Search Results (468)

Cinnamaldehyde (CA) is a potential substitute for antibiotic growth promoters in animal breeding. In this study, we investigated its effects as a dietary supplement on growth performance, serum antioxidant capacity, intestinal digestive enzyme activities, intestinal morphology, and caecal microbiota in meat rabbits. Weaned meat rabbits (n = 450) were randomly assigned to five groups, Groups A, B, C, D, and E, and fed 0, 50, 100, 150, and 200 mg/kg CA diets, respectively, for 47 days. Biological samples including serum (antioxidants), duodenal/caecal content (enzymes), intestinal tissue (morphology), and caecal digesta (microbiota) were collected at day 47 postweaning for analysis. Groups C and D showed significantly higher final body weights than Group A, with Group D (150 mg/kg CA) demonstrating superior growth performance including 11.73% longer duodenal villi (p < 0.05), 28.6% higher microbial diversity (p < 0.01), and 62% lower diarrhoea rate versus controls. Digestive enzyme activity as well as serum antioxidant capacity increased with increasing CA dose, Microbiota analysis revealed CA increased fibre-fermenting Oscillospiraceae (+38%, p < 0.01) while reducing Ruminococcaceae (−27%, p < 0.05). Thus, dietary CA supplementation at 150 mg/kg was identified as the optimal CA dose for improving meat rabbit production. These findings highlight CA as a functional feed additive for promoting sustainable rabbit production. Full article

Antimicrobial resistance (AMR) poses a critical global health threat by rendering existing antibiotics ineffective against infections, leading to increased mortality, prolonged illnesses, and higher healthcare costs. Developing new antibiotics is essential to combat resistant pathogens, safeguard modern medical procedures, and prevent a return to a pre-antibiotic era where common infections become untreatable. We report a series of chiral tricarbonyl rhenium(I) complexes incorporating enantiopure pinene-substituted bipyridine ligands (L#) of the general formula fac-[Re(CO)₃L#X] and fac-[Re(CO)₃L#Py]⁺ (where X = Cl or Br and Py = pyridine). These complexes were isolated as mixtures of two diastereomers, characterized by standard techniques, and evaluated for cytotoxic activity against methicillin-resistant and methicillin-sensitive Staphylococcus aureus (MRSA and MSSA). The results revealed notable antibacterial efficacy (MIC = 1.6 μM), reflected in high therapeutic indices (Ti > 10). In contrast, analogous complexes bearing non-chiral 2,2′-bipyridine ligands exhibited no activity, underscoring the critical role of chirality in modulating biological interactions at the molecular level. These findings highlight the potential of chiral Re(I) complexes as promising scaffolds for the development of more potent and selective antibacterial agents. Full article

Quorum quenching (QQ) is of interest for potential application as a sustainable strategy for bacterial disease control via communication interruption. The QQ enzyme can be used as a good alternative antagonist to combat antibiotic abuse and bacterial resistance. Here, genomic DNA sequencing was performed on N-acyl homoserine lactonase from the deep-sea strain Bacillus velezensis DH82 with Cluster of Orthologous Groups of proteins (COGs) annotation. The homologous sequences with β-lactamase domain-containing protein were predicted to be potential QQ enzymes and were cloned and expressed to study their quorum quenching properties by comparing them with the reported enzyme AiiA_3DHB. The experimental results of enzyme activity analysis and steady-state kinetics, as well as enzyme structure and substrate docking simulations and predictions, all consistently demonstrated that YtnP_DH82 presented superior enzyme structural stability and higher degradation efficiency of N-acyl homoserine lactones than AiiA_DH82 under the effects of pH, and temperature, and performed better on short -chain and 3-O-substituted AHSLs. The findings revealed the structural and biochemical characterization of YtnP_DH82 from the deep sea, which provide the capacity for further application in sustainable aquaculture as an alternative to antibiotics. Full article

Boronic acids are an important class of molecules diversely used in organic synthesis, catalysis, medicinal chemistry, and for the design of functional materials. Particularly, aryl boronic acids in the solid state are known to exhibit pharmaceutical and photoluminescent properties for antimicrobial, sensing, and drug delivery applications. Furthermore, the phenazine molecule is known for its diverse pharmacological properties, including antibiotic activity. In the case of molecular crystalline solids, it is well established that understanding noncovalent interactions remains key to designing or engineering their functional properties. While both aryl boronic acids and phenazine molecules individually represent an important class of compounds, their co-assembly in the crystalline state is of interest within the context of supramolecular chemistry and crystal engineering. Herein, we report the supramolecular features of two newly synthesized cocrystals, which are composed of para-F/CF₃-substituted phenylboronic acids, respectively, and phenazine, as demonstrated by structure analysis by single-crystal X-ray diffraction. Full article

The increasing circulation of multi-drug-resistant pathogens, coupled with the sluggish development of new antibiotics, is weakening our capacity to combat human infections, resulting in elevated death tolls. To address this worldwide crisis, antimicrobial peptides (AMPs) are viewed as promising substitutes or adjuvants for combating bacterial infections caused by multidrug-resistant organisms. Here, the antimicrobial activity and structural characterization of a novel 13-amino acid cationic peptide named RKW (RKWILKWLRTWKK-NH2), designed based on known AMPs sequences and the identification of a key tryptophan-rich structural motif, were described. RKW displayed a broad-spectrum and potent antimicrobial and antibiofilm activity against Gram-positive and Gram-negative pathogens, including ESKAPE bacteria and fungi with minimal inhibitory concentrations (MBC) ranging from 5 µM to 20 μM. Structural results by fluorescence and Circular Dichroism (CD) spectroscopy revealed that the peptide was folded into a regular α-helical conformation in a membrane-like environment, remaining stable in a wide range of pH and temperature for at least 48 h of incubation. Furthermore, RKW showed low toxicity in vitro against mammalian fibroblast cells, indicating its potential as a promising candidate for the development of new antimicrobial or antiseptic strategies. Full article

Zinc oxide nanoparticles (ZnO NPs) have attracted significant attention due to their wide-ranging applications in animal production, largely because of their notable biocompatibility, low toxicity, and strong antimicrobial activity. These properties make ZnO NPs a promising substitute for traditional antibiotics. Their application could address the growing concern of antibiotic resistance in livestock industries. This review examines the unique physicochemical characteristics of ZnO NPs, including their nanoscale size and high surface area, which contribute to their biological functionality. Emphasis is placed on green synthesis methods that minimize environmental impact while producing high-quality ZnO NPs. In animal farming, ZnO NPs play a crucial role not only in promoting growth and improving immune responses, but also in enhancing meat and egg quality. Additionally, this review discusses the environmental and safety implications of ZnO NPs, considering their sustainable application potential in future animal production practices, aimed at fostering a more eco-friendly and efficient livestock sector. Full article

Background/Objectives: Research efforts and substantial funding have been dedicated to finding cost-effective and sustainable alternatives to antibiotics. Probiotics have been proposed as promising substitutes for antibiotics in human nutrition and livestock production; however, their functional mechanisms remain incompletely understood, limiting their sustainable applications as food supplements, feed additives and for therapeutic and cosmetic purposes. Methods: In this study, the probiotic potential of two bacterial genomes, Ligilactobacillus saerimneri and Ligilactobacillus salivarius, were explored. Their protein-coding hypothetical proteins were analyzed for their potential to induce interleukin-5 (IL-5) and interleukin-13 (IL-13). Results: The IL-5- and IL-13-inducing peptides were identified as immunogens against bacterial and tumor peptides. Conclusions: These findings provide insights into the probiotic bacteria’s immune functionality pathways, sustainability and potential as therapeutic feed additives, food supplements and candidates for vaccine development. Full article

The polysaccharide of Millettia speciosa Champ. ex Benth (MSCP) has antioxidant properties, but its impact on chicken growth and development is not yet known. This study used chlortetracycline as a control to assess MCSP as a feed antibiotic substitute and its effects on Wenchang chicken production, slaughter performance, and meat quality. A total of 576 healthy 80-day-old Wenchang chickens were randomly allocated to six experimental groups. The control group (Control) received a basal diet, while the antibiotic group (CTC) was supplemented with 2 g/kg chlortetracycline (CTC). Four additional experimental groups were administered varying doses of MSCP: 400 mg/kg (MSCP₄₀₀), 800 mg/kg (MSCP₈₀₀), 1600 mg/kg (MSCP₁₆₀₀), and 3200 mg/kg (MSCP₃₂₀₀), respectively. The study discovered that incorporating MSCP and CTC into chicken diets significantly boosted the final body weight and average daily feed intake compared to the control group (p < 0.01), with MSCP notably enhancing average daily weight gain. With the addition of 800 mg/kg MSCP, chicken growth performance is comparable to that achieved with antibiotics in feed. However, it did not impact slaughtering performance (p > 0.05). In addition, MSCP significantly raised the pH after 24 h (p < 0.05) and decreased the yellowness (p < 0.01) of breast muscle. MSCP increased the essential amino acids (EAA) proportion in breast muscle (p < 0.05), EAA to nonessential amino acids (NEAA) ratio (p < 0.05), and diversity of fatty acids while decreasing C20:0 and increasing C18:2N6 and C22:1N9 content. Moreover, MSCP significantly reduced muscle fiber size (p < 0.01), increased fiber density (p < 0.01), boosted MYOD1 expression (p < 0.05), and decreased MSTN expression in breast muscle (p < 0.01). Overall, our study showed that supplementing the diet with MSCP, particularly at a dose of 800 mg/kg, enhanced growth, meat quality, muscle morphology, amino acid content, fatty acid composition, and gene expression related to muscle development in breast muscle. The results indicate that MSCP is a feed additive with the potential to replace antibiotics and improve meat quality, showing promising application potential. Full article

Vancomycin, a cornerstone antibiotic against severe Gram-positive infections, is increasingly challenged by resistance in Methicillin-resistant Staphylococcus aureus (MRSA) and Vancomycin Enterococcus spp. (VRE), necessitating the development of novel therapeutic strategies. This review examines how structural modifications to vancomycin can enhance its antibacterial activity and explores the critical role of computational approaches in designing the next generation of analogs. By analyzing the existing literature, we highlight how strategic alterations, such as the introduction of lipophilic side chains, substitutions on the sugar moieties, and modifications to the aglycone core, have yielded derivatives with improved antibacterial potency. Notably, certain analogs (e.g., Vanc-83, Dipi-Van-Zn) have demonstrated expanded activity against Gram-negative bacteria and exhibited enhanced pharmacokinetic profiles, including prolonged half-lives and improved tissue penetration, crucial for effective treatment. Semisynthetic glycopeptides like telavancin, dalbavancin, and oritavancin exemplify successful translation of structural modifications, offering sustained plasma concentrations and simplified dosing regimens that improve patient compliance. Complementing these experimental efforts, computational methods, including molecular docking and molecular dynamics simulations, provide valuable insights into drug–target interactions, guiding the rational design of more effective analogs. Furthermore, physiologically based pharmacokinetic modeling aids in predicting the in vivo behavior and optimizing the pharmacokinetic properties of these novel compounds. This review highlights a critical path forward in the fight against multidrug-resistant infections. By meticulously examining the previously carried out structural refinement of vancomycin, guided by computational predictions and validated through rigorous experimental testing, we underscore its immense potential. Full article

The health benefits associated with microbial species inhabiting aquatic animals have garnered increasing attention, as it is expected that the colonization and efficacy of native probiotic bacteria adapted to the internal environment of the target species will be more active than non-native bacteria. In this study, six isolates were obtained from the intestinal tract of largemouth bass. Three of these isolates demonstrated higher growth ability compared to the others and were further characterized using in vitro assays. Lactococcus lactis LBM15 was found to exhibit antibacterial activity against common pathogens affecting largemouth bass; the adhesion inhibition capabilities of the isolates were systematically evaluated through competitive, repulsive, and substitutive adhesion assays. The strain inhibited adhesion to all six tested pathogen strains, with competitive adhesion inhibition rates ranging from 42% to 54%, the highest of which was observed against V. anguillarum. Repulsive adhesion inhibition rates ranged from 27% to 55%, with the highest rate noted for Edwardsiella tarda. Additionally, substitutive adhesion inhibition rates were found to range from 48% to 76%, with the highest inhibition observed against Aeromonas hydrophila. Furthermore, LBM15 exhibited favorable antimicrobial susceptibility profiles, showing sensitivity to 21 antibiotics tested. Notably, safety assessment trials were performed exposing fish to LBM15 at a concentration of 1 × 10⁹ CFU/mL by injection and at a concentration of 1 × 10⁸ CFU/mL by feed administration. No clinical abnormalities, behavioral alterations, or mortality were documented in either exposure group, confirming the safety of LBM15 for application in aquaculture. The results suggested that LBM15 isolates from largemouth bass have potential for further investigation and possible application as probiotic candidates. Full article

Delafloxacin is one of the newest fluoroquinolones with a unique structure, determining better pharmacokinetic and pharmacodynamic properties, a better safety profile, and a broader spectrum of activity compared to older quinolones. We aimed to examine the susceptibility rates of delafloxacin, the genetic mechanisms contributing to resistance, and the serotype distribution in both invasive and non-invasive Streptococcus agalactiae strains. A total of 301 streptococcal strains were tested for minimal inhibitory concentration (MIC) to delafloxacin. All delafloxacin-resistant strains were subjected to serotyping, PCRs for quinolone-resistant genes, and sequence analysis for missense and silent mutations. Among the tested isolates, we found a 5.6% non-susceptibility rate to delafloxacin. The MICs ranged between 0.09 and 0.38 µg/mL, with a breakpoint for nonsusceptibility set as >0.03 µg/L, according to EUCAST criteria. All resistant isolates harboured missense mutations that led to amino acid substitutions in both GyrA (S81L) and ParC (S79F). Two common serotypes were determined among the resistant isolates: V (47.1%) and III (41.2%). Two strains were non-typable (11.7%). A statistical significance in the distribution of serotypes between delafloxacin-resistant and delafloxacin-susceptible strains was found. These findings highlight a concerning pattern of drug resistance developing prior to the introduction of a new medication, attributed to the extensive use of current antibiotics. Full article

The fermentation product FP-WeiGuangSu is regarded as a novel, green and efficient antibiotic substitute. Such products constitute one of the principal strategies for addressing bacterial diseases in aquaculture in the future. This study investigates the effects of FPs derived from Bacillus subtilis on the antioxidant capacity and gut microbiota of Largemouth Bass (Micropterus salmoides). Experimental diets containing 0, 1%, 3% and 5% FPs (Control, H1, H2 and H3) were fed to M. salmoides. Although short-term administration of FPs exerted no significant influence on the growth performance of Largemouth Bass, serological findings demonstrated that supplementation with FPs decreased the contents of the liver injury markers ALT, AST and AKP, along with liver MDA content, and enhanced antioxidant capacity (SOD, CAT and GSH-px). Notably, the addition of 1% FPs significantly improved the systemic antioxidant performance (SOD, CAT, GSH-px and T-AOC). Moreover, the FP supplementation increased the expression levels of il-10 and IgM, and lipolysis-related genes. The results of gut microbiota analysis revealed that FPs significantly altered the diversity and structure of gut microbiota. The LEfSe results indicated that the microbial marker of the control group was Cetobacterium, those of the H1 group were Bacillus and Mycoplasma, those of the H2 group were Acinetobacter, Paenibacillus and g_unclassified_Rhizobiaceae, and that of the H3 group was Enterococcus. The most significant microbial marker upon the addition of FPs was Paenibacillus, and the pathways for biosynthesis of secondary metabolites, biosynthesis of antibiotics, and biosynthesis of amino acids were significantly activated. The Bugbase analysis results suggested that, compared with the control group, the abundance of anaerobic bacteria in the FP group decreased, while the abundance of microorganisms with mobile-element-containing and oxidative-stress-tolerant phenotypes increased. Hence, this study demonstrated that 1–3% FP dietary supplementation can be used to enhance antioxidant ability, and liver and intestine health of M. salmoides in the aquaculture industry and can be regarded as a promising feed additive in aquaculture. Full article

Background: The well-studied 18-residue-long proline-rich antimicrobial designer peptide Api137 utilizes at least two lethal intracellular mechanisms that target the bacterial 70S ribosome. First, Api137 stalls the ribosome by binding to the peptidyl-transferase center, trapping the release factor, and inhibiting protein expression. Second, Api137 disrupts the assembly of the large 50S subunit of the ribosome, resulting in partially assembled pre-50S dead-end particles that are unable to form the functional 70S ribosome. Methods: All six proline residues in Api137 were substituted with 4S- and 4R-fluoro-l-proline (Fpr), which promote the cis- and trans-conformer ratio of the preceding Xaa-Pro-bond, respectively. The effect on the antibacterial activity was studied using Escherichia coli. The underlying mechanisms were investigated by studying 70S ribosome binding, inhibition of in vitro translation, and ribosome profile analysis. Results: Interestingly, the analogs were equipotent to Api137, except for the 4S-Fpr11 and 4S-Fpr16 analogs, which were four times more or less active, respectively. The most active 4S-Fpr11 analog competed the least with Api137 for its ribosome binding site, suggesting a shifted binding site. Both Fpr14 and the 4S-Fpr16 analogs disturbed 50S subunit assembly less than Api137 or not at all. The strongest effect was observed with the 4R-Fpr16 analog resulting in the lowest 70S ribosome content and the highest pre-50S particle content. This peptide also showed the strongest competition with Api137 for its binding site. However, its antibacterial activity was similar to that of Api137, possibly due to its slower cellular uptake. Conclusions: Api137 inhibits protein translation and disrupts 50S assembly, which can be adjusted by substituting specific proline residues with fluoroproline. 4R-Fpr16 potently inhibits ribosome assembly and offers a novel, unexploited clinical mechanism for future antibiotic development. Full article

In poultry production, antibiotics have been excessively used as growth promoters to support well-being and decrease mortality caused by pathogenic microorganisms. The overuse of antibiotics has led to the emergence of antibiotic-resistant bacteria and the presence of antibiotic residues in poultry products. To counteract this problem, probiotics could be used as adjuncts or as substitutes for preserving a diverse and balanced microflora to prevent the colonization and multiplication of pathogenic bacteria in the GI tract. This study aimed to isolate and characterize the potential probiotic properties of lactic acid bacteria from the small intestine of 23-week-old broiler breeders, with the goal of identifying potential probiotic candidates. Four phenotypically healthy broiler breeders were selected, and intestinal contents were aseptically collected and cultured on MRS agar. From the initial pool of 39 colonies, six isolates were identified based on Gram-positive and catalase-negative characteristics and further classified using 16S rRNA sequencing as Levilactobacillus brevis (n = 3), Pediococcus pentosaceus (n = 2), and Streptococcus salivarius (n = 1). These strains were further evaluated for probiotic properties such as transit resistance to simulated upper gastrointestinal conditions, antagonist activity, haemolytic activity, and cell surface properties such as autoaggregation, co-aggregation and hydrophobicity, in vitro. L. brevis NKFS8 showed good tolerance to pH 3, while P. pentosaceus NKSF10 exhibited good tolerance to pH 4 acidic conditions. All isolates demonstrated good survivability in bile salt concentration of 3% (w/v), with P. pentosaceus NKSF10 exhibiting the highest tolerance. The isolates showed a wide range of antagonistic activity against the test pathogens Pseudomonas aeruginosa (ATCC 27853), Salmonella typhimurium, Salmonella enterica (ATCC 13314), Staphylococcus aureus (ATCC 29213), and Listeria monocytogenes (ATCC 7644). Furthermore, these strains exhibited good auto-aggregation, co-aggregation, and hydrophobicity properties. In conclusion, lactic acid bacteria from the small intestine of broiler breeders present a valuable prospect for the development of effective probiotics. These probiotics can be utilized as a supplementary inclusion in poultry feed, obviating the need for antibiotics as growth promoters. Nevertheless, additional in vivo studies are required to closely monitor and assess the effects of probiotics on the gastrointestinal system of chickens. Full article

In response to the global antimicrobial resistance and residue issues, most countries and regions have implemented comprehensive bans on the use of growth-promoting antibiotics in animal feed formulations. Catechins are a group of polyphenolic compounds that are naturally present in many fruits and plant-derived foods, emerging as potential antibiotic-alternative additives for promoting gut health and production performance in poultry farming. The compounds demonstrate dual biological functions: mitigating oxidative tissue damage and actively remodeling gut microbiota composition by suppressing enteric pathogens (e.g., Clostridium) and enriching beneficial bacteria (e.g., Bifidobacterium). Such multifaceted regulation enhances intestinal barrier integrity, thereby improving nutrient absorption and translating into measurable production benefits, including elevated growth rates and feed conversion efficiency. The current research suggests that the added levels of catechins in chicken diets ranges from 40 to 600 mg/kg. However, the research and application of catechins in chicken production are still at the initial stage, which requires more attention worldwide and further mechanism exploration. This mini-review synthesizes recent research findings on the effects of catechins on chicken health, aiming to promote the formulation of feed additive strategies using plant-derived compounds such as catechins as substitutes for antibiotics, to maintain the health of poultry and other animals while preserving production performance. Full article