Integrating biocontrol efficacy and genomic potential of Bacillus velezensis BJ-1141: from broad-spectrum antagonism to tomato Fusarium wilt suppression.

Systematic Investigation of the Biocontrol Potential of Bacillus velezensis B05 against Soybean Root Rot Pathogen Fusarium spp.

Results indicate that B. velezensis B05 has potential as a multifunctional biocontrol agent for sustainable management of soybean root rot.

Identification and genomic insights into a plant probiotic Bacillus subtilis strain CF1 isolated from Protaetia brevitarsis frass.

BACKGROUND Plant probiotic bacteria offer a sustainable strategy for enhancing crop health and productivity. Insect frass has emerged as a unique niche for isolating beneficial microorganisms with novel traits. In this study, we isolated a bacterial strain CF1 from the frass of Protaetia brevitarsis and characterized its biocontrol and plant growth‑promoting potential against Fusarium crown rot of wheat. RESULTS Based on whole‑genome analysis, strain CF1 was identified as Bacillus subtilis. CF1 exhibited strong antagonistic activity against Fusarium graminearum and F. asiaticum, with inhibition rates of 34.67% and 33.95%, respectively. Its cell‑free filtrate showed dose‑dependent antifungal activity, reaching 43.70% inhibition against F. graminearum at a 5‑fold dilution. Phenotypic characterization confirmed its ability to produce IAA equivalents, siderophores, and solubilized phosphate. In pot experiments, CF1 effectively suppressed Fusarium crown rot, achieving a biocontrol efficacy of 43.47%, comparable to that of the well‑characterized strain B. velezensis SQR9 (44.07%). The inoculation of CF1 also promoted wheat growth, increasing plant height and plant biomass. Whole-genome sequencing revealed a 4.11 Mb genome encoding 4,277 genes, with 11 biosynthetic gene clusters for secondary metabolites, including bacillaene, fengycin, bacillibactin, surfactin, bacilysin, subtilomycin, subtilosin A, and pulcherriminic acid, along with three biosynthetic gene clusters of unknown function, suggesting potentially unique bioactivities. Genome mining further uncovered numerous genes associated with plant growth promotion, rhizosphere colonization, stress resistance, and volatile organic compound production. CONCLUSIONS B. subtilis CF1 is a promising microbial agent that combines strong antifungal activity, plant growth‑promoting traits, and a diverse set of genetic features that may confer unique properties, warranting further field validation for sustainable wheat production.

The Biocontrol Strain Bacillus subtilis Z-294 Alleviates Pepper Phytophthora capsici Disease Associated with Microbial Community Structure

The soil-borne oomycete pathogen Phytophthora capsici poses a serious threat to plant growth and results in substantial economic impact on the pepper industry. Therefore, the isolation of multifunctional biocontrol agents has become a major research priority. In this study, we isolated a biocontrol strain, Bacillus subtilis Z-294, which demonstrated strong inhibition of P. capsici in both plate and greenhouse experiments. This strain Z-294 exhibited broad-spectrum antagonistic activities as well as plant growth-promoting ability. Phylogenetic analysis based on core-genome and average nucleotide identity (ANI) further identified Z-294 as B. subtilis. Importantly, we found that the strain Z-294 alleviates the P. capsici disease through mechanisms associated with changes in the plant microbiome. Plants treated with Z-294 showed higher alpha-diversity. The application of B. subtilis Z-294 showed that the relative abundance of Alphaproteobacteria, Bacilli, Bacteroidia, Agaricomycetes, and Eurotiomycetes increased, while the relative abundance of Gammaproteobacteria and Sordariomycetes declined. Strain Z-294 holds great promise as a multifunctional biocontrol agent for the sustainable management of diseases and the enhancement of plant health, laying a solid foundation for its future agricultural applications.

Biological control of wheat root rot using rhizosphere isolates of Bacillus sp. and Trichoderma harzianum

Abstract Soil-borne fungal pathogens significantly limit wheat production in Kazakhstan, particularly Fusarium solani (Mart.) Sacc. 1881 and Bipolaris sorokiniana (Sacc.) Shoemaker, 1959, which cause root rot and early seedling decline. This study aimed to isolate and characterize indigenous rhizosphere antagonists with biocontrol potential against these pathogens and to evaluate their effects on wheat seed germination and early growth. More than 20 microbial isolates were obtained from the rhizosphere of winter wheat. Two active antagonistic strains were selected by dual-culture assays: Bacillus sp. NK1 and Trichoderma harzianum S1. Inhibition zones against F. solani reached 23.75 ± 0.67 mm for NK1 and 32.89 ± 0.67 mm for S1. Cell-free culture supernatants significantly reduced mycelial growth and completely inhibited spore germination. Molecular identification based on 16S rRNA sequencing and TEF-1α/RPB2 analysis confirmed the taxonomic affiliation of both isolates. Seed treatment significantly improved germination (88%), root length, shoot length, and seedling vigor compared with untreated controls (P < 0.01). In pot experiments, both strains promoted biomass accumulation and improved seedling growth under pathogen pressure, with the Bacillus strain showing the strongest growth-promoting effect. Combined inoculation did not result in a synergistic response. These findings highlight the potential of indigenous rhizosphere microorganisms as biological control agents for the management of wheat root rot pathogens.

Klebsiella sp. IR6, an endophytic rhizobacteria with potential as a plant growth-promoting agent for Jalapeño pepper (Capsicum annum L.) production.

IR6 exhibited the most notable agronomic performance, increasing seedling leaf area, fruit production, and fruit size under field conditions and demonstrating antagonistic activity against Fusarium oxysporum, confirming its potential as a biocontrol agent and PGPR.

Beneficial microbes isolated from the strawberry rhizosphere: development of growth-promoting and anthracnose-suppressive SynComs