Genomics-guided isolation and identification of active secondary metabolites of Bacillus velezensis BA-26

Unlocking the growth-promoting and antagonistic power: A comprehensive whole genome study on Bacillus velezensis strains

Bacillus species are extensively documented as plant growth-promoting rhizobacteria, contributing significantly to the enhancement of soil fertility, nutrient recycling, and the control of phytopathogens. Utilizing them as biocontrol agents represents an environmentally friendly strategy, particularly within the rhizospheric community. This study presents the comprehensive genome sequences of three B. velezensis strains (LGMB12, LGMB319, and LGMB426) which were previously isolated from root samples of maize (Zea mays L.), along with a type strain FZB42. The research assesses the capability of the three strains for antagonizing fungi, specifically Fusarium graminearum, Fusarium verticillioides, Colletotrichum graminicola, and Stenocarpella sp. In paired cultures involving maize fungi, treatments containing bacteria B. velezensis exhibited statistically significant differences compared to both negative and positive treatments in terms of antagonism. Furthermore, genome mining techniques were employed to explore their inherent antagonistic potential. The assembly revealed that strains LGMB12, LGMB319, LGMB426, and FZB42 exhibit genome sizes of 4,187,541 bp, 4,244,954 bp, 3,976,537 bp, and 3,990,518 respectively. Their respective G + C content stands at 46.42 %, 46.50 %, 46.51 %, and 46.38 %. Moreover, the genomes present multiple gene clusters responsible for the synthesis of secondary metabolites and carbohydrate-active enzymes (CAZymes). These clusters highlight a diverse array of antibacterial and antifungal properties, complemented by numerous plant growth-promoting genes. These results highlight the potential of B. velezensis LGMB12, LGMB319, and LGMB426 strains as biocontrol and plant growth promotion agents, being promising candidates for further studies in agricultural production, including field trials.

Genome sequence of the plant-growth-promoting bacterium Bacillus velezensis EU07

Many Gram-positive spore-forming rhizobacteria of the genus Bacillus show potential as biocontrol biopesticides that promise improved sustainability and ecological safety in agriculture. Here, we present a draft-quality genome sequence for Bacillus velezensis EU07, which shows growth-promotion in tomato plants and biocontrol against Fusarium head blight. We found that the genome of EU07 is almost identical to that of the commercially used strain QST713, but identified 46 single-nucleotide differences that distinguish these strains from each other. The availability of this genome sequence will facilitate future efforts to unravel the genetic and molecular basis for EU07's beneficial properties.

A novel biocontrol agent Bacillus velezensis K01 for management of gray mold caused by Botrytis cinerea

Gray mold is a destructive plant disease caused by a fungal pathogen Botrytis cinerea. The use of plant growth promoting rhizobacteria (PGPR) has proven to be a promising method to control this disease. Bacillus velezensis K01 was isolated from the rhizosphere of planting tomatoes. Strain K01 has a range of roles, including the ability to solubilize phytate phosphorus, stimulate resistant response, and produce indoleacetic acid (IAA), protease, cellulase, and antimicrobial substances. Strain K01 was found to inhibit 12 phytopathogenic fungi and 5 phytopathogenic bacteria. Specially, strain K01 demonstrated a biocontrol efficiency of over 78% against gray mold caused by B. cinerea on the leaves and fruits of tomato and pepper. Additionally, K01 was found to promote the growth of maize seedlings. Further genomic analysis revealed that K01 belongs to B. velezensis, which is consistent with phylogenetic analysis, average nucleotide polymorphism (ANI), and digital DNA-DNA hybridization (dDDH). The genome of strain K01 had a size of 3,927,799 bp and deduced 3866 predicted genes, with an average guanine-cytosine (GC) content of 46.5%. Based on the analyses of genomic secondary metabolites, over 18.4% of the genome was annotated to 12 gene clusters related to antimicrobial metabolite synthesis. Additionally, genome annotation and comparative genomics identified several genes associated with plant growth promotion and environmental adaption. These findings suggest that B. velezensis K01 has the potential to serve as a new biocontrol agent for management of gray mold on tomato and pepper.

Characterization of a Novel Bacillus glycinifermentans Strain MGMM1 Based on Full Genome Analysis and Phenotypic Properties for Biotechnological Applications

Bacillus species have gained much attention based on their phenotypic characteristics and their genetic architecture as biological control agents and plant growth-promotor with bioremediation potential. In this study, we analyzed the whole genome of a novel strain, Bacillus glycinifermentans MGMM1, isolated from the rhizosphere of a weed plant (Senna occidentalis) and assayed its phenotypic characteristics, as well as antifungal and biocontrol ability. The whole genome analysis of MGMM1 identified 4259 putative coding sequences, with an encoding density of 95.75% attributed to biological functions, including genes involved in stimulating plant growth, such as acetolactate synthase, alsS, and genes involved in the resistance to heavy metal antimony (arsB and arsC). AntiSMASH revealed the presence of biosynthetic gene clusters plipastatin, fengycin, laterocidine, geobacillin II, lichenysin, butirosin A and schizokinen. Tests in vitro confirmed that MGMM1 exhibited antifungal activity against Fusarium oxysporum f.sp. radicis-lycopersici (Forl) ZUM2407, Alternaria alternata, F. graminearum and F. spp. and produce protease, lipase amylase and cellulase. Bacillus glycinifermentans MGMM1 demonstrated proteolytic (4.82 ± 1.04 U/mL), amylolytic (0.84 ± 0.05 U/mL) and cellulosic (0.35 ± 0.02 U/mL) enzymatic activities, as well as indole-3-acetic acid production (48.96 ± 1.43 μg/mL). Moreover, the probiotic strain MGMM1 demonstrated a high biocontrol potential of inhibiting (up to 51.45 ± 8.08%) the development of tomato disease caused by Forl ZUM2407. These results suggest that B. glycinifermentans MGMM1 has significant potential as a biocontrol, plant growth-promoting agent in agriculture.