Search Results (176)

Microbial communities found in arid environments often exhibit unique genetic and metabolic adaptations that enable them to synthesize potent bioactive compounds. Bacillus thuringiensis (Bt) is widely recognized for its biocontrol potential against various insects. This study aims to investigate the insecticidal potential of Bt strains isolated from Qatar’s soil against dipteran and lepidopteran larvae. The microscopic analysis identified distinct crystal types, including bipyramidal, cuboidal, spherical smooth, and spherical rough forms, with distinct cry, cyt, and vip genes. Strains producing bipyramidal crystals carry cry1A, cry2A, and vip3A genes, while only two strains producing spherical crystals carry cry4B and cyt1A genes. Bipyramidal crystal-producing strains (QBT552 and QBT877) showed potent insecticidal activity, achieving 100% mortality against Corcyra cephalonica larvae, with LC₅₀ values of 25 µg/g. Spherical smooth crystal-producing strain (QBT862) exhibited high toxicity against Culex pipiens insect larvae (LC₅₀ = 2 µg/L). The quantification of bipyramidal crystal protein production of strains QBT877 and QBT552 exhibited the highest δ-endotoxin yield (1334.4 ± 6.7 and 1188.7 ± 5.0 µg/mL, respectively), while smooth spherical crystal strains QBT758 and QBT862 were 577.5 ± 8.4 and 567.6 ± 8.4 µg/mL, respectively. These findings highlighted the potential of Bt QBT strains for biocontrol applications, with strains showing promise for producing effective δ-endotoxins. Full article

(1) Background: Oat (Avena sativa L.) is a crop that is widely used in human nutrition, while it also plays an important role in animal husbandry as a high-quality forage crop. However, this crop is particularly susceptible to combined biotic stressors, including insect pests (Agriotes lineatus) and fungal infections (Fusarium spp.). These stresses act synergistically: root damage caused by wireworms increases the plant’s susceptibility to fungal infection, while pathogens further limit nutrient uptake and root system development. In recent years, the reduced efficacy of chemical pesticides against both insect pests and fungal pathogens has highlighted the need for alternative strategies in oat protection, leading to an increased focus on developing bacterial bio-inoculants as sustainable and effective biocontrol agents. (2) Methods: This study aimed to identify bacterial strains capable of suppressing wireworms (Agriotes lineatus) and Fusarium spp. in oats, while simultaneously promoting plant growth. Bacterial isolates were screened for key Plant Growth Promoting (PGP) and biocontrol traits, including IAA and siderophore production, phosphate solubilization, and the presence of toxin- and antibiotic-coding genes. (3) Results: The highest insecticidal effect against wireworms was recorded for Bacillus velezensis BHC 3.1 (63.33%), while this isolate also suppressed the growth of F. proliferatum for 59%, F. oxysporum for 65%, F. poae for 71%, and F. graminearum for 15%. The most effective Bacillus strains (with insecticidal and antifungal activity) were identified and tested in two pot experiments, where their ability to enhance plant growth in the presence of insects and fungi was evaluated under semi-controlled conditions. An increase in plant biomass, grain yield, and nitrogen content was observed in oat inoculated with B. velezensis BHC 3.1 and B. thuringiensis BHC 2.4. (4) Conclusions: These results demonstrate the strong potential of both strains as multifunctional bio-inoculants for enhancing oat growth and mitigating the adverse effects of wireworm damage and Fusarium infection. Full article

This study systematically evaluated insect resistance in transgenic poplar lines carrying three distinct Bacillus thuringiensis (Bt) gene vector architectures: a single-gene pb vector (Cry1Ac), a reverse-oriented double-gene n19 vector (Cry1Ac-Cry3A), and a forward-oriented double-gene n5 vector (Cry3A-Cry1Ac). The transgenic lines were accordingly designated as pb8/pb9, n19a/n19b, and DB7/DB16, respectively. Molecular analyses confirmed stable Bt gene integration, with the expression of Cry3A being consistently higher than that of Cry1Ac expression. Bioassays showed that dual-gene lines conferred broader insect resistance to pests than that of single-gene lines against both lepidopteran (Hyphantria cunea) and coleopteran (Plagiodera versicolora, Anoplophora glabripennis) pests. In contrast, the single-gene line pb9 exhibited specialized, high efficacy against H. cunea, achieving 100% mortality. Transcriptomic analysis of P. versicolora larvae fed the double-gene high-resistance n19a line and low-resistance DB16 line revealed multi-level molecular responses to Bt stress, including up-regulation of toxin-activating proteases, altered receptor expression, and suppression of growth-related genes. These changes were associated with significant developmental delay (8.33–20.83% reduction in the molting index). Our findings characterize the insect resistance and molecular profiles of the six transgenic poplar lines, as follows: multi-gene lines (n19a/n19b and DB7/DB16) confer broad-spectrum pest resistance, whereas single-gene lines (pb8/pb9) exhibit targeted efficacy. These results support the utility of these lines for pest-specific poplar breeding programs. Full article

This study characterizes two novel Bacillus phages, B450T and B450C, isolated from Bacillus thuringiensis VKM B-450 via mitomycin C induction, along with their endolysin, PlyC19. Both phages, siphoviruses with 41,205 bp genomes, lysed 38% of the tested Bacillus cereus sensu lato strains, with B450C showing enhanced lytic activity due to mutations in the repressor protein. PlyC19 lysed 56% of the strains tested, including Priestia flexa, demonstrating broader efficacy. Its Amidase_2 domain and dual SH3 cell wall-binding domains enable targeted peptidoglycan hydrolysis, with optimal activity at pH 9.0 and thermal stability up to 40 °C. We propose the taxonomic designation Bquatquinnuvirus eskimopiis for these phages, with B450T and B450C representing distinct strains, based on genomic divergence in the repressor protein’s HTH_Xre domain, consistent with their turbid and clear plaque morphologies, respectively. PlyC19′s broad specificity underscores its potential as an enzybiotic against multidrug-resistant Bacillus cereus group strains in food safety and medicine. Full article

Root-knot nematodes (RKNs), Meloidogyne spp., are the most economically important plant parasites with a worldwide distribution and a very wide host spectrum. The use of rhizobacteria for biocontrol has seen a marked increase in recent years, with particular emphasis on members of the Bacillaceae family in Brazil. This work reports on five years of experience using Bacillus-based products as nematicides, including both commercial and experimental formulations. Trials on cotton (200–300 mL/100 kg of seeds) against M. incognita race 3 produced inconsistent results: one trial achieved approximately 50% control, while another showed no significant effect. In soybean, Bacillus-based biological products (200–300 mL/100 kg) were able to reduce the final population of M. javanica and M. incognita by an average of approximately 30%, although in some cases, no effect was observed. The use of different doses of a product containing the RTI 545 strain (B. thuringiensis) resulted in control efficiencies of approximately 60–80% at a dose of 500 mL/100 kg, when applied as a seed treatment in soybean. This dose is too high to employ in field conditions. In tomato crop, strain S2538 of Priestia aryabhattai and strain RTI 545 (150 mL/100 kg) reduced the final population of M. incognita by 45–50%, confirming the results obtained in previous trials. Additionally, microscopic observations of Bacillus spp. against Meloidogyne spp. in soybean were made during histopathological studies. The bacteria were found to colonize root tissues early, including the cortex and vascular cylinder, probably producing chemical compounds and later disrupting giant cells. This microscopic observation suggests a mechanism aligned with induced resistance. Currently, biological products must be used in integrated management, such as resistant varieties, crop rotation, and other agronomic practices that aim to balance the physical, chemical and biological conditions of soils. Full article

Bradysia difformis is a notorious pest in mushroom production in China. Biological control using Bacillus thuringiensis (Bt) offers an environmentally friendly and effective strategy against this pest. Here, we show that the complete genome of strain JW-1 consists of one circular chromosome and seven circular plasmids. JW-1-Plasmid 4 comprises 127,921 bp with a GC content of 33.9%, and is predicted to contain 131 genes, including six insecticidal genes: cry4Aa, cry4Ba, cry10Ab, cry11Aa, cyt1Aa, and cyt2Ba. A 3542-bp fragment containing the cry4Aa gene was amplified from this strain. Phylogenetic analysis based on Cry4 toxin sequences showed that JW-1 Cry4 toxin belongs to the Cry4Aa toxin cluster. A Cry4Aa fusion protein was subsequently expressed in E. coli and purified using Ni-IDA affinity chromatography. A larval feeding assay showed that purified Cry4Aa was toxic to B. difformis larvae, with an LC₅₀ of 2.71 ng/mL. These results confirmed the identity and bioactivity of Cry4Aa from strain JW-1, offering a promising biological control agent against this major pest. Full article

In this study, titanium dioxide nanoparticles (TiO₂-NPs) were produced via green routes using blueberry extracts obtained with isopropanol (I-TiO₂-NPs) and methanol (M-TiO₂ NPs). HPLC-DAD confirmed phenolic/flavonoid profiles in the extracts, and spectroscopy/microscopy established anatase, polyhedral, mesoporous TiO₂-NPs with Eg ≈ 3.0 eV, hydrodynamic sizes ≈ 130–150 nm and negative ζ-potentials (−33 to −50 mV). The in vitro compatibility between TiO₂-NPs and the plant-growth-promoting microorganisms (PGPMs) Bacillus subtilis (Bs), Bacillus thuringiensis (B), and Trichoderma harzianum (T) sustained increased growth up to 150 µg/mL without visible negative effects. In greenhouse experimentation of Capsicum annuum exposed to low-moderate TiO₂-NPs, an increased leaf number and plant height were observed, while root length did not exceed the controls. I-TiO₂ at moderate concentrations, particularly with a single PGPM (B or T), promoted fresh and dry biomass accumulation. Biochemically, peroxidase rose sharply for M-TiO₂ at a low dose with consortium, whereas I-TiO₂ elicited broader antioxidant responses; total protein increased at higher doses for both formulations, and total chlorophyll was highest with I-TiO₂ (high dose with or without PGPMS). Collectively, the nano-bio system shows a formulation- and dose-dependent biphasic behavior: (I) I-TiO₂ enhances biomass and photosynthetic pigments; (II) M-TiO₂ favors strong POX induction under specific microorganism-dose combinations; and (III) single PGPM co-application with I-TiO₂-NPs or M-TiO₂ NPs outperforms consortia under our experimental conditions. Green synthesis thus provides surface functionalities that improve dispersion, microbial compatibility, and predictable physiological/biochemical outcomes for precision agriculture. Full article

4-Nonylphenol (4-NP), an important fine chemical precursor, can cause endocrine disruption, resist natural degradation, and bioconcentrate. Biodegradation is an effective and environmentally sustainable approach to its remediation. This study employed a mixture comprising equal proportions of six non-pathogenic Bacillus strains to screen and identify strains capable of degrading 4-NP, and degradation rate was measured using an ELISA kit, and metabolomic analyses and whole-genome sequencing were used to investigate the response of Bacillus to 4-NP and elucidate pathways involved in 4-NP degradation. The results revealed DY and LY strains isolated at 500 μg/L 4-NP. The DY strain was identified as Bacillus thuringiensis, and the LY strain was identified as Bacillus cereus via physiological, biochemical and PCR analyses. The degradation efficiency of a DY and LY strain mixture was 79.45% after 7 days. At 1000 μg/L 4-NP, only the LY strain was successfully isolated. Whole-genome sequencing indicated that the LY strain (accession number: CRA021210) shares the highest homology with B. cereus strain FORC-047. Notably, it showed a degradation rate of 86.34% after 7 days. Metabolomics analysis indicates that 4-NP affects the degradation pathways of aromatic compounds and benzoic acid in B. cereus. Combined with genome data, it is hypothesized that the 4-NP degradation pathway involves its conversion to p-hydroxybenzoic acid, catalyzed by monooxygenases, dioxygenases and oxidases. Subsequently, p-hydroxybenzoic acid degrades via one of two potential pathways: it produces phenol through decarboxylase or is oxidized to benzoic acid by monooxygenase. In summary, the DY and LY strains are capable of degrading 4-NP. Furthermore, we postulate potential 4-NP degradation pathways, providing insights for the remediation of 4-NP in aquatic environments. Full article

Background: Airborne transmission of bacteria, viruses, and fungal spores poses a major threat in enclosed settings, particularly nursing homes where residents are highly vulnerable. Compressive Heating Air Sterilization Technology (CHAST) applies compressive heating to inactivate microorganisms without reliance on filtration or chemicals. Methods: CHAST efficacy was evaluated in laboratory and deployed for a feasibility and performance validation study of air sterilization in a nursing home environment. Laboratory studies tested prototypes (300–5000 CFM; 220–247 °C) against aerosolized surrogates including Bacillus globigii (Bg), B. stearothermophilus (Bst), B. thuringiensis (Bt), Escherichia coli, and MS2 bacteriophage. Viral inactivation thresholds were further assessed by exposing MS2 to progressively lower treatment temperatures (64.5–143 °C). Feasibility and performance validation evaluation involved continuous operation of two CHAST units in a nursing home, with pre- and post-treatment air samples analyzed for bacterial and fungal burden. Results: Laboratory testing demonstrated consistent microbial inactivation, with most prototypes achieving > 6-log (99.9999%) reductions across bacterial spores, vegetative bacteria, and viruses. A 5000 CFM prototype achieved > 7-log (99.99999%) elimination of B. globigii. MS2 was completely inactivated at 240 °C, with modeling suggesting a threshold for total viral elimination near 170 °C. In the feasibility study, baseline sampling revealed bacterial (35 CFU/m³) and fungal (17 CFU/m³) contamination, dominated by Bacillus, Staphylococcus, Cladosporium, and Penicillium. After 72 h of CHAST operation, discharge air contained no detectable viable organisms, and fungal spore counts showed a 93% reduction relative to baseline return air. Units maintained stable operation (464 °F ± 2 °F; 329–335 CFM) throughout deployment. Conclusion: CHAST reproducibly and scalably inactivated airborne bacteria, viruses, and fungi under laboratory and feasibility field studies, supporting its potential as a chemical-free strategy to improve infection control and indoor air quality in healthcare facilities. Full article

Bare soil expansion in urban forests, driven by persistent high-intensity trampling, degrades both macro-scale natural resources and micro ecological conditions. Targeted interventions are therefore essential. In this study, trampled bare ground in forest parks and artificially cultivated Ophiopogon japonicus were used as experimental models We employed trampled bare ground in forest parks as well as artificially cultivated O. japonicus as experimental models. Five treatments were implemented: enclosure control (CK), ploughing (F), Bacillus thuringiensis NL-11 application (J), biochar addition (C), and co-application of B. thuringiensis NL-11 with biochar (JC). Our results indicate that, compared with CK, biochar treatments reduced soil bulk density by 30%, increased soil porosity by 89%, and improved water-holding capacity. The soil nitrate nitrogen content in the NL-11 treatment was increased by 113.8% compared with CK, while the co-application of NL-11 with biochar exhibited the highest sucrase and urease activities. Notably, the co-application of B. thuringiensis NL-11 with biochar exhibited the most pronounced effects on aboveground biomass, plant height, and root development, followed by the B. thuringiensis NL-11 treatment. Microbial β-diversity shifts under co-application of B. thuringiensis NL-11 with biochar treatment strongly correlated with soil enzyme activation and plant growth enhancement (Mantel test, p < 0.05). Correlation analysis confirmed that exogenous nutrient inputs significantly influenced enzyme activities, thereby promoting plant development. These results highlight the effectiveness of integrating microbial inoculation with biochar to restore trampled urban forest soils. Full article

This study aims to evaluate the insecticidal activity of four bacterial strains against M. cerasi under both laboratory and field conditions, in order to provide a more sustainable and eco-friendly alternative to chemical insecticides. Four environmentally friendly bacterial strains were evaluated for their potential as biocontrol agents: Brevibacillus brevis (FD-1), Bacillus cereus (FD-63), Bacillus thuringiensis subsp. kenyae (FDP-8), and Bacillus thuringiensis subsp. kurstaki (FDP-41). Experiments were conducted under both controlled laboratory and field conditions. Data showed that mortality rates ranged from 33.33% to 93.33% under controlled conditions and from 13.33% to 50% under field conditions over the 96 h period. B. thuringiensis subsp. kurstaki (FDP-41) and B. thuringiensis subsp. kenyae (FDP-8) were the most effective bacterial strains against the aphids in controlled conditions. The percentage of mortality related to these applications was 93.33% and 80% in 96 h under laboratory conditions. However, the effectiveness of B. thuringiensis subsp. kurstaki (FDP-41) was 50% at 96 h in the field. These findings suggest that B. thuringiensis subsp. kurstaki and B. thuringiensis subsp. kenyae hold significant potential as biological control agents against M. cerasi. Additionally, FDP-41 showed the lowest LT₅₀ value of 25.37 h in the laboratory and 86.40 h in the field. This indicates a much more rapid and potent effect on M. cerasi compared to other strains. As a result, it was concluded that these bacterial strains may be used successfully as biocontrol agents in the biological control of M. cerasi. Their successful use could reduce reliance on synthetic insecticides, thereby minimizing pesticide residues on crops and contributing to safer agricultural production and environmental sustainability. Full article

Dehydroshikimate (DHS) dehydratase (DSD) catalyzes the conversion of DHS into 3,4-dihydroxybenzoic acid (3,4-DHBA), a compound with promising applications across various industries. The DSD from Podospora anserina (DSD_Pa) was characterized and its catalytic properties were compared with those of previously investigated enzymes, AsbF (Bacillus thuringiensis), Qa-4 (Neurospora crassa), and QsuB (Corynebacterium glutamicum), both in vitro and in vivo using tube fermentation. Escherichia coli and C. glutamicum were used as platforms to construct model 3,4-DHBA producers. To increase DHS availability in both hosts, shikimate dehydrogenase AroE was inactivated, and the plasmid pVS7-aroG4, encoding 3-deoxy-D-arabinoheptulosonate 7-phosphate synthase (E. coli), was introduced. In E. coli, heterologous 3,4-DHBA synthesis was achieved through chromosomal integration of dsd genes. The fungal genes were codon-optimized for this bacterium. The same genes were cloned into the pVK9 vector and introduced into C. glutamicum, where 3,4-DHBA degradation was disrupted (ΔpcaHG). AsbF (k_cat ~ 1 s⁻¹) showed poor 3,4-DHBA accumulation in both hosts (1–1.5 g/L). The enzymes with better catalytic characteristics, QsuB (k_cat ~ 60 s⁻¹), DSD_Pa (k_cat ~ 125 s⁻¹), and Qa-4 (k_cat ~ 220 s⁻¹), provided 5 g/L 3,4-DHBA in E. coli and 3 g/L 3,4-DHBA in C. glutamicum, except for Qa-4. The low production (~1.5 g/L) observed for Qa-4 in C. glutamicum might be attributed to a non-optimal nucleotide sequence rich in codons rare for C. glutamicum. 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

This study investigated the therapeutic potential of Bacillus thuringiensis extracellular polysaccharide BPS-2 in dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) murine models. BPS-2 demonstrated significant efficacy in ameliorating UC-associated pathologies through three principal mechanisms: (1) attenuating histopathological damage while preserving colon epithelial integrity, (2) modulating immune marker expression patterns in colon tissues, and (3) restoring gut microbiota homeostasis. BPS-2 exhibited multi-faceted protective effects on the gut by mitigating oxidative stress responses and enhancing short-chain fatty acid biosynthesis, leading to an improved gut microbial community structure. Molecular docking analysis displayed strong binding affinity (ΔG = −7.8 kcal/mol) between the BPS-2U fragment and the Nuclear Factor κB (NF-κB) p50/p65 heterodimer, suggesting the potential disruption of NF-κB signaling pathways. Complementary molecular dynamics simulations revealed exceptional conformational stability in the p65-BPS-2U complex. These findings establish BPS-2 as a natural food additive that modulates the microbiota-barrier–inflammation axis through dietary intervention, offering a novel strategy to alleviate UC. Full article

Commercial production of the button mushroom, Agaricus bisporus (Lange) Imbach, is threatened by various pests and mycopathogenic microorganisms. Sciarid flies (Sciaridae) of the genus Lycoriella are considered as major pests, while major pathogens include the fungi Lecanicillium fungicola (Preuss), Zare and Gams, Hypomyces perniciosus Magnus, Cladobotryum spp., and Trichoderma aggressivum Samuels & W. Gams, the causative agents of dry bubble, wet bubble, cobweb, and green mold diseases, respectively. Control of mushroom pests and diseases has long relied on synthetic chemical pesticides. Pesticide resistance and various health and environmental issues have created a need for sustainable and eco-friendly alternatives to the use of synthetic chemical pesticides for mushroom pest and disease control. The concept of bioprotection, which involves using biological control agents (BCAs) and biopesticide products, offers a viable alternative. The entomopathogenic nematode Steinernema feltiae (Filipjev) and predatory mite Stratiolaelaps scimitus (Womersley) are the most important invertebrate BCAs, while the bacteria Bacillus thuringiensis Berliner, B. amyloliquefaciens, and B. velezensis stand out as the most widely used microbial BCAs/biopesticides. Azadirachtin- and pyrethrum-based products are the most important biochemical biopesticides. Bioprotection agents require inclusion in the integrated pest and disease management (IPDM) programs in order to achieve their full effectiveness. Full article