Search Results (917)

Plant growth-promoting rhizobacteria (PGPRs) are well known for their capacity to enhance the growth and survival of in vitro-grown plants. However, their effect on Nardostachys jatamansi (D. Don) DC., a critically endangered medicinal plant in the Indian Himalayan Region, is still unknown. In this study, a simple, reproducible protocol for in vitro propagation of N. jatamansi was established using shoot tip explants, cultured on Murashige and Skoog (MS) medium supplemented with different plant growth regulators, including N6-benzylaminopurine, thidiazuron (TDZ), and naphthalene acetic acid (NAA). MS media supplemented with 2.0 μM TDZ and 0.5 µM NAA created a significant shoot induction with an average of 6.2 shoots per explant. These aseptically excised individual shoots produced roots on MS medium supplemented with Indole Butyric Acid or NAA within 14 days of the transfer. The PGPR, viz., Bacillus subtilis and Pseudomonas corrugata, inoculation resulted in improved growth, higher chlorophyll content, and survival of in vitro-rooted plants (94.6%) after transfer to the soil. Moreover, the PGPRs depicted a two-fold higher total phenolics (45.87 mg GAE/g DW) in plants. These results clearly demonstrate the beneficial effects of P. corrugata and B. subtilis on the growth, survival, and phytochemical content of N. jatamansi. Full article

Background/Objectives: Listeria monocytogenes is a foodborne pathogen of major public health concern due to its ability to invade host cells and cause severe illness. This study aimed to develop and validate a multi-tiered screening pipeline to identify Bacillus strains with probiotic potential against L. monocytogenes. Methods: A total of 26 Bacillus isolates were screened for antimicrobial activity, gastrointestinal resilience, and host cell adhesion. A fluorescence-based infection assay using mCherry-expressing HCT 116 cells was used to assess cytoprotection against L. monocytogenes NCTC 7973. Eight strains significantly improved host cell viability and were validated by quantification of intracellular CFU. Two top candidates were tested in a murine model of listeriosis. The genome of the lead strain was sequenced to evaluate safety and biosynthetic potential. Results: B. subtilis CECT 8266 completely inhibited intracellular replication of L. monocytogenes in HCT 116 cells, reducing bacterial recovery to undetectable levels. In vivo, it decreased splenic bacterial burden by approximately 6-fold. Genomic analysis revealed eight bacteriocin biosynthetic clusters and silent antibiotic resistance genes within predicted genomic islands, as determined by CARD and Alien Hunter analysis. The strain also demonstrated bile and acid tolerance, as well as strong adhesion to epithelial cells. Conclusions: The proposed pipeline enables efficient identification of probiotic Bacillus strains with intracellular protective activity. B. subtilis CECT 8266 is a promising candidate for translational applications in food safety or health due to its efficacy, resilience, and safety profile. Full article

Microorganisms in their natural ecological niches are constantly challenged by other inhabitants. Antagonisms exhibited by interacting microbial species are directed towards survival and increasing of their fitness. The Soft Rot Pectobacteriaceae (SRP) is a good model to study these complex microbial interactions. Along with being present in various environments, SRPs are often transferred between environments, allowing the bacteria to encounter members of other species. In this study, we investigated interactions between Dickeya solani, a representative of SRPs and a causative agent of potato soft rot, and Bacillus subtilis, which is known to be a potent producer of secondary metabolites mediating antibiosis. We have found that the soil isolate B. subtilis MB73/2 not only suppresses in vitro soft-rotting of infected potato tubers but is also able to cause directional, coordinated escape of natural isolates D. solani IFB0102 and IPO2222. While this coordinated movement of D. solani depends on surfactin produced by B. subtilis MB73/2, we show that both Dickeya strains exhibit different antagonistic interaction phenotypes toward the competing Bacillus. We prove that this antagonism depends on a single nucleotide polymorphism in one of transcriptional regulators of D. solani belonging to the LysR family. Full article

Restricting the use of chemical pesticides in forestry requires the search for alternative solutions. These could be volatile organic compounds produced by three investigated species of bacteria (Bacillus amyloliquefaciens (ex Fukumoto) Priest, B. subtilis (Ehrenberg) Cohn and B. thuringiensis Berliner), which inhibit the growth of the pathogen F. oxysporum Schltdl. emend. Snyder & Hansen in forest nurseries. The highest inhibition of fungal growth (70%) was observed with B. amyloliquefaciens after 24 h of antagonism test, which had a higher content of carbonyl compounds (46.83 ± 8.41%) than B. subtilis (41.50 ± 6.45%) or B. thuringiensis (34.62 ± 4.77%). Only in the volatile emissions of B. amyloliquefaciens were 3-hydroxybutan-2-one, undecan-2-one, dodecan-5-one and tetradecan-5-one found. In contrast, the main components of the volatile emissions of F. oxysporum were chlorinated derivatives of benzaldehyde (e.g., 3,5-dichloro-4-methoxybenzaldehyde) and chlorinated derivatives of benzene (e.g., 1,4-dichloro-2,5-dimethoxybenzene), as well as carbonyl compounds (e.g., benzaldehyde) and alcohols (e.g., benzyl alcohol). Further compounds were found in the interactions between B. amyloliquefaciens and F. oxysporum (e.g., $\alpha$-cubebene, linalool, undecan-2-ol, decan-2-one and 2,6-dichloroanisole). Specific substances were found for B. amyloliquefaciens (limonene, nonan-2-ol, phenethyl alcohol, heptan-2-one and tridecan-2-one) and for F. oxysporum (propan-1-ol, propan-2-ol, heptan-2-one and tridecan-2-one). The amounts of volatile chemical compounds found in B. amyloliquefaciens or in the bacterium–fungus interaction can be used for further research to limit the pathogenic fungus. In the future, one should focus on the compounds that were found exclusively in interactions and whose content was higher than in isolated bacteria. In order to conquer an ecological niche, bacteria increase the production of secondary metabolites, including specific chemical compounds. The results presented are a prerequisite for creating an alternative solution or supplementing the currently used methods of plant protection against F. oxysporum. Understanding and applying the volatile organic compounds produced by bacteria can complement chemical plant protection against the pathogen, especially in greenhouses or tunnels where plants grow in conditions that favour fungal growth. Full article

The cultivation of cowpea (Vigna unguiculata), a vital vegetable crop, faces significant threats from Fusarium spp.-induced root rot. In this study, three fungal pathogens (Fusarium falciforme HKFf, Fusarium incarnatum HKFi, and Fusarium oxysporum HKFo) were isolated from symptomatic cowpea plants, and we screened 90 rhizobacteria from healthy rhizospheres using six culture media. Among these pathogens, Priestia megaterium TSA-10E showed a notable suppression of F. oxysporum HKFo (63.21%), F. incarnatum HKFi (55.16%), and F. falciforme HKFf (50.93%). In addition, Bacillus cereus KB-6 inhibited the mycelial growth of F. incarnatum HKFi and F. oxysporum HKFo by 42.39% and 47.93%, respectively. Critically, cell-free filtrates from P. megaterium TSA-10E and B. cereus KB-6 cultures reduced conidial germination in F. oxysporum HKFo and F. incarnatum HKFi, highlighting their role in disrupting the early infection stages. In greenhouse trials, TSA-10E and KB-6 reduced disease severity by 48.7% and 40.4%, respectively, with treated plants maintaining healthy growth while untreated controls succumbed to wilting. Broad-spectrum assays revealed that B. subtilis TSA-6E and P. megaterium TSA-10E were potent antagonists against both economic and grain crop pathogens. These findings underscore the potential of rhizobacteria as sustainable biocontrol agents for managing root rot disease caused by Fusarium spp. in cowpea cultivation. Full article

Background/Objectives: The ongoing evolution of SARS-CoV-2 has highlighted the limitations of parenteral vaccines in preventing viral transmission, largely due to their failure to elicit robust mucosal immunity. Methods: Here, we evaluated an intranasal (IN) vaccine formulation consisting of recombinant receptor-binding domain (RBD) adsorbed onto human probiotic Bacillus subtilis DG101 spores. Results: In BALB/c mice, IN spore-RBD immunization induced strong systemic and mucosal humoral responses, including elevated specific IgG, IgM, and IgA levels in serum, bronchoalveolar lavage fluid (BALF), nasal-associated lymphoid tissue (NALT), and saliva. It further promoted mucosal B cell and T cell memory, along with a Th1/Tc1-skewed T cell response, characterized by increased IFN-γ-expressing CD4⁺ and CD8⁺ T cells in the lungs. Conclusions: All in all, these findings highlight the potential of intranasal vaccines adjuvanted with probiotic B. subtilis spores in inducing sterilizing immunity and limiting SARS-CoV-2 transmission. Full article

Daucus is a large genus of the Apiaceae family, comprising around forty-five accepted species, that has a worldwide distribution. Species of this genus have been reported to have several traditional medicinal uses, and some of them are also largely used as food and spices. Daucus nebrodensis Strobl. is an endemic species of Sicily growing in the montane environments of the Madonie and the Nebrodi Mountains. In this work, the essential oil of D. nebrodensis (DnEO), collected wild near Messina (Italy), was chemically and biologically investigated. The hydrodistilled essential oil (yield 0.15%), obtained from fresh aerial parts, was evaluated by GC-MS, and It was particularly rich in monoterpene hydrocarbons, with sabinene (33.6%), α-pinene (17.2%), γ-terpinene (9.8%), and α-terpinene (7.6%) as the main metabolites. DnEO, and its main constituents, have been tested to evaluate their biological properties. Given the current problem of antibiotic resistance, it is of great interest to identify alternative molecules that could counteract the its progression. Therefore, DnEO was tested against Gram-negative species, such as E. coli DH5α and P. aeruginosa PAOI, and Gram-positive species, such as S. aureus ATCC6538P, B. subtilis AZ54, and M. smegmatis MC²155, showing notable antibacterial activity. The MIC for Bacillus subtilis, the most sensitive strain, was 18 mg/mL, while the MIC for Pseudomonas aeruginosa, the least sensitive strain, was 30 mg/mL. Moreover, interesting antibiofilm activity was observed against Mycobacterium smegmatis with a 55% inhibition. Its ability to form biofilms contributes to its persistence and resistance in clinical settings. These findings highlight the potential of D. nebrodensis EO as a source of bioactive compounds with promising antimicrobial and antibiofilm properties. Full article

This study investigates the potential for the microbial transformation of camelliagenin B, a saponin derived from Camellia oleifera seed cake meal, to develop novel metabolites. We employed three microbial strains, specifically Bacillus subtilis ATCC 6633, Bacillus megaterium CGMCC 1.1741, and Streptomyces griseus ATCC 13273, to biotransform camelliagenin B into its derivatives. The compounds were purified and separated using chromatographic techniques, such as high-performance liquid chromatography (HPLC). Structural identification was carried out using spectroscopic methods, including nuclear magnetic resonance (NMR) and mass spectrometry (MS). Ten bioactive compounds were obtained (1a-1j), of which nine were novel with multiple tailoring reactions, such as allyl oxidation, C-C double-bond rearrangement, hydroxylation, dehydrogenation, and glycosylation, observed in camelliagenin B analogs. The structures of these compounds were determined by 1D/2D NMR and HR-ESI-MS analysis. Therefore, this study showcases the capacity of microbial transformation as a sustainable and environmentally friendly method for generating bioactive compounds from C. oleifera seed cake meals. The individual chemicals can potentially facilitate the design of novel medicinal agents, functional foods, and natural preservatives. Full article

A previously undescribed cis-clerodane diterpenoid, diangelate solidagoic acid J (1), along with two known cis-clerodane diterpenoids, solidagoic acid C (2) and solidagoic acid D (3), as well as two known unsaturated monoacylglycerols, 1-linoleoyl glycerol (4) and 1-α-linolenoyl glycerol (5), were isolated and characterized from the n-hexane leaf extract of Solidago gigantea (giant goldenrod). Compounds 2–5 were identified first in this species, and compounds 4 and 5 are reported here for the first time in the Solidago genus. The bioassay-guided isolation procedure included thin-layer chromatography (TLC) coupled with a Bacillus subtilis antibacterial assay, preparative flash column chromatography, and TLC–mass spectrometry (MS). Their structures were elucidated via extensive spectroscopic and spectrometric techniques such as one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy and high-resolution tandem mass spectrometry (HRMS/MS). The antimicrobial activities of the isolated compounds were evaluated by a microdilution assay. All compounds exhibited weak to moderate antibacterial activity against the Gram-positive plant pathogen Clavibacter michiganensis, with MIC values ranging from 17 to 133 µg/mL, with compound 5 being the most potent. Only compound 1 was active against Curtobacterium flaccumfaciens pv. flaccumfaciens, while compound 3 demonstrated a weak antibacterial effect against B. subtilis and Rhodococcus fascians. Additionally, the growth of B. subtilis and R. fascians was moderately inhibited by compounds 1 and 5, respectively. None of the tested compounds showed antibacterial activity against Gram-negative Pseudomonas syringae pv. tomato and Xanthomonas arboricola pv. pruni. No bactericidal activity was observed against the tested microorganisms. Compounds 2 and 3 displayed weak antifungal activity against the crop pathogens Bipolaris sorokiniana and Fusarium graminearum. Our results demonstrate the efficacy of bioassay-guided strategies in facilitating the discovery of novel bioactive compounds. Full article

Soil degradation exerts profound impacts on soil ecological functions, global food security, and human development, making the development of effective technologies to mitigate degradation a critical research focus. Microorganisms play a leading role in rehabilitating degraded land, improving soil hydraulic properties, and enhancing soil structural stability. Mosses contribute to soil particle fixation through their unique rhizoid structures; however, the mechanisms underlying their interactions in mixed inoculation remain unclear. Therefore, this study addresses soil and water loss caused by rainfall erosion in the cold black soil region. We conducted controlled laboratory experiments cultivating Bacillus subtilis and cold-adapted moss species, evaluating the erosion mitigation effects of different biological treatments under gradient slopes (3°, 6°, 9°) and rainfall intensities (70 mm h⁻¹, 120 mm h⁻¹), and elucidating their carbon-based structural reinforcement mechanism. The results indicated that compared to the control group, Treatment C significantly increased the mean weight diameter (MWD) and geometric mean diameter (GMD) of soil aggregates by 121.6% and 76.75%, respectively. In separate simulated rainfall events at 70 mm h⁻¹ and 120 mm h⁻¹, Treatment C reduced soil loss by 95.70% and 96.75% and decreased runoff by 38.31% and 67.21%, respectively. Crucially, the dissolved organic carbon (DOC) loss rate in Treatment C was only 21.98%, significantly lower than that in Treatment A (32.32%), Treatment B (22.22%), and the control group (51.07%)—representing a 59.41% reduction compared to the control. This demonstrates the following: (1) Bacillus subtilis enhances microbial metabolism, driving carbon conversion into stable pools, while mosses reduce carbon leaching via physical barriers, synergistically forming a dual “carbon protection–structural reinforcement” barrier. (2) The combined inoculation optimizes soil structure by increasing the proportion of large soil particles and enhancing aggregate stability, effectively suppressing soil loss even under extreme rainfall erosion. This study elucidates, for the first time, the biological pathway through which microbe–moss interactions achieve synergistic carbon sequestration and erosion resistance by regulating aggregate formation and pore water dynamics. It provides a scalable “carbon–structure”-optimized biotechnology system (co-inoculation of Bacillus subtilis and moss) for the ecological restoration of the cold black soil region. 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

Staphylococcus pseudintermedius, an opportunistic pathogen of veterinary and zoonotic concern, harbors diverse biosynthetic gene clusters (BGCs) that may contribute to its ecological fitness and virulence. In this study, we performed a comparative genomic analysis of 6815 S. pseudintermedius isolates. Using Roary, we identified core and accessory genomes, revealing the subtilosin A gene (sboA) as part of the accessory genome, present in a subset of S. pseudintermedius isolates from clinical (n = 657), environmental (n = 1031), and unclassified sources (n = 487). AntiSMASH v8.0.0 analysis confirmed the presence of subtilosin A BGCs annotated as a sactipeptide with low similarity confidence to Bacillus subtilis subsp. spizizenii ATCC 6633 subtilosin A cluster. Further characterization using BAGEL4 identified multiple genes homologous to the Bacillus subtilis subtilosin A biosynthetic machinery (sbo-albABCDEFG), although albB, albG, and sboX were not annotated, raising questions about cluster completeness and functionality. BLAST v2.12.0 analysis of the full BGC identified by BAGEL4, revealing high conservation (99.6–100% pairwise identity) of gene content and order in 395 clinical, 593 environmental, and 417 unclassified S. pseudintermedius isolates. Incomplete clusters were identified in 763 clinical, 942 environmental, and 201 unclassified S. pseudintermedius isolates. The discrepancy between the number of isolates containing sboA and those harboring the full cluster may reflect evolutionary divergence or could be attributed to limitations in assembly quality. The functional implications of the identified cluster in S. pseudintermedius remain to be elucidated; however, its potential role in conferring competitive fitness by inhibiting closely related species is supported by previous findings in other staphylococci. Full article

The increasing resistance of pathogenic microorganisms to antimicrobials has driven the search for safe and sustainable alternatives. In this context, microbial biosurfactants have gained prominence due to their antimicrobial activity, low toxicity, and high stability under extreme conditions. This study presents the production and characterization of a biosurfactant with antimicrobial potential, obtained from Bacillus subtilis isolated from soil, for application in the control of resistant strains. Bacterial identification was performed using mass spectrometry (MALDI-TOF), confirming it as Bacillus subtilis. The strain B. subtilis UCP 1533 was cultivated using different carbon sources (glucose, soybean oil, residual frying oil, and molasses) and nitrogen sources (ammonium chloride, sodium nitrate, urea, and peptone), with evaluations at 72, 96, and 120 h. The best condition involved a mineral medium supplemented with 2% soybean oil and 0.12% corn steep liquor, resulting in the production of 16 g·L⁻¹ of biosurfactant, with a critical micelle concentration (CMC) of 0.3 g·L⁻¹ and a reduction in water surface tension to 25 mN·m⁻¹. The biosurfactant showed an emulsification index of 100% for used motor oil and ranged from 50% to 100% for different vegetable oils, maintaining stability across a wide range of pH, salinity, and temperature. FT-IR and NMR analyses confirmed its lipopeptide nature and anionic charge. Toxicity tests with Tenebrio molitor larvae showed 100% survival at all the tested concentrations. In phytotoxicity assays, seed germination rates above 90% were recorded for Solanum lycopersicum and Lactuca sativa. Antimicrobial tests revealed inhibitory activity against resistant strains of Escherichia coli and Pseudomonas aeruginosa, as well as against species of the genus Candida (C. glabrata, C. lipolytica, C. bombicola, and C. guilliermondii), highlighting the biosurfactant as a promising alternative in combating antimicrobial resistance (AMR). These results indicate the potential application of this biosurfactant in the development of antimicrobial agents for pharmaceutical formulations and sustainable strategies for phytopathogen control in agriculture. Full article

The major objective was to investigate the protective capabilities of endophytic bacterial strains isolated from a number of medicinal plant species towards Aspergillus spp. secured from the internal tissues of fungi-infected peanuts. Among 32 fungal isolates surveyed for mycotoxin production in various culture media (PDA, RBCA, YES, CA), 10 isolates qualitatively producing AFB₁, besides 10 OTA-producers, were assayed by HPLC for quantitative toxin production. Aspergillus spp. isolate Be 13 produced an extraordinary quantity of 1859.18 μg mL⁻¹ AFB₁, against the lowest toxin level of 280.40 μg mL⁻¹ produced by the fungus isolate IS 4. The estimated amounts of OTA were considerably lower and fell in the range 0.88–6.00 μg mL⁻¹; isolate Sa 1 was superior, while isolate Be 7 seemed inferior. Based on ITS gene sequencing, the highly toxigenic Aspergillus spp. isolates Be 13 and Sa 1 matched the description of A. novoparasiticus and A. ochraceus, respectively, ochraceus, respectively, which are present in GenBank with identity exceeding 99%. According to 16S rRNA gene sequencing, these antagonists labeled Ar6, Ma27 and So34 showed the typical characteristics of Pseudomonas aeruginosa, Bacillus subtilis and Bacillus velezensis, respectively, with similarity percentages of 99–100. The plant growth-promoting activity measurements of the identified endophytes indicated the production of 16.96–80.00 μg/100 mL culture medium of IAA. Phosphate-solubilizing capacity varied among endophytes from 2.50 to 21.38 μg/100 mL. The polysaccharide production pool of bacterial strains ranged between 2.74 and 6.57 mg mL⁻¹. P. aeruginosa Ar6 and B. velezensis successfully produced HCN, but B. subtilis failed. The in vitro mycotoxin biodegradation potential of tested bacterial endophytes indicated the superiority of B. velezensis in degrading both mycotoxins (AFB₁-OTA) with average percentage of 88.7; B. subtilis ranked thereafter (85.6%). The 30-day old peanut (cv. Giza 6) seedlings grown in gnotobiotic system severely injured due to infection with AFB₁/OTA-producing fungi, an effect expressed in significant reductions in shoot and root growth traits. Simultaneous treatment with the endophytic antagonists greatly diminished the harmful impact of the pathogens; B. velezensis was the pioneer, not P. aeruginosa Ar6. In conclusion, these findings proved that several endophytic bacterial species have the potential as alternative tools to chemical fungicides for protecting agricultural commodities against mycotoxin-producing fungi. Full article

In this comprehensive study, we investigated the degradation capacity and tolerance of the bacterial strain Bacillus subtilis in culture media with high concentrations of heavy crude oil (HCO) as the sole carbon source. Using a meticulously designed experimental approach conducted at room temperature (25 °C), we systematically examined various culture media with HCO concentrations of 20%, 35%, and 50% v/v over a 10-week period. The results revealed the microorganism’s remarkable resistance to these HCO concentrations. Biotransformation capacity was confirmed by quantifying CO₂ production via gas chromatography, showing substantial bioconversion with a 42% increase in CO₂ production. Additionally, changes in surface tension were monitored using the Du Noüy ring method, showing a reduction in the aqueous phase tension from 72.3 to 47.43 mN/m. At the end of the bioconversion period, all treated samples exhibited visible emulsification, indicative of biosurfactant production. This phenomenon was consistent with the observed decrease in surface tension, providing further evidence of biosurfactant-mediated mechanisms. These findings highlight the immense biotechnological potential of B. subtilis to address HCO-related challenges, offering promising prospects for crude oil bioremediation and bioupgrading. Full article