Jul 2026· Journal of Advanced Research· 0 citations· 43 references
Medicine
TL;DR
Sperbactin is identified as a highly promising, narrow-spectrum biocontrol candidate for the targeted management of rice bacterial diseases, and offers a sustainable and eco-friendly alternative to chemical pesticides, supporting the advancement of sustainable agriculture.
Abstract
INTRODUCTION
Lysobacter enzymogenes OH11 is widely recognized for its potent antagonistic activity against diverse plant pathogens, including bacteria, fungi, and oomycetes. However, the specific compound responsible for its activity against Gram-negative bacteria had remained unidentified.
Objectives
This study aimed to identify the specific anti-Gram-negative bacterial compound produced by OH11 and to evaluate its potential as a biocontrol agent.
Methods
Methods included MS/NMR for structure elucidation, antagonism/greenhouse/UV-vis assays for function evaluation, medium/precursor optimization for yield enhancement, and gene knockout/enzyme assays for biosynthetic pathway identification.
Results
The isolated compound was identified as a spermidine-containing siderophore, designated Sperbactin. Through broad-spectrum screening, Sperbactin was discovered to exert highly targeted antagonistic effects specifically against rice pathogens (Xanthomonas oryzae). In greenhouse trials, Sperbactin demonstrated remarkable efficacy against rice bacterial blight, achieving a disease control efficacy of 85.31%, which is comparable to conventional chemical agents. The Sperbactin-Fe(III) complex was found to have a 1:1 M ratio and displayed a high affinity for ferric iron, with an association constant (Ka) of 2.16 × 1029 M-1. Furthermore, the fermentation yield of Sperbactin was increased by 3.29-fold, reaching 290.46 ± 6.22 mg/L. spbB and spbD were identified as essential genes for Sperbactin biosynthesis.
Conclusion
This study identifies Sperbactin as a highly promising, narrow-spectrum biocontrol candidate for the targeted management of rice bacterial diseases. Its development offers a sustainable and eco-friendly alternative to chemical pesticides, supporting the advancement of sustainable agriculture.
Bacterial wilt caused by Ralstonia solanacearum is a destructive soil-borne disease affecting numerous crops worldwide. Although synthetic pesticides and antibiotics are commonly used for disease management, their excessive application has raised concerns regarding environmental pollution, human health risks, and the emergence of antibiotic-resistant pathogens. As a sustainable alternative, rhizosphere microorganisms have gained attention as potential biocontrol agents. In our previous study, strain JCK-8401 exhibited strong antibacterial activity against R. solanacearum. In the present study, its biocontrol potential was comprehensively characterized through analyses of physiological and biochemical traits, antagonistic activity against phytopathogens, induction of salicylic acid (SA)-mediated defense responses using Arabidopsis thaliana PR1::GUS reporter line, and in vivo suppression of tomato bacterial wilt. Based on 16S rRNA sequence analysis, JCK-8401 was identified as Streptomyces virginiae. The strain utilized diverse carbon sources and produced hydrolytic enzymes and indole-3-acetic acid. Furthermore, it exhibited antibacterial activity against various phytopathogenic bacteria and oomycetes, though it lacked antifungal activity. Both cell suspension and culture filtrate of the strain induced GUS expression, indicating activation of the SA-mediated defense pathway. In vivo assay demonstrated that seed treatment with JCK-8401 achieved 96.40% control efficacy against tomato bacterial wilt. Additionally, pretreatment with diluted culture filtrates (250-, 500-, and 1000-fold) effectively suppressed disease incidence regardless of the application method, strongly suggesting the activation of induced systemic resistance. Overall, Streptomyces virginiae JCK-8401 is a highly promising, multifunctional biocontrol agent for managing soil-borne diseases through a synergistic combination of antibiosis, bioinoculation, and the induction of host plant defense responses.
L. T. Nguyen, A. Park, H. Le et al.· Plant Pathology Journal· 0 citations
Endophytic bacteria represent a promising, sustainable alternative to synthetic agrochemicals for plant disease management by actively antagonizing phytopathogens and stimulating host immune responses. Despite its traditional use as an antimicrobial remedy, Wedelia chinensis remains underexplored as a source of beneficial endophytes. This study aimed to isolate and screen endophytic bacteria from W. chinensis for their antifungal activity against Fusarium oxysporum. Among 14 endophytic isolates, Bacillus subtilis LS1-5 showed the strongest antifungal activity by dual culture assay. Its cell-free culture filtrate effectively inhibited fungal spore germination by 91.3% at a 20% concentration. Crucially, B. subtilis LS1-5 produced several extracellular enzymes, including cellulase, amylase, chitinase, pectinase, gelatinase, lipase, and protease. Furthermore, the LS1-5 strain exhibited a broad array of plant growth-promoting and environmental resilience traits. Notably, it synthesized indole-3-acetic acid (IAA) at 2.11 ± 0.27 µg/mL in an LB medium without L-tryptophan, significantly promoted a 34.19% increase in root elongation, and demonstrated remarkable tolerance to extreme conditions, including high salinity (11% NaCl) and broad pH levels ranging from 6 to 12. Additionally, volatile organic compounds (VOCs) emitted by LS1-5 significantly inhibited the severe bacterial pathogens Xanthomonas oryzae (45.83%) and Xanthomonas citri (47.99%). These findings highlight B. subtilis LS1-5 as a highly effective candidate for biological control and sustainable agricultural applications.
D. Nguyen, Dong Tang Vien, Ngoc-Minh Truong Bui et al.· IOP Conference Series: Earth...· 0 citations
The integrated experimental and in silico approach highlights soil-derived actinomycetes as versatile and sustainable bioresources with significant pharmaceutical and biotechnological potential, emphasizing their role in combating antimicrobial resistance and enabling the rational development of novel therapeutic and industrial products.
Meghana Arivilu, Shaziya Sulthana, Vijay Ramesh et al.· Journal of Pure and Applied...· 0 citations
An engineered strain is constructed by overexpressing the transcriptional regulator OmpR, which significantly enhanced nematicidal activity against Meloidogyne incognita J2s and increased secondary metabolite production, providing a promising engineered strain and lead compounds for developing novel microbial nematicides.
Yue-Yu Ma, Jin-Fang Li, Jian Wu et al.· Journal of Agricultural and...· 0 citations