Search Results (426)

The increasing demand for sustainable agriculture has intensified interest in beneficial microbes as eco-friendly alternatives to chemical pesticides for plant disease control. Among these, plant growth-promoting rhizobacteria (PGPR) have attracted great interest because they can suppress plant pathogens and strengthen plant health through molecular mechanisms. Recent studies suggest that PGPR protect plants from disease not only by directly attacking pathogens but also by changing how plant immune genes are expressed through epigenetic processes. This review brings together current knowledge on epigenetic regulation in plant–PGPR interactions, focusing on DNA methylation, histone modifications, and non-coding RNA pathways. PGPR colonization activates plant immune signaling through pattern recognition receptors, MAPK cascades, reactive oxygen species, and plant hormones. The review also covers the range of bacterial signals—including lipopolysaccharides, flagellin, cyclic lipopeptides, and volatile organic compounds—that prepare plant defenses, and explains how the recognition of these signals reshapes chromatin structure at defense genes. In addition, the review discusses how these changes may influence induced systemic resistance and examines emerging, though still limited, evidence on whether they could potentially be transmitted to subsequent generations. A better understanding of how microbial signals regulate host epigenetics may reveal new ways to improve plant immunity and balance growth with defense. Overall, available evidence indicates that PGPR-induced epigenetic changes represent a promising and environmentally friendly approach to crop protection; however, field-level validation and mechanistic confirmation in non-model crop species remain necessary before this strategy can be considered practically applicable. Full article

Background: ESKAPE constitutes a group of six nosocomial bacteria that can evade available antimicrobials due to their great potential to develop multi-drug resistance and biofilm-forming abilities. These pathogens often cause hospital-acquired infections and pose a serious threat to public health. The search for efficient innovative therapeutic strategies to fight ESKAPE bacteria have been intensively investigated topics. One promising approach to fight resistant pathogens and their biofilms is combination therapy, which allows the effectiveness against microorganisms to be increased while reducing the applied concentrations and risks of potential unwanted side effects. Objectives: The object of the study was to determine if there is an interaction of short lipopeptides ((C₁₀)₂-KKKK-NH₂, C₁₆-KK-NH₂) together with erythromycin and tetracycline against pathogens of the ESKAPE group (Acinetobacter baumannii, Enterobacter aerogenes, Enterococcus faecium Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus). Methods: The checkerboard assay was used to examine the activity of compounds applied in combinations against ESKAPE strains in planktonic cells and toward biofilms formed by Staphylococcus aures and Pseudomonas aeruginosa. Results: The lipopeptides demonstrated a great potential of their application as additives to conventional antimicrobials against Gram-negative bacteria, including microorganisms within biofilms. Full article

Muskmelon (Cucumis melo L.) is an economically important crop that remains highly susceptible to destructive fungal diseases, including gummy stem blight, downy mildew, Fusarium wilt, and anthracnose. Although fungicides and resistant cultivars are widely used, reliance on chemical control raises concerns regarding environmental safety, food quality, and the emergence of fungicide-resistant pathogen populations. Consequently, microbial biopesticides, particularly Bacillus species, have attracted increasing attention as sustainable alternatives. In this study, muskmelon plants exhibiting leaf wilting, chlorosis, and stem yellowing were collected from Guangming Farm in Wufeng, Taichung, Taiwan, and associated pathogens were isolated from stem tissues and identified to determine the causal agent of these symptoms. In addition, the biocontrol efficacy of Bacillus subtilis strain MCLB2 against melon fruit rot, as well as its underlying mechanisms, was evaluated. Pathogenicity assays confirmed that isolate F01 was the causal agent. Based on morphological characteristics and internal transcribed spacer (ITS) sequence analysis, this isolate showed 99.8% identity to Fusarium pernambucanum URM 7559 (GenBank accession no. NR_163754), and phylogenetic analysis further placed it within the Fusarium incarnatum-equiseti species complex (FIESC). Antagonistic assays demonstrated that B. subtilis MCLB2 significantly inhibited mycelial growth and suppressed the spore germination of F. pernambucanum. In addition, culture filtrates of strain MCLB2 effectively reduced Fusarium-induced fruit rot in melon and disrupted fungal cellular respiration. Liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis revealed that the strain produced surfactin-family lipopeptides. In conclusion, B. subtilis MCLB2 exhibits potential as a sustainable biocontrol agent for managing Fusarium fruit rot in melon, likely through surfactin-mediated disruption of fungal cellular respiration. Full article

Biofilms rapidly form on medical devices such as urinary catheters and surgical materials. These biofilms compromise patient safety and undermine infection prevention and control (IPC). Biofilms also reduce the effectiveness of antibiotics and disinfectants. As a result, they increase healthcare-associated infections and increase costs through device failure and the need for maintenance or replacement. Researchers are increasingly exploring biosurfactants (BSs) as surface coatings and cleaning additives to prevent microbial attachment and disrupt early biofilm formation on medical devices and healthcare-related surfaces. This review examines the translational potential of biosurfactants as preventive, disruptive, and adjunctive antibiofilm agents for medical devices and healthcare-related surfaces. Literature evidence on glycolipids (rhamnolipids, sophorolipids) and lipopeptides (surfactin) from static, flow-based, and microfluidic in vitro models that used clinically relevant materials, such as silicone and polydimethylsiloxane (PDMS), were examined. In our literature search, we focused on pathogens central to IPC, such as Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus spp., and Candida spp., and it was generally noted that BSs reduced microbial adhesion and delayed early biofilm formation on medical devices and healthcare-related surfaces. Significant evidence also suggests that they partially disrupt biofilms and improve antimicrobial penetration when co-applied, mainly through membrane disruption, destabilization of extracellular substances, interfering with quorum sensing, and synergistic and/or antagonistic interactions with other molecules. Their performance varied with class, formulation, hydrodynamic conditions, and microbial composition. BSs function better as preventive and adjunctive IPC tools than stand-alone antimicrobial agents and can help to reduce biofilm formation on devices and improve surface disinfection. However, translating this promise into practice demands more robust data on long-term safety, stability, and product quality. Full article

Postbiotics derived from Bacillus species are recognized as promising natural antimicrobial agents. This study aimed to systematically evaluate the inhibitory activity of postbiotics derived from B. velezensis 906 against L. monocytogenes, elucidate the underlying antibacterial mechanisms using agar diffusion assays, broth microdilution, growth kinetics, flow cytometry, phospholipid competition assays, whole-genome mining, and non-targeted metabolomics, and characterize the bioactive metabolites responsible for their antibacterial effects. The postbiotics exhibited significant antagonistic activity against Gram-positive bacteria, Gram-negative bacteria, and fungi. They also inhibited pathogens such as Salmonella and Enterobacter sakazakii. Against L. monocytogenes, the minimum inhibitory concentration was 0.0083 mg/mL. At 1× MIC, the OD600 after 24 h remained at approximately 0.8, compared with 1.3–1.4 in the untreated control, whereas treatment at 4× MIC almost completely inhibited bacterial growth. Mechanistic analyses suggested that the postbiotics interact with membrane phospholipids, resulting in membrane disruption, increased intracellular reactive oxygen species accumulation, and enhanced membrane permeability. Integrated genome mining and non-targeted metabolomics indicated that the antibacterial activity was associated with a coordinated antimicrobial network involving lipopeptides, polyketides, bacteriocin-related compounds, and siderophore-associated metabolites. These findings provide insight into the antibacterial basis of B. velezensis 906 postbiotics and support their potential application in food safety control. Full article

The pervasive environmental dispersal of glyphosate has established this herbicide as a dominant anthropogenic xenobiotic, necessitating advanced bioremediation strategies to restore soil integrity. This study assessed the bioremediation efficacy of biosurfactants produced by Serratia ureilytica BM01-BS in glyphosate-contaminated soils, establishing their adsorption dynamics and ecotoxicological safety. The strain S. ureilytica BM01-BS gave a biosurfactant yield of 3.7 g·L⁻¹ with promising surface properties, utilizing babassu (Attalea speciosa) waste as the sole nutrient source. Whole-Genome Sequencing and Biosynthetic Gene Cluster mining identified a Nonribosomal Peptide Synthetase cluster homologous to rhizomide-type lipopeptides responsible for biosurfactant production. Bioremediation assays in glyphosate-contaminated soils demonstrated a removal efficiency exceeding 95% in approximately 60 min, outperforming the synthetic surfactant SDS (20–30% efficiency). Kinetic and isothermal modeling suggest that the bioremediation process is governed by chemisorption, adhering to a pseudo-second-order model (R² = 0.998) with a maximum adsorption capacity of 845 µg·kg⁻¹. Fourier-Transform Infrared spectroscopy confirmed that the biosurfactant effectively removes glyphosate and restores the soil’s mineral integrity, as evidenced by the complete disappearance of glyphosate-associated phosphonic and carboxylic bands. Ecotoxicological assessments verified the environmental safety of the bioremediation process. These findings position the BM01-BS biosurfactant as a sustainable, biodiversity-based adjuvant for enhancing ecological resilience in glyphosate-impacted landscapes. Full article

Botrytis cinerea, the causative agent of gray mold, is a major fungal pathogen affecting a wide range of economically important crops. To identify sustainable alternatives to chemical fungicides, this study characterized the biocontrol potential of two bacterial strains, Serratia quinivorans NFX21 and Pseudomonas thivervalensis NFX104, through genomic analysis and functional assays targeting key stages of fungal growth and plant infection. The NFX21 and NFX104 strains significantly inhibited B. cinerea mycelial growth (~35%) and strongly suppressed conidial germination with performances comparable to the reference biocontrol strain Bacillus amyloliquefaciens QST 713. In tomato detached-leaf and whole-plant pot assays, application of NFX21 and NFX104 significantly reduced gray mold incidence and lesion severity relative to nontreated infected plants (53–64%, detached leaves; 12–13%, whole-plant assays), achieving disease control levels similar to those obtained with the commercial biofungicide Serenade ASO^®. Whole-genome sequencing allowed the taxonomic assignment of the NFX strains and revealed a rich repertoire of biosynthetic gene clusters and antifungal determinants. The NFX21 genome contained genes associated with N-acyl-homoserine lactone-mediated quorum-sensing and production of lipopeptides, siderophores, and extracellular lytic enzymes. The NFX104 genome harbored clusters involved in the biosynthesis of multiple siderophores, 2,4-diacetylphloroglucinol and hydrogen cyanide. Moreover, both the NFX21 and NFX104 genomes contained additional low-homology clusters that potentially encode for novel unexplored metabolites. Collectively, these results support the translational potential of NFX21 and NFX104 as biocontrol candidates for sustainable, integrated management of gray mold caused by B. cinerea. Full article

Canker and dieback diseases caused by fungal pathogens represent an increasing threat to woody plants in both urban and forest environments, where sustainable management options are urgently needed. In this study, the biocontrol potential of Bacillus strain N1 was investigated against Neofusicoccum parvum and Gnomoniopsis smithogilvyi, causal agents of canker diseases on Eucalyptus globulus and Castanea sativa, respectively. The whole-genome sequence confirmed the taxonomic identification of strain N1 as B. velezensis, showing high average nucleotide identity and digital DNA–DNA hybridization values with reference strains. AntiSMASH analysis revealed the presence of multiple biosynthetic gene clusters associated with the production of antimicrobial secondary metabolites, including polyketides, non-ribosomal peptides, and lipopeptides, reflecting strain N1’s genomic potential to produce compounds that may contribute to its antifungal activity. Moreover, B. velezensis strain N1 significantly inhibited the growth of N. parvum and G. smithogilvyi and showed a biocontrol efficacy on detached eucalyptus and chestnut shoots. In both preventive and curative treatments and pathosystems, the application of B. velezensis N1 resulted in a significant reduction in the length of necrotic lesions, compared to pathogen-only controls, while no phytotoxic effects were observed on treated shoots. Overall, this study supported B. velezensis N1 as a promising candidate for the sustainable control of canker-associated pathogens in woody plants. Full article

Lactic Acid Bacteria contribute to heightened acidity in the fermentation process of Jiang-flavor Baijiu due to their production of lactic acid. High-temperature Daqu may act as a reservoir for beneficial microorganisms and antimicrobial compounds. In this study, we utilized 16S rRNA and ITS amplicon sequencing to identify microbial taxa in high-temperature Daqu that inhibit the primary lactic acid bacterium involved in Jiang-flavor Baijiu fermentation, Acetilactobacillus jinshanensis, followed by the selection of antagonistic strains. The strain exhibiting the strongest antagonistic activity was identified as Bacillus velezensis based on whole-genome sequencing. Genome analysis revealed 12 secondary metabolite biosynthetic gene clusters, from which one lipopeptide was identified. This lipopeptide was demonstrated to antagonize A. jinshanensis AJS1 by disrupting the cell membrane and inducing leakage of intracellular contents. Collectively, strain A1 and its secondary metabolites exhibit considerable promise as antagonistic agents to mitigate acidity increases triggered by A. jinshanensis AJS1 during the fermentation of Jiang-flavor Baijiu. Full article

Microbial biosurfactants, derived from diverse aquatic and extreme ecosystems, offer a sustainable and environmentally compatible strategy for enhanced oil recovery by fundamentally altering subsurface rock wettability. These biologically produced amphiphiles can efficiently transform oil-wet rock surfaces into water-wet states, thereby mobilizing otherwise trapped crude oil. The primary aim of this review is to provide an integrative understanding of how these biomolecules function at the interface between aquatic microbial ecology and subsurface petroleum engineering, with a particular focus on wettability alteration as a key mechanism for enhancing oil recovery. This review surveys major biosurfactant classes—glycolipids, lipopeptides, and polymeric bioemulsifiers—and their core mechanisms, emphasizing their relevance to challenging reservoir conditions such as high temperature and salinity. A detailed assessment is devoted to persistent hurdles such as stability, adsorption onto rock formations, and economic scalability. Future prospects center on three key approaches: advancing synergistic “bio-hybrid” systems that integrate biosurfactants with complementary agents such as biopolymers and nanomaterials; achieving cost-effective production through the valorization of waste feedstocks; and expanding targeted bioprospecting of microbial diversity from extreme aquatic environments. Together, these strategies are reviewed to drive the advancement of robust, green microbial-enhanced oil recovery (MEOR) technologies, charting a course from fundamental insights to field-scale implementation. Full article

Pear scab, caused by Venturia pyrina, poses a threat to pear cultivation, with particularly severe consequences for Portugal’s high-value Rocha pear industry. Despite its economic impact, few biological control agents are currently available. In this work, the phenotypic and genomic characterization of Pseudomonas capeferrum NFX1 is performed and its role as an effective biocontrol agent against V. pyrina is reported. Detailed genomic analysis revealed that strain NFX1 and other members of the Pseudomonas capeferrum species contain key biosynthetic gene clusters involved in pathogen antagonism, including the cyclic lipopeptide putisolvin. Phenotypic assays showed that strain NFX1 significantly inhibited V. pyrina growth, spore germination, and reduced pear scab lesion severity and fungal colonization in detached leaf assays. Moreover, strain NFX1 reprogrammed the Rocha pear leaf transcriptome to be consistent with a priming state and induced systemic resistance. A novel image-based method quantifying lesion darkening as a proxy for pear scab severity in detached leaves and a qPCR assay targeting the V. pyrina ef1-α gene and optimized for fungal DNA detection in infected pear leaves were also developed, thereby establishing a laboratory workflow specifically tailored to biocontrol evaluation against V. pyrina. Ultimately, the obtained results demonstrated the potential of P. capeferrum NFX1 for sustainable pear scab control. Full article

The cactus pear (Opuntia spp.) is a crop of major economic and ecological importance in arid and semi-arid regions. However, with its domestication and intensification, symptoms of fungal diseases have begun to emerge in different cultivation areas. This study was conducted to identify the pathogenic fungi associated with symptoms observed on cladodes in different regions of Morocco and to evaluate the effectiveness of bacterial and fungal antagonists. The study enabled the isolation and identification of several fungal agents from symptomatic cladodes, namely Alternaria alternata, Alternaria tenuissima, Colletotrichum gloeosporioides, and Aspergillus tubingensis. Among these pathogens, A. alternata proved to be the most aggressive and was therefore selected for in vitro and in vivo antagonism assays. Twelve bacterial isolates belonging to the genera Bacillus and Pseudomonas, as well as one isolate of Trichoderma harzianum, were evaluated for their antifungal activity. All antagonists showed significant inhibitory effects against A. alternata in vitro preliminary assay. However, the bacterial isolates B. siamensis, B. halotolerans, and P. peli, as well as T. harzianum, exhibited the highest efficacy. This efficacy was confirmed through direct confrontation tests in vivo on one-year-old cladodes for the three bacterial isolates. In contrast, T. harzianum showed significant pathogenic potential on cladodes of O. ficus-indica and O. megacantha. Investigation of the mechanisms of action of the three most effective bacterial isolates revealed their ability to produce antifungal volatile organic compounds. Enzymatic analyses showed differential production of amylase, chitinase, cellulase and protease among the three isolates, while genes associated with the biosynthesis of antifungal lipopeptides were detected only in P. peli. Full article

Fruit spoilage caused by fungal pathogens jeopardizes food safety and inflicts significant economic damage. Cyclic lipopeptides (CLPs) have been applied as biofungicides by disrupting the cell membrane and intracellular components; however, the first target for antifungal action is the fungal cell wall. This study elucidates the molecular mechanism by which CLPs compromise cell wall integrity using molecular dynamics simulation and experimental validation. Among Surfactin C, Iturin A, and Fengycin A, Surfactin C exhibited the strongest binding to β-glucan (ΔE = −1970.536 kcal/mol) and the lowest free volume (7.302%), with enhanced effects at higher concentrations. Key interaction sites were identified at C=O of D-Leu3, -N-H of Leu2, and -COOH of Glu1 by Radial distribution function. In vivo assays with Aspergillus niger confirmed a MIC of 40 µg/mL and Surfactin-induced β-glucan exposure. FTIR and XPS analyses revealed structural reorganization and hydrogen bonding, while SEM/TEM showed spore deformation and wall rupture. These findings demonstrate that Surfactin disrupts fungal cell walls via direct complexation with β-glucan, leading to structural collapse and cell death, supporting its potential as a targeted biofungicide. Full article

Microbial bioprospecting in contaminated environments is a promising strategy for identifying biosurfactant-producing bacteria; however, translating environmentally adapted strains into predictable cultivation processes remains challenging. In this study, a microbial consortium subjected to long-term evolutionary laboratory adaptation in oily sludge was investigated to evaluate strain-specific phenotypic responses related to biosurfactant production. Phylogenetic analysis based on 16S rDNA sequencing identified three taxonomically distant isolates: Faucicola sp. strain BS5C, Pseudomonas sp. strain BS16B, and Enterobacter sp. BS14MR. Biosurfactant production was evaluated using a sequential Design of Experiments (DOE) approach, including fractional factorial and central composite rotatable designs, with the emulsification index (E24) used as a semi-quantitative response variable. Initial screening revealed a statistically significant negative effect (p < 0.10) of high dextrose concentrations for all isolates. Strain-specific differences in model adequacy were observed, with a statistically adequate quadratic model obtained for Pseudomonas sp. BS16B (R² = 0.8658, p = 0.0225), whereas the other isolates showed significant lack of fit (p < 0.05). ATR-FTIR analysis revealed spectral profiles consistent with lipopeptide-like compounds. Overall, these results indicate that isolates derived from the same long-term adapted system may differ substantially in process predictability, suggesting that productivity-based screening alone may be insufficient for selecting robust strains. Full article