Lipopeptides from Bacillus velezensis induced apoptosis-like cell death in the pathogenic fungus Fusarium concentricum.

AIMS: Stem rot caused by Fusarium concentricum is a new disease of Paris polyphylla reported by our research group. The present study investigates the growth inhibitory and apoptotic effects of Bacillus velezensis FJAT-54560 lipopeptide against F. concentricum. METHODS AND RESULTS: HPLC preparation and LC-MS analysis results show that the crude lipopeptides secreted by Bacillus velezensis FJAT-54560 isolated from Jasminum sambac consist of C14-17 iturin A, C14 fengycin B, C16 fengycin A/A2, C18 fengycin A, C20 fengycin B2, C21 fengycin A2, C22-23 fengycin A, C12-16 surfactin A, and C15 surfactin A derivatives. The mass ratios (g/g) of iturin, fengycin, and surfactin in lipopeptides are 2.40, 67.51, and 30.08%, respectively. Through inhibition zone and inhibition rate experiments, we found that crude lipopeptides and purified fengycin exhibit strong antifungal activity against F. concentricum, including accumulation of reactive oxygen species, loss of mitochondrial membrane potential, DNA fragmentation, Ca2+ accumulation, chromatin condensation, and phosphatidylserine externalization. Transcriptomic analysis indicates that crude lipopeptide-induced apoptosis in F. concentricum cells may be mediated by apoptosis-inducing factors and apoptosis mediators and can serve as a metacaspase-independent model. CONCLUSION: Lipopeptides from Bacillus velezensis FJAT-54560 can control the pathogenic fungus F. concentricum by inducing apoptosis.

Engineering of Bacillus thuringiensis Cry2Ab toxin for improved insecticidal activity.

Bacillus thuringiensis Cry2Ab toxin was a widely used bioinsecticide to control lepidopteran pests all over the world. In the present study, engineering of Bacillus thuringiensis Cry2Ab toxin was performed for improved insecticidal activity using site-specific saturation mutation. Variants L183I were screened with lower LC50 (0.129 µg/cm2) against P. xylostella when compared to wild-type Cry2Ab (0.267 µg/cm2). To investigate the molecular mechanism behind the enhanced activity of variant L183I, the activation, oligomerization and pore-formation activities of L183I were evaluated, using wild-type Cry2Ab as a control. The results demonstrated that the proteolytic activation of L183I was the same as that of wild-type Cry2Ab. However, variant L183I displayed higher oligomerization and pore-formation activities, which was consistence with its increased insecticidal activity. The current study demonstrated that the insecticidal activity of Cry2Ab toxin could be assessed using oligomerization and pore-formation activities, and the screened variant L183I with improved activity might contribute to Cry2Ab toxin's future application.

Association between lactate-to-albumin ratio and 28-days all-cause mortality in patients with sepsis-associated liver injury: a retrospective cohort study.

BACKGROUND: The mortality rate of sepsis-associated liver injury (SALI) is relatively high, but there is currently no authoritative prognostic criterion for the outcome of SALI. Meanwhile, lactate-to-albumin ratio (LAR) has been confirmed to be associated with mortality rates in conditions such as sepsis, heart failure, and respiratory failure. However, there is a scarcity of research reporting on the association between LAR and SALI. This study aimed to elucidate the association between LAR and the 28-day mortality rate of SALI. METHODS: In this retrospective cohort study, data were obtained from the Medical Information Mart for Intensive Care IV (v2.2). Adult patients with SALI were admitted to the intensive care unit in this study. The LAR level at admission was included, and the primary aim was to assess the relationship between the LAR and 28-day all-cause mortality. RESULTS: A total of 341 patients with SALI (SALI) were screened. They were divided into a survival group (241) and a non-survival group (100), and the 28-day mortality rate was 29.3%. Multivariable Cox regression analysis revealed that for every 1-unit increase in LAR, the 28-day mortality risk for SALI patients increased by 21%, with an HR of 1.21 (95% CI 1.11 ~ 1.31, p < 0.001). CONCLUSIONS: This study indicates that in patients with SALI, a higher LAR is associated with an increased risk of all-cause mortality within 28 days of admission. This suggests that LAR may serve as an independent risk factor for adverse outcomes in SALI patients.

Association between BMI and Efficacy of SGLT2 Inhibitors in Patients with Heart Failure or at Risk of Heart Failure: A Meta-Analysis Based on Randomized Controlled Trials.

INTRODUCTION: This meta-analysis aimed to investigate the effect of SGLT2 inhibitors on the prognosis of patients with heart failure (HF) or at risk of HF across different body mass index (BMI). METHODS: We searched PubMed, Embase, Web of Science, and Cochrane Library for all randomized controlled trials comparing SGLT2 inhibitors with placebo in patients with HF or at risk of HF and extracted relevant data up to April 2023 for meta-analysis. RESULTS: A total of 29,500 patients were enrolled in the selected five studies. The results showed that patients treated with SGLT2 inhibitors had lower HF hospitalization (HHF) or cardiovascular (CV) mortality compared to those taking placebo (hazard ratio [HR] = 0.73, p < 0.001). Patients taking SGLT2 inhibitors also had a lower all-cause mortality rate than those taking placebo (HR = 0.85, p = 0.017). In BMI subgroup analysis, the HHF rate in the experimental group was lower than that in the control group at BMI ≤24.9 kg/m2, 25.0-29.9 kg/m2, and ≥30.0 kg/m2. There was no significant difference in CV mortality between the two groups at BMI ≤24.9 kg/m2 (HR = 0.91, p = 0.331) and 25.0-29.9 kg/m2 (HR = 0.92, p = 0.307). However, when the BMI was ≥30.0 kg/m2, CV mortality with SGLT2 inhibitors was lower than in the control group (HR = 0.79, p = 0.002). When patients had a BMI ≤24.9 kg/m2 (HR = 0.85, p = 0.033) and 25.0-29.9 kg/m2 (HR = 0.83, p = 0.046), the all-cause mortality was lower in the experimental group than in the control group. However, there was no significant difference between the 2 groups in patients with a BMI ≥30.0 kg/m2 (HR = 0.87, p = 0.094). CONCLUSION: SGLT2 inhibitors improve the prognosis in patients with HF or at risk of HF. This effect is affected by BMI.

Recent advances and perspectives of functionalized carbon dots in bacteria sensing.

Bacterial infectious diseases are severe threats to human health and increase substantial financial burdens. Nanomaterials have shown great potential in timely and accurate bacterial identification, detection, and monitoring to improve the cure rate and reduce mortality. Recently, carbon dots have been evidenced to be ideal candidates for bacterial identification and detection due to their superior physicochemical properties and biocompatibility. This review outlines the detailed recognition elements and recognition strategies with functionalized carbon dots (FCDs) for bacterial identification and detection. The advantages and limitations of different kinds of FCDs-based sensors will be critically discussed. Meanwhile, the ongoing challenges and perspectives of FCDs-based sensors for bacteria sensing are put forward.

Effects of grape seed extract on the properties of pullulan polysaccharide/xanthan gum active films for apple preservation.

Grape seed extract (GSE) was added to pullulan polysaccharide (PP)/xanthan gum (XG) as composite film (PP/XG/GSE or PXG). The observed composite morphology indicated their biocompatibility. Sample PXG100 (contain 100 mg/L GSE) demonstrated the best mechanical properties, with tensile strength of 16.62 ± 1.27 MPa, and the elongation at break of (22.60 ± 0.48)%. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging activity of PXG150 were the highest at (81.52 ± 1.57)% and (90.85 ± 1.54)%, respectively. PXG films also demonstrated inhibitory effects on Staphylococcus aureus, Escherichia coli, and Bacillus subtilis. The PXG films could also prolong the shelf life of fresh-cut apples because it could decrease the rate of weight loss and retain more vitamin C and total polyphenol even on the 5th day. The weight loss rate of PXG150 was decreased from (8.58 ± 0.6)% (control) to (4.15 ± 0.19)%. It was able to achieve vitamin C and total polyphenol retention rate of 91 % and 72 %, respectively, which was significantly higher that the control sample. Therefore, GSE had contributed in enhancing the antibacterial, antioxidant properties, mechanical strength, UV protection and water resistance in PXG composite films. This effectively extend the shelf life of fresh-cut apples, which it will be an excellent food packaging material.

Effects of Polygonatum cyrtonema extracts on the antioxidant ability, physical and structure properties of carboxymethyl cellulose-xanthan gum-flaxseed gum active packaging films.

A novel film composed of Polygonatum cyrtonema extracts (PCE), xanthan gum (XG), flaxseed gum (FG) and carboxymethyl cellulose (CMC) was prepared (XFCP). Addition of PCE has decreased the light transmittance, while enhanced the UV blocking performance, antioxidant activity, tensile strength and elongation at break of XFCP due to polysaccharides, polyphenols, and flavonoid in PCE. Structural analyses by FTIR and XRD indicated the hydrogen-bonding interaction between PCE, XG, FG and CMC. It was found that compared with the control sample, XFCP2.5% with the lowest WVTR was able to prolong the shelf life of mango. The overall quality of mango was also improved in terms of lower decay rate, weight loss rate, total soluble solid, and polyphenol oxidase, higher titratable acidity, Vc, and superoxide dismutase than control mango upon 8 days of storage. This effectively expanded the application of PCE into food packaging in addition to merely as Chinese traditional medicine herbs.

Degradation of Aflatoxin B1 by recombinant laccase extracellular produced from Escherichia coli.

Bioenzymatic degradation of aflatoxin B1 (AFB1) is a safe, efficient and environmentally friendly detoxification technology. In this work, AFB1 was successfully degraded by recombinant laccase (fmb-rL103) in the absence of a mediator. The laccase gene was cloned from Bacillus vallismortis fmb-103, and was expressed in heterologous host Escherichia coli after codon optimization. The extracellular production of fmb-rL103 could be induced by adding methanol (6 %, v/v), and the maximum yield was 1545.6 U/L. In the 10 L bioreactor, the extracellular yield increased to 50,950.6 U/L after 20 h of induction, accounting for three quarters of the total yield. The mechanism of methanol-induced extracellular secretion was further studied by measuring acetate content, lac103 gene expression and cell membrane permeability. Furthermore, we explored the biochemical properties of fmb-rL103 and its degradation conditions on AFB1. The degradation efficiency increased constantly with increase in incubation pH and temperature, and exceeded 60 % at pH 7.0 and 37 °C. This work provides new insight into developing the large-scale production of laccase and its application to degrade AFB1.

Stability is essential for insecticidal activity of Vip3Aa toxin against Spodoptera exigua.

Vegetative insecticidal proteins 3A (Vip3A) were important insecticidal proteins for control of lepidopteran pests. Previous study demonstrated that Vip3Aa and Vip3Ad showed significant difference in insecticidal activities against Spodoptera exigua, while the molecular mechanism remained ambiguous. Here we demonstrated that the difference in insecticidal activities between Vip3Aa and Vip3Ad might be caused by the difference in stability of Vip3Aa and Vip3Ad in S. exigua midgut protease. Vip3Aa was quite stable while Vip3Ad could be further degraded. Molecular dynamics simulation revealed that Vip3Aa was more stable than Vip3Ad, with smaller RMSD and RMSF value. Amino acid sequence alignment indicated that three were three extra prolines (P591, P605 and P779) located on Vip3Aa. We further identified that residue P591 played a crucial role on stability and insecticidal activity of Vip3Aa. Taken together, our study demonstrated that the stability was essential for the insecticidal activity of Vip3A toxins, which might provide new insight into the action mode of Vip3A toxins and contribute to the design Vip3A variants with improved stability and insecticidal activity.

Development of xanthan gum/hydroxypropyl methyl cellulose composite films incorporating tea polyphenol and its application on fresh-cut green bell peppers preservation.

The aim of this work was to develop an edible packaging material with good performance that can be used for fresh-cut vegetables preservation. The xanthan (XG)-hydroxypropyl methylcellulose (HPMC)-tea polyphenols (TP) composite film (XHT) was prepared by adding TP to the composite film-forming solution of XG and HPMC. At optimum TP dosage of 6% (XHT6), the tensile strength and elongation at break were at the maximum. The antioxidant activity and antibacterial properties were also enhanced, demonstrated good inhibitory ability to Staphylococcus aureus. After 8 days, the amount of Vitamin C that was retained by XHT6 was 127.81% and 7.83% higher than unpackaged and XHT0, respectively. Additionally, the MDA content in green peppers were 39.16% and 78.87% higher than that of unpackaged and XHT0, respectively. Practical applications of XHT films in preserving fresh-cut bell peppers had also shown positive results, making it possible as potential food packaging.

Polyvinyl alcohol/xanthan gum composite film with excellent food packaging, storage and biodegradation capability as potential environmentally-friendly alternative to commercial plastic bag.

Polyvinyl alcohol (PVA)-xanthan gum (XG) composite films with good degradation properties were prepared by casting method. The effects of XG amount on thickness, moisture content, water solubility, water vapor transmission (WVP), transmittance and mechanical properties of the composite film were investigated. All composite films produced uniform and transparent films and Fourier transform infrared (FT-IR) spectroscopy, as well as X-ray diffraction (XRD) had proven the formation of hydrogen bonds and subsequently compatibility of the two polymers. In general, addition of XG in PVA was able to decrease moisture content, water solubility and WVP more than the pure PVA films, with sample PX30 demonstrated the best performance. This sample also had the best mechanical properties. It also demonstrated food packaging and capability better than that of commercial plastic bag. More importantly, our sample can be fully decomposed in soil and water within 12 h, which was not only significantly shorter than commercial plastic bag, but also other biodegradable materials. Therefore, PVA/XG-based food packaging material has demonstrated huge potential to be commercialized and replaces commercial plastic bag as an alternative packing material which is renewable, sustainable and environmentally friendly.

Effect of metal ions on lipopeptide secretion from Bacillus subtilis strain FJAT-4: Negative regulation by Ca2.

AIMS: This study aimed to investigate the effect of metal ions on lipopeptide production by Bacillus subtilis strain FJAT-4 and the mechanism of negative regulation by Ca2+ . METHODS AND RESULTS: The quantitative measurement of lipopeptides in response to K+ , Na+ , Mg2+ and Ca2+ addition was carried out by LC-MS. The contents of fengycin and surfactin varied within the range of 116.24-129.80 mg/L and 34.03-63.11 mg/L in the culture media containing K+ , Na+ and Mg2+ , while the levels were 0.86 and 0.63 mg/L in the media containing Ca2+ . Ca2+ at a high concentration (45 mM) did not adversely affect the growth of strain FJAT-4, but caused significant downregulation of lipopeptide synthesis-related gene expression, corresponding to a decrease in lipopeptide production. This inhibition by Ca2+ was further investigated by proteomic analysis. In total, 112 proteins were upregulated and 524 proteins were downregulated in the presence of additional Ca2+ (45 mM). Among these differentially expressed proteins (DEPs), 28 were related to phosphotransferase activity, and 42 were related to kinase activity. The proteomics results suggested that altered levels of three two-component signal-transduction systems (ResD/ResE, PhoP/PhoR and DegU/DegS) might be involved in the control of expression of the fen and srfA operons of FJAT-4 under high calcium stress. CONCLUSIONS: The Ca2+ at the high concentration (45 mM) triggers a decrease in lipopeptide production, which might be attributed to the regulation of three two-component signal-transduction systems ResD/ResE, PhoP/PhoR and DegU/DegS. SIGNIFICANCE AND IMPACT OF THE STUDY: The regulatory effect of calcium on the expression of genes encoding lipopeptide synthetases can be applied to optimize the production of lipopeptides.

Development of hydroxypropyl methylcellulose film with xanthan gum and its application as an excellent food packaging bio-material in enhancing the shelf life of banana.

A novel film composed of xanthan gum (XG) and hydroxypropyl methylcellulose (HPMC) was prepared (XH). The films were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The light transmittance, mechanical properties and water vapor transmission rate (WVTR) indicated the good compatibility between XG and HPMC with hydrogen-bond interaction and XG had a significant effect on the chemical structure, crystalline texture and microstructure of the XH composite film. The best XH sample with optimum XG concentration of 2 g/L was used as food packaging via coating onto banana, whereby the weight loss rate on banana was able to decreased from 25 ± 3% (without XH coating) to 16 ± 4% (with XH coating). Consequently, the release of flavor substances was also decreased. Banana shelf life has qualitatively improved with XH composite film for food preservation and affirmed the uses in food packaging applications.

Gellan gum/graphene oxide aerogels for methylene blue purification.

Stable gellan gum (GG)/graphene oxide (GO) aerogels were prepared by freeze-drying a mixture of GG and GO. On introduction of GO, the GG/GO aerogels had different level pore structures due to the different freezing temperatures. The volume per gram (1/ρ) of GG/GO aerogels ranges from 76.80 ± 1.54-158.30 ± 2.30 cm3/g. The porosity of GG/GO-3 (-80 °C) and GG/GO-6 (-20 °C) was 45.53 % and 61.30 %, respectively. The resulting three-dimensional GG/GO aerogels exhibited excellent performance in methylene blue (MB) adsorption. The pseudo-first-order and Freundlich isotherm models produced the best fits for the adsorption kinetics and adsorption equilibrium, respectively. The Gibbs free energy, enthalpy, and entropy of adsorption indicated that the adsorption was a spontaneous, exothermic, and entropy-increasing process. It is illustrated that the GG/GO aerogels exhibited faster adsorption kinetics and adsorption capacity. These GG/GO aerogels can remove MB from aqueous solutions.

pH-responsive poly(gellan gum-co-acrylamide-co-acrylic acid) hydrogel: Synthesis, and its application for organic dye removal.

A poly(gellan gum-co-acrylamide-co-acrylic acid) (GGDA) hydrogel was synthesized by modifying gellan gum (GG) with partly neutralized acrylic acid (AAc) and acrylamide (AAm) under the crosslinking agent trimethylolpropane triglycidyl ether. With the introduction of carboxyl and amino groups by the AAc and AAm, the GGDA showed better regularity than GG, leading to a more porous structure and higher thermal stability. Methylene blue (MB) was used as a model organic dye to evaluate the adsorption capacity of the GGDA. The GGDA exhibited excellent MB adsorption abilities and pH sensitivity. The pseudo-second-order and Freundlich isotherm models produced the best fits for the adsorption kinetics and adsorption equilibrium, respectively. The Gibbs free energy, enthalpy, and entropy of adsorption indicated that the adsorption was a spontaneous, exothermic, and entropy-decreasing process. The maximum equilibrium adsorption capacity of MB was 423.46 ± 13.60 mg/g. This pH-sensitive hydrogel is a potential alternative absorbent for organic dye removal in aqueous solutions.

Modified xanthan gum for methyl orange uptake: Kinetic, isotherm, and thermodynamic behaviors.

A novel hydrogel, named XGTTE, was prepared by modification of acrylamide and trimethylolpropane triglycidyl ether (TTE) on xanthan gum (XG). XGTTE was utilized as an adsorbent to remove methyl orange (MO) from an aqueous solution. Functional groups present in the external surface of XGTTE, such as carboxyl, hydroxyl, and amino groups, were identified, and these functional groups are responsible for the occurrence of the mechanism for MO adsorption. The structure of XGTTE after MO adsorption became more disordered. The adsorption dynamics and isotherms of MO onto XGTTE conformed well to the pseudo-second-order kinetics and the Freundlich equation, indicated that the adsorption included physical and chemical adsorption, with electrostatic interaction and hydrogen-bonding interaction. The calculated values of the thermodynamic parameters, such as changes in enthalpy (ΔH) and entropy (ΔS) were 27.30 kJ/mol and 125.63 J/mol/K, respectively. The changes in free energy (ΔG) were - 9.53 kJ/mol (293.15 K), -10.16 kJ/mol (298.15 K), -10.78 kJ/mol (303.15 K), -11.41 kJ/mol (308.15 K), and - 12.04 kJ/mol (313.15 K), respectively, indicating the adsorption process is endothermic, spontaneous, and entropic. The maximum adsorption capacities of XGTTE2, XGTTE3, XGTTE4, XGTTE5, and XGTTE6 for MO were 18.62 ± 0.99, 21.92 ± 0.84, 28.60 ± 0.84, 29.56 ± 0.99, and 12.38 ± 0.84 mg/g, respectively.

Modified xanthan gum for crystal violet uptake: kinetic, isotherm, and thermodynamic behaviors.

Modified xanthan gum (XG-AM-TTE) was employed as an adsorbent to study the adsorption behavior, thermodynamics and kinetics of crystal violet (CV) from an aqueous solution. Fourier transform infrared spectroscopy analysis indicates that the functional groups present in the adsorbent, such as carboxyl, ester and hydroxyl groups, are included on the external surface of the material, and these groups are potential active sites for interaction with CV. According to X-ray diffraction results, the structure of XG-AM-TTE after CV adsorption became more disordered, and the microstructure change is an indication of effective adsorption of CV to the surface, with CV becoming remarkably dispersed in the adsorbent according to the scanning electron microscopy observations. The adsorption kinetics and adsorption equilibrium were best described by the pseudo-second-order model and Freundlich isotherms, respectively. The thermodynamic parameters, as the Gibbs-free energy (ΔG), enthalpy (ΔH) and entropy (ΔS), indicated that the adsorption is a spontaneous, endothermic and entropy increase process. The maximum adsorption capacity of XG-AM-TTE was 183 ± 12 mg/g, suggesting that XG-AM-TTE is an efficient adsorbent.

pH-responsive poly (xanthan gum-g-acrylamide-g-acrylic acid) hydrogel: Preparation, characterization, and application.

Poly (xanthan gum-g-acrylamide-g-acrylic acid) (XGDA) hydrogel was prepared by grafting acrylamide (AM) and partly neutralized acrylic acid (AA) onto xanthan gum (XG) with trimethylolpropane triglycidyl ether as a cross-linking agent. With the introduction of amino and carboxyl groups by AM and AA, the XG molecules were rearranged with better regularity, leading to higher thermal stability and a more porous structure. The resulting hydrogel exhibited excellent performance in Cu (II)-adsorption and possessed sensitivity to external pH stimuli. The adsorption kinetics and adsorption equilibrium were best described by a pseudo-second-order model and Freundlich isotherms, respectively. The thermodynamic parameters indicated that the adsorption is a spontaneous, endothermic, and a process that increases entropy. The maximum equilibrium adsorption capacity of Cu (II) was 130.31 ± 2.97 mg/g. The XGDA can be regenerated and reused in the following adsorption process. This pH-sensitive hydrogel has potential to be used for the uptake of heavy metal ions from aqueous solution.

The synthesis and characterization of a xanthan gum-acrylamide-trimethylolpropane triglycidyl ether hydrogel.

To improve the thermal stability and adsorption performance, xanthan gum was modified with acrylamide and trimethylolpropane triglycidyl ether (TTE). The modified xanthan gum (XGTTE) was characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractogram (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The characteristic peaks at 3449, 1655, 1611 and 1420 cm-1 in the FT-IR confirm the modification. The XGTTE crystal grew well upon addition of TTE. The XRD and DSC data revealed that the XGTTE enhanced its thermal stability. Analysis of SEM revealed that the grafting introduced major changes on the microstructure making it porous and resulting in the adsorption of crystal violet (CV) with flocculation. The CV adsorption capacity of the hydrogel with different dosages of TTE (XGTTE2, XGTTE3, XGTTE4, XGTTE5 and XGTTE6) were between 28.13 with 35.12 mg/g. In addition, the adsorption capacity, thermal stability, and swelling property of XGTTE4 were the best.

Preparation of Gallic Acid-Grafted Chitosan Using Recombinant Bacterial Laccase and Its Application in Chilled Meat Preservation.

To improve the antibacterial and antioxidant properties of chitosan (CS), CS grafted with gallic acid (GA) using recombinant bacterial laccase from Bacillus vallismortis fmb-103 (fmb-rL103) as a catalyst. The structures of grafted chitosans were identified using Fourier transform infrared spectroscopy (FT-IR) and UV visible spectrum (UV-Vis spectroscopy). After gallic acid grafting, the antibacterial properties of chitosans against Pseudomonas, Acinetobacter, Brochothrix thermosphacta, Escherichia coli, Staphylococcus aureus, Salmonella, and Listeria monocytogenes were significantly improved. Meanwhile, 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging results showed that the antioxidant properties of grafted CS increased as well. The preservative effects of the grafted chitosan on chilled meat were then investigated. For this purpose, the quality indexes of the chilled meat during the storage were monitored, including total bacterial count, total basic volatile nitrogen (TVB-N) content, pH value, color and thiobarbituric acid reactive substances (TBARS) and so on. The results showed that coating with the grafted chitosan retarded the growth of spoilage bacteria, and decreased TVB-N and TBARS values of meat. The shelf life of chilled meat coated by CS grafted with GA (GA-g-CS) also extended from 6 days to 18 days at 4°C. These results provided a theoretical basis for the future application of the GA-g-CS in the preservation of chilled meat. Highlights: (1)The temperature and pH-stable bacterial laccase was used to synthesize gallic acid grafted chitosan.(2)Antioxidant and antibacterial properties of chitosan were improved through grafting gallic acid.(3)Storage properties of chilled meat were improved by coating with gallic acid grafted chitosan.