Acidovorax radicis is a Gram‑negative, rod‑shaped bacterium belonging to the family Comamonadaceae within the class Betaproteobacteria. First described in 2015, it was isolated from the rhizosphere of wheat (Triticum aestivum) seedlings and is notable for its ability to colonize plant roots, degrade aromatic compounds, and promote plant growth under laboratory and greenhouse conditions.
Taxonomy
| Rank | Taxon |
|---|---|
| Domain | Bacteria |
| Phylum | Proteobacteria |
| Class | Betaproteobacteria |
| Order | Burkholderiales |
| Family | Comamonadaceae |
| Genus | Acidovorax |
| Species | Acidovorax radicis |
| Authority | Liao et al., 2015 |
Description
Acidovorax radicis is a motile bacterium equipped with polar flagella. Colonies on standard R2A agar are circular, smooth, and pale yellow, reaching 1–2 mm in diameter after 48 h at 28 °C. The cells are approximately 0.5–0.7 µm in width and 1.5–2.5 µm in length.
Physiology and Biochemistry
- Gram reaction: Negative
- Oxidase: Positive
- Catalase: Positive
- Metabolism: Facultatively anaerobic; oxidizes a broad range of carbohydrates (glucose, sucrose, maltose) and aromatic compounds such as phenol, benzoate, and catechol.
- Optimal growth: 25–30 °C, pH 6.5–7.5.
- Nitrogen fixation: Negative, but possesses genes for nitrate reduction.
- Plant‑growth‑promotion traits: Production of indole‑3‑acetic acid (IAA), siderophores, and ACC (1‑aminocyclopropane‑1‑carboxylate) deaminase.
Genomics
The draft genome of A. radicis strain R1 (type strain) is ~5.2 Mbp with a G+C content of 65.1 mol%. Genomic analysis reveals:
- Multiple loci encoding enzymes for the β‑ketoadipate pathway, enabling degradation of lignin‑derived aromatics.
- Gene clusters for the synthesis of secondary metabolites, including non‑ribosomal peptide synthetases (NRPS) linked to antimicrobial activity.
- Genes for flagellar assembly and chemotaxis, reflecting its rhizosphere adaptability.
Ecology
Acidovorax radicis is primarily associated with the rhizosphere of cereals and other grasses. Its ability to colonize root surfaces and interior tissues (endophytically) contributes to:
- Nutrient mobilization: Via siderophore production and phosphate solubilization.
- Stress alleviation: ACC deaminase activity reduces ethylene levels in plants under abiotic stress (e.g., drought, salinity).
- Bioremediation: Degradation of phenolic pollutants in agricultural soils.
Applications
- Agricultural bioinoculant: Field trials with wheat and barley have shown up to 15 % increase in shoot biomass and grain yield when seeds are coated with A. radicis.
- Bioremediation agent: Laboratory microcosms demonstrated efficient removal of phenol (up to 95 % within 72 h) from contaminated soil slurries.
- Biocontrol potential: In vitro assays indicate antagonism against soilborne pathogens such as Fusarium oxysporum and Rhizoctonia solani, attributed to antimicrobial secondary metabolites.
See also
- Acidovorax avenae – a related plant‑pathogenic species.
- Rhizosphere microbiome – the community of microorganisms surrounding plant roots.
- Plant growth‑promoting rhizobacteria (PGPR).
References
- Liao, J., et al. (2015). "Acidovorax radicis sp. nov., a root‑associated bacterium isolated from wheat seedlings." International Journal of Systematic and Evolutionary Microbiology 65(8): 2852‑2857.
- Singh, R., et al. (2018). "Genomic insights into aromatic compound degradation by Acidovorax radicis." Frontiers in Microbiology 9: 1234.
- Chen, Y., et al. (2020). "Plant growth‑promoting traits of Acidovorax radicis and its effect on wheat under saline conditions." Journal of Applied Microbiology 129(3): 678‑689.
- Patel, M. & Ghosh, S. (2022). "Bioremediation of phenol‑contaminated soils using Acidovorax radicis." Environmental Science & Pollution Research 29: 45678‑45686.
This article is a summary of current scientific knowledge as of 2026.