Antibacterial Substances Research Articles

Gallic acid functionalized silk fibroin/gelatin composite wound dressing for enhanced wound healing

As the incidence of chronic wounds increases, the requirements for wound dressings are rising. The specific aim of this study is to propose a novel gallic acid (GA) functionalized silk fibroin (SF) and gelatin (Gel) composite wound dressing in which GA is used as an antibacterial and wound healing substance. Via electrospinning, SF, Gel, and GA mixed solutions could be conveniently fabricated into a composite nanofiber mat (SF-Gel-GA), consisting of uniform fibers with an average diameter around 134.57 ± 84 nm. The internal mesh structure of SF-Gel-GA provides sufficient drug loading capacity, proper moisture permeability, and proper degradation rate. SF-Gel-GA presents excellent biocompatibility. NIH-3T3 fibroblast cells could adhere and spread stably on the SF-Gel-GA surface with slightly promoted proliferation. In the presence of SF-Gel-GA, the growth of both Gram-positive and Gram-negative bacteria, includingStaphylococcus aureusandPseudomonas aeruginosa, is significantly inhibited in both plate and suspension cultures. A cutaneous excisional mouse wound model proves the efficient ability of SF-Gel-GA to promote wound healing. Compared with pure SF dressing and commercial Tegaderm Hydrocolloid3Mdressing, the wound closure rate with SF-Gel-GA treatment is significantly improved. The histological assessments further demonstrate SF-Gel-GA could facilitate collagen deposition, neovascularization, and epithelialization at wound sites to promote wound healing. In conclusion, a novel SF-Gel-GA composite wound dressing with efficient wound healing activities have been developed for chronic wound treatment with broad healing potential.

The role of hydroponic solution of Ulva fasciata in modulating the antibiotic resistance of Vibrio alginolyticus.

This study aimed to ascertain the active substances in the hydroponic solution of Ulva (U.) fasciata (HSUF) and their effects on antibiotics resistance of pathogenic bacteria Vibrio alginolyticus (Va.) at environmental levels. Analytical results of HSUF by solid-phase extraction and gas chromatography-mass spectrometry showed that HSUF contained rich active substances and dominated by 2,4,6-tribromophenol, acetal, mono (2-ethylhexyl) phthalate and 2- (4-hydroxybenzene) ethanol, etc. Thereinto, 2,4,6-tribromophenol had the lowest minimal inhibitory concentrations (MICs) of 64-128μg mL-1 for Va. strains. The rich antibacterial substances of HSUF inhibited 47%-63% of isolated Va. strains. After 20 generations of subculture for Va. strains in three dilutes (1/2 (HT), 1/20 (MT) and 1/50 (LT)) of HSUF (20g L-1), the resistance to streptomycin of Va. S1 and Va. M3 changed from intermediate resistance ability to susceptible level. The large promotion of reactive oxygen species was observed in different HSUF levels, but the biofilm formation of Va. S1 did not changed significantly. Transcriptome sequencing of Va. S1 demonstrated that antibiotic resistance gene lpxA was down-regulated at different HSUF levels. Live U. fasciata excreted a variety of active secondary metabolites (SMs) in HSUF, which exhibited strong inhibitory effects on three isolated Va. strains. HSUF changed the antibiotic resistance of Va. Strain, especially at a higher HSUF concentrations.

Antibacterial, Herbicidal, and Plant Growth-Promoting Properties of Streptomyces sp. STD57 from the Rhizosphere of Adenophora stricta

Bacterial wilt triggered by the soil-borne pathogenic bacterium Ralstonia solanacearum is one of the most serious diseases in tomato plants, leading to huge economic losses worldwide. Biological control is considered an environmentally friendly and sustainable way to manage soil-borne diseases. In this study, Streptomyces sp. STD57 isolated from the rhizosphere of Adenophora stricta showed strong antibacterial activity against R. solanacearum. Pot experiments showed that strain STD57 exhibited a significant biocontrol effect (81.7%) on tomato bacterial wilt in the greenhouse environment. Furthermore, strain STD57 could inhibit the growth of weeds (Amaranthus retroflexus, Portulaca oleracea, and Echinochloa crusgalli) but promote the growth of crops (wheat, rice, and tomato). The plant growth-promoting substance was identified as indoleacetic acid (IAA) by high-pressure liquid chromatography–mass spectrometry and genome analysis. Coarse separation of the fermented extracts revealed that the antibacterial and herbicidal substances were mainly in the fermentation supernatant and belonged to different products. These findings suggested that strain STD57 may be a potential biocontrol and bioherbicide agent useful in agriculture.

Marine Gastropod Planaxis sulcatus (Born, 1778) of Uvari Coastal Waters: A Comprehensive Study on Its Antibacterial Activity, Biochemical Composition and FTIR Spectroscopy

Diverse nutritional profiles and potent antimicrobial properties distinguish marine gastropods from other members of the phylum Mollusca. This study targets the investigation of the antibacterial activity, biochemical and FTIR analysis of ethanol extracts of marine gastropod mollusc Planaxis sulcatus. The well diffusion method was used to carry out the antibacterial assay. The extract showed the maximum inhibition (21±2 mm inhibitory zone) against the human bacterial pathogen S. aureus, whereas K. pneumonia showed the lowest susceptibility (12 mm). The extracts had MIC values between 0.21 and 1.04 mg/ml. The biochemical assay's findings revealed that the majority of the snail's flesh (51%) is made up of protein, with only 5% of the mass coming from carbohydrates and very trace amounts of fat (0.2%). The FTIR analysis represents the presence of alkyl halides, nitro compounds, aromatic compounds, alkynes, nitriles, carboxylic acid, aldehyde, alkanes and alcohol in the gastropod extracts. The aforementioned observational result demonstrates the abundance of antibacterial substances in the gastropod extracts. Further research is necessary to fully understand the structural composition of the antibacterial substances found in this marine snail.

Recent Progress in Terrestrial Biota Derived Antibacterial Agents for Medical Applications

Conventional antibiotic and multidrug treatments are becoming less and less effective and the discovery of new effective and safe antibacterial agents is becoming a global priority. Returning to a natural antibacterial product is a relatively new current trend. Terrestrial biota is a rich source of biologically active substances whose antibacterial potential has not been fully utilized. The aim of this review is to present the current state-of-the-art terrestrial biota-derived antibacterial agents inspired by natural treatments. It summarizes the most important sources and newly identified or modified antibacterial agents and treatments from the last five years. It focuses on the significance of plant- animal- and bacteria-derived biologically active agents as powerful alternatives to antibiotics, as well as the advantages of utilizing natural antibacterial molecules alone or in combination with antibiotics. The main conclusion is that terrestrial biota-derived antibacterial products and substances open a variety of new ways for modern improved therapeutic strategies. New terrestrial sources of known antibacterial agents and new antibacterial agents from terrestrial biota were discovered during the last 5 years, which are under investigation together with some long-ago known but now experiencing their renaissance for the development of new medical treatments. The use of natural antibacterial peptides as well as combinational therapy by commercial antibiotics and natural products is outlined as the most promising method for treating bacterial infections. In vivo testing and clinical trials are necessary to reach clinical application.

Endophytic Fungus UJ3-2 from Urtica fissa: Antibacterial Activity and Mechanism of Action against Staphylococcus aureus

Taking the endophytic fungus UJ3-2, isolated from Urtica fissa, as the experimental material, this study aimed to explore the composition of its metabolites and the underlying mechanisms by which it inhibits Staphylococcus aureus. Initially, the MIC, MBC, inhibitory curves, biofilm growth, and extracellular nucleic acids and proteins of S. aureus in response to the metabolites were measured. Secondly, PI staining and SEM were used to evaluate the impact of the metabolites on the integrity of the cell wall and overall morphology of S. aureus. Additionally, UPLC-MS was employed to analyze the composition of the secondary metabolites. The UJ3-2 strain was identified as Xylaria grammica based on ITS sequencing and designated as Xylaria grammica UJ3-2. Our results revealed that the metabolites of UJ3-2 exhibited excellent in vitro antibacterial activity against S. aureus, with both MIC and MBC values of 3.125 mg/mL. The inhibitory curve confirmed that 1 MIC of UJ3-2 metabolites could completely inhibit the growth of S. aureus within 24 h. With increasing concentrations of UJ3-2 metabolites, the growth of S. aureus biofilms was significantly suppressed, and obvious leakage of nucleic acids and proteins was observed. PI fluorescence staining indicated that various concentrations of UJ3-2 metabolites disrupted the integrity of the S. aureus cell membrane. SEM observation revealed that the treated S. aureus surfaces became rough, and the bacteria shrank and adhered to each other, showing a dose-dependent effect. UPLC-MS analysis suggested that the main components of the fermented metabolites were 6-oxocineole (17.92%), (S)-2-acetolactate (9.91%), 3-methyl-cis,cis-muconate (4.36%), and 8-oxogeranial (3.17%). This study demonstrates that the endophytic fungus UJ3-2 exhibits remarkable in vitro antibacterial effects against S. aureus, primarily by enhancing the permeability of the S. aureus cell membrane, causing the leakage of its intracellular contents, and altering the bacterial surface morphology to inhibit the pathogen. The endophytic fungus UJ3-2 has a good antibacterial effect on S. aureus, which gives it certain application prospects in the screening and industrial production of new and efficient natural antibacterial active substances.

Applications of Organic Acids in Poultry Production: An Updated and Comprehensive Review

Feed additive antibiotics have been used for many decades as growth promotors or antibacterial substances worldwide. However, the adverse impacts of using antibiotics in animal or poultry feeds are not widely recognized. Therefore, the search for alternatives, such as probiotics, prebiotics, phytobiotics, post-biotics, bacteriophages, enzymes, essential oils, or organic acids (OAs), has become urgent. OAs are produced by beneficial intestinal bacteria through the fermentation of carbohydrates. OAs and their salts are still used as feed preservatives. They have long been added to feed in order to minimize contamination and the growth of harmful bacteria and fungi, reduce deterioration, and prolong the shelf life of feed commodities. Moreover, they have been mostly added to poultry feed as a blend to obtain maximal beneficial effects. The supplementation of poultry with OAs could improve the growth performance parameters and carcass traits, promote the utilization of nutrients, boost the immune response, and inhibit the growth of pathogenic bacteria. Therefore, this review article provides valuable insights into the potential benefits of using OAs in reducing microbial load, enhancing performance parameters in broilers and layers, improving gut health, and boosting the immune response.

Isolation and identification of endophytic fungi from Alhagi sparsifolia Shap. and their antibacterial activity

In order to explore the endophytic resources of Alhagi sparsifolia Shap. and identified novel antibacterial substances. Thirty endophytic fungal strains were isolated from the stems and roots of A. sparsifolia Shap. Morphological and molecular biology methods were used to identify ten strains of fungi, including four strains of Aspergillus niger, three strains of Alternaria alternata, two strains of Aspergillus flavus, and one strain of Fusarium incarnatum. All these strains were isolated from A. sparsifolia Shap. for the first time, and of these Aspergillus was the dominant genus. Antibacterial activity of the ten strains against Escherichia coli, Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa were evaluated using the disc diffusion method. The results demonstrated that the metabolites from all the strains had inhibitory effects on at least one indicator bacterium. Notably, the endophytic fungi AFJ3 and AFG6 demonstrated strong broad-spectrum antibacterial activity, particularly against E. coli, with inhibition zones measuring 32.0 ± 0.3 and 31.3 ± 0.3 mm, respectively. The three endophytic fungi (AFG1, AFG2, and AFG3) isolated from the roots demonstrated significant antibacterial activity against P. aeruginosa forming an inhibition zone of diameter 31.3 ± 0.1, 25.6 ± 0.2, and 25.6 ± 0.2 mm, respectively. However, the strains of endophytic fungi demonstrated no significant inhibitory effects on C. albicans. Ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry/mass spectrometry (UPLC-QTOF-MS/MS) analysis depicted that the ethyl acetate phase of AFJ3 and AFG6 fermentation broth predominantly contained organic acids, phenolic acids, flavonoids, and fatty acids. These secondary metabolites often exhibited good antibacterial activity. This study broadens our understanding of endophytic fungi in A. sparsifolia Shap. The antibacterial activity of some strains of endophytic fungi was significant, making it worthy of further research on their active material.

Assessment of the bioflocculant production and safety properties of Metabacillus hrfriensis sp. nov. based on phenotypic and whole-genome sequencing analysis

Bioflocculant is considered to have broad application prospect in multi fields for the nontoxic and biodegradation properties. Screening new bioflocculant-producing bacteria with high flocculating activity, stress resistance characteristics, and application security is a significant action in the development of the biofloc technique. A novel bioflocculant-producing species, Metabacillus hrfriensis CT-WN-B3, was isolated from alkali-tolerant strains distributing in Daqing, Heilongjiang Province, China. A strong activity flocculant was detected in the extracellular polymeric substance (EPS) of CT-WN-B3, which could form biofloc more effectively under alkali conditions, with a flocculating rate of more than 70 %. The principal component of the bioflocculant was identified as the polysaccharide of extracellular polymeric substance (EPS) because of its 75.183 ± 2.268 % flocculation contribution, which was very significantly higher than that of the protein and the lipid (p < 0.01). Basing on the whole-genome sequencing analysis of CT-WN-B3, none gene encodes a known virulence factor, but two genes correspond to antibiotic resistance. Antibiotic resistance tests showed CT-WN-B3 was resistant to clindamycin. In the assessment of the antimicrobial spectrum, no antibacterial active substance was detected in the supernatant of CT-WN-B3 culture. Totally, the results of the safety assessment had eliminated the doubts about the application risk of CT-WN-B3. These results indicated that CT-WN-B3 is an alkali-suitable flocculant-producing bacterium for application in multiple fields, under alkali conditions especially.

Suspension-Sprayed Calcium Phosphate Coatings with Antibacterial Properties.

Prosthesis loosening due to lack of osteointegration between an implant and surrounding bone tissue is one of the most common causes of implant failure. Further, bacterial contamination and biofilm formation onto implants represent a serious complication after surgery. The enhancement of osteointegration can be achieved by using bioconductive materials that promote biological responses in the body, stimulating bone growth and thus bonding to tissue. Through the incorporation of antibacterial substances in bioconductive, biodegradable calcium phosphate (CaP) coatings, faster osteointegration and bactericidal properties can be achieved. In this study, Cu-doped CaP supraparticles are spray-dried and suspension-sprayed CaP ceramic coatings with antibacterial properties are prepared using high-velocity suspension flame spraying (HVSFS). The objective was to increase the coatings' porosity and investigate which Cu-doped supraparticles have the strongest antibacterial properties when introduced into the coating layers. Biocompatibility was tested on human Osteosarcoma cells MG63. A porosity of at least 13% was achieved and the supraparticles could be implemented, enhancing it up to 16%. The results showed that the addition of Cu-doped supraparticles did not significantly reduce the number of viable cells compared to the Cu-free sample, demonstrating good biocompatibility. The antimicrobial activity was assessed against the bacterial strains Escherichia coli and Staphylococcus aureus, with Safe Airborne Antibacterial testing showing a significant reduction in both Gram-positive and Gram-negative strains on the Cu-doped coatings.

Dialdehyde cellulose nanofibrils/polyquaternium stabilized ultra-fine silver nanoparticles for synergistic antibacterial therapy

Dialdehyde cellulose nanofibrils (DACNF) and Polyquaternium-10 (PQ: chloro-2-hydroxy-3-(trimethylamino) propyl polyethylene glycol cellulose) have become increasingly favored as antibacterial substances due to their advantageous characteristics. DACNF exhibits exceptional mechanical properties and biocompatibility, whereas PQ demonstrates a positive charge that enhances its antibacterial activity. Combined in a DACNF/PQ mixture, they provide an excellent template material for preparing and stabilizing ultra-fine (~ 10.3 nm) silver nanoparticles (AgNPs) at room temperature. Here, the dialdehyde group of DACNF functions as a reducing agent, while the quaternary ammonium of PQ and carboxylate groups of DACNF synergistically helped in-situ generation of AgNPs uniformly. The synthesized nanocomposites, namely PQ@AgNPs, AgNPs@DACNF, and AgNPs@DACNF/PQ, were subjected to comprehensive characterization using various advanced analytical techniques. The films containing AgNPs@DACNF and AgNPs@DACNF/PQ, fabricated via vacuum filtration, exhibited excellent mechanical properties of 9.78 ± 0.21 MPa, and demonstrated superior antibacterial activity against both Escherichia coli and Staphylococcus aureus. Additionally, the silver ion leaching from the prepared composite films was well controlled. The fabricated nanocomposites also effectively inhibited bacterial biofilm formation. It was also found to be highly biocompatible and non-toxic to human skin fibroblast cells. Furthermore, the nanocomposites exhibited enhanced migration of human dermal fibroblasts, suggesting their potential in facilitating wound healing processes.

Antimicrobial potential of carvacrol against Edwardsiella piscicida in vitro

With the alarming rise of antibiotic-resistant bacteria, novel antibacterial substances are urgently needed for controlling and treating multidrug-resistant bacterial infections. Edwardsiella piscicida is an important zoonotic enteric pathogen, that can cause systemic hemorrhagic septicemia in fish. Carvacrol, a major terpene of oregano essential oil, has a wide range of antibacterial activities. This study aimed to analyze the effect of carvacrol on the growth and virulence of E. piscicida in vitro. The minimum inhibitory concentration (MIC) of carvacrol against E. piscicida was 125 μg/mL. The sub-inhibitory concentrations of carvacrol significantly decreased the biofilm formation of E. piscicida in a dose dependent manner, whereas increased the hemolytic activity with a negative correlation. The quantitative real-time PCR results showed that carvacrol at sub-MICs downregulated the expression of related virulence genes, including flagellum (fimA, fliC, flgN), hemolysins (ethA, ethB), quorum sensing systems (luxR, qseB), T3SS (esrB, esrC) and T6SS (evpB, evpC). Moreover, carvacrol (≤1/8 MIC) reduced the cytotoxicity, adherence and internalization activities of E. piscicida to the EPC cells. In vivo trial, the diet mixed with carvacrol increased the survival of zebrafish infected with E. piscicida. Overall, these findings suggested that carvacrol might be a promising therapeutic agent against E. piscicida infection in aquaculture.

Using gardenia pigment for ultrasonic natural dyeing of hemp fiber: A step towards sustainable dyeing

In recent years, with the country advocating the establishment of a resource-saving and environmentally friendly society, people have been pursuing a green and healthy quality of life. The non-toxic, harmless, and biodegradable characteristics of grass and wood dyeing have brought this method back to people's lives. Despite the presence of antibacterial substances such as tetrahydrocannabinol in cannabis fibers, they are still susceptible to microbial attacks. In recent years, scholars have conducted more research on the separation and purification of gardenia flower pigments, but there has been less analysis on the dyeing fibers and performance testing of gardenia flowers. The renewable characteristics, fewer side effects, and low cost increase the use of natural drugs as antibacterial agents in plant extracts or their active ingredients. This experiment used gardenia flowers as the raw material for dyeing experiments, and the dyeing percentage was used as the inspection index. Ultrasonic dyeing was carried out on hemp fibers after degumming treatment. It also aims to endow these dyed fabrics with natural antibacterial properties. During the sorting process, a liquid bath ratio of 1:20 was selected and experiments were conducted under different parameter variations. During the dyeing process, potassium aluminum sulfate (alum) is used as a mordant, and ultrasound is used as an auxiliary dyeing method. After dyeing, evaluate the fibers based on the percentage of exhaustion of obtained fiber and antibacterial activity against Staphylococcus aureus and Escherichia coli. At the same time, the FT-IR analysis, strength, and color fastness of the sorted samples were also checked. Single factor experiments were conducted by controlling the ultrasonic frequency, dyeing temperature, time, and mordant concentration to analyze the effect of gardenia pigment on the dyeing percentage. Response surface design experiments were used to optimize the dyeing process parameters. The research results indicate that the optimal process conditions for dyeing gardenia flowers are ultrasonic power of 85 %, dyeing temperature of 77 ℃, dyeing time of 60 min, and mordant concentration of 15 g/L. The main and secondary order of factors affecting the dyeing effect of hemp fibers is: mordant concentration>ultrasonic power>dyeing temperature. After optimal dyeing process, the hemp fiber shows a bright yellow color with a dyeing percentage of 57.32 %. The single fiber strength is not affected, and the color fastness to water washing and sun exposure meets the requirements for consumption. The infrared spectrum shows good dyeing effect. It has a certain antibacterial effect on Staphylococcus aureus, but the antibacterial effect on Escherichia coli is not significant. Due to these processes, it has been determined that hemp fiber can obtain antibacterial activity through the use of gardenia flowers and can be effectively colored.

Formulasi Sabun Cair Berbahan Baku Virgin Coconut Oil VCO dengan Penambahan Ekstrak Daun Pepaya Carica Papaya L. untuk Peningkatan Aktivitas Anti Bakteri Staphylococcus Epidermidis ATCC 12238

Acne is a chronic inflammatory disease caused by Staphylococcus epidermidis. Papaya leaves (Carica papaya L.) contain antibacterial substances, namely alkaloids carpaine, flavonoids, tocophenols. Of this study was to determine the physical quality of liquid soap, increasing antibacterial activity. Papaya leaves were extracted with 96% ethanol solvent, then evaporated with a water bath. Antibacterial activity test using the disc diffusion method in concentrations of 5%, 15% and 25% and liquid soap will be made F0 0%, F1 5%, F2 10%, and F3 25% against Staphylococcus epidermidis ATCC 12238. Amoxicillin tab as a positive control and distilled water as a negative control. Bacterial activity appears a clear zone around the disc paper. And see the physical quality test according to the requirements. The results of the bacterial test data are made in table form, and analyzed using the SPSS method Formula with the addition of papaya leaf extract can be made and according to the physical quality conditions of liquid soap. The results of the 25% concentration extract test are an inhibition zone of 20.8 mm, the highest liquid soap formula is an inhibition zone of 23.8 mm in inhibiting the growth of Staphylococcus epidermidis ATCC 12238. Liquid soap preparations and papaya leaf extract have antibacterial activity against Staphylococcus epidermidis ATCC 12238 bacteria and according to the physical quality requirements of liquid soap.

Optimization of cultivation system for Bacillus Siamese strain and its biocontrol effect on postharvest Colletotrichum gloeosporioides

In this study, we established an effective cultivation system for Bacillus Siamese (N-1), identified key antibacterial substances, and explored the underlying mechanisms of optimized N-1 fermentation for controlling pathogens. Our results demonstrate that the optimized system significantly enhanced the inhibitory effect of N-1 on five types of pathogens affecting tropical fruits. Additionally, non-targeted metabolomics analysis and ultra-high performance liquid chromatography triple quadrupole mass spectrometer system (UPLC-MS/MS) revealed the presence of lipopeptides, including Surfactin and FengycinA, in the optimized fermentation. Furthermore, in vitro experiments indicated that lipopeptide treatment (LT) at a concentration of 3.125 mg mL−1 significantly distorted the hyphae, decreased the activity of antioxidant enzymes, increased the levels of reactive oxygen species (ROS), malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents, and enhanced protein exosmosis rate of C. gloeosporioides. Moreover, LT markedly reduced the activities of energy metabolism-related enzymes, including succinate dehydrogenase (SDH), Na+K+-ATPase, and Ca2+Mg2+-ATPase, as well as ATP content, leading to apoptosis of C. gloeosporioides. In vivo experiments revealed that LT significantly inhibited the expansion of disease spots caused by C. gloeosporioides in mango fruit. These findings suggest that the established culture system could serve as a potential strategy to enhance biocontrol efficacy and prevent fruit decay.

Metal-phenolic networks spontaneously reinforced carrageenan-based packaging films with antibacterial and antioxidant properties

The burdens of microbial food safety and environmental contamination make it necessary to search sustainable, safe, antibacterial and antioxidant active food packaging materials. This contribution proposed the use of copper-ferulic acid networks (CuFA NWs) as antibacterial substances. By immobilizing CuFA NWs into carrageenan matrix, a CuFA network-reinforced carrageenan-based packaging film (Carr/CuFA) was obtained via spontaneously hydrogen bond and electrostatic interaction indicated by ATR-IR and XPS. Interestingly, the addition of CuFA NWs increased the mechanical strength, surface hydrophobicity, and water vapor barrier properties of the carrageenan-based film, and imparted the film with UV-shielding capacity. Importantly, the Carr/CuFAx film exhibited effective antioxidant activity, and antibacterial performance against four foodborne bacteria. As a result, after confirming the safety of Carr/CuFA3 films by releasing, hemolysis and cell viability experiments, the Carr/CuFA3 film exhibited great potential in the safety control and preservation of fresh fruit by using blueberry and cherry as model fruit. In summary, this work provides a feasible candidate for the preservation and contamination control of fresh fruit.

Hurdle Concept and The Role of Lactic Acid Bacteria

The hurdle idea is a food preservation technique that includes building up a number of barriers to prevent microbes from growing and prolong the shelf life of perishable goods. The idea of using lactic acid bacteria (LAB), which are essential for food preservation, is one that is significant. Through a variety of processes, including fermentation, competitive exclusion, metabolite generation, biofilm formation, nutritional competition, and metabolic activity, LAB support the hurdle concept. Lactic acid bacteria (LAB) ferment glucose to produce lactic acid, which results in an acidic environment that prevents infections and spoiling germs from growing. Additionally, LAB generates antimicrobial substances such as hydrogen peroxide, organic acids, and bacteriocins, which work by competitively excluding harmful germs from growing. Furthermore, metabolites of lactic acid bacteria (LAB) such acetic acid, diacetyl, and carbon dioxide enhance the flavor of fermented foods and serve as organic preservatives. Moreover, LAB have the ability to create biofilms that shield them from antimicrobial agents and environmental stressors, increasing their survival and persistence in food matrices. By means of nutritional competition, LAB outcompetes pathogenic or spoilage bacteria in the consumption of available resources, hence restricting their growth. In addition, LAB produces enzymes and antibacterial substances, among other metabolic activities that further impede the growth of infections.

Study of antibacterial properties of extracts of the herb Speranskia tuberculata (Bunge) Baill

The article deals with the problem of developing antibacterial drugs of plant origin, focusing on the properties of the herb Speranskia Tuberculata (Bunge) Baill, which is still understudied. The aim was to determine the antibacterial activity of preparations of the herb Speranskia Tuberculata (Bunge) Baill, extracted with different solvents. Materials and methodology. Crude extracts were obtained using four solvents: petroleum ether, ethyl acetate, n-butanol, and aqueous solutions. Subsequently, the dried extracts were weighed and dissolved in dimethylsulfoxide to prepare working solutions with 10 to 500 µg/mL concentrations. Colonies of three types of bacteria, Staphylococcus aureus, Escherichia coli, and Propionibacterium Acnes, were used as the object of the study. The degree of antibacterial activity was determined by measuring the antibacterial zone formed after treating bacteria with different concentrations of extracts compared to the control group (treatment with distilled water). In addition, the total content of phenolic compounds and flavonoids was determined by chemical methods. Antioxidant activity, volume of the dry residue of crude extracts, and content of flavonoids and phenolic compounds were compared with the results of liquid chromatography-mass spectrometry on the presence of antibacterial substances in the extracts known from the literature. It was shown that the ethyl acetate extract among the 4 studied extracts had a clearly expressed antibacterial effect. The calculated value of IC50 for this extract varied between 112‒135 μg/mL for different bacteria. Other solvents did not show a pronounced antibacterial effect. The weakest effect was associated with petroleum ether extracts. At the same time, the mass of the dry residue, when extracted with petroleum ether, was the maximum among all solvents; on the contrary, with ethyl acetate, it was the minimum. Regarding the content of phenolic compounds and flavonoids, the results of the studies were opposite; namely, the maximum concentrations were characteristic of the ethyl acetate extract, and the minimum concentrations were characteristic of the petroleum ether extract. According to the literature, twelve compounds found in the extracts have pronounced antibacterial activity. Suppose the presence of an aromatic ring and a carbon-linked hydroxyl group OH- is taken as the main sign of belonging to phenolic compounds. In that case, 8 of 12 invented antibacterial compounds belong to phenols and flavonoids. Experimentally proven high antibacterial activity of preparations of the herb Speranskia Tuberculata (Bunge) Baill based on ethyl acetate extracts. This property is related to the extract's high content of phenolic compounds and flavonoids.

Screening of Antagonistic Bacteria against Three Aquatic Pathogens and Characterization of Lipopeptides in Bacillus cereus BA09.

Screening for antagonistic bacteria on aquatic pathogens and identification of antagonistic ingredients are essential to reduce the use of chemicals in aquaculture. In this study, strain BA09, subsequently identified as Bacillus cereus, simultaneously displayed strong antagonistic effects on Edwardsiella tarda, Vibrio harveyi, and Streptococcus anisopliae in the initial screening and rescreening. In addition, the methanol extract of BA09 was subjected to antibacterial activity verification and one-dimensional (1D) reversed-phase liquid chromatography (RPLC) preparation. A total of 27 fractions were collected, 6 of which were subjected to two-dimensional (2D) RPLC separation and tracked as antibacterial. A total of 14 lipopeptides that included 9 fengycin homologs, 3 bacillomycin homologs, and 2 surfactin homologs were identified by tandem high-resolution mass spectrometry. Through characterization of the antibacterial substance in Bacillus cereus BA09, which simultaneously inhibited E. tarda, V. harveyi, and S. agalactiae, the current study provides a theoretical basis for the development of antibacterial drugs in aquaculture.

Inhibitory effects of potassium sorbate and ZnO nanoparticles on Escherichia coli and Staphylococcus aureus in milk-based beverage

Antibacterial substances have played a crucial role in food preservation. Herein, the inhibitory effects of potassium sorbate and ZnO nanoparticles (ZnO NPs) on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in milk-based beverages were examined through the determination of their minimum inhibitory concentrations (MICs) with an automated method for measuring bacterial growth curves. We revealed that the MICs of potassium sorbate and ZnO NPs against E. coli were 16.0 mg/mL and 8.0 mg/mL, respectively. While against S. aureus they were 24.0 mg/mL and 8.0 mg/mL, respectively. ZnO NPs demonstrated higher antibacterial efficacy compared to potassium sorbate. The combination of potassium sorbate and ZnO NPs showed an indifferent effect on E. coli, but an additive effect on S. aureus. The addition of 3 × MIC of either potassium sorbate or ZnO NPs resulted in a complete suppression of bacterial growth for 5 days. This study underscored the efficacy of potassium sorbate and ZnO NPs, either alone or in combination, in combating E. coli and S. aureus, highlighting their potential commercial utility in safeguarding milk-based beverages from spoilage.