Antibacterial Substances Research Articles

Biosafety characteristics and antibacterial activity of probiotic strains against Streptococcus mutans, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis

BackgroundOral diseases with high prevalence worldwide are recognized as severe health problems. Probiotics are used to prevent oral diseases, including dental caries, oral malodor, periodontitis, and subgingival plaque. In this study, we aimed to confirm the antibacterial effect of probiotics on oral pathogens and to assess their characterization and safety as probiotics.MethodsThe antibacterial effects of Lacticaseibacillus rhamnosus MG4706, Lacticaseibacillus paracasei MG4715, and Limosilactobacillus reuteri MG4722 on the growth biofilm formation of Streptococcus mutans, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis were evaluated. We also investigated the production of antibacterial substances (H2O2 and reuterin) by these strains and their ability to adhere to oral epithelial cells. The safety of L. reuteri MG4722 was verified through whole-genome sequencing analysis and antibiotic susceptibility, lactate dehydrogenase activity, hemolytic activity, and bile acid hydrolase activity. The reuterin biosynthesis genes of L. reuteri MG4722 were identified using genomic analysis.ResultsL. reuteri MG4722 significantly inhibited the growth of S. mutans, A. actinomycetemcomitans, and P. gingivalis and suppressed the biofilm formation by A. actinomycetemcomitans. In addition, it showed considerable adhesion ability to oral epithelial cells. L. reuteri MG4722 produced H2O2 and reuterin as antibacterial substances, as confirmed by the presence of genes encoding the antibacterial compounds reuterin, reuteran, and reutericyclin. L. reuteri MG4722 showed no hemolysis, bile salt hydrolase activity, antibiotic resistance or toxicity to HT-29 cells, and no antibiotic-resistance genes were identified.ConclusionL. reuteri MG4722 demonstrated antibacterial effects on oral pathogens by producing antibacterial substances and adhering to oral epithelial cells. These results suggest that L. reuteri MG4722 could be an effective probiotic for oral health.

Identifying a Biocontrol Bacterium with Disease-Prevention Potential and Employing It as a Powerful Biocontrol Agent Against Fusarium oxysporum

Biocontrol microbes are environment friendly and safe for humans and animals. To seek biocontrol microbes effective in suppressing Fusarium oxysporum is important for tomato production. F. oxysporum is a soil-borne pathogen capable of causing wilt in numerous plant species. Therefore, we found a biocontrol bacterium with an excellent control effect from the rhizosphere soil of plant roots. In this work, we focus on two parts of work. The first part is the identification and genomic analysis of the biocontrol bacterium Y-4; the second part is the control efficiency of strain Y-4 on F. oxysporum. For this study, we identified strain Y-4 as Bacillus velezensis. It is an aerobic Gram-positive bacterium that can secrete a variety of extracellular enzymes and siderophores. Strain Y-4 also contains a large number of disease-resistant genes and a gene cluster that forms antibacterial substances. In addition, we found that it significantly inhibited the reproduction of F. oxysporum in a culture dish. In the indoor control effect test, after treatment with strain Y-4 suspension, the disease index of tomato plants decreased significantly. Furthermore, the control efficiency of the plants was 71.88%. At the same time, Y-4 bacterial suspension induced an increase in POD and SOD enzyme activities in tomato leaves, resulting in increased plant resistance. Taken together, strain Y-4 proves to be an effective means of controlling F. oxysporum in tomatoes.

Antibacterial Activity of Lemongrass (Cymbopogon citratus) Against Staphylococcus aureus in Cellulose Nanofibers from Lignocellulosic Biomass and Glycerol

Lemongrass oil (LGO) has great antimicrobial effects, it increases shelf life as a food coating. Incorporating LGO into cellulose nanofibres (CNFs)-(Glycerol)-(Starch) was done by a mixing procedure and the antibacterial characteristics were evaluated. The interaction of LGO in the composite systems was studied by Scanning electron microscopy (SEM), microbial analysis by total plate count, antimicrobial by inhibitory zone, film thickness, and by the support of Fourier-transform infrared spectroscopy (FT-IR). The results indicated that the best composite systems could maintain LGO by 0.15 g at all predetermined cellulose concentrations. Its antibacterial substance can be integrated into a polymer matrix for active coating.

Deciphering the Antimicrobial and Antibiofilm Efficiency of Thyme Essential Oil Encapsulated Zeolitic Imidazole Framework-8 Against Foodborne Pathogens.

Food Packaging using antibacterial substances plays a vital role in food industry in controlling contamination caused by food borne pathogens. Stability and pH dependent degradation characteristics of zeolitic imidazole framework-8 (ZIF-8) makes its suitable candidate for biomedical applications. The present study focuses on thyme essential oil (TEO) encapsulated in ZIF-8 to achieve a synergistic antibacterial effect and prolonged drug release, aiming to extend the shelf life of food products. Optical, structural and surface characterizations of TEO encapsulated within ZIF-8 (ZIF-8@TEO) reveals successful incorporation of TEO into ZIF-8 nanoparticles. High drug loading and pH dependent release rate with higher release rate at acidic condition (75%) makes ZIF-8 a promising drug delivery system. ZIF-8@TEO exhibited potent antimicrobial against Staphylococcus aureus, Bacillus subtilius and Pseudomonas aeruginosa, also attenuated the biofilm forming ability of these food borne pathogens. In vitro and in vivo toxicity studies reveal the non-hemolytic and non-toxic nature indicating its biocompatible nature. The results of the study reveal that ZIF-8@TEO nanoconjugate can be used for the development of novel antibacterial nanocomposite-based films for food packaging applications.

Antibacterial and cytotoxic properties of endophytic extracts for oral application

Abstract Endophytic fungal extracts possess great potential as alternative antibacterial substances. Here, two extracts from the Australian endemic plant Eremophila longifolia were shown to reduce biomass and metabolic activity of the oral bacteria Streptococcus oralis and Porphyromonas gingivalis. As the effective concentration towards S. oralis was lower than the cytotoxic concentration towards oral epithelial cells, more detailed studies are warranted in the future.

Bacteriocin Mining in Lactiplantibacillus pentosus PCZ4 with Broad-Spectrum Antibacterial Activity and Its Biopreservative Effects on Snakehead Fish.

Some lactic acid bacteria (LAB) produce antibacterial substances such as bacteriocins, making them promising candidates for food preservation. In our study, Lactiplantibacillus pentosus PCZ4-a strain with broad-spectrum antibacterial activity-was isolated from traditional fermented kimchi in Sichuan. Whole-genome sequencing of PCZ4 revealed one chromosome and three plasmids. Through BAGEL4 mining, classes IIa and IIb bacteriocin plantaricin S were identified. Additionally, two new antibacterial peptides, Bac1109 and Bac2485, were predicted from scratch by limiting open reading frames. Furthermore, during refrigerated storage of snakehead fish, PCZ4 crude extract reduced the total bacterial count, slowed the increase in TVB-N and pH values, improved the sensory quality of the snakehead, and extended its shelf life by 2 days. Meanwhile, PCZ4 effectively inhibited the growth of artificially contaminated Aeromonas hydrophila in snakehead fish. These findings indicate that Lp. pentosus PCZ4 can produce multiple antibacterial substances with strong potential for food preservation applications.

Evaluating the Antibacterial Properties of a Zeolite-Chitosan Biocomposite for Medical Applications

: Antibacterial substances have garnered significant interest in recent years due to their applications in medical equipment, prostheses, and drug delivery systems. Consequently, it is essential to identify and develop biomaterials with antibacterial properties tailored to specific target sites. This study utilizes two natural biomaterials: Chitosan and zeolite. Zeolite, a bioceramic with an aluminosilicate structure, exhibits high mechanical resistance, making it ideal for use in areas of the body that endure significant pressure, such as bones and teeth. Chitosan, on the other hand, possesses excellent properties for application in various bodily tissues. However, natural polymers like chitosan are often combined with other materials in composites to enhance their mechanical resistance. This research investigates the antibacterial properties of a biocomposite made from zeolite and chitosan against two types of bacteria: Staphylococcus aureus (gram-positive) and Escherichia coli (gram-negative). The results revealed that the composite exhibited strong resistance against E. coli but comparatively lower resistance to S. aureus. Furthermore, the findings suggest that chitosan plays a more significant role in conferring these antibacterial properties.

Selenocompounds as Potent Efflux Pump Inhibitors on Gram-positive Bacteria.

In recent years, selenocompounds have gained increasing attention as potential anticancer and antibacterial agents. Several selenoderivatives have been confirmed to act as MDR efflux pump inhibitors, based on their in vitro results against the bacterial AcrAB-TolC system and the cancer MDR efflux pump P-glycoprotein. Efflux pumps can contribute directly or indirectly to the virulence of bacteria, as they can reduce the intracellular concentration of antibacterial substances by expelling them out of the cell. The present work aims to study the antibacterial and efflux pump inhibiting properties of four families of selenoesters, namely aspirin-selenoesters, phenone-selenoesters, hydroxy-selenoesters, and benzyl-selenoesters. The real-time ethidium bromide accumulation assay confirmed that these derivatives inhibited the efflux systems of methicillin-resistant Staphylococcus aureus (MRSA) without exerting any antibacterial effect. The relative expression of efflux pump gene of NorA transporter was also monitored in the presence of the most potent derivatives on reference S. aureus, finding that these derivatives could change the expression of the tested efflux pump gene. Regarding the anti-biofilm activity, aspirin-selenoesters, benzyl-selenoesters, and hydroxy-selenoesters could efficiently inhibit the biofilm production of the MRSA strain. It can be concluded that selenocompounds could act as efflux pump inhibitors, thus reducing the virulence of biofilm-producing bacteria.

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 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 change significantly. Transcriptome sequencing of Va. S1 demonstrated that antibiotic resistance gene lpxA was downregulated at different HSUF levels. Live U. fasciata excreted a variety of active secondary metabolites in HSUF, which exhibited strong inhibitory effects on three isolated Va. strains. HSUF changed the antibiotic resistance of Va. Strain, especially at higher HSUF concentrations.

The Equilibrium of Bacterial Microecosystem: Probiotics, Pathogenic Bacteria, and Natural Antimicrobial Substances in Semen.

Semen is a complex fluid that contains spermatozoa and also functions as a dynamic bacterial microecosystem, comprising probiotics, pathogenic bacteria, and natural antimicrobial substances. Probiotic bacteria, such as Lactobacillus and Bifidobacterium, along with pathogenic bacteria like Pseudomonas aeruginosa and Escherichia coli, play significant roles in semen preservation and reproductive health. Studies have explored the impact of pathogenic bacteria on sperm quality, providing insights into the bacterial populations in mammalian semen and their influence on sperm function. These reviews highlight the delicate balance between beneficial and harmful bacteria, alongside the role of natural antimicrobial substances that help maintain this equilibrium. Moreover, we discuss the presence and roles of antimicrobial substances in semen, such as lysozyme, secretory leukocyte peptidase inhibitors, lactoferrin, and antimicrobial peptides, as well as emerging antibacterial substances like amyloid proteins. Understanding the interactions among probiotics, pathogens, and antimicrobial agents is crucial for elucidating semen preservation and fertility mechanisms. Additionally, the potential for adding probiotic bacteria with recombinant antibacterial properties presents a promising avenue for the development of new semen extenders. This review offers updated insights to understand the equilibrium of the bacterial microecosystem in semen and points toward innovative approaches for improving semen preservation.

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.

Fabrication of Antibacterial and Flexible Hydrogels Based on Citric Acid Containing Tannic Acid for Wound Dressing

ABSTRACTIn this research, a biomonomer based on hydroxyethyl methacrylate, citric acid, and polyethylene glycol (HEMA‐CA‐PEG) was synthesized. After confirming the reaction through 1H‐NMR and FT‐IR tests and obtaining the intended monomer, a flexible hydrogel was synthesized as a wound dressing, and its mechanical properties were evaluated using tensile strength, DMTA, and rheometry tests. This synthesized hydrogel exhibited sufficient mechanical properties. To enhance the efficiency of this hydrogel wound dressing and its effectiveness in facilitating wound healing, tannic acid (TA), as an antibacterial and antioxidant substance, was incorporated into it. In the second phase, antibacterial activity and animal studies were conducted. The comparison of the CA–based hydrogel with and without TA demonstrated that the TA–containing hydrogel achieved more than 99.9% inhibition and elimination of bacteria. The use of CA–based hydrogel with TA shown in treating burns on the backs of rats caused the wound to close after 17 days, and hair growth was observed by the 21st day. This synthesized flexible hydrogel wound dressing, along with suitable mechanical properties, exceptional antibacterial activity, increased granulation tissue formation, re‐epithelialization, angiogenesis, and collagen deposition, showed good performance in wound healing.

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.

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.

Evaluation of Antibacterial and Antibiofilm Effects from Soil Streptomyces spp. against Multidrug-Resistant Bacteria

The global increase in multidrug-resistant (MDR) bacterial infection has rapidly gained concern globally. This study aimed to investigate antibacterial and antibiofilm potential of 25 soil actinomycete strains against MDR strains including Escherichia coli strain M4, Pseudomonas aeruginosa strain M19, Klebsiella pneumoniae strain M19, Bacillus subtilis strain M18, and Methicillin Resistant Staphylococcus aureus (MRSA). In this study, three actinomycete isolates encoded APM-7, APM-11, and APM-21 showed a strong and broad antibacterial spectrum. The minimum inhibitory concentration (MIC) of extracts derived from these isolates was ranged from 78 μg/ml to 10,000 μg/ml. In addition, The extracts also displayed significant biofilm inhibition values ranging from 6.06 to 72.4%. Based on the results, APM-21 extract had the best antibacterial and antibiofilm activities with the strongest values against MRSA. According to the nucleotide sequencing of the 16S rRNA gene, APM-7, APM-11, and APM-21 strains possessed similar identities with Streptomyces cyaneus, Streptomyces coerulescens, and Streptomyces panayensis, respectively. Based on Liquid Chromatography Tandem-Mass Spectrometry (LC-MS/MS) analysis, two antibacterial compounds, namely rancimanycin III, and enteromycin were detected in all those three extracts. Interestingly, APM-21 extract also contained two prominent antibacterial substances including paramagnetoquinone C, and caerulomycin I, suggesting their contribution to the most potential activities. Moreover, new insights were provided into a promising candidate for use in an active compound combating strategy to control MDR bacterial strain infection.

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.