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In order to effectively prevent and treat microbial contamination in foods, L-methionine-modified microcrystalline cellulose (M-MCC) with antibacterial effect was prepared by loading L-methionine (L-Met) on microcrystalline cellulose (MCC). The morphology, element composition and stability of M-MCC were characterized, indicating the successful grafting of L-Met. M-MCC had a good scavenging effect on 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cationic radicals, with a scavenging percentage of 97.47% at 20 mg/mL. M-MCC had a marked antibacterial activity against the Gram-positive bacteria Listeria monocytogenes and Staphylococcus aureus, with minimal inhibitory concentration and minimum bactericidal concentration of 15 and 30 mg/mL, respectively. Finally, the effect of M-MCC on the cell membrane permeability, cell membrane integrity, cellular contents and DNA content of the two bacteria was studied. The results showed that M-MCC treatment had a significant inhibitory effect on the growth of L. monocytogenes and S. aureus, and delayed the time taken to reach the logarithmic phase compared with the untreated group. Furthermore, it resulted in obvious changes in extracellular conductivity and the contents of nucleic acid and protein, which was closely related to the treatment time. This study shows that M-MCC has great application potential as an antibacterial agent.

Hemopexin as an acute-phase protein binds heme with a high affinity and participates in a variety of processes of physiology and pathology. Hemopexin plays an important role in regulating inflammatory response by regulating pro-/anti-inflammatory cytokines. In this study, the hemopexin gene was identified from black rockfish. The open reading frame of the black rockfish hemopexin (SsHPX) gene was predicted and amplified. The different expression patterns of SsHPX in microbial-challenged tissues and peripheral blood leukocytes (PBLs) were analyzed by RT-qPCR. The results indicated that SsHPX showed high evolutionary conservations in sequence and structure. The expression of SsHPX was significantly induced in a time-dependent manner in black rockfish intestine after Edwardsiella piscicida infection, while the evidently down-regulations were observed in the PBLs following the stimulations of two microbial ligands. The recombinant SsHPX protein (rSsHPX) exhibited microbial binding ability. In addition, rSsHPX could reduce bacterial proliferation with effect, thereby alleviating the inflammatory responses induced by bacteria. Moreover, almost all the expressions of pro-inflammatory cytokines (tnfα, il-1β, il-8 and il-17c) and anti-inflammatory cytokine (IL-10) were inhibited in black rockfish intestine cells stimulated by the mixing solution of LPS + rSsHPX comparing with the group with LPS stimulation. Overall, this study provides a theoretical basis for investigating the key roles of an acute-phase protein hemopexin in bacteriostatic ability and inflammatory regulations in black rockfish during bacterial infection. These findings also contribute to a better understanding of the relatively stable and conserved biological function of hemopexin during species evolution.

The unique properties of silver nanoparticles (AgNPs), such as size, surface charge, and the ability to release silver ions, contribute to DNA damage, inducing of oxidative stress, and apoptosis in cancer cells. Thus, the potential application of AgNPs in the field of biomedicine, and cancer therapy are rapidly increasing day by day. Therefore, in this study, AgNPs were synthesized by extract of Chuanminshen violaceum, and then the synthesized CM-AgNPs were fully characterized. The biological activity of CM-AgNPs was investigated for antibacterial, antioxidant, and anticancer activities. The cytotoxic activity of CM-AgNPs was tested for various kinds of cancer cells including MKN45 gastric cancer cells, HCT116 human colon cancer cells, A549 human lung cancer cells, and HepG2 liver cancer cells. Among these cancer cells, the induced apoptosis activity of CM-AgNPs on HCT116 cancer cells was better and was used for further investigation. Besides, the CM-AgNPs exhibited great antioxidant activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) with 50% free radical scavenging activity, and CM-AgNPs also showed a significant antibacterial activity against Escherichia coli and Staphylococcus aureus. Thus, our pilot data demonstrated that the green synthesis of CM-AgNPs would be considered a good candidate for the treatment of HCT116 cancer cells, with its strong antioxidant activity and antibacterial effects.

As a natural preservative, nisin is widely used in the food industry, while its application in biomedicine is limited due to its susceptibility to interference from external conditions. In this study, a nanoparticle–hydrogel composite system was designed to encapsulate and release nisin. Nisin nanoparticles were identified with a smooth, spherical visual morphology, particle size of 122.72 ± 4.88 nm, polydispersity coefficient of 0.473 ± 0.063, and zeta potential of 23.89 ± 0.37 mV. Based on the sample state and critical properties, three temperature-sensitive hydrogels based on chitosan were ultimately chosen with a rapid gelation time of 112 s, outstanding reticular structure, and optimal swelling ratio of 239.05 ± 7.15%. The composite system exhibited the same antibacterial properties as nisin, demonstrated by the composite system’s inhibition zone diameter of 17.06 ± 0.83 mm, compared to 20.20 ± 0.58 mm for nisin, which was attributed to the prolonged release effect of the hydrogel at the appropriate temperature. The composite system also demonstrated good biocompatibility and safety, making it suitable for application as short-term wound dressings in biomedicine due to its low hemolysis rate of less than 2%. In summary, our nanoparticle-based hydrogel composite system offers a novel application form of nisin while ensuring its stability, thereby deepening and broadening the employment of nisin.

In order to improve the stability and bacteriostasis of patchouli essential oil, high-energy emulsification method was used to prepare patchouli essential oil nanoemulsion by using a mixture of tween 80, thiamine pyrophosphate and chitosan, its structure, particle size, ζ potential and polymer dispersity index were analysed. The results showed that the particle size of the newly prepared patchouli essential oil nanoemulsion was about 89.5 nm. The encapsulation rate of patchouli essential oil was 95.85%, and the retention rate remained above 85% for up to 7 days at room temperature. Furthermore, fluorescence microscopy and scanning electron microscopy demonstrated that the droplets of the emulsion were spherical and the dispersion of oil droplets was relatively uniform. It was also showed that the patchouli essential oil was encapsulated in nanoemulsion based on the Fourier transform infrared spectroscopy and X-ray diffraction experiments. The results of the antioxidation and antibacterial experiments showed that the patchouli essential oil nanoemulsion exhibited a better oxidation stability, it had a good inhibitory effect on Staphylococcus aureus and Escherichia coli within a period of 7 days. Altogether, patchouli essential oil nanoemulsion showed a better stability and bacteriostatic activity compared to pure essential oil, and had a broad application prospect in the fields of food preservation.

The use of endovascular stent-graft has become an important option in the treatment of aortic pathologies. However, the currently used endograft membranes have limited ability to prevent bacterial colonization. This makes them unsuitable for the treatment of mycotic aneurysms, as the infection is prone to progress after endograft implantation. Moreover, even in non-mycotic aortic pathologies, endograft infections can occur in the short or long term, especially for patients with diabetes mellitus or in immune insufficiency conditions. So, this study aimed to develop a kind of Ag-NPs-loaded endograft membrane by coaxial electrospinning technique, and a series of physical and chemical properties and biological properties of the Ag-NPs-loaded membrane were characterized. Animal experiments conducted in pigs confirmed that the Ag-NPs-loaded membrane was basically non-toxic, exhibited good biocompatibility, and effectively prevented bacterial growth in a mycotic aortic aneurysm model. In conclusion, the Ag-NPs-loaded membrane exhibited good biocompatibility, good anti-infection function and slow-release of Ag-NPs for long-term bacteriostasis. Thus, the Ag-NPs-loaded membrane might hold potential for preventing infection progression and treating mycotic aortic aneurysms in an endovascular way.

The ultrasonic-assisted extraction process of polysaccharides from Stropharia rugosoannulata in Bo'ai County and the antibacterial and antioxidant activities were analyzed. On the basis of single factor experiments, with the polysaccharide yield as response value, the ultrasonic-assisted extraction process of polysaccharides from Stropharia rugosoannulata in Bo'ai County was optimized using Box-Behnken experimental design with three factors and three levels. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the polysaccharides extracted from Stropharia rugosoannulata in Bo'ai County were determined using the double dilution method and the plate coating method, respectively. The antioxidant activity was determined using ABTS method and FRAP methods. The results showed that the optimal ultrasonic-assisted extraction conditions were 62 ℃ (ultrasonic temperature), 1:30 g/mL (solid-liquid ratio) and 62 min (ultrasonic time). Under these conditions, the average yield of polysaccharide was 13.25%, which agreed well with the predicted value of 13.35%, the relative error was 0.75%. Among the five common pathogenic bacteria tested, the polysaccharide extract showed the strongest inhibitory effect on Salmonella typhimurium with the minimum inhibitory concentration of 6.25 mg/mL and the minimum bactericidal concentration of 12.5 mg/mL. Meanwhile, the polysaccharide extract showed strong ability to scavenge ABTS+ free radicals and reduce Fe3+, and showed dose-effect relationship within a certain concentration range, although weaker than the positive control (VC) at the same concentration. The results suggested that the regression models were stable and feasible for polysaccharide extraction from Stropharia rugosoannulata in Bo'ai County and the extract had strong antioxidant and antibacterial activities, but its antibacterial effect was selective.

At present, effective fixation and anti-infection implant materials represent the mainstay for the treatment of open fractures. However, external fixation can cause nail tract infections and is ineffective for fixing small fracture fragments. Moreover, closed reduction and internal fixation during the early stage of injury can lead to potential bone infection, conducive to bone nonunion and delayed healing. Herein, we designed a bone adhesive with anti-infection, osteogenic and bone adhesion fixation properties to promote reduction and fixation of open fractures and subsequent soft tissue repair. It was prepared by the reaction of gelatin (Gel) and oxidized starch (OS) with vancomycin (VAN)-loaded mesoporous bioactive glass nanoparticles (MBGNs) covalently cross-linked with Schiff bases. Characterization and adhesion experiments were conducted to validate the successful preparation of the Gel-OS/VAN@MBGNs (GOVM-gel) adhesive. Meanwhile, in vitro cell experiments demonstrated its good antibacterial effects with the ability to stimulate bone marrow mesenchymal stem cell (BMSCs) proliferation, upregulate the expression of alkaline phosphatase (ALP) and osteogenic proteins (RunX2 and OPN) and enhance the deposition of calcium nodules. Additionally, we established a rat skull fracture model and a subcutaneous infection model. The histological analysis showed that bone adhesive enhanced osteogenesis, and in vivo experiments demonstrated that the number of inflammatory cells and bacteria was significantly reduced. Overall, the adhesive could promote early reduction of fractures and antibacterial and osteogenic effects, providing the foothold for treatment of this patient population.

Marine fish are rich in minerals (calcium and iron), vitamins (riboflavin and niacin), nutrients that are beneficial for brain (fatty acids), docosahexaenoic acid that prevent cardiovascular and cerebrovascular diseases, and are an important source of protein for humans. In recent years, the nexus between the increased demand of high-quality protein and the decrease in marine fishery resources resulted in the intensification of marine farming. However, this high-density farming has led to various bacterial diseases frequently due to lack of disease control methods, which has caused economic losses in the farming industry and impeded the healthy development of the industry. Therefore, it is particularly important to reduce the rates of bacterial diseases and improve the survival rate of cultured fish. It is of particular concern on how to maintain intestinal health of cultured fish under this farming method. Probiotics, a kind of living microorganisms, are beneficial to the health of the host. In the 1980s, probiotics have been viewed as an environmentally friendly and effective product in aquaculture; they improve the host health by influencing intestinal microbiota and nonspecific immunity to increase disease resistance ability. Moreover, they can be used as an ideal substitute for antibiotics in aquaculture production. Probiotics from Bacillus, lactic acid bacteria, saccharomyces, and nitrobacteria are diverse, and the function of each varies widely. As the typical representative of probiotics, lactic acid bacteria, may inhibit the growth of pathogens by the production of its metabolites, such as lactic acid, acetic acid, peroxide hydrogen, and bacteriocin. Lactic acid bacteria are also able to balance intestinal microecological imbalance and maintain intestinal microbiota balance when the intestinal microbiota contains pathogenic bacteria or the host is treated with antibiotics. Bacillus is an aerobic or facultative anaerobic gram-positive bacteria, which is stable, possesses strong stress resistance and high resurrection rate, and can produce various macromolecules, such as proteases and amylases and thus can improve the digestive function of the host by promoting the absorption of nutrients. Furthermore, as a non-specific immune antigen, Bacillus can improve the immune resistance of the host by stimulation of the components of cells or cell walls. The application of lactic acid bacteria and Bacillus has demonstrated favorable results, but this has been limited in marine fish culture because the non-fish origin of some strains and the different specificity of strains for different fish species or the same growth stage make their application difficult. Thus, it is essential to develop marine fish-derived probiotics, analyze their characteristics, define growth conditions, verify safety effects, and determine dosage and methods for their administer in marine fish culture. In this study, probiotics from marine fish were screened for the development of microbial ecological agents; 80 strains of culturable bacteria were obtained by separating bacteria from the mucosa samples of the digestive tract of wild Sebastes schlegelii and Hexagrammos otakii. The enzyme-producing ability of the strains was determined using a selective culture medium. The common pathogenic bacteria infecting marine fish were selected as indicator bacteria to determine the antibacterial activity of the isolated strains. Two potential probiotics, strains TS2 and TH8, were screened, and their physiological and biochemical identification, 16S rDNA sequence, growth characteristics, and host safety were determined. The results showed that TS2 had the strongest ability to hydrolyze starch, protein, and fat, and its sterile culture products could significantly inhibit the growth of Vibrio anguillarum, V. parahaemolyticus, V. Harvey, and Pseudoalteromonas nigrifaciens. TH8 has the strongest ability to hydrolyze protein and fat, and its sterile culture products could significantly inhibit the growth of V. anguillarum, V. alginolyticus, V. parahaemolyticus, P. nigrifaciens, Aeromonas hydrophila, Staphyloccocus aureus, and Escherichia coli. According to the analysis of the physiological and biochemical characteristics of the bacteria and 16S rDNA sequence alignment analysis, strain TS2 was identified as Bacillus subtilis and strain TH8 as Vagococcus fluvialis. Strain TS2 showed significant growth at 15–40 ℃, sodium chloride concentration of 0–0.08 g/L, and pH of 5–9; it entered the logarithmic phase after 6 h and the stable phase after 26 h. TH8 grew rapidly at 20–40 ℃, sodium chloride concentration of 0–0.08 g/L, and pH of 5–12; it entered the logarithmic phase after 2 h and the stable phase after 14 h. The safety of strains TS2 and TH8 was analyzed on a homologous host, and it was found that the strains were relatively safe for the homologous host at the concentration of 108 CFU/mL. The screened B. subtilis TS2 and V. fluvialis TH8 strains have a strong enzyme production ability and inhibit the growth of various pathogens by their metabolites; they have the following advantages: Wide temperature and salt tolerance, acid and alkali resistance, and fast growth speed. Thus, they could be considered as potential probiotic candidates for the development of microbial pharmaceuticals and can be used in more applications in marine aquaculture.

Objective: By analyzing bacteriostasis and efficacy, the possibility of Artemisia argyi extract to be a plant extract preservative is clarified. It provides a message for the development of natural non-irritating plant extract preservative. Methods: Water and ethanol extracts of A. argyi were prepared. The content of its main active components was determined. Its inhibitory effect and stability on Escherichia coli and Staphylococcus aureus were analyzed. Antioxidant activity, ultraviolet absorption capacity and security were also discussed. Results: The ethanol extract of A. argyi had a significant inhibitory effect on the two kinds of bacteria, which was related to the content of active components to some extent. Temperature and UV irradiation had no significant effect on antibacterial activity, while pH had a greater effect on antibacterial activity. At the concentration of 0.96 mg/mL, ethanol extract of A. argyi leaves could eliminate 98% of DPPH and ABTS free radicals, and more than 50% of superoxide anion and hydroxyl free radicals. When the concentration was 0.5 mg/mL, the two extracts had good ultraviolet absorption capacity. The HET-CAM test showed that the extract of A. argyi had high security at the concentration of 62.5 mg/mL. Conclusion: The ethanol extract of A. argyi has good and stable bacteriostatic effect, certain antioxidant activity, ultraviolet absorption performance and security.

Objective: The effects of ginkgo powder on the physicochemical indexes of wheat flour, as well as the nutrition, sensory, texture, cooking quality and bacteriostasis of noodles were studied. Methods: The physicochemical, nutritional and microbial indexes of flour and noodles were determined by instrumental analysis and chemical analysis respectively. And the sensory indexes of noodles were evaluated by sensory method. Results: The results showed that adding 0~18% ginkgo powder to wheat flour could reduce dough stability time, falling number wet and gluten content. It could increase the water absorption, whiteness of wheat flour, the taste and hardness of noodles. The contents of protein, dietary fiber, fat and ash in noodles showed an upward trend. The total number of bacteria in noodles showed a downward trend. When the appropriate addition amount of ginkgo powder in wheat flour was 12%, the elasticity, chewiness, sensory quality and cooking quality of noodles reached the maximum. Conclusion: Ginkgo powder could improve the sensory quality, nutritional value, preservation and freshness of wheat flour noodles, which has good application value in wheat flour noodles.

Rapid wilting after harvest greatly decreases the ornamental and economic value of fresh-cut flowers. To determine how chlorine dioxide (ClO2) affects postharvest flower quality, Paeonia lactiflora ‘Hushui Dangxia’ cut flowers in bottles were treated with different concentrations of ClO2 (0, 25, 50, 75, and 100 mg L−1). Among the treatments, ClO2 75 (i.e., 75 mg L−1) decreased the bacterial growth and lignin content at the P. lactiflora flower stem base, while also decreasing the degree of flower stem vessel blockage. Additionally, the ClO2 75 treatment increased the relative fresh weight, water balance, soluble sugar content, soluble protein content, and antioxidant enzyme activities (superoxide dismutase, peroxidase, and catalase), but decreased the malondialdehyde content and ethylene release rate of P. lactiflora cut flowers. Thus, the aging of P. lactiflora flowers was delayed, thereby maintaining the cut flower quality. Furthermore, the vase life (i.e., ornamental period) increased by three days.

Fermented meat products are vulnerable to microbial contamination because of their long production cycle and rich nutrients, which can affect product quality and result in adverse effects on human health. As consumers pay increasing attention to the flavor and safety of fermented meat products, it is very important to explore the safety and flavor characteristics of meat products. Lactic acid bacteria were the first microorganisms isolated from fermented meat products, which are important dominant microorganisms in traditional fermented meat products and are closely related to product quality. In fermented meat products, lactic acid bacteria can not only produce antibacterial substances that inhibit the growth of harmful microorganisms and therefore improve the safety of meat products, but also improve the flavor of fermented meat products by affecting carbohydrate metabolism as well as protein and lipid decomposition and oxidation. This paper reviews the effect of lactic acid bacteria on improving the product quality by inhibiting the growth of harmful microorganisms in fermented meat products and the effect of lactic acid bacteria the flavor of fermented meat products in order to provide new ideas for future research of fermented meat products.

Hydrogel is a polymer material composed of a hydrophilic three-dimensional network structure, which can quickly absorb water, swell, and maintain the swollen state to avoid significant water loss. It can provide sufficient capacity to accommodate a variety of materials, including small molecules, polymers and particles, among which, those that exhibit antibacterial properties are called antibacterial hydrogels. Antibacterial hydrogels have been widely used in many fields, such as biomedicine, textile, chemical industry, agriculture, and tissue engineering. They have great application potential in food packaging, food quality indication, and food preservation, but have not attracted enough attention. According to the type of active ingredients, antibacterial hydrogels can be divided into three categories: Natural polymer antibacterial hydrogel, hydrogels loaded with inorganic/organic antibacterial substances, and antibacterial hydrogels containing light-activated or light-responsive materials. This review expounds on the antibacterial mechanism and application status of these three types of antibacterial hydrogels, in order to provide a broader idea for the application of hydrogels in the field of food to exert its antibacterial effect.

Objective: To isolate and identify Lactobacillus gasseri from 125 fecal samples of healthy infants, and to evaluate its safety and antimicrobial activity. Methods: In this study, fecal samples of 1-month-old healthy infants were taken, and the strains were separated by MRS medium, Gram staining, biochemical identification and 16S rRNA sequencing technology were used to strain identification. Subsequently, the hemolysis of the isolated L. gasseri was evaluated by blood agar. The drug sensitivity of antibiotics was determined by micro broth dilution method, and the safety of the isolated strains were evaluated. Finally, the inhibitory effects of the 15 isolated L. gasseri strains on E. coli ATCC 25922 and S. aureus ATCC 25923 were detected by Oxford cup method. Results: Fifteen strains of L. gasseri were successfully isolated from 125 fecal samples of healthy infants. Hemolysis test results showed that 14 strains of them was hemolytic negative. The 15 tested strains were highly sensitive to tetracycline, vancomycin, linezolid and rifampicin, completely sensitive to imipenem and completely resistant to trimethoprim. The results of antibacterial activity test showed that 6 strains could effectively in inhibiting both E. coli and S. aureus. Conclusion: In this study, three strains of L. gasseri were successfully isolated from healthy infant’s fecal samples, which could not only inhibit E. coli and S. aureus, but also passed the safety test (LGI 6-1, LGI 6-2 and LGI 6-3). As potential probiotic resources, they could provide a research target for further research on function exploring.

Pea polyphenols are secondary metabolites widely existing in peas, mainly including flavonoids (populin, kaempferol, quercetin), phenolic acids (p-coumaric acid, erucic acid, ferulic acid) and tannins (catechins). The content, species and distribution of pea polyphenols depend on pea varieties, but they are affected by environment and inducing factors in the process of their growth. The extraction method of pea polyphenols has gradually changed from inefficient solvent extraction to microwave extraction technology with high efficiency and high extraction rate. The research on its physiological activity has gradually developed to the molecular and cellular level, and its application scope has gradually expanded to meat products, aquatic products, flour products and other industries. In order to further understand the chemical properties and potential utilization value of pea polyphenols, this paper expounds in detail the distribution of pea polyphenols, the factors affecting the types and content of pea polyphenols, the separation and extraction, physiological activity and its application in food industry, in order to provide a theoretical basis for the development and research of pea polyphenols.

Aerobic fermentation is an effective technique for the large-scale processing of tobacco waste. However, the specificity of the structure and composition of tobacco-derived organic matter and the toxic alkaloids in the material make it currently difficult to directly use microbial agents. In this study, a functional strain FYZ1-3 was isolated and screened from thermophilic phase samples of tobacco waste composting. This strain could withstand temperatures as high as 80°C and grow normally at 0.6% nicotine content. Furthermore, it had a strong decomposition capacity of tobacco-derived starch and protein, with amylase activity of 122.3 U/mL and protease activity and 52.3 U/mL, respectively. To further understand the mechanism of the metabolic transformation of the target, whole genome sequencing was used and the secondary metabolite gene cluster was predicted. The inhibitory effect of the strain on common tobacco fungi was verified using the plate confrontation and agar column methods. The results showed that the strain FYZ1-3 was Bacillus subtilis, with a genome size of 4.17 Mb and GC content of 43.68%; 4,338 coding genes were predicted. The genome was annotated and analyzed using multiple databases to determine its ability to efficiently degrade starch proteins at the molecular level. Moreover, 14 functional genes related to nicotine metabolism were identified, primarily located on the distinct genomic island of FYZ1-3, giving a speculation for its nicotine tolerance capability on the molecular mechanism. By mining the secondary metabolite gene cluster prediction, we found potential synthetic bacteriocin, antimicrobial peptide, and other gene clusters on its chromosome, which may have certain antibacterial properties. Further experiments confirmed that the FYZ1-3 strain was a potent growth inhibitor of Penicillium chrysogenum, Aspergillus sydowii, A. fumigatus, and Talaromyces funiculosus. The creation and industrial use of the functional strains obtained in this study provide a theoretical basis for its industrial use, where it would be of great significance to improve the utilization rate of tobacco waste.

The present study investigated the mechanical characteristics, hydrophobicity, antioxidant and antibacterial properties, FTIR, SEM and XRD of films fabricated with corn starch and pullulan (CS/PUL) by adding different concentrations of Gallic acid (GA) (0%, 0.5%, 1.0%, 1.5% w/v). The mechanical strength and opacity of CS/PUL films were enhanced by the addition of 1.0% GA. The water vapor permeability (WVP) of CS/PUL films was significantly lower in films with GA compared to those without (P

The application of packing agents affects the final surgical outcomes in treating otitis media (OM) and introduces the risk of infection. To decrease the infectious risks of packing agents and even introduce positive bacteriostatic functions, a kind of PPDO-grafted Ag-incorporated TiO2 nanoparticles (Ag@TiO2-PPDO NP)-coated gauzes were prepared by a solution immersion method. Morphologies and in vitro Ag+ releasing of Ag@TiO2-PPDO NP coated gauzes were determined by scanning electron microscope (SEM) and inductively coupled plasma-mass spectrum (ICP-Ms). Ag@TiO2-PPDO NP could respond to visible light, which might make Ag@TiO2-PPDO NP inhibit the proliferation of bacteria continually and positively with irradiation of visible light. Then the bacteriostatic effects of these gauzes on OM pathogens were investigated in vitro and in vivo. These gauzes could inhibit the proliferation of pathogenic Staphylococcus aureus (S. aureus) and Streptococcus pneumoniae (S. pneumoniae) in vitro and rat subcutaneous infection models. Specifically, the bacteriostatic effect of these gauzes on S. aureus and S. pneumoniae could be enhanced with irradiation by visible light in vitro. Further, the rat external auditory canal infection model verified the enhanced bacteriostatic effect of Ag@TiO2-PPDO-coated gauzes on S. aureus with irradiation by visible light. The Ag@TiO2-PPDO-coated gauzes are promising for packing materials after OM surgery and could reduce postoperative antibiotic requirements.

Abstract This article intends to improve the recycling of waste sugarcane (Saccharum officinarum) tops and the value-added utilization of pyroligneous acid. Fresh sugarcane tops can be used by ruminants, but they are prone to dehydration and mildew during storage, reducing their feeding value. Pyroligneous acid, a by-product in the process of making biochar, has good antibacterial effects. Adding pyroligneous acid to sugarcane tops for silage fermentation may be an effective way to promote the recycling of sugarcane tops. Thus, the fermentation quality and bacterial community of sugarcane tops ensiled with or without 1–2% pyroligneous acid for 5, 10, 20, or 100 days were investigated. Results showed that pyroligneous acid increased the acetic acid content and reduced ammonia-N concentration, and numbers of coliform bacteria and molds in sugarcane tops silages. On the other hand, the addition of pyroligneous acid decreased the diversity of bacteria in sugarcane-top silage. Pyroligneous acid decreased Firmicutes and Leuconostoc relative abundances while increasing Lactobacillus relative abundances. Fermentation was also limited by the addition of pyroligneous acid, which reduced metabolic activities during ensiling. Graphical abstract

Objective: This study aimed to optimize the optimal extraction process of total flavonoids from the root of Clausena anisum-olens and determine the yield and antibacterial effect of total flavonoids from different producing areas. Methods: The total flavonoids were extracted by ultrasonic method from the roots of C. anisum-olens. Through single factor and orthogonal test, the effect of ultrasonic assisted extraction conditions on the extraction rate of total flavonoids from the root of C. anisum-olens was investigated, and the extraction and antibacterial test of total flavonoids from various producing areas were carried out. Results: The optimum extraction process of total flavonoids from C. anisum-olens was as follows: temperature 70 ℃, ultrasonic power 50 W, ethanol concentration 90%, solid-liquid ratio 1∶16 (g/mL), extraction time 40 min. Under the control of these conditions, the extraction rate of total flavonoids was 3.361%, and the yield of total flavonoids in the root bark of C. anisum-olens in Chongzuo city was the highest, up to 4.781%; the total flavonoids of C. anisum-olens had strong inhibitory effects on Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, borer killing bacteria and Escherichia coli, indicating that it had broad-spectrum antibacterial activity. Conclusion: Ultrasonic method was suitable for the extraction of flavonoids from the root of C. anisum-olens. The yield of flavonoids from different producing areas varied greatly, and the total flavonoids had broad spectrum antibacterial activity.

CSFL caused by spinal dural defect is a common complication of spinal surgery, which need repair such as suture or sealants. However, low intracranial pressure symptoms, wound infection and prolonged hospital associated with pin-hole leakage or loose seal effect were often occurred after surgical suture or sealants repair. Stable, pressure resistance and high viscosity spinal dural repair patch in wet environment without suture or sealants was highly needed. Herein, a bioactive patch composed of alginate and polyacrylamide hydrogel matrix cross-linked by calcium ions, and chitosan adhesive was proposed. This fabricated patch exhibits the capabilities of promoting defect closure and good tight seal ability with the bursting pressure is more than 790 mm H2O in wet environment. In addition, the chitosan adhesive layer of the patch could inhibit the growth of bacterial in vitro, which is meaningful for the postoperative infection. Furthermore, the patch also significantly reduced the expression of GFAP, IBA-1, MBP, TNF-α, and COX-2 in early postoperative period in vivo study, exerting the effects of anti-inflammatory, analgesic and adhesion prevention. Thus, the bioactive patch expected to be applied in spinal dural repair with the good properties of withstanding high pressure, promoting defect closure and inhibiting postoperative infection.

In this study, antibacterial PVA-SS-LJ-AgNPs composite films were made by using polyvinyl alcohol (PVA) and soluble starch (SS) as ingredients, glycerol as plasticizer, and lemon juice (LJ) as reducing agent to in situ reduced AgNPs from AgNO3. After single factor and orthogonal experiments, the optimum films preparation process was PVA 3 g, SS 0.5 g, glycerol 3 g, LJ 7 mL, AgNO3 130 mmol/L. Under the optimal process, the tensile strength, elongation at break, water vapor permeability coefficient, moisture absorption rate, and light transmittance of the membrane were 12.16 MPa, 1111.59%, 0.09 g/0.01 h·m2, 12.56%, 48.05%, respectively. Through the analysis of physical properties and structure of the films, lemon juice could successfully restore AgNPs in situ to films. Compared with the PVA-SS films, the tensile strength and elongation at break of the composite films were improved up to 11.51 MPa and 1470.20%, respectively. Compared with PVA-SS-LJ films, the water vapor penetration and moisture absorption were effectively balanced, AgNPs evenly dispersed in the composite films, the compound films had good inhibition effect for E. coli, Salmonella, Bacillus subtilis, S. aureus, P. aeruginosa. In summary, PVA-SS-LJ-AgNPs composite films met the current new requirements of food packaging materials, and had its potential application prospects.

In this study, based on the traditional hot water extraction-ethanol precipitation method for fucoidan, the ethanol-free extraction process of kelp fucoidan was studied in accordance with the difference in the fucose contents and sulfate groups of fucoidans and their beneficial biological activities. Three extraction methods including hot water extraction-ethanol precipitation method, hot water extraction-acid precipitation method, and hot water extraction-acid precipitation-enzymatic hydrolysis assisted extraction method, were applied to prepare fucoidans, and three fucoidan samples (sample 1, sample 2 and sample 3) were obtained, respectively. Fucose and sulfuric acid group-contents and biological activities (antioxidant, antibacterial activities) analysis results showed that the contents of fucose and sulfate groups in fucoidan (sample 3) prepared by hot water extraction-acid precipitation-enzymatic assisted hydrolysis method were 41.10%±0.87% and 24.90%±0.15%, respectively, which were significantly higher than the Trade Standard requirements of fucoidan (SC/T 3404-2012), samples 1 and sample 2. Meanwhile, the sample 3 also had the best antioxidant and antibacterial activities in three fucoidan samples. The Response surface methodology (RSM) was used to optimize the key process conditions of hot water extraction-acid precipitation-enzymatic hydrolysis assisted extraction of fucoidan. The best extraction process parameters were obtained as follows: Extraction temperature was 90℃, extraction time was 2.0 h, liquid material ratio was 40:1 mL/g, and the extraction yield reached 9.65%±0.11%. In this study, raction rate of fucoidan and the biological activity of fucoidan prepared by hot water extraction-acid precipitation-enzymatic assisted hydrolysis method were significantly higher than those prepared by hot water extraction-ethanol precipitation method and hot water extraction-acid precipitation method, therefore, the hot water extraction-acid precipitation-enzymatic assisted hydrolysis method digestion would be a good process to effectively replace the hot water extraction-ethanol precipitation method for fucoidan extraction.

Fermentation is an important means of fish preservation and processing. Fermentation gives fish unique flavor and texture, and microorganisms play an important role in the process of fermentation. This paper introduces the composition of microorganisms in fermented fish and its role in inhibiting miscellaneous bacteria, substance degradation, flavor formation and biogenic amine accumulation, in order to help understand the dominant microorganisms and their fermentation characteristics, prepare industrial starter and improve the yield and quality of fermented fish. In addition, the further study of fermented fish is prospected.

The purpose of this experiment was to study the antibacterial effect of saponins from different sources on common food-borne pathogens, and to develop the application of saponins in the field of food. The size of inhibition zone, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of saponins from three different sources (Gleditsia sinensis shell, green tea and Camellia oleifera seed) were determined by Oxford cup method and double dilution method, respectively. The results showed that the three saponins from different sources all had antibacterial effect on four common food-borne pathogenic bacteria, namely Bacillus subtilis, Staphylococcus aureus, Salmonella sp. and Escherichia coli. Among them, the saponins derived from Gleditsia sinensis shell had the best antibacterial effect. The double dilution method showed that their MICs for the two Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus were both 4 mg/mL, and the MBCs were 16 mg/mL and 8 mg/mL respectively; The MIC of Salmonella and E.coli of two Gram-negative bacteria were 4 mg/mL and 8 mg/mL, and MBC were 8 mg/mL and 16 mg/mL respectively. The results provide devidence for the research and development of safe, high effective and natural plant food preservatives.

The objective of the study was preliminarily explore the antibacterial activity and stability of Thamnolia subuliformis in vitro, the plate drilling method was used to determine the antibacterial activity of methanol extract of Thamnolia subuliformis against common pathogenic bacteria in vitro. The indicator bacteria of Staphylococcus aureus was used to determine the effects of factors such as different temperature, pH and UV irradiation time on antibacterial stability. Petroleum ether, ethyl acetate and n-butanol were used to extract the methanol extract, determine the polarity of its antibacterial active substances, and determine the content of usnic acid. The results showed that the methanol extract of Thamnolia subuliformis had good antibacterial effect on Gram-positive bacteria such as Staphylococcus aureus, Bacillus subtilis, Listeria stephensi, Staphylococcus surface, Listeria evansi, Salmonella paratyphi A, Salmonella paratyphi B of Gram-negative bacteria and Candida albicans. The minimum inhibitory concentration and minimum bactericidal concentration against Staphylococcus aureus were 0.625 and 10 mg/mL respectively; The results of antibacterial stability test showed that temperature had no significant effect on the antibacterial activity of methanol extract of Thamnolia subuliformis (P>0.05), and it still had high antibacterial activity after treatment at 100 ℃ for 30 min; The antibacterial activity of UV irradiation for 40 min and 50 min decreased significantly (P0.05）, showing high antibacterial activity. When the pH was high (8.0, 10.0) or low (2.0, 4.0), the antibacterial activity of the treatment group decreased significantly (P

Titanium is widely used as surgical bone implants due to its excellent mechanical properties, corrosion resistance, and good biocompatibility. However, due to chronic inflammation and bacterial infections caused by titanium implants, they are still at risk of failure in interfacial integration of bone implants, severely limiting their broad clinical application. In this work, chitosan gels crosslinked with glutaraldehyde were prepared and successfully loaded with silver nanoparticles (nAg) and catalase nanocapsules (n (CAT)) to achieve functionalized coating on the surface of titanium alloy steel plates. Under chronic inflammatory conditions, n (CAT) significantly reduced the expression of macrophage tumor necrosis factor (TNF-α), increased the expression of osteoblast alkaline phosphatase (ALP) and osteopontin (OPN), and enhanced osteogenesis. At the same time, nAg inhibited the growth of S. aureus and E. coli. This work provides a general approach to functional coating of titanium alloy implants and other scaffolding materials.

The microbial contamination of food poses a threat to human health. Chestnut shells, which are byproducts of chestnut processing, contain polyphenols that exert various physiological effects, and thus have the potential to be used in food preservation. This study investigates the bacteriostatic effect and mechanism(s) of the action of chestnut shell polyphenols (CSPs) on three food-spoilage bacteria, namely Bacillus subtilis, Pseudomonas fragi, and Escherichia coli. To this end, the effect of CSPs on the ultrastructure of each bacterium was determined using scanning electron microscopy and transmission electron microscopy. Moreover, gene expression was analyzed using RT-qPCR. Subsequent molecular docking analysis was employed to elucidate the mechanism of action employed by CSPs via the inhibition of key enzymes. Ultrastructure analysis showed that CSPs damaged the bacterial cell wall and increased permeability. At 0.313 mg/mL, CSPs significantly increased the activity of alkaline phosphatase and lactate dehydrogenase, as well as protein leakage (p < 0.05), whereas the activity of the tricarboxylic acid (TCA) cycle enzymes, isocitrate dehydrogenase and α-ketoglutarate dehydrogenase, were inhibited (p < 0.05). The expression levels of the TCA-related genes gltA, icd, sucA, atpA, citA, odhA, IS178_RS16090, and IS178_RS16290 are also significantly downregulated by CSP treatment (p < 0.05). Moreover, CSPs inhibit respiration and energy metabolism, including ATPase activity and adenosine triphosphate (ATP) synthesis (p < 0.05). Molecular docking determined that proanthocyanidins B1 and C1, the main components of CSPs, are responsible for the antibacterial activity. Therefore, as natural antibacterial substances, CSPs have considerable potential for development and application as natural food preservatives.

The antibacterial properties of tea polyphenols make them suitable for drinking water disinfection, but it is necessary to clarify the influence of metal ions on the sterilization efficacy. Epigallocatechin gallate (EGCG) was selected as a representative tea polyphenol, and the effects of calcium ion (Ca2+) concentration on its disinfection properties in Escherichia coli cultures were investigated. Changes in bacterial growth and structures were detected. The presence of low concentration Ca2+ (1–5 mM) inhibited the disinfection effect of EGCG but higher concentrations (6–10 mM) enhanced its effects. As Ca2+ concentration increased, the proportion of damaged bacteria also increased (15–43%). The presence of Ca2+ lessened the damaging effects of EGCG on the surface structures of E. coli but may have facilitated the entry of EGCG into the bacteria, enhancing its antibacterial efficacy. Tea polyphenols may be useful additives for the disinfection of groundwater and other raw waters containing calcium ions. HIGHLIGHTS Low concentration calcium ions inhibit the disinfection effect of EGCG, but high concentrations enhance disinfection.; Rate of EGCG-induced E. coli damage rises, as calcium ion concentration increases.; Calcium ions inhibit EGCG-induced damage to cell walls and membranes but promote internal structural damage.; Tea polyphenols may be useful for processing raw water with high calcium ion concentrations.;

Reuterin can be produced from glycerol dehydration catalyzed by glycerol dehydratase (GDHt) in Lactobacillus reuteri and has broad application prospects in industry, agriculture, food, and other fields as it is active against prokaryotic and eukaryotic organisms and is resistant to proteases and lipases. However, high concentrations of glycerin inhibit reuterin production, and the mechanism behind this phenomenon is not clear. To elucidate the inhibitory mechanism of glycerol on reuterin synthesis in L. reuteri and provide reference data for constructing an L. reuteri culture system for highly effective 3-hydroxypropionaldehyde synthesis, we used transcriptome-sequencing technology to compare the morphologies and transcriptomes of L. reuteri cultured in a medium with or without 600 mM of glycerol. Our results showed that after the addition of 600 mM of glycerol to the culture medium and incubation for 10 h at 37 °C, the culture medium of L. reuteri LR301 exhibited the best bacteriostatic effect, and the morphology of L. reuteri cells had significantly changed. The addition of 600 mM of glycerol to the culture medium significantly altered the transcriptome and significantly downregulated the transcription of genes involved in glycol metabolism, such as gldA, dhaT, glpK, plsX, and plsY, but significantly upregulated the transcription of genes related to D-glucose synthesis.

Plant essential oils are widely used in food, medicine, cosmetics, and other fields because of their bacteriostatic properties and natural sources. However, the bacteriostatic range of unilateral essential oils is limited, and compound essential oil has become an effective way to improve the antibacterial properties of unilateral essential oils. In this study, based on the analysis of the antibacterial properties of Chinese cinnamon bark oil and oregano oil, the proportion and concentration of the compound essential oil were optimized and designed, and the antibacterial activity of the compound essential oil was studied. The results showed that the antibacterial activity of Chinese cinnamon bark oil was higher than that of oregano oil. The compound essential oil prepared by a 1:1 ratio of Chinese cinnamon bark oil and oregano oil with a concentration of 156.25 ppm showed an excellent antibacterial activity against Escherichia coli and Staphylococcus aureus. The GC-MS results showed that cinnamaldehyde was the main antibacterial component of Chinese cinnamon bark essential oil, and carvacrol and thymol in oregano oil were the main antibacterial components.

We used 60Co-γ ray and electron beam irradiation to mutate Bacillus velezensis to breed genetically stable mutant strains. The mutant strains were screened and re-screened by plate confrontation and the four-point method to study their antibacterial effects on Colletotrichum gloeosporioides. The results demonstrated that the D10 value of Bacillus velezensis suspension irradiated by 60Co-γ ray was 2 366 Gy, and the lethality rate increased with an increase in the irradiation coefficient dose in the range of 100-2 000 Gy. The lethality rate of Bacillus velezensis was 81.8% at 2 000 Gy irradiation coefficient dose, and five mutants (B004, B112, B114, B117, and B118) were screened. The inhibition rate against Colletotrichum gloeosporioides increased from 51.2% of the original strain to 57.5%, 58.0%, 57.0%, 57.7%, and 59.9%, respectively. The Bacillus velezensis suspension was irradiated by an electron beam (10 MeV), the D10 value was 499 Gy, and the lethality rate increased with an increase in the irradiation coefficient dose in the range of 100-600 Gy. The lethality rate of Bacillus velezensis was 91.8% at 400 Gy irradiation coefficient dose. Two mutant strains (D115 and D243) were screened, and their inhibition rates against Colletotrichum gloeosporioides increased from 55.2% of the emitted strains to 58.4 and 58.1%, respectively. The inhibitory effects of B004, B112, B117, and B118 mutants on Colletotrichum gloeosporioides were genetically stable within six generations. In conclusion, γ-ray and electron beam irradiation have potential application value in the mutation breeding of Bacillus velezensis. The results provide a basis for Bacillus velezensis mutation breeding and a theoretical reference for the biological control of Colletotrichum gloeosporioides.

The performance of wound dressing determines the effect of wound closure and recovery. Water absorption and bacteriostasis of wound dressings play an important role in wound recovery and healing. In this study, an optimized chitosan wound dressing-tough chitosan dressing (TCS) with high water absorption, high bacteriostasis, and degradability was developed. The chemical structure of chitosan remained stable during the process of optimized treatment, and an increase in mechanical properties was obtained for the dressing. After optimization, the water absorption and antibacterial properties of the chitosan dressing were greatly improved, which is significantly better than sodium alginate dressing. The authors believe that TCS dressing with high hygroscopicity and high bacteriostasis has great potential application value in the field of wound recovery and healing.

With the widespread use and abuse of antibiotics, Helicobacter pylori (H. pylori) has become seriously drug resistant. The development of new antibiotics is an important way to solve H. pylori's drug resistance. Screening antibacterial ingredients from natural products is a convenient way to develop new antibiotics. Phillygenin, an effective antibacterial component, was selected from the natural product, forsythia, in this study. Its minimal inhibitory concentration (MIC) for 18 H. pylori strains was 16–32 μg/ml. The minimum bactericidal concentration (MBC) of H. pylori G27 was 128 μg/ml; the higher the drug concentration and the longer the time, the better the sterilization effect. It was non-toxic to gastric epithelial cell (GES)-1 and BGC823 cells at the concentration of 100 μg/ml. It presented a better antibacterial effect on H. pylori in an acidic environment, and after 24 days of induction on H. pylori with 1/4 MIC of phillygenin, no change was found in the MIC of H. pylori. In the mechanism of action, phillygenin could cause ATP leakage and inhibit the biofilm formation; the latter was associated with the regulation of spoT and Hp1174 genes. In addition, phillygenin could regulate the genes of Nhac, caggamma, MATE, MdoB, flagellinA, and lptB, leading to the weakening of H. pylori's acid resistance and virulence, the diminishing of H. pylori's capacity for drug efflux, H. pylori's DNA methylation, the initiation of human immune response, and the ATP leakage of H. pylori, thus accelerating the death of H. pylori. In conclusion, phillygenin was a main ingredient inhibiting H. pylori in Forsythia suspensa, with a good antibacterial activity, high safety, strong specificity, better antibacterial effect under acidic conditions, and low risk of resistance development by H. pylori. Its mechanism of action was mainly associated with inhibiting the biofilm formation and resulting in ATP leakage. In addition, phillygenin was shown to be able to reduce the acid resistance and virulence of H. pylori.

Complex processes and mismatches of anti-corrosive undercoats and anti-fouling (anti-bacterial) topcoats have serious effects on the production efficiencies and performances of coatings for marine installations. This study reports a rare dual-function coating of antimicrobial effect and anti-corrosion performance. The coating was prepared by adding cuprous oxide/polyaniline (Cu2O/PANI) composite to acrylic resin. Cu2O/PANI core–shell structure was constructed through the oxidation–reduction method. According to the different weight percentages of Cu2O in Cu2O/PANI (0%, 35%, 46%, and 100%), the performance and protection mechanism of Cu2O/PANI composites were researched. Cu2O/PANI-2 (weight percentages of Cu2O was 35%) displays an excellent anti-corrosive effect, due to the improved dispersibility of PANI in coating and the enlarged area of effective contact between the PANI and Fe-based metal. And the superior antimicrobial property of Cu2O/PANI-2 is responsible for the better adsorbability towards bacteria, which can be accurately anchored and shortens the function routes of Cu2+. Considering the anti-corrosive and antibacterial applications, the developed Cu2O/PANI-2 has a far-reaching influence on marine development.

Lactobacillus reuteri is a probiotic with bacteriostatic effects, which can effectively inhibit the activity of pathogens. However, the molecular mechanism underlying the inhibition of pathogens by L. reuteri in intestinal cells remains unclear. Using the porcine intestinal cell line IPEC-J2 as a model, we combined RNA-seq and ATAC-seq methods to delineate the porcine genome-wide changes in biological processes and chromatin accessibility in IPEC-J2 cells stimulated by Salmonella enterica BNCC186354, as well as L. reuteri ATCC 53608. Overall, we found that many porcine transcripts were altered after S. enterica BNCC186354 treatment, while L. reuteri ATCC 53608 treatment partially restored this alteration, such as salmonella infection and PI3K/AKT and MAPK pathways. Combined analysis of these two datasets revealed that 26 genes with similar trends overlapped between gene expression and chromatin accessibility. In addition, we identified potential host functional transcription factors (TFs), such as GATA1, TAL1, TBP, RUNX1, Gmeb1, Gfi1b, RARA, and RXRG, in IPEC-J2 cells that might play a critical role and are targeted by L. reuteri ATCC 53608. Moreover, we verified that PI3K/AKT, MAPK, and apoptosis pathways are potentially regulated by S. enterica BNCC186354 but restored by L. reuteri ATCC 53608. The PI3K/AKT pathway was activated by L. reuteri ATCC 53608, thereby potentially inhibiting S. enterica BNCC186354 infection. In conclusion, our data provide new insights into the expression pattern of functional genes and the epigenetic alterations in IPEC-J2 cells underlying the bacteriostatic action of L. reuteri ATCC 53608.

The excellent properties of nanomaterials have been confirmed in many fields, but their effects on plants are still unclear. In this study, different concentrations of bismuth vanadate (BV) were added to the growth medium to analyze the growth of seedlings, including taproots, lateral roots, leaf stomata, root activity, and superoxide anion O2.- generation. Gene expression levels related to root growth were determined by quantitative PCR in Arabidopsis thaliana. The results showed that BV promoted the growth of taproots and the development of lateral roots, enhanced the length of the extension zone in roots, increased the number and size of leaf stomata and root activity, reduced the accumulation of ROS in seedlings, and changed the expression levels of genes related to polyamines or hormones. At the same time, we investigated the antibacterial activity of BV against a variety of common pathogens causing crop diseases. The results showed that BV could effectively inhibit the growth of Fusarium wilt of cotton and rice sheath blight. These results provide a new prospect for the development of nanomaterial-assisted plants, which is expected to become one of the ways to solve the problem of controlling and promoting the development of plants. At the same time, it also provides a reference for the study of the effect of BV on plants.

Diseases caused by pathogenic bacteria in animals (e.g., bacterial pneumonia, meningitis and sepsis) and plants (e.g., bacterial wilt, angular spot and canker) lead to high prevalence and mortality, and decomposition of plant leaves, respectively. Melatonin, an endogenous molecule, is highly pleiotropic, and accumulating evidence supports the notion that melatonin’s actions in bacterial infection deserve particular attention. Here, we summarize the antibacterial effects of melatonin in vitro, in animals as well as plants, and discuss the potential mechanisms. Melatonin exerts antibacterial activities not only on classic gram-negative and -positive bacteria, but also on members of other bacterial groups, such as Mycobacterium tuberculosis. Protective actions against bacterial infections can occur at different levels. Direct actions of melatonin may occur only at very high concentrations, which is at the borderline of practical applicability. However, various indirect functions comprise activation of hosts’ defense mechanisms or, in sepsis, attenuation of bacterially induced inflammation. In plants, its antibacterial functions involve the mitogen-activated protein kinase (MAPK) pathway; in animals, protection by melatonin against bacterially induced damage is associated with inhibition or activation of various signaling pathways, including key regulators such as NF-κB, STAT-1, Nrf2, NLRP3 inflammasome, MAPK and TLR-2/4. Moreover, melatonin can reduce formation of reactive oxygen and nitrogen species (ROS, RNS), promote detoxification and protect mitochondrial damage. Altogether, we propose that melatonin could be an effective approach against various pathogenic bacterial infections.

Streptococcus mutans (S. mutans) is a gram-positive facultatively anaerobic bacterium and the most common pathogen associated with tooth caries. The organism is acid tolerant and can undergo physiological adaptation to function effectively in acid environments such as carious dental plaque. Some cannabinoids have been found to have potent anti-microbial activity against gram-positive bacteria. One of these is the non-psychoactive, minor phytocannabinoid Cannabigerol (CBG). Here we show that CBG exhibits anti-bacterial activities against S. mutans. CBG halts the proliferation of planktonic growing S. mutans, which is affected by the initial cell density. High-resolution scanning electron microscopy showed that the CBG-treated bacteria become swollen with altered membrane structures. Transmission electron microscopy provided data showing that CBG treatment leads to intracellular accumulation of membrane structures. Nile red, DiOC2(3) and laurdan staining demonstrated that CBG alters the membrane properties, induces membrane hyperpolarization, and decreases the membrane fluidity. CBG-treated bacteria showed increased propidium iodide uptake and reduced calcein AM staining, suggesting that CBG increases the membrane permeability and reduces the metabolic activity. Furthermore, CBG prevented the drop in pH caused by the bacteria. In summary, we present here data showing the mechanisms by which CBG exerts its anti-bacterial effect against S. mutans.

Studies on trimethylamine (TMA) in egg yolk have focused on how it impacts the flavor of eggs, but there has been little focus on its other functions. We designed an in vitro antibacterial test of TMA according to TMA concentrations that covered the TMA contents typically found in egg yolk. The change in TMA content in yolk was analyzed at different storage temperatures and for different storage durations. The known antibacterial components of eggs, including the cuticle quality of the eggshell and the lysozyme activity and content in egg white, were also assessed. The total bacterial count (TBC) of different parts of eggs were detected. The results showed that the inhibitory effect of TMA on Escherichia coli (E. coli) growth increased with increasing TMA concentration, and the yolk TMA content significantly increased with storage duration (p < 0.05). The cuticle quality and lysozyme content and activity significantly decreased with storage time and increasing temperature, accompanied by a significant increase in the TBC on the eggshell surface and in the egg white (p < 0.05). This work reveals a new role for trace TMA in yolks because it reduces the risk of bacterial colonization, especially when the antibacterial function of eggs is gradually weakened during storage.

Abstract Drug‐resistant bacterial infection is a global threat to public health due to the high mobility of the population. Novel therapy methods have been intensively studied for the eradication of antibiotic‐resistant bacteria, including photothermal treatment, which has established outstanding bacterial killing efficiencies under laser radiation, and superhydrophobic surfaces have exhibited excellent antifouling properties. However, an effective, scalable, and affordable bactericidal coating for eliminating drug‐resistant bacteria is lacking. Herein, a novel graphene coating using one‐step laser‐induced graphene and simultaneous laser‐induced forward transfer is introduced. The graphene coating shows high photothermal conversion and superhydrophobic performance, and these synergistic effects can make the bacteria number decrease with over 99.99% proportions under one sun illumination. The superhydrophobic properties can also reduce 99.87% of bacteria compared to the control sample when the solar energy is not available. This additive and scalable method can quickly coat functional graphene onto various substrates, with bacterial applications in many areas, such as water pipeline robots.

Pulcherriminic acid is a cyclic dipeptide found mainly in Bacillus and yeast. Due to the ability of pulcherriminic acid to chelate Fe3+ to produce reddish brown pulcherrimin, microorganisms capable of synthesizing pulcherriminic acid compete with other microorganisms for environmental iron ions to achieve bacteriostatic effects. Therefore, studying the biosynthetic pathway and their enzymatic catalysis, gene regulation in the process of synthesis of pulcherriminic acid in Bacillus can facilitate the industrial production, and promote the wide application in food, agriculture and medicine industries. After initially discussing, this review summarizes current research on the synthesis of pulcherriminic acid by Bacillus, which includes the crystallization of key enzymes, molecular catalytic mechanisms, regulation of synthetic pathways, and methods to improve efficiency in synthesizing pulcherriminic acid and its precursors. Finally, possible applications of pulcherriminic acid in the fermented food, such as Chinese Baijiu, applying combinatorial biosynthesis will be summarized.