NRSF regulates age-dependently cognitive ability and its conditional knockout in APP/PS1 mice moderately alters AD-like pathology.

NRSF/REST (neuron-restrictive silencer element, also known as repressor element 1-silencing transcription factor), plays a key role in neuronal homeostasis as a transcriptional repressor of neuronal genes. NRSF/REST relates to cognitive preservation and longevity of humans, but its specific functions in age-dependent and Alzheimer's disease (AD)-related memory deficits remain unclear. Here, we show that conditional NRSF/REST knockout either in the dorsal telencephalon or specially in neurons induced an age-dependently diminished retrieval performance in spatial or fear conditioning memory tasks and altered hippocampal synaptic transmission and activity-dependent synaptic plasticity. The NRSF/REST deficient mice were also characterized by an increase of activated glial cells, complement C3 protein and the transcription factor C/EBPß in the cortex and hippocampus. Reduction of NRSF/REST by conditional depletion upregulated the activation of astrocytes in APP/PS1 mice, and increased the C3-positive glial cells, but did not alter the Aß loads and memory retrieval performances of 6- and 12-month-old APP/PS1 mice. Simultaneously, overexpression of NRSF/REST improved cognitive abilities of aged wild type, but not in AD mice. These findings demonstrated that NRSF/REST is essential for the preservation of memory performance and activity-dependent synaptic plasticity during aging and takes potential roles in the onset of age-related memory impairments. However, while altering the glial activation, NRSF/REST deficiency does not interfere with the Aß deposits and the electrophysiological and cognitive AD-like pathologies.

A Roadmap for Ferroelectric-Antiferroelectric Phase Transition.

Antiferroelectric materials have shown great potential in electronic devices benefiting from the reversible phase transition between ferroelectric and antiferroelectric phases. Understanding the dipole arrangements and clear phase transition pathways is crucial for design of antiferroelectric materials-based energy storage and conversion devices. However, the specific phase transition details remain largely unclear and even controversial to date. Here, we have grown a series of PbZrO3 on SrTiO3 substrates and elucidated the fine atom structures and phase transition pathways using atomic-resolution transmission electron microscopy. Specifically, a roadmap for ferroelectric to antiferroelectric phase transitions, here with increasing film thickness, is determined as ferroelectric rhombohedral (R3c)-ferroelectric monoclinic (Pc)-ferrielectric orthorhombic (Ima2)-antiferroelectric orthorhombic (Pbam), where Pc and Ima2 phases act as structural bridges. Moreover, the phase transition pathway is strongly related to the synergistic effect of oxygen octahedral tilting and cation displacement. These findings provide an insightful understanding for the theories and related properties of antiferroelectrics.

Large Polarization Near 50 µC/cm2 in a Single Unit Cell Layer SrTiO3.

The generally nonpolar SrTiO3 has attracted more attention recently because of its possibly induced novel polar states and related paraelectric-ferroelectric phase transitions. By using controlled pulsed laser deposition, high-quality, ultrathin, and strained SrTiO3 layers were obtained. Here, transmission electron microscopy and theoretical simulations have unveiled highly polar states in SrTiO3 films even down to one unit cell at room temperature, which were stabilized in the PbTiO3/SrTiO3/PbTiO3 sandwich structures by in-plane tensile strain and interfacial coupling, as evidenced by large tetragonality (∼1.05), notable polar ion displacement (0.019 nm), and thus ultrahigh spontaneous polarization (up to ∼50 µC/cm2). These values are nearly comparable to those of the strong ferroelectrics as the PbZrxTi1-xO3 family. Our findings provide an effective and practical approach for integrating large strain states into oxide films and inducing polarization in nonpolar materials, which may broaden the functionality of nonpolar oxides and pave the way for the discovery of new electronic materials.

Constructing the Fulde-Ferrell-Larkin-Ovchinnikov State in a CrOCl/NbSe2 van der Waals Heterostructure.

Time reversal symmetry breaking in superconductors, resulting from external magnetic fields or spontaneous magnetization, often leads to unconventional superconducting properties. In this way, an intrinsic phenomenon called the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state may be realized by the Zeeman effect. Here, we construct the FFLO state in an artificial CrOCl/NbSe2 van der Waals (vdW) heterostructure by utilizing the superconducting proximity effect of NbSe2 flakes. The proximity-induced superconductivity demonstrates a considerably weak gap of about 0.12 meV, and the in-plane upper critical field reveals the behavior of the FFLO state. First-principles calculations uncover the origin of the proximitized superconductivity, which indicates the importance of Cr vacancies or line defects in CrOCl. Moreover, the FFLO state could be induced by the inherent large spin splitting in CrOCl. Our findings not only provide a practical scheme for constructing the FFLO state but also inspire the discovery of an exotic FFLO state in other two-dimensional vdW heterostructures.

Hypoxia inducible factor-1α regulates microglial innate immune memory and the pathology of Parkinson's disease.

Neuroinflammation is one of the core pathological features of Parkinson's disease (PD). Innate immune cells play a crucial role in the progression of PD. Microglia, the major innate immune cells in the brain, exhibit innate immune memory effects and are recognized as key regulators of neuroinflammatory responses. Persistent modifications of microglia provoked by the first stimuli are pivotal for innate immune memory, resulting in an enhanced or suppressed immune response to second stimuli, which is known as innate immune training and innate immune tolerance, respectively. In this study, LPS was used to establish in vitro and in vivo models of innate immune memory. Microglia-specific Hif-1α knockout mice were further employed to elucidate the regulatory role of HIF-1α in innate immune memory and MPTP-induced PD pathology. Our results showed that different paradigms of LPS could induce innate immune training or tolerance in the nigrostriatal pathway of mice. We found that innate immune tolerance lasting for one month protected the dopaminergic system in PD mice, whereas the effect of innate immune training was limited. Deficiency of HIF-1α in microglia impeded the formation of innate immune memory and exerted protective effects in MPTP-intoxicated mice by suppressing neuroinflammation. Therefore, HIF-1α is essential for microglial innate immune memory and can promote neuroinflammation associated with PD.

ELAVL4 promotes the tumorigenesis of small cell lung cancer by stabilizing LncRNA LYPLAL1-DT and enhancing profilin 2 activation.

Small cell lung cancer (SCLC) is one of the most malignant tumors that has an extremely poor prognosis. RNA-binding protein (RBP) and long noncoding RNA (lncRNA) have been shown to be key regulators during tumorigenesis as well as lung tumor progression. However, the role of RBP ELAVL4 and lncRNA LYPLAL1-DT in SCLC remains unclear. In this study, we verified that lncRNA LYPLAL1-DT acts as an SCLC oncogenic lncRNA and was confirmed in vitro and in vivo. Mechanistically, LYPLAL1-DT negatively regulates the expression of miR-204-5p, leading to the upregulation of PFN2, thus, promoting SCLC cell proliferation, migration, and invasion. ELAVL4 has been shown to enhance the stability of LYPLAL1-DT and PFN2 mRNA. Our study reveals a regulatory pathway, where ELAVL4 stabilizes PFN2 and LYPLAL1-DT with the latter further increasing PFN2 expression by blocking the action of miR-204-5p. Upregulated PFN2 ultimately promotes tumorigenesis and invasion in SCLC. These findings provide novel prognostic indicators as well as promising new therapeutic targets for SCLC.

Pyroptosis-mediator GSDMD promotes Parkinson's disease pathology via microglial activation and dopaminergic neuronal death.

GSDMD-mediated pyroptosis occurs in the nigrostriatal pathway in Parkinson's disease animals, yet the role of GSDMD in neuroinflammation and death of dopaminergic neurons in Parkinson's disease remains elusive. Here, our in vivo and in vitro studies demonstrated that GSDMD, as a pyroptosis executor, contributed to glial reaction and death of dopaminergic neurons across different Parkinson's disease models. The ablation of the Gsdmd attenuated Parkinson's disease damage by reducing dopaminergic neuronal death, microglial activation, and detrimental transformation. Disulfiram, an inhibitor blocking GSDMD pore formation, efficiently curtailed pyroptosis, thereby lessening the pathology of Parkinson's disease. Additionally, a modification in GSDMD was identified in the blood of Parkinson's disease patients in contrast to healthy subjects. Therefore, the detected alteration in GSDMD within the blood of Parkinson's disease patients and the protective impact of disulfiram could be promising for the diagnostic and therapeutic approaches against Parkinson's disease.

Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Is Associated With Recurrence and Survival of Resectable Non-Small Cell Lung Cancer (NSCLC): A Retrospective Study.

INTRODUCTION: Curative lung resection remains the key therapeutic strategy for early-stage non-small cell lung cancer (NSCLC). However, a proportion of patients still experience variable outcomes and eventually develop recurrence or die from their disease. Proprotein convertase subtilisin/kexin type 9 (PCSK9) has been identified as a deleterious factor that inhibits tumor cells apoptosis and leads to reduction of lymphocyte infiltration. However, there has been no research on the predicted role of PCSK9 as an immunohistochemical biomarker with survival in resectable NSCLC. METHODS: One hundred sixty-three patients with resectable NSCLC were retrospectively reviewed, and PCSK9 expression of resected NSCLC was analyzed by immunohistochemistry using tissue microarrays. RESULTS: PCSK9 was associated with recurrence (42.1% relapsed in the PCSK9lo group versus 57.9% relapsed in the PCSK9hi group, P = 0.006) and survival status (39.6% dead in PCSK9lo group versus 60.4% dead in PCSK9hi group, P = 0.004) in patients with resectable NSCLC. Moreover, resectable NSCLC patients with higher PCSK9 expression in tumor tissue experienced poorer disease-free survival (median disease-free survival: 10.5 versus 25.2 mo, hazard ratio = 1.620, 95% confidence interval: 1.124-2.334) and overall suvrival (median overall suvrival: 20.0 versus 54.1 mo, hazard ratio = 1.646, 95% confidence interval: 1.101-2.461) compared to those with lower PCSK9 expression. CONCLUSIONS: High PCSK9 expression of tumor was correlated with recurrence and worse survival status of resectable NSCLC in our retrospective study, which indicated that PCSK9 in NSCLC may be an immunohistochemical biomarker of poor prognosis for patients with resectable NSCLC. Further large-scale prospective studies are warranted to establish these results.

Associations between insufficient sleep, skipping breakfast and depressive symptoms in children and adolescents: A school-based cross-sectional study in China.

OBJECTIVE: Insufficient sleep and skipping breakfast are increasingly prevalent among children and adolescents. Both behaviors are associated with the onset of depression. This study aims to examine the independent and joint associations of these two behaviors with depressive symptoms, and investigate whether these associations varied by age or sex. METHODS: The Center for Epidemiological Studies Depression Scale (CES-D) was used to evaluate the depressive symptoms. This cross-sectional study including 11,887 students aged 11-19 years using a stratified cluster, multistage sampling method in Ningbo, China. Multiple logistic regressions were conducted to evaluate the independent and joint association between insufficient sleep, skipping breakfast and depressive symptoms. Sensitivity analyses and stratified analyses by age and sex were performed using the same modelling strategies. RESULTS: The overall prevalence of depressive symptoms was 15.27%. Skipping breakfast (Odds Ratio (OR) = 2.557, 95% Confidence Interval (CI) = 2.236-2.925) and insufficient sleep (OR = 1.547, 95%CI = 1.390-1.723) was independently associated with depressive symptoms. Compared to students with "sufficient sleep and breakfast every day", the OR was 4.385 (95%CI = 3.649-5.271) for those with "insufficient sleep and skipping breakfast". Meanwhile, the joint association was moderated by age group, with a more apparent association observed in the 11-15-year-old group compared to the 16-19-year-old group. CONCLUSIONS: These findings indicated that insufficient sleep and skipping breakfast were independently and jointly associated with depressive symptoms. Insufficient sleep and skipping breakfast could be considered as two of the predictors of depression.

Fermented natto powder alleviates obesity by regulating LXR pathway and gut microbiota in obesity rats.

AIM: This study aimed to investigate the positive effect of natto powder on obese rats fed with a high-fat diet (HFD). METHODS AND RESULTS: Sprague-Dawley rats were fed with a HFD for 8 weeks continuously and gavaged with natto powder, respectively, for 8 weeks starting from the ninth week. The results showed that natto powder significantly reduced the body weight of rats and maintained the balance of cholesterol metabolism in the body by inhibiting the activity of liver X receptors (LXR) target genes, increasing the active expression of cholesterol 7 alpha-hydroxylase, and reducing the active expression of sterol-regulatory element-binding protein and 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR). Furthermore, natto powder increased the relative abundance of potentially beneficial microbiota in gut and decreased the relative abundance of obesity-related harmful bacteria, and also increased the Bacteroidetes/Firmicutes ratio and improved the composition of gut microbiota. CONCLUSIONS: Natto powder maintains the balance of cholesterol metabolism by inhibiting the LXR pathway and regulating the gut microbiota.

Atomic Insight into the Successive Antiferroelectric-Ferroelectric Phase Transition in Antiferroelectric Oxides.

Antiferroelectrics characterized by voltage-driven reversible transitions between antiparallel and parallel polarity are promising for cutting-edge electronic and electrical power applications. Wide-ranging explorations revealing the macroscopic performances and microstructural characteristics of typical antiferroelectric systems have been conducted. However, the underlying mechanism has not yet been fully unraveled, which depends largely on the atomistic processes. Herein, based on atomic-resolution transmission electron microscopy, the deterministic phase transition pathway along with the underlying lattice-by-lattice details in lead zirconate thin films was elucidated. Specifically, we identified a new type of ferrielectric-like dipole configuration with both angular and amplitude modulations, which plays the role of a precursor for a subsequent antiferroelectric to ferroelectric transformation. With the participation of the ferrielectric-like phase, the phase transition pathways driven by the phase boundary have been revealed. We provide new insights into the consecutive phase transformation in low-dimensional lead zirconate, which thus would promote potential antiferroelectric-based multifunctional devices.

NOD-like receptor NLRC5 promotes neuroinflammation and inhibits neuronal survival in Parkinson's disease models.

Parkinson's disease (PD) is mainly characterized by the progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and neuroinflammation mediated by overactivated microglia and astrocytes. NLRC5 (nucleotide-binding oligomerization domain-like receptor family caspase recruitment domain containing 5) has been reported to participate in various immune disorders, but its role in neurodegenerative diseases remains unclear. In the current study, we found that the expression of NLRC5 was increased in the nigrostriatal axis of mice with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP)-induced PD, as well as in primary astrocytes, microglia and neurons exposed to different neurotoxic stimuli. In an acute MPTP-induced PD model, NLRC5 deficiency significantly reduced dopaminergic system degeneration and ameliorated motor deficits and striatal inflammation. Furthermore, we found that NLRC5 deficiency decreased the expression of the proinflammatory genes IL-1ß, IL-6, TNF-α and COX2 in primary microglia and primary astrocytes treated with neuroinflammatory stimuli and reduced the inflammatory response in mixed glial cells in response to LPS treatment. Moreover, NLRC5 deficiency suppressed activation of the NF-κB and MAPK signaling pathways and enhanced the activation of AKT-GSK-3ß and AMPK signaling in mixed glial cells. Furthermore, NLRC5 deficiency increased the survival of primary neurons treated with MPP+ or conditioned medium from LPS-stimulated mixed glial cells and promoted activation of the NF-κB and AKT signaling pathways. Moreover, the mRNA expression of NLRC5 was decreased in the blood of PD patients compared to healthy subjects. Therefore, we suggest that NLRC5 promotes neuroinflammation and dopaminergic degeneration in PD and may serve as a marker of glial activation.

The expanding Pandora's toolbox of CD8+T cell: from transcriptional control to metabolic firing.

CD8+ T cells are the executor in adaptive immune response, especially in anti-tumor immunity. They are the subset immune cells that are of high plasticity and multifunction. Their development, differentiation, activation and metabolism are delicately regulated by multiple factors. Stimuli from the internal and external environment could remodel CD8+ T cells, and correspondingly they will also make adjustments to the microenvironmental changes. Here we describe the most updated progresses in CD8+ T biology from transcriptional regulation to metabolism mechanisms, and also their interactions with the microenvironment, especially in cancer and immunotherapy. The expanding landscape of CD8+ T cell biology and discovery of potential targets to regulate CD8+ T cells will provide new viewpoints for clinical immunotherapy.

Experimental evidence to understand mechanical causes of retinal detachment following blunt trauma.

PURPOSE: This study aimed to perform an in vitro experiment to simulate retinal detachment caused by blunt impact, and provide experimental evidence to understand mechanical causes of traumatic retinal detachment. METHODS: The experiment was conducted on twenty-two fresh porcine eyes using a bespoke pendulum testing device at two energy levels (0.1J for low energy and 1.0J for high energy). We examined dynamic forces and mechanical responses to the impact, including global deformations, intraocular pressure changes and the energy absorption. Another set of twenty-two eyes underwent pathological examination immediately after being subjected to blunt impact. Twelve additional intact eyes were examined as controls. All pathological sections were scored to indicate whether retinal detachment had occurred. RESULTS: A dynamic variation in intraocular pressure was detected following impact and exhibited an approximate sinusoidal oscillation-attenuation profile. The peaks of impact force were 12.9 ± 1.9 N at low-energy level and 34.8 ± 9.8 N at high-energy level, showing a significant difference (p < 0.001). The positive and negative peaks of intraocular pressure were 149.4 ± 18.9 kPa and -10.9 ± 7.2 kPa at low-energy level, and 274.5 ± 55.2 kPa and -35.7 ± 23.7 kPa at high-energy level, showing significant differences (p < 0.001 for both levels). Retinal detachments were observed in damaged eyes while few detachments were found in control eyes. The occurrence rate of retinal detachment differed significantly (p < 0.05) between the high- and low-energy impact groups. CONCLUSIONS: This study provided experimental evidence that shockwaves produced by blunt trauma break the force equilibrium and lead to the oscillation and negative pressure, which mainly contribute to traumatic retinal detachment.

Photoelectric performance of InSe vdW semi-floating gate p-n junction transistor.

Semi-floating gate transistors based on vdW materials are often used in memory and programmable logic applications. In this paper, we propose a semi-floating gate photoelectric p-n junction transistor structure which is stacked by InSe/h-BN/Gr. By modulating gate voltage, InSe can be presented as N-type and P-type respectively on different substrates, and then combined into p-n junction. Moreover, InSe/h-BN/Gr device can be switched freely between N-type resistance and p-n junction. The resistance value of InSe resistor and the photoelectric properties of the p-n junction are also sensitively modulated by laser. Under dark conditions, the rectification ratio of p-n junction can be as high as 107. After laser modulation, the device has a response up to 1.154 × 104A W-1, a detection rate up to 5.238 × 1012Jones, an external quantum efficiency of 5.435 × 106%, and a noise equivalent power as low as 1.262 × 10-16W/Hz1/2. It lays a foundation for the development of high sensitivity and fast response rate tunable photoelectric p-n junction transistor.

The association between sleep duration and risk of myopia in Chinese school-aged children: a cross-sectional study.

BACKGROUND: Myopia is one of the most commonly diagnosed refractive disorders worldwide. Identifying risk factors for myopia at an early age may help to characterize children who would benefit most from individualized lifestyle advice and early interventions. The influence of sleep duration on myopia risk remains controversial and thus needs to be evaluated. METHODS: A population-based cross-sectional study of Chinese school-aged children was conducted. Information on sleep duration was derived. The association between sleep duration and myopia risk was investigated by logistic regression analysis. RESULTS: Myopia prevalence among 9530 Chinese school-aged children was 75.4% and decreased from 84.9%, 76.5%, 65.8%, to 61.3% along with the extension of sleep duration. Univariate logistic regression found longer sleep duration of 8-9 h (OR = 0.58, 95% CI: 0.51-0.66), 9-10 h (OR = 0.34, 95% CI: 0.30-0.39), and ≥ 10 h (OR = 0.28, 95% CI: 0.24-0.33) were protective factors for myopia in all participants (P for trend < 0.001). In the multivariate analyses, sleep duration was inversely associated with the risk of myopia, and a dose-effect relationship was observed when the analysis was split by age category. CONCLUSIONS: Long sleep duration was associated with decreased risk of myopia in Chinese school-aged children.

Age-related differences in upper limb motor performance and intrinsic motivation during a virtual reality task.

BACKGROUND: In recent years, virtual reality (VR) has evolved from an alternative to a necessity in older adults for health, medical care, and social interaction. Upper limb (UL) motor skill, is an important ability in manipulating VR systems and represents the brain's regulation of movements using the UL muscles. In this study, we used a haptic-feedback Virtual Box and Block Test (VBBT) system and an Intrinsic Motivation Inventory (IMI) to examine age-related differences in UL motor performance and intrinsic motivation in VR use. The findings will be helpful for the development of VR applications for older adults. METHODS: In total, 48 young and 47 older volunteers participated in our study. The parameters including VBBT score, number of velocity peaks, velocity, grasping force and trajectory length were calculated to represent the task performance, manual dexterity, coordination, perceptive ability and cognitive ability in this study. RESULTS: Age-related differences could be found in all the parameters (all p <  0.05) in VR use. Regression analysis revealed that the task performance of young adults was predicted by the velocity and trajectory length (R2 = 64.0%), while that of older adults was predicted by the number of velocity peaks (R2 = 65.6%). Additionally, the scores of understandability, relaxation and tiredness were significantly different between the two groups (all p <  0.05). In older adults, the understandability score showed large correlation with the IMI score (|r| = 0.576, p <  0.001). In young adults, the correlation was medium (|r| = 0.342, p = 0.017). No significant correlation was found between the IMI score and VBBT score (|r| = 0.142, p = 0.342) in older adults, while a medium correlation (|r| = 0.342, p = 0.017) was found in young adults. CONCLUSIONS: The findings demonstrated that decreased smoothness in motor skills dominated the poor VR manipulation in older adults. The experience of understandability is important for older adults' intrinsic motivation in VR use.

Quantification and holistic quality evaluation of Wulingzhi extract by UHPLC-Q-Orbitrap-HRMS coupled with chemometric approaches.

The excreta of Trogopterus xanthipes ("Wulingzhi" in Chinese, WLZ) is a well-known traditional Chinese medicine. It has been used for centuries to treat amenorrhea, menstruation and postpartum abdominal pain. However, a systematic quality study on WLZ chemical markers has yet to be conducted. This study aimed to establish an ultra-high-performance liquid chromatography coupled with a hybrid quadruple extraction Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap-HRMS) method for the simultaneous quantitative determination of 20 compounds in 53 batches of WLZ; the method rapidly and sensitively determined the 20 plant- or animal-derived compounds. Firstly, the proposed approach was validated to satisfy the method's linearity, detection limits, precision, repeatability, stability and accuracy. Subsequently, multivariate analysis was used to identify correlations between the samples and feed, processing and regions. Finally, this method was used to further identify chemical markers for quality control in combination with chemometrics. This is the first report on pinusolide, betaine, hippuric acid, 4-oxorentinoic acid, 15-methoxypinusolidic acid and 4-oxoisotrentinoin in WLZ; the quality of WLZ became homogeneous after processing with vinegar (V-WLZ). Moreover, we screened for potential component markers, including uridine, allantoin, amentoflavone, hippuric acid, 3,4-dihydroxybenzoic acid, pinusolide, quercetin and kaempferol. These results were practical and efficient for the chemical clarification of WLZ and V-WLZ.

Quantitative Lipidome Analysis of Boiled Chicken Egg Yolk under Different Heating Intensities.

The effects of the four heating intensities (hot-spring egg yolk, HEY; soft-boiled egg yolk, SEY; normal-boiled egg yolk, NEY; and over-boiled egg yolk, OEY) on lipidomes of boiled egg yolks were investigated. The results indicated that four heating intensities had no significant effect on the total abundance of lipids and lipid categories except for bile acids, lysophosphatidylinositol, and lysophosphatidylcholine. However, of all the 767 lipids quantified, the differential abundance of 190 lipids was screened among the egg yolk samples at four heating intensities. Soft-boiling and over-boiling altered the assembly structure of the lipoproteins through thermal denaturation and affected the binding of lipids and apoproteins, resulting in an increase in low-to-medium-abundance triglycerides. The decreased phospholipid and increased lysophospholipid and free fatty acid in HEY and SEY suggests potential hydrolysis of phospholipids under relatively low-intensity heating. Results provide new insights into the effect of heating on the lipid profiles of egg yolk and would support the public's choice of cooking method for egg yolks.

Structural Characterization and Properties of Modified Soybean Meal Protein via Solid-State Fermentation by Bacillus subtilis.

Soybean meal (SBM) is a high-quality vegetable protein, whose application is greatly limited due to its high molecular weight and anti-nutritional properties. The aim of this study was to modify the protein of soybean meal via solid-state fermentation of Bacillus subtilis. The fermentation conditions were optimized as, finally, the best process parameters were obtained, namely fermentation temperature of 37 °C, inoculum amount of 12%, time of 47 h, and material-liquid ratio of 1:0.58, which improved the content of acid-soluble protein. To explore the utilization of modified SBM as a food ingredient, the protein structure and properties were investigated. Compared to SBM, the protein secondary structure of fermented soybean meal (FSBM) from the optimal process decreased by 8.3% for α-helix content, increased by 3.08% for ß-sheet, increased by 2.71% for ß-turn, and increased by 2.51% for random coil. SDS-PAGE patterns showed that its 25-250 KDa bands appeared to be significantly attenuated, with multiple newborn peptide bands smaller than 25 KDa. The analysis of particle size and zeta potential showed that fermentation reduced the average particle size and increased the absolute value of zeta potential. It was visualized by SEM and CLSM maps that the macromolecular proteins in FSBM were broken down into fragmented pieces with a folded and porous surface structure. Fermentation increased the solubility, decreased the hydrophobicity, increased the free sulfhydryl content, decreased the antigenicity, improved the protein properties of SBM, and promoted further processing and production of FSBM as a food ingredient.