Search Results (14)

Temperature is a key environmental factor that influences mosquito phenotypic traits and the effectiveness of vector control strategies. Bacillus velezensis (Bv) has shown promise as a microbial biocontrol agent due to its insecticidal properties; however, its effects on mosquitoes under different environmental conditions are still unexplored. This study investigated the effects of Bv (strain WHk23) exposure on the life history traits of Culex quinquefasciatus at two temperature conditions (20 °C and 30 °C), focusing on development, longevity, and reproductive fitness. Results showed that temperature significantly affected mosquito development and longevity, with faster development and shorter adult longevity observed at 30 °C compared to 20 °C. Exposure to Bv further accelerated larval development and reduced adult emergence, with the effects being more pronounced at 30 °C than at 20 °C. Exposure to Bv reduced adult longevity regardless of temperature. In addition, Bv-exposed females had larger body sizes but lower fecundity and fertility, suggesting that Bv exposure may cause physiological stress that disrupts reproductive processes. These findings highlight the importance of considering environmental factors in mosquito control programs while reinforcing the efficacy of Bv as a sustainable biocontrol agent under a variety of environmental conditions. Full article

In 2022, an outbreak of fungal rot disease affected luffa crops in Shanghai and Zhejiang Province. Infected plants exhibited symptoms including yellowing, chlorosis, wilting, and water-soaked occurred on leaves and fruits. Dark brown, concave lesions developed, often accompanied by white or pale pink mold under moist conditions. Fourteen pathogen strains, morphologically resembling Fusarium species, were isolated. Molecular analysis confirmed Fusarium incarnatum as the causative agent. Pathogenicity tests on luffa plants fulfilled Koch’s postulates, with inoculated plants displaying the same symptoms. Re-isolation of the fungus from the inoculated plants confirmed its role in the disease. To our knowledge, this is the first report of F. incarnatum causing leaf spot and fruit rot on luffa in China. Moreover, the soil bacterial strain Bacillus velezensis BV171 displayed strong inhibition of F. incarnatum mycelia growth and promoted the growth of sponge gourd plants. These findings lay the foundation for the development of diagnostic tools, disease management strategies, and the breeding of resistant luffa varieties. Full article

Plant diseases, particularly root rot caused by Phytophthora species, pose a significant threat to plants. In this study, we investigated the antagonistic activity of a Bacillus velezensis strain (Bv-SM1) against Phytophthora palmivora isolates, NKST002 and CP002, which cause root rot in durian. In vitro assays using dual-plate, pour-plate, and volatile organic compounds demonstrated a strong inhibition of Phytophthora mycelial growth by Bv-SM1. Phylogenomic analysis based on 1000 genes confirmed that Bv-SM1 is most closely related to B. velezensis. Genome analysis revealed the presence of key genes that contribute to biocontrol activity, including genes encoding cell wall-degrading enzymes (β-glucanase and cellulase) and siderophore production. Additionally, 13 biosynthetic gene clusters are responsible for the production of various antimicrobial compounds, such as fengycin, bacillaene, macrolactin, and bacilysin. These findings are the first to demonstrate the potential of Bv-SM1 as a promising biocontrol agent for managing Phytophthora-induced root rot in durian, with potential applications in other crops. Full article

Camellia oleifera (C. oleifera) is one of the four main, woody, edible oil tree species in the world, while C. oleifera anthracnose is mainly caused by the fungus Colletotrichum fructicola (C. fructicola), which severely affects the yield of C. oleifera and the quality of tea oil. Bacillus velezensis (B. velezensis) CSUFT-BV4 is an antagonistic endophytic bacterium isolated from healthy C. oleifera leaves. This study aimed to investigate the biocontrol potential of strain CSUFT-BV4 against C. oleifera anthracnose and its possible functional mechanism, and to determine its growth-promoting characteristics in host plants. In vitro, CSUFT-BV4 was shown to have efficient biofilm formation ability, as well as significant functions in the synthesis of metabolic substances and the secretion of probiotic substances. In addition, the CSUFT-BV4 fermentation broth also presented efficient antagonistic activities against five major C. oleifera anthracnose pathogens, including C. fructicola, C. gloeosporioides, C. siamense, C. camelliae, and C. kahawae, and the inhibition rate was up to 73.2%. In vivo, it demonstrated that the growth of C. oleifera treated with CSUFT-BV4 fermentation broth was increased in terms of stem width, plant height, and maximum leaf area, while the activities of various defense enzymes, e.g., superoxide dismutase (SOD), phenylalanine aminotransferase (PAL), and polyphenol oxidase (PPO), were effectively increased. The remarkable antagonistic activities against C. oleifera anthracnose, the growth-promoting characteristics, and the induction of host defense responses indicate that endophytic bacterium CSUFT-BV4 can be effectively used in the biological control of C. oleifera anthracnose in the future, which will have a positive impact on the development of the C. oleifera industry. Full article

Bacterial spore-forming Bacillaceae species, including Bacillus subtilis and Heyndrickxia coagulans, are increasingly utilized for probiotic dietary supplementation. Bacillus velezensis is a Bacillus species that is frequently used as a direct-fed microbial in animal feed but less so as a probiotic for humans. The objective of this study was to characterize the suitability of the Bacillus velezensis strain BV379 for probiotic applications by (1) in silico screening for both adverse genetic elements and putatively beneficial traits, (2) in vitro evaluation of interactions with human intestinal epithelial cells, and (3) in vitro characterization of BV379 spore viability at various temperatures, pH, and in the presence of bile salt. In silico screening of the BV379 genome revealed few genes encoding Bacillaceae-associated toxins, virulence factors, and enzymes involved in the production of toxins. While BV379 encodes five antimicrobial resistance genes, minimum inhibitory concentration assays determined that BV379 is susceptible to all eight clinically relevant antibiotics tested. Preliminary cell culture experiments showed that BV379 lysates did not adversely impact human intestinal epithelial cell viability and monolayer permeability. It was also determined that BV379 spores can easily tolerate the harsh pH, bile salt, and microaerobic conditions typical of the GI tract. Altogether, the results presented herein support the safety and potential of Bacillus velezensis strain BV379 for use as an oral probiotic. Full article

Fusarium oxysporum, a primary soil-borne fungus that affects rice seedlings globally, is responsible for rice seedling blight (RSB), which reduces seedling quality and survival rates. The synthetic fungicides used to treat this disease negatively affect human health and the environment. A biocontrol bacterial isolate, Bacillus velezensis Bv S3, isolated from the rice rhizosphere, showed a strong antagonistic effect on RSB-causing F. oxysporum. The ratio of the longest to the shortest radius of F. oxysporum following Bv S3 inoculation was 2.52 (cm/cm) in a plate standoff experiment. This was different from the other biocontrol strains. Bv S3 exhibits a wide spectrum of antifungal activity against various pathogenic fungi that cause RSB. When 10% Bv S3 liquid culture filtrate was applied, it dramatically reduced F. oxysporum spore germination and mycelial growth, with inhibition rates of 66.7%, and 45.7%, respectively, and caused hyphal malformations. Furthermore, the Bv S3 suspension (1 × 10⁸ CFU/mL) reduced RSB by 65.5% and 76.5% in pot experiments, effectively promoted the growth of rice seedlings, and improved the activities of neutral phosphatase, urease, invertase, and catalase in rice rhizosphere soil. The active substances produced by Bv S3 were sensitive to temperature and ultraviolet irradiation, and the antifungal effect significantly increased after 90 min of exposure, with antifungal effect observed at pH 7. Bv. S3 effectively reduced the incidence of RSB and showed potential as a biocontrol agent. Full article

Bacillus velezensis (B. velezensis) is a cellulose-degrading strain that has the potential as an additive in fermented feed. B. velezensis BV-10 was isolated and screened from the termite gut. We sequenced the whole genome of this new source of B. velezensis to reveal its potential for use in cellulose degradation. Whole-genome sequencing of B. velezensis BV-10 showed that it has a circular chromosome of 3929792 bp containing 3873 coding genes with a GC content of 45.51% and many genes related to cellulose, hemicellulose, and lignin degradation. King grass silage was inoculated with B. velezensis BV-10 and mixed with other feed additives to assess the effect of B. velezensis BV-10 on the fermentation quality of silage. Six treatment groups were established: the control, B. velezensis BV-10, molasses, cellulase, B. velezensis BV-10 plus molasses, and B. velezensis BV-10 plus cellulase groups. After 30 days of silage-fermentation testing, B. velezensis BV-10 was found to rapidly reduce the silage pH value and significantly reduce the acid-detergent fiber (ADF) content (p < 0.05). The addition of B. velezensis BV-10 plus molasses and cellulase in fermented feed significantly reduced the silage neutral-detergent fiber and ADF content and promoted organic-acid accumulation (p < 0.05). The above results demonstrate that B. velezensis BV-10 promotes the fermentation quality of silage and that this effect is greater when other silage-fermentation additives are included. In conclusion, genes involved in cellulose degradation in B. velezensis BV-10 were identified by whole-genome sequencing and further experiments explored the effects of B. velezensis BV-10 and different feed additives on the fermentation quality of king grass silage, revealing the potential of Bacillus velezensis as a new silage additive. Full article

To evaluate the potential of a bacterial strain as a fungal disease control agent and plant growth promoter, its inhibitory effects on phytopathogens such as Bipolaris sorokiniana, Botrytis cinerea, Colletotrichum capsici, Fusarium graminearum, F. oxysporum, Neocosmospora rubicola, Rhizoctonia solani, and Verticillium dahliae were investigated. The results showed that the inhibitory rates in dual-culture and sterile filtrate assays against these eight phytopathogens ranged from 57% to 83% and from 36% to 92%. The strain was identified as Bacillus velezensis based on morphological and physiological characterization as well as phylogenetic analyses of 16S rRNA and the gyrase subunit A protein (gyrA) regions. The results demonstrated that B. velezensis was able to produce fungal cell-wall-degrading enzymes, namely, protease, cellulase, and β-1,3-glucanase, and the growth-promotion substances indole-3-acetic acid (IAA) and siderophore. Furthermore, B. velezensis BV01 had significant control effects on wheat root rot and pepper Fusarium wilt in a greenhouse. Potted growth-promotion experiments displayed that BV01 significantly increased the height, stem diameter, and aboveground fresh and dry weights of wheat and pepper. The results imply that B. velezensis BV01, a broad-spectrum biocontrol bacterium, is worth further investigation regarding its practical applications in agriculture. Full article

Biological control of plant diseases has gained attraction for controlling various bacterial diseases at a field trial stage. An isolated endophytic bacterium, Bacillus velezensis 25 (Bv-25), from Citrus species had strong antagonistic activity against Xanthomonas citri subsp. citri (Xcc), which causes citrus canker disease. When Bv-25 was incubated in Landy broth or yeast nutrient broth (YNB), the ethyl acetate extract of Landy broth exhibited higher levels of antagonistic activity against Xcc compared to that of YNB. Therefore, the antimicrobial compounds in the two ethyl acetate extracts were detected by high performance liquid chromatography–mass spectrometry. This comparison revealed an increase in production of several antimicrobial compounds, including difficidin, surfactin, fengycin, and Iturin-A or bacillomycin-D by incubation in Landy broth. RNA sequencing for the Bv-25 grown in Landy broth were performed, and the differential expressions were detected for the genes encoding the enzymes for the synthesis of antimicrobial compounds, such as bacilysin, plipastatin or fengycin, surfactin, and mycosubtilin. Combination of metabolomics analysis and RNA sequencing strongly suggests that several antagonistic compounds, especially bacilysin produced by B. velezensis, exhibit an antagonistic effect against Xcc. Full article

To effectively treat the environmental pollution caused by discarded crab shell, chitin was extracted from discarded crab shells by a combined chemical and biological process. The chitin extraction waste liquid was used to culture bacteria to synthesize biogenic vaterite (BV). The mineral morphology and physico-chemical properties of BV were characterized, and the loading characteristics and adsorption mechanism of doxorubicin hydrochloride (DOX) were investigated. The results showed that chitin could be extracted from crab shells using a combination of chemical and biological methods, and the purity of the extracted chitin reached 89.79%; cultivation of Bacillus velezensis using extraction waste liquid can induce the synthesis of stable BV; the maximum drug loading of BV towards DOX was 447.58 mg/g and its adsorption behavior fitted the Freundlich model. The findings provide new information for the processing utilization of waste crab shells and the development of novel drug carriers. Full article

The present study demonstrates the biocontrol potential of a plant growth-promoting bacterial strain using three different approaches: (i) an in vitro evaluation of antagonistic activity against important phytopathogenic fungi; (ii) an evaluation under greenhouse conditions with strawberry plants to assess the control of gray mold; and (iii) an in silico whole genome sequence mining to assign genetic features such as gene clusters or isolated genes to the strain activity. The in vitro assay showed that the B.BV10 strain presented antagonistic activity, inhibiting the mycelial growth in all the phytopathogenic fungi evaluated. The application of the Bacillus velezensis strain B.BV10 under greenhouse conditions reduced the presence of Botrytis cinerea and increased the mean fruit biomass. The genome of B.BV10 was estimated at 3,917,533 bp, with a GC content of 46.6% and 4088 coding DNA sequences, and was identified as B. velezensis. Biosynthetic gene clusters related to the synthesis of the molecules with antifungal activity were found in its genome. Genes related to the regulation/formation of biofilms, motility, and the important properties for the rhizospheric colonization were also found in the genome. The current study offers a comprehensive understanding of the genomic architecture and control activity of phytopathogenic fungi by the B. velezensis strain B.BV10 that may substantiate the industrialization of this strain in the future. Full article

Many putative sRNAs have been characterized using bioinformatic analysis and high-throughput sequencing in Gram-positive Bacillus strains, but there are only a few functional studies on the sRNAs involved in the spore formation developmental process. In particular, there is no sRNA confirmed experimentally to regulate the late stages of sporulation. Bvs196 is an sRNA with a length of 294 nucleotides that is abundantly expressed in the stationary phase of several media and independently transcribed in Bacillus velezensis strain PEBA20, as validated by RNA-seq and Northern blot,. It is also confirmed, by qRT-PCR, that Bvs196 is transcribed abundantly throughout the intermediate and late stages of sporulation. Using the gfpmut3a gene transcriptional reporter demonstrates that Bvs196 is expressed specifically in the forespore during sporulation and controlled by σ^F and σ^G (mainly by σ^G). This was observed by fluorescence microscopy and multi-function microplate reader. Further evolutionary conservation analysis found that Bvs196 is widely present in Bacillus with a strongly conserved and stable secondary structure. Resistance phenotypic assays of spores formed from the Bvs196 deletion mutant, the overexpressed Bvs196 mutant, and the wild-type strain revealed that the absence of Bvs196 led to reduced heat and UV resistance and enhanced formaldehyde resistance. We determined, by MST analysis, that Bvs196 can directly interact with spo0A and sspN-tlp mRNAs in vitro, and that short incomplete complementary paired bases affect the binding affinity of Bvs196 to target mRNAs. Our results suggest that Bvs196 is a novel sporulation-specific sRNA of B. velezensis, 294 nt in length, independently transcribed under the control of σ^F and σ^G in the forespore during sporulation, and that it affects spore resistance, and is able to directly interact with spo0A and sspN-tlp mRNAs. The remarkable conservation and impressive expression level of Bvs196 imply that it acts as an important conservative regulator, presumably by interacting with many other unknown targets in the forespore, and therefore contributing to spore properties. This work provides new clues for further understanding of the spore formation regulatory network. Full article

Amylases account for about 30% of the global market of industrial enzymes, and the current amylases cannot fully meet industrial needs. This study aimed to identify a high α-amylase producing bacterium WangLB, to clone its α-amylase coding gene, and to characterize the α-amylase. Results showed that WangLB belonged to Bacillus velezensis whose α-amylase gene was 1980 bp coding 659 amino acids designated as BvAmylase. BvAmylase was a hydrophilic stable protein with a signal peptide and a theoretical pI of 5.49. The relative molecular weight of BvAmylase was 72.35 kDa, and was verified by SDS-PAGE. Its modeled structure displayed that it was a monomer composed of three domains. Its optimum temperature and pH were 70 °C and pH 6.0, respectively. It also showed high activity in a wide range of temperatures (40–75 °C) and a relatively narrow pH (5.0–7.0). It was a Ca²⁺-independent enzyme, whose α-amylase activity was increased by Co²⁺, Tween 20, and Triton X-100, and severely decreased by SDS. The K_m and the V_max of BvAmylase were 3.43 ± 0.53 and 434.19 ± 28.57 U/mg. In conclusion, the α-amylase producing bacterium WangLB was identified, and one of its α-amylases was characterized, which will be a candidate enzyme for industrial applications. Full article

Plant growth-promoting rhizobacteria (PGPR) are increasingly used in crops worldwide. While selected PGPR strains can reproducibly promote plant growth under controlled greenhouse conditions, their efficacy in the field is often more variable. Our overall aim was to determine if pectin or orange peel (OP) amendments to Bacillus velezensis (Bv) PGPR strains could increase soybean growth and nodulation by Bradyrhizobium japonicum in greenhouse and field experiments to reduce variability. The treatments included untreated soybean seeds planted in field soil that contained Bv PGPR strains and non-inoculated controls with and without 0.1% (w/v) pectin or (1 or 10 mg/200 μL) orange peel (OP) amendment. In greenhouse and field tests, 35 and 55 days after planting (DAP), the plants were removed from pots, washed, and analyzed for treatment effects. In greenhouse trials, the rhizobial inoculant was not added with Bv strains and pectin or OP amendment, but in the field trial, a commercial B. japonicum inoculant was used with Bv strains and pectin amendment. In the greenhouse tests, soybean seeds inoculated with Bv AP193 and pectin had significantly increased soybean shoot length, dry weight, and nodulation by indigenous Bradyrhizobium compared to AP193 without pectin. In the field trial, pectin with Bv AP193 significantly increased the shoot length, dry weight, and nodulation of a commercial Bradyrhizobium japonicum compared to Bv AP193 without pectin. In greenhouse tests, OP amendment with AP193 at 10 mg significantly increased the dry weight of shoots and roots compared to AP193 without OP amendment. The results demonstrate that pectin-rich amendments can enhance Bv-mediated soybean growth promotion and nodulation by indigenous and inoculated B. japonicum. Full article