biomechanical changes compared to the ventral side. Degeneration of the LF involves complex processes that affect tissue histology, chemical composition, and biomechanics. It is crucial to fully understand these changes to develop new and effective treatments for spinal stenosis. These findings can improve diagnostic accuracy, identify potential biomarkers and treatment targets, guide personalized treatment strategies, advance tissue engineering approaches, help make informed clinical decisions, and educate patients about LF degeneration.

Survival predictor in emergency resuscitative thoracotomy for blunt trauma patients: Insights from a Chinese trauma center.

PURPOSE: Emergency resuscitative thoracotomy (ERT) is a final salvage procedure for critically injured trauma patients. Given its low success rate and ambiguous indications, its use in blunt trauma scenarios remains highly debated. Consequently, our study seeks to ascertain the overall survival rate of ERT in blunt trauma patients and determine which patients would benefit most from this procedure. METHODS: A retrospective case-control study was conducted for this research. Blunt trauma patients who underwent ERT between January 2020 and December 2023 in our trauma center were selected for analysis, with the endpoint outcome being in-hospital survival, divided into survival and non-survival groups. Inter-group comparisons were conducted using Chi-square and Fisher's exact tests, the Kruskal-Wallis test, Student's t-test, or the Mann-Whitney U test. Univariate and multivariate logistic regression analyses were conducted to assess potential predictors of survival. Then, the efficacy of the predictors was assessed through sensitivity and specificity analysis. RESULTS: A total of 33 patients were included in the study, with 4 survivors (12.12%). Multivariate logistic regression analysis indicated a significant association between cardiac tamponade and survival, with an adjusted odds ratio of 33.4 (95% CI: 1.31 - 850, p = 0.034). Additionally, an analysis of sensitivity and specificity, targeting cardiac tamponade as an indicator for survivor identification, showed a sensitivity rate of 75.0% and a specificity rate of 96.6%. CONCLUSION: The survival rate among blunt trauma patients undergoing ERT exceeds traditional expectations, suggesting that select individuals with blunt trauma can significantly benefit from the procedure. Notably, those presenting with cardiac tamponade are identified as the subgroup most likely to derive substantial benefits from ERT.

External electric field driven conformation transition between lithium salts and electride-like molecules: intriguing NLO switches in Li@corannulene.

The external electric field has emerged as a powerful tool for building molecular switches with excellent properties. In this work, we investigate the impact of an external electric field on the transition between lithium salt and electride-like molecule conformations in Li@corannulene. Remarkably, the distance between the Li atom and the corannulene bottom displays a sharp increase under the influence of an external electric field strength of F-z = 110 × 10-4 a.u. As the external electric field strength increases, the Li atom brings about different directions of charge transfer (CT). The natural population analysis (NPA) charge and the molecular electrostatic potential (ESP) results show that the intermolecular CT occurs from the Li atom to the corannulene with the F-z ranging from 0 to 100 × 10-4 a.u. Interestingly, when the external electric field reaches F-z = 110 × 10-4 a.u., the CT is oriented from the corannulene to the Li atom. Moreover, electron localization function (ELF) basins are presented under an F-z of 110 × 10-4 a.u., which indicates that Li@corannulene exhibits electride-like (e-⋯[Li@corannulene]+) molecules and lithiation salt (Li+[corannulene]-) under an F-z of 0 to 100 × 10-4 a.u. Significantly, the differences in charge transfer also contribute to a significant improvement in hyperpolarizabilities (ßtot) during the conformation transition from lithiation salt (Li+[corannulene]-) to electride-like (e-⋯[Li@corannulene]+) molecules. This study explores the potential of Li@corannulene as a promising second-order NLO material, and the external electric field provides an efficient strategy for designing and developing NLO switching devices.

Targeted muscle reinnervation at the time of amputation to prevent the development of neuropathic pain.

INTRODUCTION: Targeted muscle reinnervation (TMR) is an established modality for the surgical management of neuropathic pain. Although the preventive effect of primary (acute) TMR at the time of amputation has been demonstrated previously, it remains unclear how many and which patients benefit most. Therefore, this study investigated the proportion of patients achieving sustained pain prophylaxis following amputation, as well as factors associated with its efficacy. METHODS: Primary patients who underwent TMR with a minimum follow-up of 6 months between 2018 and 2023 were enrolled. Pain outcomes (numeric rating scale [NRS], 0-10), comorbidities, and surgical factors were collected from chart review. Patients achieving sustained pain prophylaxis (NRS of ≤3 for ≥3 months until final follow-up) were identified. Multilevel mixed-effect models and multivariable regression were used to visualize pain courses and identify associated factors. RESULTS: Seventy-five patients who underwent primary TMR were included (median follow-up: 2.0 years), of whom 57.3% achieved sustained pain prophylaxis whereas 26.7% reported pain disappearance. Distal amputation levels (p = 0.036), a lower Elixhauser Comorbidity Index (p = 0.001), and the absence of psychiatric comorbidities (p = 0.039) were associated with pain prophylaxis. CONCLUSION: This study demonstrates that more than half of all patients undergoing primary TMR achieved sustained pain prophylaxis, and approximately a quarter of patients achieved sustained pain disappearance. Several factors associated with these favorable outcomes are described. These results will aid in preoperative counseling, managing patient expectations, and selecting patients who may benefit most from primary TMR surgery. LEVEL OF EVIDENCE: IV - Therapeutic.

Fast Determination of Eleven Food Additives in River Water Using C18 Functionalized Magnetic Organic Polymer Nanocomposite Followed by High-Performance Liquid Chromatography.

A novel magnetic nanomaterial with Fe3O4 as the core, PS-DVB as the shell layer, and the surface modified with C18 (C18-PS-DVB-Fe3O4) had been synthesized by seeded emulsion polymerization. C18-PS-DVB-Fe3O4 retains the advantages of the chemical stability, large porosity, and uniform morphology of organic polymers and has the magnetic properties of Fe3O4. A simple, flexible, and efficient magnetic dispersive solid phase extraction (Mag-dSPE) method for the extraction of preservatives, sweeteners, and colorants in river water was established. C18-PS-DVB-Fe3O4 was used as an adsorbent for Mag-dSPE and was coupled with high-performance liquid chromatography (HPLC) to detect 11 food additives: acesulfame, amaranth, benzoic acid, tartrazine, saccharin sodium, sorbic acid, dehydroacetic acid, sunset yellow, allura red, brilliant blue, and erythrosine. Under the optimum extraction conditions, combined with ChromCoreTMAQC18 (5 µm, 4.6 × 250 mm), 20 mmol/L ammonium acetate aqueous solution and methanol were used as mobile phases, and the detection wavelengths were 240 nm and 410 nm. The limits of detection (LODs) of 11 food additives were 0.6-3.1 µg/L with satisfactory recoveries ranging from 86.53% to 106.32%. And the material could be reused for five cycles without much sacrifice of extraction efficiency. The proposed method has been used to determine food additives in river water samples, and results demonstrate the applicability of the proposed C18-PS-DVB-Fe3O4 Mag-dSPE coupled with the HPLC method to environment monitoring analysis.

Empagliflozin Prevent High-Glucose Stimulation Inducing Apoptosis and Mitochondria Fragmentation in H9C2 Cells through the Calcium-Dependent Activation Extracellular Signal-Regulated Kinase 1/2 Pathway.

A previous study showed that high-glucose (HG) conditions induce mitochondria fragmentation through the calcium-mediated activation of extracellular signal-regulated kinase 1/2 (ERK 1/2) in H9C2 cells. This study tested whether empagliflozin could prevent HG-induced mitochondria fragmentation through this pathway. We found that exposing H9C2 cells to an HG concentration decreased cell viability and increased cell apoptosis and caspase-3. Empagliflozin could reverse the apoptosis effect of HG stimulation on H9C2 cells. In addition, the HG condition caused mitochondria fragmentation, which was reduced by empagliflozin. The expression of mitochondria fission protein was upregulated, and fusion proteins were downregulated under HG stimulation. The expression of fission proteins was decreased under empagliflozin treatment. Increased calcium accumulation was observed under the HG condition, which was decreased by empagliflozin. The increased expression of ERK 1/2 under HG stimulation was also reversed by empagliflozin. Our study shows that empagliflozin could reverse the HG condition, causing a calcium-dependent activation of the ERK 1/2 pathway, which caused mitochondria fragmentation in H9C2 cells.

Molecular cloning and functional characterization of mitochondrial RNA splicing 2 in fish Megalobrama amblycephala, and its potential roles in magnesium homeostasis and mitochondrial function.

Mitochondrial function can be regulated by ion channels. Mitochondrial RNA splicing 2 (Mrs2) is a magnesium ion (Mg2+) channel located in the inner mitochondrial membrane, thereby mediating the Mg2+ influx into the mitochondrial matrix. However, its potential role in regulating the Mg homeostasis and mitochondrial function in aquatic species is still unclear. This study molecularly characterizes the gene encoding Mrs2 in fish M. amblycephala with its functions in maintaining the Mg homeostasis and mitochondrial function verified. The mrs2 gene is 2133 bp long incorporating a 1269 bp open reading frame, which encodes 422 amino acids. The Mrs2 protein includes two transmembrane domains and a conserved tripeptide Gly-Met-Asn, and has a high homology (65.92-97.64%) with those of most vertebrates. The transcript of mrs2 was relatively high in the white muscle, liver and kidney. The inhibition of mrs2 reduces the expressions of Mg2+ influx/efflux-related proteins, mitochondrial Mg content, and the activities of mitochondrial complex I and V in hepatocytes. However, the over-expression of mrs2 increases the expressions of Mg2+ influx/efflux-related proteins, mitochondrial Mg content, and the complex V activity, but decreases the activities of mitochondrial complex III and IV and citrate synthase in hepatocytes. Collectively, Mrs2 is highly conserved among different species, and is prerequisite for maintaining Mg homeostasis and mitochondrial function in fish.

The spatial-temporal distribution of hepatitis B virus infection in China,2006-2018.

OBJECTIVES: Hepatitis B is a liver disease caused by Hepatitis B virus (HBV) infection and is highly prevalent in China. To better understand the epidemiological characteristics of hepatitis B in China and develop effective disease control strategies, we employed temporal and spatial statistical methods. METHODS: We obtained HBV incidence data from the Public Health Science Data Center of the Chinese Center for Disease Control and Prevention for the years 2006 to 2018. Using Geographic Information System (GIS) and SaTScan scanning technology, we conducted spatial autocorrelation analysis and spatiotemporal scan analysis to create a map and visualize the distribution of hepatitis B incidence. RESULTS: While hepatitis B incidence rebounded in 2011 and 2017, the overall incidence in China decreased.In the trend analysis by item, the incidence varies from high to low. The global spatial autocorrelation analysis revealed a clustered distribution, and the Moran index analysis of spatial autocorrelation within local regions identified five provinces as H-H clusters (hot spots), while one province was an L-L cluster (cold spot). Spatial scan analysis identified 11 significant spatial clusters. CONCLUSIONS: We found significant clustering in the spatial distribution of hepatitis B incidence and positive spatial correlation of hepatitis B incidence in China. We also identified high-risk times and regional clusters of hepatitis B incidence.

Erratum: Corrigendum: Liu W-B, Wang C-Y, Tang Y-N, Wang Y, Pei W-X, Yan C-C (2024) Six new species of Cryptochironomus Kieffer (Diptera, Chironomidae) from the Nearctic region. ZooKeys 1200: 275-302. doi: 10.3897/zookeys.1200.119225.

[This corrects the article DOI: 10.3897/zookeys.1200.119225.].

Aquaporin-3 is down-regulated by LMP1 in nasopharyngeal carcinoma cells to regulate cell migration and affect EBV latent infection.

Epstein-Barr virus (EBV) infection has a strong correlation with the development of nasopharyngeal carcinoma (NPC). Aquaporin 3 (AQP3), a member of the aquaporin family, plays an important role in tumor development, especially in epithelial-mesenchymal transition. In this study, the expression of AQP3 in EBV-positive NPC cells was significantly lower than that in EBV-negative NPC cells. Western blot and qRT-PCR analysis showed that LMP1 down-regulated the expression of AQP3 by activating the ERK pathway. Cell biology experiments have confirmed that AQP3 affects the development of tumor by promoting cell migration and proliferation in NPC cells. In addition, AQP3 can promote the lysis of EBV in EBV-positive NPC cells. The inhibition of AQP3 expression by EBV through LMP1 may be one of the mechanisms by which EBV maintains latent infection-induced tumor progression.

The relationship between trait anger and reactive aggressive behavior in middle school students: the mediating role and intervention of hostile attribution bias.

BACKGROUND: The reactive aggressive behavior in individuals typically shows a rapid growth trend as individuals enter adolescence, and peaks during middle-school period. According to the Comprehensive Cognitive Model of Trait Anger, trait anger and hostile attribution bias play important roles in the development of reactive aggressive behavior. Based on this, current study explored the relationship between trait anger and reactive aggressive behavior in middle school students, as well as the mediating role of hostile attribution bias and interventions. METHODS: The current study consisted of three sub-studies. Study 1 recruited 87 middle school students with an average age of 12.367 ± 0.889 years, investigated the relationship between trait anger and reactive aggressive behavior, as well as the mediating role of trait hostile attribution bias. Study 2 recruited 62 middle school students with an average age of 13.376 ± 0.963 years, investigated the relationship between trait anger and reactive aggressive behavior, as well as the mediating role of state hostile attribution bias. Study 3 recruited 80 middle school students with an average age of 13.392 ± 0.977 years, implemented an intervention targeting trait hostile attribution bias in middle school students with high trait anger to reduce their reactive aggressive behavior. In current study, data management was performed using SPSS 22.0. Descriptive statistics, independent samples t-test, paired samples t-test, repeated measures analysis of variance (ANOVA), and path analysis were used for statistical analysis. FINDINGS: The results of Study 1 showed that trait anger predicted reactive aggressive behavior through trait hostile attribution bias. The results of Study 2 indicated that trait and state hostile attribution bias played mediating role intermediary, and trait hostile attribution bias had a stronger mediating effect than state hostile attribution bias. The results of Study 3 suggested that the intervention effectively decreased trait hostile attribution bias and reactive aggressive behavior. CONCLUSIONS: Trait anger can predict the reactive aggressive behavior of junior high school students, with trait hostility attribution bias and state hostility attribution bias mediating this relationship. Intervening in the hostility attribution bias of high-anger junior high school students can effectively reduce their reactive aggressive behavior.

Mechanism underlying the sustained stimulatory effects of energization on biomethane recovery from food waste post-energization cessation.

Microbial electrolysis cell-assisted anaerobic digestion represents a promising approach for enhancing methanogenesis. This study investigated the impact of varying energy levels followed by long-term open circuit on biogas recovery from food waste. The results demonstrated that a mild voltage of 0.4 V resulted in 61.7% increase in methane yield, with a methane composition reaching 78.89% vol and a remarkable reduction in digestion time by 8 days. Additionally, the facilitated effects remained after prolonged periods of open-circuit. In-depth study revealed that energization significantly enhanced organic hydrolysis, redox proteins secretion and sludge electro-activity. Microbial communities showed that the ever-present energization enriched the hydrolytic bacterium and electrophiles. Subsequent investigations also revealed the upgradation of enzyme-encoding genes associated with hydrolysis and the synthesis of flavin and its homologs (i.e. ribE, ssuE and nfrA2). These findings collectively demonstrated the enduring benefits of energization were linked to the enhanced hydrolysis and regulated mediator-mediated electron transfer pathway.

Xylooligosaccharides alleviate the carbohydrate-enriched diet-induced intestinal barrier dysfunction in carp Megalobrama amblycephala by promoting intestinal development, immunity and gut microbiota.

To date, although the high-carbohydrate (HC) feed has been extensively adopted in the aquaculture industry, its effects on the intestinal function and development of aquatic animals still remain unclear. In addition, the corresponding nutritional intervention is still barely reported. This study aimed to evaluate the influence of xylooligosaccharides (XOS) on the intestinal health of Megalobrama amblycephala subjected to a HC feeding. Fish (average weight: 44.55 ±â€¯0.15 g) were randomly offered 3 diets, including a control one (29 % carbohydrate), a HC one (41 % carbohydrate), and a XOS supplemented one (HC + 1.0 % XOS, HCX) respectively for 12 weeks. The HC feeding caused morphological abnormalities of intestine, an increased intestinal permeability, and the intestinal immunosuppression, all of which were markedly reversed by XOS administration. In addition, compared with the HC group, HCX feeding remarkably promoted the intestinal activities of digestive and brush border enzymes, and the expressions of cell proliferation-related proteins (Wnt10b and Cyclin D1). The 16s rDNA sequencing also revealed that XOS administration increased the abundance of beneficial bacteria, and decreased that of pathogenic ones. In conclusion, dietary supplementation of XOS improved the intestinal histomorphology, barrier function, cell proliferation and bacterial communities of carbohydrate-overloaded fish Megalobrama amblycephala.

Unveiling the common laws of extracellular polymeric substances (EPS) properties on short-chain fatty acids production from sludge by EPS disintegration pretreatment.

The production of short-chain fatty acids (SCFAs) from sludge is promising, but the efficiency and product quality often vary because of extracellular polymeric substances (EPS) characteristics and pretreatment principles. This study adopted specific EPS disintegration pretreatment to treat different types of sludge. By correlation coefficient matrix analysis and correlation dynamics change resolution, the intrinsic relationships between the nature of EPS and the production of SCFAs from sludge was unveiled. We demonstrate that tight-bound EPS (TB-EPS) is a principal carbon reservoir, positively impacting SCFAs yields, in the fermentation system with EPS as the main fermentation substrate, it can contribute about 29.2 % for SCFAs growth during fermentation. Conversely, TB-EPS exhibits a negative correlation during fermentation due to EPS-SCFAs interconversion, while loosely bound EPS (LB-EPS) correlates positively. Proteins and polysaccharides in TB-EPS, especially proteins, significantly enhance individual SCFAs yields, predominantly acetic, propionic, and isovaleric acids. The findings would provide a theoretical basis for developing pretreatments and process-control technologies aimed at improving SCFAs production efficiency and quality.

Structural Basis of Substrate Recognition by the Postmitosane Modification Enzyme MitM in Mitomycin Biosynthesis.

Mitomycins make up a class of natural molecules produced by Streptomyces with strong antibacterial and antitumor activities. MitM is a key postmitosane modification enzyme involved in mitomycin biosynthesis in Streptomyces caespitosus. This protein was previously suggested to catalyze the aziridinium methylation of mitomycin A and the mitomycin intermediate 9a-demethyl-mitomycin A as an N-methyltransferase. The structural basis for MitM to recognize cofactor S-adenosyl-l-methionine (SAM) and substrate mitomycin A is unknown. Here, we determined the crystal structures of apo-MitM and MitM-mitomycin A-S-adenosylhomocysteine (SAH) ternary complexes with resolutions of 2.23 and 2.80 Å, respectively. We found that MitM adopts a class I SAM-dependent methyltransferase fold and forms a homodimer in solution. Conformational changes in a series of residues involved in the formation of active pockets assist MitM in binding SAH and mitomycin A. In particular, the 28ALGAASLGE36 loop changes most significantly. When mitomycin A binds, the bending direction of this loop is reversed, changing the entrance of the active site from open to closed. This study provides structural insights into MitM's involvement in the postmitosane stage of mitomycin biosynthesis and provides a template for the engineering of methyltransferases.