Abstract:Zearalenone (ZEN) and deoxynivalenol (DON) are common mycotoxins found in grain, and long-term dietary exposure can cause serious harm to organisms. Currently, simultaneous immunoassays for ZEN and DON mostly rely on their respective monoclonal antibodies. However, the preparation of traditional monoclonal antibodies requires long production cycles and high costs. In this study, bispecific antibodies(Bis-scFv) that could simultaneously recognize both ZEN and DON were obtained in a short time using recombinant antibody expression technology. An indirect competitive enzyme-linked immunosorbent assay(IC-ELISA) based on Bis-scFv was established. The half-maximal inhibitory concentrations(IC₅₀) for ZEN and DON standard curves was determined to be 20.64 ng/mL and 132.29 ng/mL, respectively. Bis-scFv exhibited excellent specificity with no significant cross-reactivity with other mycotoxins. Moreover, IC-ELISA was used to conduct spike recovery experiments for ZEN and DON in corn, yielding recovery rates ranging from 86.02% to 108.14%. The study demonstrates that the developed Bis-scFv has the potential for future application in the development of synchronous and rapid detection of ZEN and DON in grain samples.

Abstract:To explore the effect of konjac glucomannan (KGM) on genomic stability in colonic epithelial cells, the normal colon cell line NCM460 and the colonic cancer cell lines SW620 and HCT116 were used as the research materials. The tested cells were treated with KGM at concentrations of 0, 0.625, 0.625, 2.5,5, 10, 20, and 40 mg/mL for 24, 48, and 72 h. Cell viability was detected by methylthiazolyldiphenyl-tetrazolium bromide(MTT) assay. The CBMN-Cyt assay was performed to detect the genome instability (GIN), nuclear division index (NDI), and apoptosis levels in the tested cells after treatment with different concentrations of KGM (5, 20, and 30 mg/mL) for 72 h. The results showed that after 72 h of treatment with different concentrations of KGM, the viability of NCM460 cells increased significantly(P<0.05) within 5~40 mg/mL, while their GIN significantly decreased(P<0.001) at 5 mg/mL KGM and significantly increased at 30 mg/mL(P<0.01). The viability of HCT116 cells was significantly inhibited by KGM at concentrations of 5~40 mg/mL (P<0.05), while KGM at a concentration of 40 mg/mL exhibited an extremely pronounced inhibitory effect on the viability of SW620 cells(P<0.01). Moreover, GIN and apoptosis rate of SW620 and HCT11 cells significantly increased at KGM concentrations of 5~30 mg/mL(P<0.001), while NDI reduced significantly(P<0.05). The results suggest that low concentration(5 mg/mL) of KGM is beneficial to maintain the genomic stability in normal epithelial cell NCM460, and various concentrations(5~30 mg/mL) of KGM increases GIN and apoptosis rate in the colon cancer cells SW620 and HCT116, which may provide a molecular basis for maintaining intestinal health.

Abstract:This study aimed to evaluate the potential application of bacteriocins produced by iLactobacillus buchneri i (L. buchneri i) in the food industry. The substance with antibacterial activity against iStaphylococcus aureus (S. aureus ) was obtained through the cultivation of L.buchneri . After purification, its molecular weight and antibacterial characteristics were identified, and the inhibition of S.aureus biofilm formation was explored. The results showed that L.buchneri reached a stable period after cultivation in MRS medium at 37 ℃ for 20 h, and the diameter of inhibition zone against S. aureus reached the peak value of(26.36±0.86) mm at 26 h. After purification by АKTA pure system in tandem with Superdex 30 Increase, the molecular weight of the antibacterial active substance(BSX01) was identified as 773.56, which was sensitive to a variety of proteases and presumed to be a class I bacteriocin. BSX01 retained good inhibitory activity even after treatment at pH 10(2 h) and 121 ℃(30 min), with a minimum inhibitory concentration(MIC) of only 12.50 μg/mL. In addition, BSX01 effectively reduced the formation of S.aureus biofilm at 1/2MIC, and completely inhibited the formation of S.aureus biofilm at 2MIC. Based on these results, the bacteriocin BSX01 produced by L. buchneri is demonstrated to be a potential bio-preservative and an effective candidate for inhibiting the formation of biofilm by foodborne pathogenic bacteria in the food industry.

Abstract:This study aimed to explore the therapeutic effect of iron-containing bovine blood peptide on iron-deficiency anemia (IDA) in rats, and to provide a theoretical basis for the development of functional products from bovine blood peptides. Early weaned female SD rats were fed with low-iron rat diet for 3 weeks to establish an iron-deficiency anemia model. Iron-containing rat diet was used as the normal control, and Shengxuening was used as the positive control. Rats were orally administered with the iron-containing bovine blood peptide until the level of haemoglobin exceeded 100 g/L. Changes in rat body weight and blood routine were monitored during the experiment. Iron-containing bovine blood peptide significantly improved the body weight and increased the hematological parameters such as leukocytes, red blood cells, hemoglobin, and hematocrit caused by iron-deficiency anemia in rats. At the meanwhile, it improved iron metabolism indicators, including serum iron and serum ferritin. The effects of low-dose bovine blood peptide were comparable to Shengxuening, while the medium-does and high-dose bovine blood peptide showed better effect than Shengxuening. Oral administration of iron-containing bovine blood peptide could effectively improve iron-deficiency anemia in rats.

Abstract:Celery(Apium graveolens L.), a leaf vegetable, is a biennial herb in Apiaceae. Soluble sugar is an important nutritional component of leafy vegetable crops. In this study, two celery cultivars of ‘Sijixiaoxiangqin’ and ‘Liuhehuangxinqin’ were selected as samples. The soluble sugar content was determined and analyzed after storage at room temperature (25 ℃), low temperature (4 ℃) and room temperature in the dark (25 ℃) for 0, 6, 24, 30, 48 and 54 h. The expression characteristics of soluble sugar metabolism-related genes (AgIVR1, AgSPP, AgSPS, AgSS1 and AgUDPG ) were detected by real-time quantitative PCR technology. The results showed that there were varietal and tissue differences in the soluble sugar content of celery under the three storage conditions. The soluble sugar content in ‘Sijixiaoxiangqin’ was higher than that in ‘Liuhehuangxinqin’, and the soluble sugar content in the petioles was higher than that in the leaves. The soluble sugar content had no obvious change under different storage conditions. After storage at low temperature for 54 h, the expression levels of AgSS1 in both celery cultivars increased significantly, and the overall expression level of AgSPS in celery exhibited a downward trend under different storage conditions. Diverse genes might co-regulate the change in soluble sugar content through interaction during celery storage. The accumulation of soluble sugar was correlated with the changes in related genes.

Abstract:Escherichia coli possesses a complex and diverse array of extracellular biofilm components. These biomolecules not only consume a large amount of energy and substrates during their synthesis and assembly, but certain components also present huge risks for pathogenicity. In order to mitigate the adverse effects, Crisp-Cas9 gene-editing method was employed to remove non-essentia biofilm components from Escherichia coli MG1655 at the genetic level. A series of mutant strains with deleted non-essential biofilm components were constructed, and the cellular characteristics of these mutant strains were investigated to identify those with superior performances. The results showed that knockout of genes encoding flagellum(fliE-R, fliY-T , and flhE-D ), type 4 capsule, sialic acid and poly- β-1,6-glucosamine could promote the growth of mutants in M9 medium. Deletion of flagellar gene clusters flgN-L and exopolysaccharide components enhanced PHB synthesis, while knocking out four gene clusters related to extracellular polysaccharide components or flagella could enhance the membrane permeability. The removal of core polysaccharides from Escherichia coli could remodel metabolic regulation and promote the production of colanic acid.

Abstract:In order to explore the application of silver-loaded hydroxyapatite/titanium dioxide (Ag-HA/TiO ₂ ) antibacterial agent in aquatic products, this study conducted the structural characterization of Ag-HA/TiO ₂ and selected Escherichia coli and Staphylococcus aureus as the test strains for a comparison between silver-loaded hydroxyapatite(AgHAp) and titanium dioxide(Ag-HA/TiO ₂ ) in antibacterial performance. A preliminary evaluation on the antibacterial rate of Ag-HA/TiO ₂ against specific spoilage bacteria(SSOs) in aquatic products was also assessed. Based on these evaluations, the study conducted practical applications to investigate the effects of the antibacterial solution concentration and the soaking time on the microorganisms in large yellow croaker and the standard for Grade I fresh meat. The results showed that Ag-HA/TiO2 maintained its crystalline structure after loading titanium dioxide and reducing silver content by half. The antibacterial rate of Ag-HA/TiO ₂ against Escherichia coli and Staphylococcus aureus was 100%, which was superior to AgHAp containing 3.00% of silver, and the minimum inhibitory concentration for both strains was 312.5 μg/mL. The antibacterial rates of 10 mg/mL Ag-HA/TiO ₂ against SSOs-pseudomonas fluorescens and shewanella putrefaciens at 0.5 h were (97.58±3.43) % and 100% respectively, reaching 100% at 1 h and 1.5 h. As the Ag-HA/TiO ₂ was applied to large yellow croaker, higher concentration of soaking solution or longer soaking time resulted in more pronounced inhibition effect on the growth of bacteria in large yellow croaker, extending the standard shelf life for Grade I fresh meat of large yellow croaker. The study demonstrates the high antibacterial effectiveness of Ag-HA/TiO ₂ and suggests its potential as an ideal antibacterial agent for aquatic products.

Abstract:In order to screen probiotic lactic acid bacteria for food with cholesterol-lowering ability from fermented vegetable. In present study, taking Weissella confusa (RW) as a reference, 5 probiotic lactic acid bacteria isolated with cholesterol-lowering ability were obtained from different fermented vegetable samples via directional separation method combined with 16SrDNA identification method. The results showed that the five strains had excellent probiotic characteristics, with exhibiting the tolerance to acid(pH 2.0), bile salt(3 g/L) and simulated gastrointestinal fluids, and superior cholesterol-lowering ability(54.79%~62.54%)，and inhibiting pathogen and adhere to Caco-2 cells. The strains showed excellent probiotic characteristics. Further, five isolates were safety with no hemolysis phenomenon, no biogenic amines producing, and showed sensitivity to a variety of antibiotics. Five isolates were identified as Lactiplantibacillus plantarum (JCSMC-1), Lactobacillus plantarum (SYB and JCSMC6-2), Lacticaseibacillus paracasei (SYD and XSMC-1) by 16S rDNA. The isolates of 1 Lactiplantibacillus plantarum, 2 Lactobacillus plantarum, and 2 Lacticaseibacillus paracasei all have the basic characteristics of probiotic lactic acid bacteria for food, providing new resources for the development of probiotic lactic acid bacteria for food.

Abstract:To address the issue of short shelf life due to microbial proliferation in the industrialized production of a traditional food Shao-Mai, the pre-made and unsteamed Shao-Mai was treated with electron beam irradiation at different doses. The growth patterns of microorganisms and changes in peroxide values in irradiated Shao-Mai under different storage temperatures were studied. The results showed that electron beam irradiation effectively reduced the microbial count in Shao-Mai and prolonged the shelf life. However, higher doses of irradiation promoted lipid oxidation. Irradiation doses of 6~8 kGy irradiation showed no promoting effect on lipid oxidation, and the irradiated Shao-Mai exhibited no significant difference in peroxide value compared to non-irradiated products (P>0.05) after 3 days of storage at 30 ℃. When refrigerated at 4 ℃, Shao-Mai irradiated at dose of 6~8 kGy had a shelf life of up to 30 days, which was 20 days longer compared to non-irradiated products. According to the changes of total bacterial count and moulds and yeasts under different storage temperatures, the corresponding Gompertz microbial growth models were established respectively. The correlation coefficients of the models were all greater than 0.95, effectively describing the dynamic changes in microbial growth of irradiated Shao-Mai during storage and predicting the microbial level over different storage times.

Abstract:This experiment aimed to investigate the effectiveness and evaluation of the reverse transcription-loop-mediated isothermal amplification(RT-LAMP) in detecting Listeria monocytogenes infection in meat products. The assay was designed to target the iap gene of Listeria monocytogenes for detection of meat samples based on the principle of RT-LAMP. The specificity, sensitivity and differentiation between living and dead bacteria of this identification were compared to Chinese national standards. This experiment optimized the RT-LAMP conditions and obtained the optimum amplification at 63 ℃ for 60 min, the optimal concentrations of the primers were 0.4 μmol/L outer primer and 0.8 μmol/L inner primer, 2.0 mmol/L MgSO₄, 1.0 mol/L betaine, 2.0 mmol/L dNTPs, 10 U/μL AMV reverse transcriptase, 320 U/mL Bst DNA polymerase. The assay has a sensitivity of 7.3×101 CFU/per reaction, which was twice as sensitive as LAMP. The specificity test demonstrated that only the target genes of Listeria monocytogenes were detected without false positives. The ability of RT-LAMP to detect Listeria monocytogenes in commercially available meat samples(n=100) was comparable to the Chinese National Standard GB 4789.30-2016, and RT-LAMP only amplified live microorganisms. Differentiation experiments between living and dead bacteria revealed that this method could eliminate the interference from dead bacteria in meat samples. In comparison with the method of national standards, RT-LAMP proves to be an effective detection method.

Abstract:A combination of 16S rRNA high-throughput sequencing technology and traditional culture methods was used to analyze and compare the microbial communities in raw materials for canned bird's nest and different production processes. Meanwhile, α and β microbial diversity analyses were used to investigate key control points for microbial contamination sources and processes in the canned production lines. The results revealed that the primary source of contamination in canned bird's nest production was the raw material of rock sugar, and the Geobacillus and Bacillus were the main contaminant genus responsible for the spoilage of canned bird's nest. Furthermore, the production processes associated with rock sugar raw materials in the production line were identified as the production critical control points. This study provides a theoretical basis for the production quality control and hygiene supervision in canned bird's nest production.

Abstract:In order to produce bacteriocin in large quantity through prokaryotic expression and investigate its physicochemical properties, this study amplified and recycled the Pediococcus acidilactici R-4 bacteriocin pedA gene. The gene was subsequently ligated into the pMD19-T vector and transferred into E. coli DH5α receptor cells for cloning. The cloned pedA gene was extracted and connected to the expression vector pET-32a(+) to form a recombinant plasmid pET-32a-pedA, which was then transferred into E. coli BL21(DE3) receptor cells. Following induction with isopropyl-β-D- thiogalactoside(IPTG), Pediococcus acidilactici R-4 bacteriocin PA-1 was expressed within E. coli BL21 (DE3) cells. The expressed protein was purified by a Ni-NTA column and its physicochemical properties were determined using Staphylococcus aureus as an indicator. The results demonstrated successful expression and purification of the 26 000 of Pediococcus acidilactici R-4 bacteriocin PA-1 in E. coli BL21 (DE3) cells. The purified Pediococcus acidilactici R-4 bacteriocin PA-1 exhibited antibacterial activity within the ranges of 14.7~15.6 mm, 14.0~16.5 mm, 15.1~15.8 mm, and 14.9 mm, respectively, under the treatment of 40~121 ℃ for 20 min, pH 2 to 12, 0~10 h ultraviolet irradiation, and 2 h catalase. However, the antibacterial activity was lost after treatment with pepsin and trypsin for 2 hours. This indicates that Pediococcus acidilactici R-4 bacteriocin PA-1 has good stability to high temperature, strong acid and alkali, UV radiation, and catalase. However, it could be deactivated by pepsin and trypsin.

Abstract:Intraflagellar transport protein 20 (IFT20) of Chlamydomonas reinhardtii is a component of the intraflagellar transport complex B(IFT-B). IFT20 is known to be involved in regulating intracellular transport processes of macromolecules, but its detailed function as a flagellar protein in flagella remains to be investigated. This study aimed to develop highly specific polyclonal antibodies against Chlamydomonas reinhardtii IFT20 from rabbit serum to lay the foundation for further investigation into its flagellar function. To achieve this goal, the N-terminal 6×His-tagged IFT20 fusion protein(6×His::IFT20) was first expressed in Escherichia coli, and 6×His::IFT20 was purified by Ni-column. The purified 6×His::IFT20 was then applied to immunize the New Zealand white rabbits. The antiserum was collected after three rounds of immunization, and the titer was determined to be 1∶102 400 by an indirect ELISA method. Subsequently, the obtained anti-serum was purified using protein A purification beads to enrich the IgG subtype antibodies. Next, N-terminal MBP-tagged IFT20(MBP::IFT20) expressed and purified from Escherichia coli was used for antigen-antibody affinity purification of IgG antiserum. The western blotting assay of whole cell protein extracts from CC-125 identified the high specificity of the obtained IFT20 polyclonal antibodies, making them suitable for future investigations on the flagellar function of IFT20 in Chlamydomonas reinhardtii.