Abstract:Intestinal stem cells (ISCs) located at the bottom of intestinal crypts are the key factors driving the repair and rapid renewal of the intestinal epithelium. Their proliferation and differentiation are finely regulated by the microenvironment of the niche. ISCs, as dietary nutrient sensors, can respond to different dietary signals to regulate intestinal homeostasis. The author systematically summarizes the main signaling pathways involved in the regulation of ISCs and reviews the effects and functioning mechanisms of dietary patterns such as high-fat diets, intermittent fasting, calorie restriction, and ketogenic diets on the homeostasis of ISCs, aiming to provide a theoretical basis for the development and application of dietary intervention strategies targeting ISCs in maintaining intestinal health and overall homeostasis.

Abstract:Zinc and selenium are essential trace elements for maintaining human normal physiological function. Deficiency of zinc or selenium can result in immune dysfunction, chronic diseases such as cardiovascular diseases and hyperlipidemia, and even increase the risk of cancer. The human body cannot independently synthesize these trace elements, which can only be obtained from the daily diet. However, natural food sources have low content of zinc and selenium, which is insufficient to meet the body’s needs. Therefore, developing fortified foods with trace nutrients is an important approach to meeting residents’ requirements. Edible fungi serve as natural carriers for enriching trace elements and ideal dietary supplements. Pleurotus spp., as a typical example, not only enrich zinc or selenium but also efficiently enhance both simultaneously. They metabolize inorganic forms of zinc and selenium into organic forms, which demonstrate various biological activities including immune enhancement, antioxidant effects, anti-inflammatory properties, and potential anti-tumor effects among others. The author summarized the research progress in the enrichment of zinc and selenium in Pleurotus spp., involving the cultivation methods, enrichment regulation, metabolites, biological activities, and related products. These findings provide a theoretical foundation for comprehensively understanding Pleurotus spp.-based refined products enriched with zinc or/and selenium while promoting their extensive application in the field of health.

Abstract:[Objective] An efficient biosynthetic system was constructed in Escherichia coli to achieve high-yield production of tyramine and its key derivative tyrosol.[Method] Through the analysis of protein expression, enzymatic properties, and whole-cell catalysis results, tyrosine decarboxylase (TDC) derived from Enterococcus faecalis was selected as the key enzyme for tyramine synthesis. Subsequently, tyramine oxidase (TYO) was introduced to construct the TDC-TYO pathway for tyrosol production. Meanwhile, the LAAD-PDC pathway for tyrosol synthesis was established. A dual-enzyme co-expression system was established, and the effects of tandem enzyme order, production pathways, and key enzyme sources on tyrosol yield were analyzed. The recombinant strain B1, carrying the plasmid pET28a-EfTDC-TYO, was obtained through whole-cell catalysis, and the reaction conditions were optimized.[Result] Under optimal reaction parameters, the recombinant strain B1 achieved a tyrosol yield of 3.96 g/L within 24 h, with a substrate conversion rate of 51.9%.[Conclusion] This study provides valuable insights for the biosynthesis of tyrosol and its derivatives.

Abstract:[Objective] The production of the aromatic compound salicylic acid (SA) is limited by its inhibitory effects on enzymes related to cellular energy metabolism. This study aims to develop a strategy for avoiding the impact of SA on enzymes related to cellular energy metabolism and increase the yield of SA.[Method] A highly efficient Escherichia coli strain was designed to improve SA production by optimizing metabolic pathways and enzyme systems.[Result] The genome-scale metabolic model GEMS1515 was employed to predict the key bottle necks in the phosphoenolpyruvic acid (PEP) pathway and SA biosynthesis pathways. The SA yield was successfully increased from 834.82 mg/L to 1 143.56 mg/L by targeted knockout of fbaA and dcuA genes. Furthermore, the enzyme fusion strategy, combining flexible and rigid peptide linkers with TRAP scaffold proteins (TRAP1 and TRAP3), further improved the catalytic efficiency. The optimized strain achieved a maximum SA yield of 2 100.00 mg/L, which represented an increase of 151% over that of the initial strain.[Conclusion] Integrating metabolic engineering, multi-enzyme cascade strategy, and machine learning demonstrate great application potential in optimizing the biosynthesis of high-value compounds.

Abstract:[Objective] This study aimed to investigate the impact of curcumin-loaded ovalbumin (OVA)-carboxymethylcellulose (CMC) (OVA-CMC-Cur) colloidal particles on the stability of fish oil emulsions.[Method] The OVA-CMC-Cur colloidal particles were prepared with OVA and CMC at varying mass ratios and pH. The colloidal particles were then used as the stabilizer to prepare fish oil emulsions. The structural characteristics, stability, and digestive behaviors of the emulsions were investigated.[Result] At the OVA-CMC mass ratio of 2∶1, the OVA-CMC-Cur particle-stabilized fish oil emulsions exhibited smaller particle sizes. These particles formed a dense, compact interfacial film at the oil-water interface, resulting in more uniform emulsion droplets. Furthermore, the OVA-CMC-Cur particle-stabilized fish oil emulsions demonstrated enhanced storage stability and antioxidant activity. Notably, when the OVA-CMC mass ratio was 2∶1, the fish oil emulsions exhibited significantly improved stability in simulated gastrointestinal fluids.[Conclusion] OVA-CMC-Cur colloidal particles significantly enhance the stability of fish oil emulsions, which provides a theoretical basis for their applications in the food and pharmaceutical fields.

Abstract:[Objective] This study aims to investigate the effects of aeration on the microbial community structure and metabolic functional genes in pickles.[Method] Amplicon sequencing was carried out for the 16S rRNA and ITS rRNA gene fragments from three groups (aerated group, sealed group, and the initial group) within the same pickle system. The EasyAmplicon pipeline and PICRUSt2 were employed to assess bacterial and fungal community diversity, composition, and functional gene variations.[Result] Compared with the initial group, the sealed group showed only minor changes in microbial diversity, whereas the aerated group exhibited significant microbial divergence from the initial group. After aeration, the number of rare taxa sharply declined, and the relative abundance of a few dominant genera (such as Lactobacillus in bacteria and Rhodotorula and Wickerhamomyces in fungi) increased substantially. In terms of functional genes, the bacteria displayed decreased relative abundance of functional genes related to amino acid metabolism, cell motility, and quorum sensing but increased relative abundance of functional genes associated with lipid metabolism, replication, and repair. Notably, the relative abundance of functional genes linked to nitrite metabolism also showed a marked increase. Additionally, among fungal functional genes associated with growth morphology, the relative abundance of saprotrophs and yeasts significantly increased. And oxygen-related energy metabolism and stress defense functional genes (such as octanoyl-acyl carrier protein biosynthesis, fatty acid β-oxidation and D-myoinositol-1 metabolism) also exhibited elevated relative abundance in fungi.[Conclusion] The significant changes in microbial community structure and metabolic functions after aeration may lead to nitrite accumulation and spoilage. Therefore, the occurrence of aeration should be minimized, and the quality of pickles can be controlled by regulating environmental factors and the microbial community in pickles.

Abstract:[Objective] This study aimed to investigate the feasibility of the fermentation process for L-lysine production by immobilized Corynebacterium glutamicum.[Method] Firstly, the effects of different volume fractions of seed medium on the fermentation stability of immobilized Corynebacterium glutamicum were examined. Subsequently, the impacts of immobilization carriers with different specifications on the fermentation performance were analyzed. Finally, a comparative analysis was conducted on the differences between the fermentation processes with free and immobilized Corynebacterium glutamicum.[Result] The addition of 5% volume fraction of seed medium adequately sustained the growth and metabolic activities of Corynebacterium glutamicum. Higher volume fractions diverted carbon sources towards bacterial growth, thereby limiting product synthesis. The most favorable fermentation metrics were achieved with a specification of 0.061 g/cm². Compared with free Corynebacterium glutamicum fermentation, immobilized Corynebacterium glutamicum exhibited a significantly shortened fermentation cycle and an increase of 16.24% in the acid production rate, which was attributable to the high cell density and protective effects of immobilization. Furthermore, the reduced biomass redirected more carbon sources towards product synthesis, resulting in higher conversion rates.[Conclusion] The novel fermentation process employing immobilized Corynebacterium glutamicum demonstrates strong application feasibility, providing important insights for its future industrial implementation.

Abstract:[Objective] This study aims to breed a fruit wine yeast strain with low methanol production by protoplast fusion.[Method] With yeast strains LAB and XR as parents, protoplast fusion was employed to breed the yeast strains for fruit wine fermentation with a low mass concentration methanol and a high volume fraction ethanol. The process of yeast protoplast preparation was optimized by single factor and orthogonal experiments with the formation rate, regeneration rate, and preparation rate of protoplasts as indicators. The parental protoplasts were inactivated by ultraviolet radiation and heating, and 35 g/dL PEG-6000 was used for chemical fusion after inactivation.[Result] The optimum conditions for protoplast preparation were as follows: a snailase mass concentration of 2.0 g/dL, enzymolysis time of 2.0 h, an EDTA-mercaptoethanol mass concentration of 1.25 g/dL, and an EDTA-mercaptoethanol treatment temperature of 30.0 ℃. Under these conditions, the formation rate, regeneration rate, and preparation rate of protoplasts were （93.61±0.86）%, （24.23±0.52）%, and （22.68±0.29）%, respectively. A total of 19 fusants were obtained by chemical fusion, and the fusant lx3 was screened out by the brewing experiment. The methanol mass concentration in the fermented fruit wine produced with lx3 was reduced by 50.87% on average compared with that produced with the parent strain XR, and the ethanol volume fraction was similar between lx3 and the parent strain.[Conclusion] This study bred a fruit wine yeast strain suitable for passion fruit shell fermentation with a low methanol mass concentration and a high ethanol volume fraction.

Abstract:[Objective] This study aims to investigate the ameliorative effects of a Lilium brownii-Plantago asiatica L. compound solid beverage on hyperuricemia and to elucidate its potential mechanisms.[Method] Network pharmacology was employed to screen the active constituents, potential targets, and related pathways. Key targets were identified based on a protein-protein interaction (PPI) network. Molecular docking was conducted between the key proteins and active constituents. An animal experiment was performed to validate the effects of the compound solid beverage on serum uric acid levels, renal function indices, activities of uric acid-producing enzymes, and the levels of renal urate transporters.[Result] Network pharmacology analysis indicated that Lilium brownii and Plantago asiatica L. contain a total of 9 active constituents and had 61 common targets with hyperuricemia, among which 13 targets were closely related to the treatment of hyperuricemia, mainly involving the NF-κB and PI3K-Akt signaling pathways. Molecular docking between the top 4 connectivity degree-ranked target proteins identified from the protein-protein interaction network and the 9 active constituents showed binding energy below -5.0 kJ/mol, indicating favorable interactions and suggesting uric acid-lowering potential. The animal experiment showed that compared with the model group, the Lilium brownii-Plantago asiatica L. compound solid beverage reduced the serum uric acid concentration by 30.46% and lowered serum creatinine and blood urea nitrogen levels (P<0.05). In addition, the beverage also decreased renal xanthine oxidase (XOD) and adenosine deaminase (ADA) enzyme activities, downregulated the urate transporter 1 (URAT1) level, and upregulated organic anion transporter 1 (OAT1) and ATP-binding cassette sub-family G member 2 (ABCG2) levels in the renal tissue.[Conclusion]The Lilium brownii-Plantago asiatica L. compound solid beverage may lower uric acid levels and improve renal function-related indices through a multi-constituent, multi-target, and multi-pathway synergistic mechanism. The findings provide a theoretical basis for the development of uric acid-lowering functional beverages.

Abstract:[Objective] This study aims to explore the impacts of single strain fermentation and mixed fermentation on the flavor,composition, and antioxidant activity of soybean whey.[Method] Gas chromatography-ion mobility spectrometry (GC-IMS) was coupled with E-nose and high-performance liquid chromatography (HPLC) to analyze the flavor and function of soybean whey fermented by the single and mixed strains.[Result] Compared with single-strain fermentation by Limosilactobacillus fermentum HJS-1 or Kluyveromyces marxianus HJS-2, mixed fermentation (Limosilactobacillus fermentum HJS-1 + Kluyveromyces marxianus HJS-2) effectively improved the levels of functional substances and antioxidant activity of soybean whey. Compared with non-fermented soybean whey, mixed fermentation increased the mass concentrations of soy isoflavones and organic acids in soybean whey by 65.53% and 182.39%, respectively. Moreover, mixed fermentation increased the proportions of sweet-taste amino acids and aromatic amino acids by 49% and 9%, while reducing the proportions of umami/sour-taste amino acids and bitter-taste amino acids by 16% and 42%, respectively. The ABTS⁺, hydroxyl, and DPPH free radical clearance rates of the soybean whey after 36 h of mixed fermentation reached (20.95±0.07)%, (9.08±0.07)%, and (37.62±0.21)%, respectively. A total of 53 volatile flavor compounds in the fermented soybean whey were identified by GC-IMS, mainly including esters, aldehydes, alcohols, and acids. Large amounts of esters such as isobutyl acetate and ethyl acetate existed in the soybean whey after mixed fermentation, which removed the beany flavor of soybean whey.[Conclusion] Mixed fermentation can effectively improve the flavor quality and antioxidant activity of soybean whey.

Abstract:[Objective] This study aims to investigate the effects of different treatments on the postharvest preservation of grapes.[Method] The impacts of 0.4 mg/L 24-epibrassinolide (EBR), 1×10⁹ CFU/mL Metschnikowia pulcherrima, and their combination (YBR) on postharvest storage of ‘Shine Muscat’ grapes were evaluated.[Result] Compared with the control (CK) group, EBR, Metschnikowia pulcherrima, and YBR treatments effectively reduced the water loss rate, maintained the firmness, and delayed the declines in protopectin and stem chlorophyll content of grape. In the later storage stage, YBR treatment delayed the decrease in flavonoid mass fraction, which was 12.95% higher than that of CK group. At the same time, YBR treatment reduced the mass molar concentrations of superoxide anion and malondialdehyde (MDA) by 25.15% and 33.84%, respectively. In addition, YBR treatment increased the peroxidase (POD) activity and inhibited the polyphenol oxidase (PPO) activity to alleviate the oxidative damage of grape during storage.[Conclusion] This study confirms the application potential of Metschnikowia pulcherrima combined with EBR.

Abstract:[Objective] This study aims to evaluate the feasibility of using the rapid test strip method for detecting key microbial quality control indicators in chilled meat, specifically the total plate count and Escherichia coli/coliforms.[Method] The performance of the rapid test strip method was assessed through repeatability tests, and the national standard plate count method was used as the reference for method comparison. Statistical significance of the quantification results was analyzed by a t-test, and linear regression was adopted to analyze the correlation.[Result] The repeatability deviation of the rapid test strip method (r≤0.25) met the requirements of ISO 4833—1:2013. No significant difference was observed between the results of the rapid test strip method and the plate count method, and the results of the two methods demonstrated a positive correlation.[Conclusion] The rapid test strip method demonstrates good repeatability and accuracy, and thus it can be used for the rapid quantification of the total plate count and Escherichia coli/coliforms in chilled meat, providing technical support for microbial safety monitoring in chilled meat.

Abstract:[Objective] This study aims to address the technical problems of insufficient nitrogen content and an imbalanced amino acid composition in very high gravity wort produced with high-level syrup adjuncts.[Method] This study investigated the effect of protease-assisted saccharification on wort protein composition. Then, a comprehensive evaluation was conducted on the brewing performance during 22 °P very high gravity beer production.[Result] During the proteolysis stage of saccharification, a synergistic addition of neutral protease and flavourzyme protease at a mass ratio of 6∶4 enabled efficient directed hydrolysis of malt proteins. In the wort, the α-amino nitrogen mass concentration was increased by 30%, while the mass concentrations of A- and B-type amino acids were increased by more than 30%. In addition, the mass concentrations of soluble nitrogen and foam proteins were increased by over 10%, with a more proper distribution of nitrogenous substances among the A, B, and C fractions. The degradation rate of reducing sugar, the reducing capacity of diacetyl and acetaldehyde, and other fermentation performance were also enhanced significantly.[Conclusion] The 22 °P very high gravity wort produced using this compound protease hydrolysis strategy supported continuous yeast reuse for five generations without a significant decline in yeast viability, meeting industrial fermentation requirements. Furthermore, beer foam quality was improved while the mellow taste and overall sensory harmony were enhanced.

Abstract:[Objective] This study aims to achieve rapid detection of AFB₁ contamination levels in peanuts through dual-band hyperspectral imaging and machine learning.[Method] A peanut AFB₁ contamination level warning model was constructed via a dual-band hyperspectral imaging system consisting of visible near-infrared spectroscopy at 400~1 000 nm and short-wave near-infrared spectroscopy at 900~1 700 nm, combined with machine learning. Peanut samples with four contamination levels were collected, in which the mass fraction of AFB₁ was determined by ultra-high performance liquid chromatography-tandem mass spectrometry. The effects of four pretreatment methods [first derivative, second derivative, multiplicative scatter correction, and standard normal variate (SNV)], two characteristic wavelength selection methods [successive projections algorithm and uninformative variables elimination (UVE)], and two machine learning methods [support vector machine (SVM) and back-propagation neural network] on classification performance were compared.[Result] The combined model SNV-UVE-SVM effectively determined AFB₁ contamination levels in both bands, with optimal performance in the 900~1 700 nm band. The characteristic wavelengths were primarily concentrated in the ranges of 1 126~1 308 nm and 1 588~1 720 nm, achieving 100.00% accuracy in both the training and test sets.[Conclusion] This paper pioneered the construction of an intelligent early-warning model for AFB₁ contamination levels in peanuts by using dual-band hyperspectral imaging and machine learning algorithms, providing a novel technical paradigm for non-destructive detection of mycotoxin contamination in agricultural products. This approach holds significant engineering application value for real-time online monitoring in processing stages.

Abstract:[Objective] This study aimed to investigate the effects of goat milk formula powder on lipopolysaccharide (LPS)-induced intestinal inflammation and barrier impairment in mice.[Method] Histopathological observation, real-time quantitative PCR, and enzyme-linked immunosorbent assay were used to assess changes in intestinal inflammation levels and barrier function-related indicators in mice following intervention with goat milk formula powder. Additionally, the composition of the gut microbiota was analyzed to elucidate its potential mechanisms of action.[Result] Goat milk formula powder alleviated intestinal histopathology and increased the number of goblet cells. Compared with the model group, the goat milk formula powder intervention reduced the mass fractions of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 by 21.88%, 28.30%, and 36.67%, respectively, while it increased the mass fraction of the anti-inflammatory cytokine IL-10 by 53.80%. Regarding intestinal permeability markers, it reduced the mass concentrations of D-lactate and enterotoxin by 16.14% and 32.52%, respectively, and decreased the activity of diamine oxidase (DAO) by 8.74%. Meanwhile, it enhanced the mRNA expression levels of tight junction [proteins ZO-1 and Claudin-1 by 2.50- and 2.89-fold. Furthermore, the intervention increased the relative abundance of beneficial gut bacteria, including Akkermansia, Alistipes, Alloprevotella, and Muribaculum, and these microbial changes were correlated with the aforementioned inflammation and intestinal barrier indicators.Conclusion] Goat milk formula powder alleviated LPS-induced intestinal inflammation and enhanced barrier function in mice, with its mechanism of action potentially related to modulation of the gut microbiota structure.

Abstract:[Objective] This study aimed to improve the yield and conversion rate of 5-methylpyrazine-2-carboxylic acid (MPCA) through biocatalysis.[Method] Escherichia coli (E.coli）was used as the model organism to construct an MPCA synthesis system, and the whole-cell catalytic reaction conditions of recombinant E. coli were optimized. In addition, the parental host strain was subjected to ultraviolet mutagenesis for the screening of host strains tolerant to high mass concentrations of 2,5-dimethylpyrazine (DMP).[Result] The recombinant mutagenized strain could completely convert 10 g/L DMP to MPCA within 12 h in a 10 mL reaction system, achieving a yield of 12.9 g/L and a corresponding molar conversion rate of 100%. The whole-cell catalyst YB-CMAB was recycled three times for 18 h, with a total MPCA yield of 20.6 g/L and an average molar conversion rate of 89%.[Conclusion] This study established an efficient whole-cell catalytic strain with a high conversion rate for MPCA synthesis, providing technical support for the industrial production of MPCA.

Abstract:[Objective] This study aims to design a fusion protein with high activities and high stability of superoxide dismutase (SOD) and catalase (CAT).[Method] Using AcSOD11 and FeCAT proteins as the research subjects, three fusion proteins of SOD and CAT were designed: AcSOD11-(GGGGS)*3-FeCAT, FeCAT-(GGGGS)*3-AcSOD11, and FeCAT-(EAAAK)*3-AcSOD11, which were named AcSOD11-G3-FeCAT, FeCAT-G3-AcSOD11, and FeCAT-E3-AcSOD11, respectively. Soluble expression of these three fusion proteins was achieved in Escherichia coli BL21(DE3). The thermal stability and pH stability of the three fusion proteins were then assessed.[Result] The three fusion proteins showed no significant difference in the specific activity of SOD, while they had significant differences in the specific activity of CAT. The specific activity of CAT was the highest (531 U/mg) in FeCAT-G3-AcSOD11 and the lowest in FeCAT-E3-AcSOD11, indicating that the flexible (GGGGS)*3 peptide linker was favorable for maintaining CAT enzyme activity. Stress resistance studies demonstrated that both CAT and SOD in FeCAT-G3-AcSOD11 exhibited strong tolerance to high temperatures and varying pH conditions.[Conclusion] This study successfully constructed three fusion proteins and obtained FeCAT-G3-AcSOD11, a highly stable fusion protein with high enzyme activities of both SOD and CAT, providing a theoretical foundation for the combined application of SOD and CAT.