Abstract:Helicobacter pylori (Hp) is a major pathogenic bacterium that infects the human stomach and can lead to various gastrointestinal disorders, including gastritis, gastric ulcers, and even gastric cancer. Currently, triple or quadruple therapy combining antibiotics with proton pump inhibitors or bismuth compounds is commonly used to treat Hp infections in clinical practice. However, the escalating antibiotic resistance of Hp has led to a gradual reduction in the effectiveness of antibiotic treatments, with monotherapy having an eradication rate of less than 80%. Recent studies have found that probiotics show promising results in the adjuvant therapy for Hp infections. They not only alleviate gastric inflammation caused by Hp but also enhance the eradication rate of Hp and reduce the side effects of antibiotic treatment. The author reviews the application of probiotics in the treatment of Hp infections, aiming to provide a reference for further research and clinical use of probiotics as an adjuvant therapy.

Abstract:The application of red pigments in food is extensive, providing not only coloring but also beneficial health properties such as antioxidant and anti-inflammatory effects. Most commercial edible red pigments are extracted from plants and animals or synthesized by chemical methods. However, these methods often suffer from high costs, environmental pollution, and failure to meet market demands. In recent years, synthetic biology and metabolic engineering have been employed to develop microbial cell factories for producing edible red pigments. Through microbial expression of heterologous proteins, metabolic pathway analysis and optimization, and AI-assisted key enzyme design, de novo synthesis of red pigments can be achieved with improved yields. Biosynthesis of edible red pigments offer advantages such as environmental friendliness, sustainability, and high efficiency. The author provides an overview of the functions, sources, and applications of lycopene, capsanthin, betanin, carminic acid, and Monascus red pigment, as well as the current status of research on the synthesis of these pigments via microbial expression systems.

Abstract:Ochratoxin A (OTA) is a mycotoxin ubiquitous in food crops, fruits, and animals. It is one of the most toxic substances, exerting teratogenic and cytotoxic effects on the human body. An aptamer is an oligonucleotide sequence obtained by screening in vitro. Since aptamers have high affinity and strong specificity to corresponding ligands, aptamer sensors can be constructed to detect OTA. These aptamer sensors have high sensitivity, strong affinity, and good stability. The author reviews the research progress in four aptamer sensors for OTA detection, summarizes the OTA detection methods of current aptamer sensors, and proposes the future research directions of aptamer sensors, which is of great significance for the trace and sensitive OTA detection.

Abstract:Objective This study aims to construct an artificial concise isopentenol utilization pathway (IUP) with isoprenol as the substrate, thus addressing the limitations (such as excessive pathway length and high cofactor demand) of the conventional MEP/MVA pathways and enhancing the biosynthesis efficiency of borneol.Method A two-step enzymatic catalysis pathway with isoprenol as the substrate was designed for the synthesis of precursor IPP/DMAPP in Escherichia coli (E.coli） BL21 to synthesize borneol. Subsequently, metabolic engineering strategies were employed to further improve the synthesis of borneol, such as improving the soluble expression level of the bornyl diphosphate synthase CbTPS1, screening different sources of prenyltransferases to enhance the metabolic flux of IPP/DMAPP to GPP, optimizing the expression levels of key enzymes in the borneol biosynthesis pathway, and screening highly active phosphatases. Finally, the effects of different metal ions on the biosynthesis of bornol were explored.Result The artificial IUP increased the borneol production efficiency by 12.70% compared with the MEP pathway. Through enzyme and pathway engineering, the titer of borneol reached 2 642.8 μg/L. Further supplementation with Mg²⁺ increased the borneol titer to 5 912.4 μg/L.Conclusion The biosynthesis of borneol was achieved via the artificial IUP, which can provide theoretical and methodological references for the biosynthesis of other terpenoids.

Abstract:Objective This study aims to explore the alleviating effect of a probiotic formula on H1N1 infection in mice and the effects of this formula on the gut microbiota and metabolites.Method Lactobacillus rhamnosus CCFM1279 with the ability to alleviate respiratory tract infections was combined with Limosilactobacillus reuteri CCFM1145, Lacticaseibacillus casei CCFM1127, and various dietary factors to prepare a probiotic formula. SPF-grade ICR mice of 3 to 4 weeks old were randomized into blank, model, positive control (oseltamivir), and probiotic formula groups. A mouse model of influenza was constructed by nasal inhalation with the H1N1 virus. The alleviating effect of the probiotic formula on H1N1 infection was evaluated based on indicators such as body mass change rate, virus load, and L-lactate dehydrogenase activity in the bronchoalveolar lavage fluid. The 16S rRNA gene sequencing was employed to evaluate changes in the gut microbiota. Non-targeted metabolomics was employed to analyze changes in gut metabolites.Result Oral administration of the probiotic formula effectively resisted H1N1 influenza by inhibiting virus replication, alleviating lung inflammation and damage, and reducing the L-lactate dehydrogenase activity in the bronchoalveolar lavage fluid. In addition, the probiotic formula regulated the mass concentrations of IL-6 and TNF-α in the host serum and the relative expression level of the antiviral protein OAS1 in the lung tissue. It significantly increased the abundance of Parabacteroids. Metabolite analysis showed that the probiotic formula significantly increased the relative abundance of metabolites such as pyruvic acid.Conclusion Oral administration of the probiotic formula can effectively resist the H1N1 virus in the mouse model of H1N1 infection. The probiotic formula may play a role in alleviating influenza progression by specifically regulating the gut microbiota and metabolites. The findings provide new research ideas for the prevention and treatment of influenza via the gut microbiota.

Abstract:Objective Cronobacter sakazakii (C. sakazakii), a milk-borne pathogen leading to high mortality, is hard to be controlled in dairy processing due to its special cell characteristics and strong environmental stress resistance. C. sakazakii produces carotenoids which are located in the cell membrane, while there are few studies on the physiological role of C. sakazakii carotenoids. This study aims to explore the effects of β-carotene hydroxylase gene (crtZ) deletion and complementation on cell characteristics and stress resistance and decipher the potential mechanisms.Method Using Red homologous recombination, the BAA-894ΔcrtZ (ΔcrtZ) mutant was constructed from C. sakazakii BAA-894 (BAA-894), and crtZ was complemented with pWSK29 to generate BAA-894ΔcrtZ/pWSK29-crtZ (ΔcrtZ/pWSK29-crtZ). The cellular characteristics and fatty acid profiles of these strains were then analyzed.Result Compared with BAA-894, ΔcrtZ exhibited enhanced outer membrane permeability, reduced membrane fluidity and biofilm formation, and attenuated resistance to various environmental stresses, whereas these changes were diminished in ΔcrtZ/pWSK29-crtZ. In addition, the number and mass fraction of unsaturated fatty acids increased significantly in ΔcrtZ, while they showed no notable changes in ΔcrtZ/pWSK29-crtZ.Conclusion Deletion of crtZ may be a critical factor influencing the cellular characteristics and environmental stress resistance of C. sakazakii. This study contributes to the theoretical understanding of stress resistance mechanisms in C. sakazakii and provides insights for food safety control strategies.

Abstract:Objective This study modified the S-adenosylmethionine (SAM)-dependent methyltransferase to relieve the feedback inhibition of the product L-hypaphorine on this enzyme in Escherichia coli (E. coli), thereby enhancing L-hypaphorine production.Method E. coli BL21(DE3) was used as the chassis strain, and the expression of the SAM-dependent methyltransferase EgtD_{M252V, E282A} (abbreviated as MsE, the encoding gene is egtD) was exogenously induced. The induction temperature and inducer concentration were optimized to enhance the soluble expression. It was observed that the enzyme activity suffered feedback inhibition when L-hypaphorine accumulated to a threshold mass concentration, which led to reduced catalytic efficiency. To address this problem, a protein engineering strategy was employed. Using Schrodinger (a molecular docking software) and PyMOL (a structural analysis software), the substrate-binding pocket and channels of MsE were simulated to screen potential mutation sites and perform alanine scanning.Result Glutamate-to-alanine mutation at position 143 (E143A) significantly attenuated product inhibition and enhanced the enzyme's catalytic capacity toward L-tryptophan. Under supplementation with 100 mg/L L-hypaphorine, the mutant MsE_E143A exhibited markedly reduced inhibition. Consequently, the L-hypaphorine yield of the recombinant strain E. coli BL21(DE3)/pET-MsE_E143A reached (10.85±0.26) mg/L, representing a 175% increase compared to that of the parental strain.Conclusion This study successfully engineered MsE through semi-rational design, not only resolving the feedback inhibition but also providing an effective strategy for enhancing L-hypaphorine biosynthesis via protein engineering.

Abstract:Objective This study aims to investigate the immunogenicity of the outer membrane protein C (OmpC) of Escherichia coli (E. coli) O157:H7.Method The recombinant plasmids pET-28a-ompc and pET-22b-ompc-SUMO were constructed, and the recombinant protein OmpC was expressed and purified. Then, whether the target antigen of the 2G12 antibody prepared by E. coli O157: H7 cells was OmpC was determined.Result Two recombinant plasmids were successfully constructed and pET-28a-ompc was successfully expressed in E. coli BL21. The optimal induction conditions for expression of recombinant OmpC were 0.2 mmol/L IPTG, 37 ℃, and 12 h. The OmpC inclusion bodies containing His tags were obtained through elution with 800 mmol/L imidazole. The soluble OmpC was renatured by urea gradient dialysis and then eluted from the Ni-NTA column with 500 mmol/L imidazole.Conclusion OmpC in both the soluble form and the inclusion body form specifically react with the monoclonal antibody 2G12. The findings lay a foundation for the further preparation of high-affinity E. coli O157:H7 monoclonal antibodies with OmpC.

Abstract:Objective The aim of this study is to improve the yield of docosahexaenoic acid (DHA).Method Based on the synthesis pathway of DHA in Schizochytrium sp., the effects of addition of key precursors, malic acid and p-aminobenzoic acid, on the DHA production was explored.Result The addition of both malic acid and p-aminobenzoic acid enhanced the yield of DHA, and the optimal dosages were 4 g/L and 0.2 g/L, respectively. On this basis, the co-feeding of malic acid and p-aminobenzoic acid was carried out in a 5-L stirred fermenter to further enhance the yield of DHA by Schizochytrium sp. S31. Compared with the control group, the co-feeding strategy enhanced both the activities of the key enzymes in the DHA biosynthetic pathway and the glucose consumption rate, while maintaining the metabolic energy at a low level of 4.1×10^-3 g/(g·h). Finally, when this co-feeding strategy was used, the mass concentration of DHA reached the highest level of 7.7 g/L, which increased by 75.0% compared with that in the control group.Conclusion The proposed co-feeding strategy of malic acid and p-aminobenzoic acid can enhance the accumulation of DHA by Schizochytrium sp. S31, which provides a reference for the commercial production and application of DHA.

Abstract:Objective This study aims to decipher the mechanisms underpinning the antioxidant and anti-aging activities of Asini Corii Colla cake prepared with Asini corii colla, walnut kernel, black sesame, and rice wine.Method In the animal experiments, 50 SPF-grade male ICR mice were randomly assigned into 5 groups (n=10): blank negative control, model positive control, and low-dose (1.67 g/kg BW), medium-dose (3.33 g/kg BW), and high-dose (6.67 g/kg BW) Asini Corii Colla cake. After 30 of continuous feeding, the serum levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), lipid peroxidation product malondialdehyde (MDA), and protein carbonyl (PCO) were determined for each group of animals. In the human trial, 110 subjects were randomly allocated into experimental and control groups. The experimental group was given Asini Corii Colla cake, and the control group had no intervention. The intervention period was 3 months. The serum levels of SOD, GSH-Px, and MDA as well as skin moisture and oil content were measured, and the VISIA test was carried out.Result In the animal experiments, Asini Corii Colla cake groups showed significantly declined serum levels of MDA and PCO and significantly elevated serum levels of SOD and GSH. In the human trial, the experimental group showed significantly increased serum levels of SOD and GSH-Px compared with the control group, indicating that Asini Corii Colla cake contributed to antioxidant effects. Meanwhile, the results of human facial index test showed that the consumption of Asini Corii Colla cake increased the skin moisture content and the facial skin oil secretion, which could ameliorate facial aging, spots, and UV-induced pigmentation to a certain extent, suggesting that the consumption of Asini Corii Colla cake could help the skin to resist aging.Conclusion This study provides a basis for investigating the mechanisms of the antioxidant and anti-aging activities produced by Asini Corii Colla cake.

Abstract:Objective The present study investigates the ameliorative effects of probiotic fermentation supernatants on cellular photoaging, exploring whether different ultrafiltration fractions can serve as effective components in anti-photoaging cosmetics.Method Three distinct ultrafiltration fractions (relative molecular mass >3 000, relative molecular mass 1 000~3 000, and relative molecular mass <1 000) of the fermentation supernatants of Lactobacillus rhamnosus (LR), Lactobacillus paracasei (LP1), and Lactobacillus plantarum (LP2) were examined for their anti-photoaging effects on UVB-induced human skin fibroblasts (NHDF) and mouse B16F10 melanoma cell models.Result All the ultrafiltration fractions of LR, LP1, and LP2 were non-toxic to cells and significantly reduced the SA-β-gal staining rate, tyrosinase activity, reactive oxygen species (ROS) level, and nitric oxide (NO) and tumor necrosis factor-α (TNF-α) concentrations, while increasing the ABTS⁺ free radical scavenging capacity. The ultrafiltration fraction with the relative molecular mass <1 000 showed the most pronounced effects, decreasing the tyrosinase activity by 50%~60% compared with the control group.Conclusion The fermentation supernatants of the three probiotics can exert anti-photoaging effects by inhibiting melanin production and exhibiting antioxidant and anti-inflammatory activities. The ultrafiltration fraction with the relative molecular mass <1 000 may serve as potential anti-photoaging active components in the cosmetic industry.

Abstract:Objective This study aims to investigate the effect of the Ginkgo biloba leaf extract (GBE) and water-soluble tomato concentrate (WSTC) complex on hyperlipidemia (HLP) rats.Method From 40 SD rats, 10 rats were selected as blank control (CON) group, and the remaining 30 rats were modeled for HLP and then randomly allocated into model control (MOD), positive control (PC), and GBE+WSTC complex groups. After 45 d of administration, serum samples were collected for the measurement of the levels of lipid indicators: concentrations of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C); mechanism indicators were determined: mass concentrations of low-density lipoprotein receptor (LDLR), hydroxy-3-methyl glutaryl coenzyme A reductase (HMG-CoAR), and cholesterol 7-hydroxylase (CYP7A1); antioxidant indicators were assayed: levels of malondialdehyde (MDA), total superoxide dismutase (T-SOD), glutathione (GSH), and glutathione peroxidase (GSH-Px).Result Compared with the MOD group, the GBE+WSTC complex group showed highly significant reducations in the concentrations of TC and LDL-C in the serum (P<0.01), and an extremely significant decrease in the concentration of TG (P<0.001), while there was no significant difference in the concentration of HDL-C (P>0.05). Among the mechanism indicators, the mass concentration of LDLR was significantly increased (P<0.05), while the mass concentration of HMG-CoA was significantly decreased (P<0.05) in the GBE+WSTC complex group in comparison with the MOD group. Particularly, the mass concentration of CYP7A1 showed an extremely significant increase (P<0.001). In terms of antioxidant indicators, the GBE+WSTC complex group showed an extremely significant declined concentration of MDA (P<0.001), an extremely significant enhanced activity of SOD (P<0.001), and no significant difference in GSH and GSH-Px (P>0.05).Conclusion The GBE+WSTC complex can effectively alleviate the symptoms of HLP in rats. The findings provide a theoretical basis for the study of the blood lipid-lowering function.

Abstract:Objective This study aims to breed an elite strain of acetic acid bacteria with ethanol tolerance and suitable for malt vinegar brewing, thereby improving the utilization of raw materials, the yield of acetic acid, and the quality of the final vinegar product.Method The fermentation capacity of Acetobacter tropicalis J-22, Gluconacetobacter saccharivorans J-15, and Acetobacter pasteurianus HN 1.01 in beer with different volume fractions (6%~10%) of ethanol was compared. Based on the acetic acid yield (acetic acid mass concentration), ethanol conversion rate, and sensory evaluation, Acetobacter tropicalis J-22 , which achieved the highest overall assessment, was identified as the original strain. Acetobacter tropicalis J-2276 was finally bred through atmospheric and room temperature plasma (ARTP) mutagenesis combined with high-throughput screening (HTS). The growth curves and malt vinegar fermentation performance of the mutant strain Acetobacter tropicalis J-2276 and the original strain Acetobacter tropicalis J-22 under different volume fractions of ethanol further verified the ethanol tolerance and fermentation capacity of the mutant strain.Result The mutant strain Acetobacter tropicalis J-2276 exhibited significantly improved growth under ethanol stress at various volume fractions and tolerated the ethanol volume fraction up to 11%. Compared with the original strain Acetobacter tropicalis J-22, the mutant strain Acetobacter tropicalis J-2276 increased the acetic acid mass concentration of malt vinegar by 65.0%. Furthermore, the mutant strain Acetobacter tropicalis J-2276 with higher ethanol tolerance produced richer flavor compounds, with the mass concentrations of total organic acids and total volatile compounds increasing by 45.3% compared with the original strain Acetobacter tropicalis J-22.Conclusion This study demonstrates the successful breeding of an ethanol-tolerant strain, Acetobacter tropicalis J-2276, by ARTP mutagenesis and HTS. The strain exhibits stable genetic traits after seven successive generations, effectively increases the acid yield in malt vinegar fermentation, and improves the flavor quality of malt vinegar products, demonstrating broad application prospects.

Abstract:Objective This study aimed to investigate the impacts of malted highland barley on beer brewing and flavor.Method Three distinct cultivars of highland barley and malted highland barley were used as adjuncts in beer production. The physicochemical properties of the saccharified wort, fermentation parameters of beer, volatile flavor compound composition, and aroma sensory characteristics were systematically analyzed.Result The malting process increased the α-amino nitrogen content in highland barley wort by 54.01%, while reducing the β-glucan content and turbidity by 11.30% and 39.92%, respectively. Regarding fermentation characteristics, the highland barley cultivar ‘Zangqing 20’ exhibited superior performance, with the fermented beer showing higher degree of fermentation (76.8%), ethanol mass fraction (4.1%), and total acid volume fraction (2.4 mL/dL). The beer produced from malted highland barley contained higher mass concentrations of volatile compounds than that from unmalted grains. A total of 73 volatile compounds were identified in the highland barley beer, with 20 key flavor compounds exhibiting odor activity values (OAV) >1. Notably, n-hexanol, phenethyl acetate, phenylethyl alcohol, ethyl acetate, isoamyl alcohol, linalool, and ethyl caprylate were identified as potential aroma markers for distinguishing between the beer produced from malted and unmalted highland barley. Furthermore, partial least squares regression analysis elucidated the significant contributions of these 20 key flavor compounds to various sensory attributes, particularly highlighting the strong correlations of esters with fruity, floral, sour, malty, and grassy aromas.Conclusion In summary, malted highland barley is more suitable as a beer adjunct than unmalted highland barley, and the beer produced with malted highland barley exhibits superior overall quality. These findings provide valuable insights into the fermentation technology of highland barley beer and offer theoretical support for the development and quality enhancement of highland barley beer products.

Abstract:Objective This study aimed to investigate the changes in volatile flavor compounds of different potato cultivars before and after cooking, providing theoretical support and data reference for parent selection and cultivar screening in potato quality breeding.Method Thirty-four potato cultivars were selected as experimental materials. The volatile flavor compounds of potatoes before and after cooking were analyzed by gas chromatography-mass spectrometry (GC-MS), complemented by electronic nose analysis. A flavor evaluation model was established by principal component analysis (PCA) to identify key flavor compounds and cultivar specificity.Result A total of 50 volatile compounds were identified in fresh potato samples, while 52 volatile compounds were detected in cooked samples. PCA results indicated evident differences in flavor profiles among cultivars, with thermal processing markedly affecting both the types and relative mass fractions of volatile compounds. Electronic nose analysis revealed that ‘Crop60’‘Dutch No.15’‘Atlantic’‘Jizhangshu’‘Kexin No.1’‘Youjinshu’ and ‘Taihe No.9’ exhibited stronger flavor profiles in the fresh state, while ‘Longshu No.7’‘Yunshu No.506’‘Taihe No.6’‘Minshu No.6’ and ‘Caribou’ exhibited stronger flavor profiles after cooking.Conclusion Distinct differences in volatile flavor profiles were observed among potato cultivars before and after cooking. Certain cultivars exhibited prominent flavor characteristics. The combined use of GC-MS and electronic nose can effectively assist potato cultivar screening and quality breeding.

Abstract:Objective This study aims to enhance the shelf life and quality stability of fresh-cut lettuce.Method The Maillard reaction products (MRP) of Zanthoxylum bungeanum seed antimicrobial peptides and chitooligosaccharides were developed and applied as a coating on fresh-cut lettuce. The fresh-keeping effect was assessed through comprehensive physicochemical and microbiological analyses.Result On day 10, the lettuce in the MRP group exhibited significantly lower weight loss, browning index, PPO, POD, and PAL activities, respiratory intensity, malondialdehyde molar concentration, and total microbial count than the CK, COS, NP-6, and MIX groups. Meanwhile, the MRP group outperformed other groups in positive quality parameters, including color retention, pigment preservation, and ascorbic acid mass fraction, demonstrating the strongest overall fresh-keeping effect.Conclusion The MRP coating possesses potent antimicrobial, antioxidant, and fresh-keeping properties, effectively prolonging the shelf life while enhancing the sensory attributes and nutritional quality of fresh-cut lettuce. This study provides novel insights for the development and application of natural preservative materials and lays a theoretical foundation for the improvement and industrial application of food preservation technologies.

Abstract:Objective The aim of this study is to determine the concentration of L-glutamine (Gln) in complex samples rapidly, economically, and accurately.Method A method for the rapid and precise quantification of Gln was developed based on the blue pigment synthetase A (BpsA) expressed by recombinant Escherichia coli (E.coli). The holoenzyme holo-BpsA was obtained by activating apo-BpsA in vitro and optimizing the measurement conditions.Result The obtained holo-BpsA can complete quantitative determination within 30 min under suitable conditions. The method showed the limit of detection being 10.46 μmol/L, the limit of quantification being 31.68 μmol/L, the interplate standard deviation of 1.41 μmol/L, and the intraplate standard deviation of 0.85 μmol/L. The average spiked recovery rate for five commonly used culture media varied between 94.7% and 106.6%, with the standard deviation mostly below 5%. There was no significant change in the enzyme activity after holo-BpsA was stored at -20 ℃ for two months.Conclusion The method developed for rapid quantitation of Gln based on BpsA is simple to operate, highly specific, and time-saving and has high sensitivity and accuracy.