Rhorizonten

Rhorizonten is a genus of soil-dwelling, filamentous bacteria within the phylum Actinobacteria. It was described from the rhizosphere of temperate grasses and cereals and is characterized by delicate, branched filaments that resemble fungal hyphae. Cells are Gram-positive with a thick cell wall, and colonies are often dry and chalky in appearance. Growth is aerobic, with an optimum around 28°C and near-neutral pH.

Metabolism includes breakdown of plant-derived polymers; several strains secrete enzymes such as cellulases and hemicellulases and can solubilize phosphate. Some isolates produce siderophores and small amounts of plant-growth-promoting compounds such as indole-3-acetic acid, suggesting potential legume and cereal crop interactions.

Ecology: In the rhizosphere, Rhorizonten adheres to root surfaces and forms biofilms, contributing to nutrient mineralization and soil structure. Its interactions with plants range from neutral to beneficial, and ongoing studies are assessing its role in plant health and resistance to pathogens.

Taxonomy and discovery: Rhorizonten was proposed in 2023 after isolation and genome sequencing of strains from multiple temperate soils. The genus name combines roots-focused terminology with a taxonomic suffix used for filamentous soil bacteria. It is presently not assigned to a detailed family within Actinobacteria, and molecular analyses support a distinct lineage with several species described and more under investigation.

Related topics include the rhizosphere and Actinobacteria.