Rice blast has long been regarded as the most important fungal disease of rice, a staple crop that feeds roughly half of the global population. The pathogen, Magnaporthe oryzae, infects leaves, stems, and panicles, producing the characteristic diamond-shaped lesions that can decimate yields under favorable humid conditions. Conventional control relies heavily on fungicide applications and the deployment of resistance genes in cultivars, but the fungus is notorious for its adaptive capacity, repeatedly overcoming single resistance genes in the field. This has driven scientists to look beyond the plant’s own genome for partners in defense, and the rhizosphere microbiome has emerged as a compelling frontier.

The rhizosphere—the narrow zone of soil influenced by root exudates—harbors some of the densest and most metabolically active microbial communities on Earth. Plant roots actively recruit and nourish specific microbes through the release of sugars, organic acids, and signaling compounds, and in return, certain bacteria can suppress pathogens, modulate plant hormones, or prime immune responses. Whether the rhizosphere communities of disease-resistant rice cultivars are fundamentally different from those of susceptible ones, and how those communities respond when the blast pathogen attacks, had remained incompletely resolved. The new greenhouse study set out to answer precisely those questions.

The research team, led by Tingting Yang and Di Han of the College of Plant Protection at Shenyang Agricultural University, together with colleagues at Liaoning Academy of Agricultural Sciences, grew blast-resistant and blast-susceptible rice cultivars under controlled greenhouse conditions and compared their rhizobacterial communities both before and after challenge with M. oryzae. Using 16S rDNA amplicon sequencing—a technique that catalogs bacterial taxa by amplifying a conserved genetic marker—they profiled the diversity and composition of the root-associated bacteria across the experimental treatments.

The sequencing results revealed statistically significant differences in rhizobacterial diversity and community composition between resistant and susceptible cultivars, confirming that the plant genotype leaves a measurable imprint on which bacteria congregate around its roots. More striking was what happened after pathogen infection: both cultivar types underwent distinct community shifts, but the direction and magnitude of those shifts differed between resistant and susceptible plants. The researchers detected differential microbial enrichment patterns across cultivars and disease states, indicating that the rhizosphere is not a passive bystander in the rice–blast interaction but a dynamic environment that responds to both plant genotype and pathogen pressure.

Among the taxa whose abundance changed, one genus stood out. Bacillus species were consistently enriched in the rhizospheres of healthy plants of resistant cultivars and, tellingly, in infected plants of susceptible cultivars. This dual pattern suggests that Bacillus populations may be associated with disease status in both contexts—either helping to maintain health in resistant plants or responding to infection in susceptible ones. Bacillus species are well known in agricultural microbiology for their ability to produce antimicrobial compounds, form protective biofilms on roots, and induce systemic resistance in host plants, which makes their enrichment patterns particularly noteworthy for biocontrol-oriented research.

To probe the structure of these microbial communities more deeply, the team applied network analysis, a computational approach that maps co-occurrence and potential ecological interactions among taxa. The analysis showed that cultivar resistance was associated with measurable differences in the architecture of the rhizosphere microbial community. In practical terms, resistant and susceptible rice varieties appear to host rhizobacterial networks with different organization, hinting that community structure—not merely the presence or absence of particular species—may contribute to the disease-suppressive potential of the root environment.

The study then moved from community profiling to the isolation and characterization of individual candidates. From the rhizosphere of healthy rice plants, the researchers recovered a bacterial strain designated Bacillus velezensis H2. The strain was characterized through a combination of morphological and biochemical tests, 16S rRNA gene sequencing, and single-nucleotide polymorphism (SNP) profiling to confirm its taxonomic identity. B. velezensis is a species that has attracted considerable attention in biocontrol research because many of its strains carry extensive biosynthetic machinery for antimicrobial secondary metabolites.

Whole-genome analysis using the antiSMASH platform—an algorithmic pipeline that scans bacterial genomes for biosynthetic gene clusters—identified multiple clusters in the H2 genome involved in secondary metabolite production. Among these were genes encoding nonribosomal peptide synthetases, the giant multifunctional enzymes responsible for assembling many of the lipopeptide antibiotics that Bacillus species are famous for, such as members of the surfactin, iturin, and fengycin families. The presence of these clusters provides a genomic rationale for the strain’s observed biological activity and suggests that H2 is genetically equipped to interfere with fungal pathogens in the root zone.

Laboratory assays confirmed that promise in practice. In vitro tests demonstrated that B. velezensis H2 exhibits strong antifungal activity against Magnaporthe oryzae, directly inhibiting the growth of the blast pathogen. While in vitro inhibition does not guarantee field-level disease suppression—greenhouse and field validation remain essential next steps—the combination of rhizosphere origin, rich biosynthetic potential, and demonstrable antagonism makes H2 a compelling candidate for development as a biocontrol agent. If it can colonize rice roots effectively and express its antifungal arsenal under realistic soil conditions, it could contribute to reducing the chemical fungicide burden in rice production systems.

The broader significance of the study lies in its integrated perspective. Rather than treating plant immunity and the microbiome as separate domains, the work links cultivar resistance, rhizobacterial community structure, pathogen-induced shifts, and a concrete antagonistic isolate into a single narrative. It reinforces a growing consensus in plant pathology: breeding for resistance and engineering beneficial microbiomes may be complementary strategies. Rice blast remains a moving target, but evidence that resistant cultivars cultivate distinct and potentially protective bacterial communities—and that strains like B. velezensis H2 can directly oppose the pathogen—offers a scientifically grounded path toward more sustainable, microbiome-aware crop protection.

Subject of Research: Rhizosphere bacterial community shifts in rice blast-resistant cultivars and the antagonistic activity of Bacillus velezensis against the rice blast pathogen

Article Title: Rhizosphere Bacterial Community Shifts in Rice Blast–Resistant Cultivars and the Antagonistic Activity of Bacillus velezensis

Article References: Yang, T., Han, D., Ding, A., Du, S., Wang, W., Huang, Y., & Ahsan, T. (2026). Rhizosphere Bacterial Community Shifts in Rice Blast–Resistant Cultivars and the Antagonistic Activity of Bacillus velezensis. Microbial Ecology. https://doi.org/10.1007/s00248-026-02858-4

Image Credits: AI Generated

DOI: 10.1007/s00248-026-02858-4

Keywords: rhizosphere microbiome, rice blast disease, Bacillus velezensis, Magnaporthe oryzae, biocontrol, 16S rDNA sequencing, secondary metabolites, nonribosomal peptide synthetases, antiSMASH, disease resistance, Rhizosphere, Bacterial

Researchers led by Nadarajan Viju of AMET University in Chennai, together with colleagues at Smykon Biotech and King Abdulaziz University, took a genomics-first approach to antifouling discovery. Rather than screening crude bacterial extracts, they mined the whole genomes of 30 marine bacteria belonging to the genera Pseudovibrio, Pseudomonas and Bacillus, all retrieved from the NCBI GenBank database. Using the open-source gene mining platform AntiSMASH, they mapped the biosynthetic gene clusters, or BGCs, the sets of genes that encode the enzymatic machinery for producing secondary metabolites. Each genome carried between 5 and 17 such clusters, yielding 278 clusters in total across the 30 organisms analysed.

The clusters fell into familiar categories: non-ribosomal peptide synthetases accounted for 28 percent, ribosomally synthesized and post-translationally modified peptides for 15 percent, terpenes for 11 percent, polyketide synthases for 9 percent, NRPS-PKS hybrids for 5 percent, siderophores for 6 percent, and a mixed bag of other clusters for the remaining 26 percent. Every species produced its own characteristic repertoire, with Pseudovibrio strains predicted to make compounds such as pyoverdin, rimosamide, prodigiosin and pseudaminic acid, Pseudomonas strains predicted to yield viscosin, pyoluteorin, mitomycin and ectoine among others, and Bacillus strains carrying genes for surfactin, bacillaene, difficidin, bacilysin and lichenysin, to name only a few.

But one compound stood out for its ubiquity. Fengycin, a cyclic lipopeptide encoded by a 22,502-base-pair non-ribosomal peptide synthetase cluster, was predicted in 26 of the 30 genomes, or 86.66 percent of all strains analysed. It was present in every one of the ten Pseudovibrio genomes, in 90 percent of the Pseudomonas genomes and in 70 percent of the Bacillus genomes. The authors argue that this broad distribution suggests fengycin acts as a conserved ecological trait, a chemical weapon that helps its producers compete for space and nutrients, colonize surfaces and survive in densely populated marine biofilms. In other words, the compound may represent a chemical defence strategy honed by evolution in exactly the kind of surface-bound microbial communities that kick off biofouling.

To test whether fengycin could plausibly block fouling at the molecular level, the team turned to structure-based virtual screening. They docked fengycin, obtained from the PubChem database, against six target proteins retrieved from the Protein Data Bank: the penicillin-binding protein of Acinetobacter baumannii and the lanosterol 14-alpha demethylase of Candida albicans as antimicrobial targets; a bacterial cell surface protein and the acyl-homoserine lactone synthase LasI, a quorum-sensing enzyme, as antibiofilm targets; and the barnacle cement protein and the mussel proximal thread matrix protein, which mediate larval adhesion, as antifouling targets. The docking was performed in PyRx using AutoDock Vina with an exhaustiveness value of eight, generating nine binding poses per ligand, with penicillin G, fluconazole and the commercial biocide DCOIT serving as reference ligands.

The results were striking. Fengycin achieved predicted binding affinities well ahead of every reference compound at every target. Against the penicillin-binding protein it scored minus 11.4 kilocalories per mole, compared with minus 6.7 for DCOIT. Against the fungal lanosterol demethylase it reached minus 13.3 kilocalories per mole, far beyond fluconazole’s minus 5.2. Its scores against the bacterial cell surface protein, the AHL synthase LasI, the barnacle cement protein and the mussel byssus protein were minus 15.3, minus 14.0, minus 14.2 and minus 13.1 kilocalories per mole respectively, while DCOIT managed only minus 7.3, minus 6.1, minus 5.5 and minus 5.61. Triplicate docking runs showed standard deviations below 0.5 kilocalories per mole, and redocking validation returned root-mean-square deviation values below the accepted threshold of 2.0 angstroms, confirming that the protocol reliably reproduced known binding orientations.

Visualization of the ligand-receptor complexes in PyMOL and BIOVIA Discovery Studio Visualizer explained the affinity. Fengycin formed extensive networks of polar and non-polar contacts: hydrogen bonds with residues such as GLU67 and LYS137 in the penicillin-binding protein, ARG381 in the fungal demethylase, SER374, SER520 and THR662 in the cell surface protein, HIS399 in LasI, GLN165 and GLU192 in the barnacle cement protein, and multiple residues in the mussel thread matrix protein, alongside dense hydrophobic contacts throughout each pocket. The researchers attribute this versatility to fengycin’s amphiphilic architecture, a rigid cyclic peptide ring fused to a hydrophobic beta-hydroxy fatty acid chain. The ring supplies multiple hydrogen bond donors and acceptors while limiting entropic penalties on binding, and the lipid tail drives van der Waals interactions within non-polar regions, allowing the molecule to engage diverse targets simultaneously.

The computational findings dovetail with decades of experimental literature on fengycin’s bioactivity. Studies have documented its antifungal action against Fusarium moniliforme, Botrytis cinerea and Magnaporthe grisea, its antibacterial effects against Xanthomonas and Pseudomonas pathogens, and, notably, its ability to disrupt quorum sensing in Staphylococcus aureus, a result reported in Nature in 2018 that aligns closely with the strong predicted interaction between fengycin and the quorum-sensing enzyme LasI in the present study. Because biofilms serve as settlement cues for many macrofoulers, a compound that interferes with both microbial adhesion and quorum sensing could in principle suppress fouling at multiple stages, from initial colonization through larval recruitment, in contrast to traditional biocides that simply poison organisms indiscriminately.

The authors are careful to frame the work as hypothesis-generating rather than conclusive. Molecular docking offers a static, simplified picture of binding that ignores protein flexibility, solvent effects, bioavailability, toxicity and cellular context, and docking scores are sensitive to ligand size, so fengycin’s large surface area may inflate its apparent advantage over small molecules like DCOIT. BGC predictions similarly depend on genome assembly quality and database annotations, and the predicted metabolites remain putative until chemically verified. The comparison with DCOIT, a biocide with documented environmental concerns of its own, must likewise be treated with caution given the compounds’ very different molecular dimensions and physicochemical properties.

Even so, the study sketches a compelling vision for the future of antifouling technology. Fengycin is biodegradable, reportedly low in toxicity, stable across ranges of temperature, pH and salinity, and potentially effective at low concentrations, making it an attractive starting point for eco-friendly coatings. More broadly, the work demonstrates that coupling genome mining with molecular docking can rapidly link biosynthetic potential to plausible biological function, providing a genomics-guided framework for prioritizing marine natural products before any laboratory assay is run. The next step is clear: in vitro and in vivo validation against real fouling organisms, together with toxicity testing, will determine whether this bacterial chemical weapon can be translated into the antifouling paints of a post-TBT world.

The study’s genome-guided strategy reflects a broader shift in natural products research. Traditional antifouling discovery relied on collecting marine organisms, extracting compounds and testing them laboriously in assays, a process that is slow, expensive and often non-specific. By contrast, mining publicly available genomes with tools like AntiSMASH allows researchers to survey the biosynthetic potential of dozens of organisms computationally before committing laboratory resources, prioritizing the most promising candidates for synthesis and testing.

Fengycin itself is well characterized biochemically. It belongs to a family of lipopeptides produced by Bacillus species alongside surfactin and iturin, and its cyclic peptide ring is assembled by large non-ribosomal peptide synthetase enzymes rather than by ribosomes, which permits the incorporation of unusual amino acids and contributes to its structural diversity. Its amphiphilic nature, combining a polar peptide head with a fatty acid tail, underlies both its surface activity and its ability to interact with biological membranes, properties that have made lipopeptides of interest as biocontrol agents in agriculture as well as in marine applications.

The choice of target proteins in the docking analysis also illustrates how antifouling can be attacked at distinct biological stages. Blocking quorum-sensing enzymes such as LasI could prevent bacteria from coordinating biofilm formation, while disrupting adhesion proteins used by barnacle larvae and mussels could stop macrofoulers from settling on a surface already colonized by microbes. A single compound active against both microbial and invertebrate targets would therefore offer multi-stage protection, a property conventional biocides achieve only through broad toxicity. The authors emphasize, however, that docking predictions must now be followed by laboratory and field validation before any practical coating can emerge.

Subject of Research: In silico prediction of the antifouling potential of the marine bacterial cyclic lipopeptide fengycin

Article Title: An in silico antifouling potential of fengycin, a cyclic lipopeptide produced by marine bacteria

Article References: Viju, N., Vijayaraghavan, P., Satheesh, S., & Jayaprakashvel, M. (2026). An in silico antifouling potential of fengycin, a cyclic lipopeptide produced by marine bacteria. Discover Oceans, 3(1), Article 51. https://doi.org/10.1007/s44289-026-00164-y

Image Credits: AI Generated

DOI: 10.1007/s44289-026-00164-y

Keywords: marine bacteria, fengycin, cyclic lipopeptide, biosynthetic gene clusters, antifouling, antibiofilm, molecular docking, AntiSMASH, biofouling, quorum sensing, natural products, silico