Search Results (443)

The aim of this study was to isolate and identify lactic acid bacteria (LAB) from a traditional fermented beverage, Boza, and to conduct an in-depth study on their fermentation and probiotic properties. The fermentation (acid production rate, acid tolerance, salt tolerance, amino acid decarboxylase activity) and probiotic properties (gastrointestinal tolerance, bile salt tolerance, hydrophobicity, self-aggregation, drug resistance, bacteriostatic properties) of the 16 isolated LAB were systematically analyzed by morphological, physiological, and biochemical tests and 16S rDNA molecular biology. This analysis utilized principal component analysis (PCA) to comprehensively evaluate the biological properties of the strains. The identified LAB included Limosilactobacillus fermentum (9 strains), Levilactobacillus brevis (2 strains), Lacticaseibacillus paracasei (2 strains), and Lactobacillus helveticus (3 strains). These strains showed strong environmental adaptation at different pH (3.5) and temperature (45 °C), with different gastrointestinal colonization, tolerance, and antioxidant properties. All the strains did not show hemolytic activity and were inhibitory to Staphylococcus aureus, and showed resistance to kanamycin, gentamicin, vancomycin, and streptomycin. Based on the integrated scoring of biological properties by principal component analysis, Limosilactobacillus fermentum S4 and S6 and Levilactobacillus brevis S5 had excellent fermentation properties and tolerance and could be used as potential functional microbial resources. Full article

As the primary biological risk threatening safe dairy production, bovine mastitis control highly relies on environmental disinfection measures. However, the mechanisms by which chemical disinfectants influence host–environment microbial interactions remain unclear. This study systematically investigated the disinfection efficacy and regulatory effects on microbial community composition and diversity of glutaraldehyde-benzalkonium chloride (BAC) and glutaraldehyde-didecyl dimethyl ammonium bromide (DAB) at recommended concentrations (2–5%), using 80 environmental samples from intensive dairy farms in Xinjiang, China. Combining 16S rDNA sequencing with culturomics, the results showed that BAC achieved a disinfection rate of 99.33%, higher than DAB’s 97.87%, and reduced the environment–gut microbiota similarity index by 23.7% via a cationic bacteriostatic film effect. Microbiome analysis revealed that BAC selectively suppressed Fusobacteriota abundance (15.67% reduction) and promoted Bifidobacterium proliferation (7.42% increase), enhancing intestinal mucosal barrier function through butyrate metabolism. In contrast, DAB induced Actinobacteria enrichment in the environment (44.71%), inhibiting pathogen colonization via bioantagonism. BAC’s long-acting bacteriostatic properties significantly reduced disinfection costs and mastitis incidence. This study first elucidated the mechanism by which quaternary ammonium compound (QAC) disinfectants regulate host health through “environment-gut” microbial interactions, providing a critical theoretical basis for developing precision disinfection protocols integrating “cost reduction-efficiency enhancement-risk mitigation.” Full article

The market for non-concentrated (NFC) orange juice is increasing rapidly due to consumer demand for nutrients and flavor. However, it encounters challenges in microbial safety, particularly from Salmonella enterica and Listeria monocytogenes. This study aimed to exploit a bio-preservative for NFC orange juice. Results showed that the cyclic peptide cyclo-zp80r had good antibacterial activity, with minimum inhibitory concentration values of 2–8 μM against S. enterica and L. monocytogenes. It exhibited bactericidal action against S. enterica and bacteriostatic action against L. monocytogenes at a concentration of 128 μM. This study explored the effect of cyclo-zp80r on the pathogenicity of S. enterica and L. monocytogenes. The mortality rate of Galleria mellonella exposed to these pathogens in NFC orange juice decreased from 100% to 60% after cyclo-zp80r treatment, surpassing the effectiveness of nisin. Cyclo-zp80r exhibited depolarization effects on S. enterica and L. monocytogenes. It increased outer membrane permeability and damaged the membrane structure of S. enterica. Cyclo-zp80r also caused distinct morphological changes, mainly cell collapse in S. enterica and localized bubble-like protrusions in L. monocytogenes. It induced reactive oxygen species production and DNA binding. The species diversity and abundance in NFC orange juice were also reduced by cyclo-zp80r, particularly in the genera Pantoea, Aeromonas, Pseudomonas, and Erwinia. Additionally, cyclo-zp80r exhibited excellent stability at high temperature (121 °C, 5 min) and in fresh orange juice. These results suggest that cyclo-zp80r could be developed as an effective food bio-preservative. Full article

Grass carp in aquaculture exhibited symptoms of bacterial infection leading to mortality. To investigate the cause of the disease and control grass carp infections, samples from diseased grass carp were collected, and a bacterial strain named XH-1 was isolated from the internal organs of the infected fish. Artificial infection experiments were conducted to determine whether the isolated strain XH-1 was the pathogenic bacterium. The biological characteristics of the isolated strain were studied through a 16S rRNA sequence analysis, physiological and biochemical identification, and phylogenetic tree construction. Extracts from 14 traditional Chinese herbs were tested to evaluate their bacteriostatic and bactericidal effects on the isolated strain. The regression infection experiment confirmed that the isolated strain XH-1 was the pathogenic bacterium causing the grass carp disease. Biological characterization studies identified the bacterium as Aeromonas veronii, which is clustered with A. veronii MW116767.1 on the phylogenetic tree. Among the 14 Chinese herbal extracts, Lignum sappa, Pericarpium granna, Artemisia argyi, Scutellaria baicalensis Georgi, Coptis chinensis, and Artemisiacapillaris thunb exhibited significant bacteriostatic effects on XH-1. Lignum sappa showed the highest sensitivity to A. veronii, with the largest inhibition zone diameter, and its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were 7.813 mg/mL and 15.625 mg/mL, respectively. As the concentration of Lignum sappa extract increased, its bacteriostatic and bactericidal effects strengthened. When the concentration exceeded 14 mg/mL, it maintained strong bactericidal activity over 32 h. This study on A. veronii XH-1 provides theoretical insights for the prevention of grass carp aquaculture diseases and the use of traditional Chinese herbs for treatment. Full article

Neisseria gonorrhoeae is the causative agent of the sexually transmitted infection gonorrhea. Preventative vaccines or novel treatments based on a better understanding of the molecular basis of N. gonorrhoeae infection are required as resistance to current antibiotics is widespread. Toxin–antitoxin (TA) systems modulate bacterial physiology by interfering with vital cellular processes; type II TA systems, where both toxin and antitoxin are proteins, are the best-studied. Bioinformatics analysis revealed genes encoding an uncharacterized type II HicAB TA system in the N. gonorrhoeae strain FA1090 chromosome, which were also present in >83% of the other gonococcal genome sequences examined. Gonococcal HicA overproduction inhibited bacterial growth in Escherichia coli, an effect that could be counteracted by the co-expression of HicB. Kill/rescue assays showed that this effect was bacteriostatic rather than bactericidal. The site-directed mutagenesis of key histidine and glycine residues (Gly22, His24, His29) abolished HicA-mediated growth arrest. N. gonorrhoeae FA1090∆hicAB and complemented derivatives that expressed IPTG-inducible hicA, hicB, or hicAB, respectively, grew as wild type, except for IPTG-induced FA1090∆hicAB::hicA. RT-PCR demonstrated that hicAB are transcribed in vitro under the culture conditions used. The deletion of hicAB had no effect on biofilm formation. Our study describes the first characterization of a HicAB TA system in N. gonorrhoeae. Full article

The pivotal component in the protection against TB is the tissue macrophages (Mф). These cells have been demonstrated to play a crucial role in the elimination of pathogens and mycobacterial killing. Elucidation of the molecular and phenotypic events that determine the outcome of infection in Mф is fundamental to understanding the key features of these cells that are so important in fighting infection. Mф activation is driven by cytokines and other inflammatory mediators secreted by T lymphocytes. The interaction between Mycobacterium tuberculosis (Mtb) and host Мф has been the subject of extensive in vitro research. This dynamic interplay represents a pivotal step in the progression of mycobacterial infection because pulmonary macrophages constitute the primary line of defense against the pathogen, thereby serving as the initial immune cells to which Mtb must adapt to establish a replicative foothold within the host. Our studies have demonstrated that highly differentiated Th1 effectors with the CD27^low phenotype exhibit superior efficacy in activating both peritoneal (Mф: T cell ratio ranging from 125:1 to 625:1) and pulmonary macrophages (Mф: T cell ratio = 5:1) compared to cells with the CD27^high phenotype. Furthermore, our findings indicate that this activation mechanism is not contingent upon the production of reactive nitrogen species. To effectively activate the bacteriostatic function of macrophages, CD27^high T lymphocytes must differentiate into effectors with the CD27^low phenotype. Full article

Background: The accumulation of agri-food waste is a major environmental and economic challenge and converting these by-products into bioactive compounds fits within the circular bioeconomy. This study aimed to evaluate the antimicrobial potential of extracts derived from Cannabis sativa L. leaves (CSE), Crocus sativus tepals (CST), and Prunus avium L. cherry waste (VCE) against four key bacterial species (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa). Methods: Minimum inhibitory concentration (MIC) assays were performed to assess antibacterial activity, while a bioinformatic pipeline was implemented to explore possible molecular targets. Full-proteome multiple sequence alignments across the bacterial strains were used to identify conserved, strain-specific proteins, and molecular docking simulations were applied to predict binding interactions between the most abundant compounds in the extracts and their targets. Results: CSE and CST demonstrated bacteriostatic activity against S. aureus and B. subtilis (MIC = 15.6 mg/mL), while VCE showed selective activity against B. subtilis (MIC = 31.5 mg/mL). CodY was identified as a putative molecular target for CSE and CST, and ChaA for VCE. Docking results supported the possibility of spontaneous binding between abundant extract constituents and the predicted targets, with high binding affinities triggering a strong interaction network with target sensing residues. Conclusions: This study demonstrates the antimicrobial activity of these agri-food wastes and introduces a comprehensive in vitro and in silico workflow to support the bioactivity of these agri-food wastes and repurpose them for innovative, eco-sustainable applications in the biotechnology field and beyond. Full article

Cytokinins, plant hormones derived from adenine, are best known for regulating growth and stress responses in plants. Recent findings suggest they may also influence microbial viability, yet their direct antimicrobial potential remains underexplored. This study evaluates the antimicrobial activities of four natural cytokinins (iPA, B, K, and p-T) and their N⁹-ribosides (iPAR, BR, KR, and p-TR) against selected human pathogens. Using the broth microdilution method, we assessed their effects on Gram-positive and Gram-negative bacteria, as well as fungal strains. While Gram-negative species showed no susceptibility, all tested compounds exhibited bacteriostatic activity against Bacillus subtilis and Enterococcus faecalis. Most notably, kinetin (K) and kinetin riboside (KR) displayed strong antifungal activity against Candida albicans, with MIC values comparable to the reference drug nystatin. Molecular docking studies supported these findings by showing that K and KR form favorable interactions with two validated antifungal targets in Candida albicans: secreted aspartic proteinase 3 (SAP3) and dihydrofolate reductase (DHFR). This is, to our knowledge, the first report linking natural cytokinins to direct antifungal action against C. albicans supported by in silico evidence. These findings highlight the potential of K and KR as promising leads for the development of cytokinin-based antifungal agents. Full article

Pichia manshurica is the main spoilage fungus that causes the deterioration of paocai. Our previous study found that the compound essential oils (CEOs) of lemon, lemongrass, and nutmeg had a good inhibitory effect; however, the antimicrobial mechanism was unknown. In order to elucidate the mechanism of action of the CEO in inhibiting P. manshurica, transcriptomics and metabolomics were used for joint analysis. The results showed that the minimum inhibitory concentration (MIC) of P. manshurica was 2 µL/mL, and the combined multi omics analyses indicated that the treatment of the CEO disrupted the ABC transporters, glycophospholipid metabolism, and nucleotide metabolism of P. manshurica, leading to the disruption of the integrity of P. manshurica cell wall and cell membrane, resulting in energy and metabolic dysfunction, and ultimately achieving the effect of inhibiting P. manshurica. The results of this study provided new insights into the mechanism of P. manshurica inhibition by CEOs, and provide a reference basis for the development of food-related bacteriostatic agents by CEOs. Full article

The development of sensitive, non-invasive methods is essential for the preservation and study of heritage books, allowing insights into their historical production processes and conservation needs. Volatile organic compound (VOC) analysis provides a valuable, non-destructive approach to assess paper composition and degradation in historical volumes. In this study, we analyzed VOC emissions from two books preserved at the Biblioteca Capitolare of Busto Arsizio, Italy: a 16th-century Latin grammar book and a 19th-century mathematics handbook for measurement conversions. Using headspace solid-phase microextraction (HS-SPME) and gas chromatography–mass spectrometry (GC-MS), VOCs were sampled after 24 h of storage at room temperature. The results revealed distinct degradation markers: Straight-chain aldehydes, indicative of lipid oxidation, were more prevalent in the 16th-century book, reflecting the higher quality and durability of its rag-based paper. In contrast, elevated furfural levels in the 19th-century book suggest accelerated cellulose hydrolysis typical of wood pulp paper. Additionally, the presence of menthol and anethole in both volumes points to the use of bacteriostatic agents for preservation. These findings not only highlight differences in material composition but also underscore the importance of tailored conservation approaches for historical documents from different eras. Full article

The World Health Organization notes that some bacteria have been demonstrated to possess significant public health risks; they have antibiotic resistance, and there are fewer alternatives for control. The n-hexane extract and cinaguaiacin obtained from Artemisia cina show promising antibacterial activity, including against multidrug-resistant bacteria that affect animal and human health. Objective: The aim of this study was to determine the antibacterial activity of the n-hexane extract of A. cina and cinaguaiacin against multidrug-resistant bacteria. Methods:A. cina was collected in the pre-flowering period, the n-hexane extract was obtained, and chromatographic techniques and structure were used to separate the lignans, which were elucidated with nuclear magnetic resonance techniques. Four ATCC strains were used, and four strains were isolated from clinical cases with different resistance profiles. The antibacterial activity was determined by calculating the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), the time-kill kinetics assay, and the cell membrane integrity and DNA release assay. Molecular docking studies of lignans demonstrated the binding mode involved in the active site of DNA gyrase B. Results: The n-hexane extract inhibited growth against 87.5% of the strains tested (MIC 5.31 to 42.5 mg/mL) and showed bactericidal activity against 25% of the strains tested (MBC 0.62 to 85 mg/mL). Cinaguaiacin inhibited growth against 100% of the strains tested (MIC, 0.56 to 2.25 mg/mL) and exhibited bactericidal activity against 25% of the strains tested (MBC, 0.62 to 85 mg/mL). Conclusions: The mechanism of cinaguaiacin’s action may be associated with damage to the plasma membrane, as the protein and DNA levels were higher than those of the positive control. The n-hexane extract and cinaguaiacin obtained from A. cina showed a bacteriostatic or bactericidal effect, depending on the strain evaluated. Full article

The search for natural antimicrobials has intensified with rising food safety demands. This study evaluated 23 probiotic strains, identifying Bifidobacterium sp. strain TF04 as a potent inhibitor against pathogens, with inhibition zone diameters of 12.85 ± 0.12 mm (Escherichia coli), 14.85 ± 0.10 mm (Staphylococcus aureus), and 17.50 ± 0.23 mm (Staphylococcus epidermidis). Preliminary analysis shows that the main antibacterial compounds produced by TF04 in the process of bacterial growth inhibition are antibacterial active proteins. TF04 exhibits optimal bacteriostatic activity within the pH range of 2–4, with a notable decline in effectiveness as the pH value increases. At the same time, the bacteriostat produced by TF04 showed strong thermal stability and ultraviolet stability. TF04 demonstrated excellent probiotic potential: surviving acidic (pH 2.0, >45% viability) and bile conditions (3% bile salts, >55% survival). It showed strong auto-aggregation (40.10%) and hydrophobicity (>30%), indicating gut colonization potential, along with notable antioxidant capacity. Safety was confirmed by absent hemolytic and gelatinase activities. These properties position TF04 as a promising multifunctional candidate for food preservation, combining antimicrobial efficacy with probiotic benefits. Further studies will purify its bioactive compounds and validate applications in food systems. Full article

Licorice roots are a rich source of bioactive compounds with multiple biological activities. The objective of this study was to evaluate the inhibitory effects of licorice root extract against a range of Listeria strains. In addition, the correlation of its phytochemical composition with antimicrobial properties was also investigated. Thus, the bacteriostatic and bactericidal effects of licorice root extract on seven Listeria monocytogenes strains, L. grayi, L. seeligeri, and L. ivanovii were determined. The minimum inhibitory and bactericidal concentrations ranged from 31.3 to 62.5 µg mL⁻¹ and from 62.5 to 250 µg mL⁻¹, respectively. The phytochemical composition of the extract was also analyzed using advanced LC-DAD- qTOF-MS; it is composed of fifty-one compounds belonging to different subgroups of flavonoids and triterpenoids. Subsequently, the anti-Listeria potency of the most abundant phytochemicals was determined using the AntiBac-Pred web tool. In silico calculation showed that liquiritin-apioside and licorice glycoside C1/C2 were strong growth inhibitors of L. monocytogenes, as their potency was comparable to well-known antibiotic substances. Overall, the present study demonstrates the potent antimicrobial effect of licorice root extract and reveals its active phytochemicals. Full article

Aphis gossypii Glover (Homoptera: Aphidinae), a major pest of Chinese pepper (Zanthoxylum bungeanum Maxim), causes significant agricultural damage. Ginger (Zingiber officinale Roscoe) has shown potential as a source for developing botanical pesticides due to its strong bacteriostatic and insecticidal properties; however, the underlying mechanisms remain poorly understood. This study evaluated the repellent activity of ginger shoot extract (GSE) across four solvent phases—petroleum ether, trichloromethane, ethyl acetate, and methanol—against A. gossypii. The results demonstrated that GSE exhibited significant repellent effects, with the methanol phase showing the most pronounced activity. Twelve fractions were chromatographically separated from the methanol phase, and electroantennography (EAG) analysis revealed that fraction 4 induced strong EAG responses in both winged and wingless aphids. Further identification of active compounds in fraction 4 by gas chromatography–mass spectrometry (GC–MS) indicated the presence of terpenes, aromatics, alkanes, esters, and phenols as major constituents. Subsequent EAG analysis identified several key compounds—octahydro-pentalene (C1), (Z)-cyclooctene (C2), dimethylstyrene (C3), tetramethyl-heptadecane (C5), tetrahydro-naphthalene (C6), and heptacosane (C9)—as responsible for eliciting EAG responses in both aphid forms. Additionally, results from Y-tube olfactometer assays showed that (Z)-cyclooctene and heptacosane were significantly attractive, while octahydro-pentalene acted as a strong repellent to both winged and wingless aphids. These findings offer valuable insights for the development of synthetic attractants and repellents for A. gossypii and provide a theoretical foundation for utilizing ginger in the creation of botanical pesticides targeting this pest. Full article

Co-trimoxazole is an antibacterial drug, a mixture of sulfamethoxazole (SMX) and trimethoprim (TMP) in a ratio of 5:1. Due to the different susceptibility of both components to decomposition under the influence of sunlight, the aim of the study was to assess the change in bacteriostatic activity during irradiation of the mixture of these antibiotics in a sunlight simulator. The bacteriostatic activity was assessed using a Microbial Assay for Risk Assessment (MARA), monitoring drug concentrations as well as the formation of photodegradation products using liquid chromatography (LC). The toxicity analysis of the SMX and TMP mixture showed synergistic bacteriostatic activity for six bacterial strains. This activity was maintained even during sample irradiation when 80–90% of SMX was degraded. This may indicate the bacteriostatic effect of SMX photoproducts and/or the lack of necessity to maintain a 5:1 ratio between SMX and TMP to maintain a strong effect of the mixture of these antibiotics. Analysis using LC with a high-resolution mass spectrometry detector revealed the presence of 11 SMX degradation products, including two with preserved sulfonamide structure, which may exhibit bacteriostatic activity. Full article