The rhizosphere is the narrow region of soil or substrate that is directly influenced by root secretions and associated soil microorganisms known as the root microbiome. Soil pores in the rhizosphere can contain many bacteria and other microorganisms that feed on sloughed-off plant cells, termed rhizodeposition, and the proteins and sugars released by roots, termed root exudates. This symbiosis leads to more complex interactions, influencing plant growth and competition for resources. Much of the nutrient cycling and disease suppression by antibiotics required by plants, occurs immediately adjacent to roots due to root exudates and metabolic products of symbiotic and pathogenic communities of microorganisms. The rhizosphere also provides space to produce allelochemicals to control neighbours and relatives.
The rhizoplane refers to the root surface including its associated soil particles which closely interact with each other. The plant-soil feedback loop and other physical factors occurring at the plant-root soil interface are important selective pressures in communities and growth in the rhizosphere and rhizoplane.
The term "rhizosphere" was used first in 1904 by the German plant physiologist Lorenz Hiltner to describe how plant roots interface with surrounding soil. The prefix rhiza- comes from the Greek, and means "root". Hiltner postulated the rhizosphere was a region surrounding the plant roots, and populated with microorganisms under some degree of control by chemicals released from the plant roots.
Plant roots may exude 20-40% of the sugars and organic acids - photosynthetically fixed carbon. Plant root exudates, such as organic acids, change the chemical structure and the biological communities of the rhizosphere in comparison with the bulk soil or parent soil. Concentrations of organic acids and saccharides affect the ability of the biological communities to shuttle phosphorus, nitrogen, potassium and water to the root cap, and the total availability of iron to the plant and to its neighbors.
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Pseudomonas fluorescens is a common Gram-negative, rod-shaped bacterium. It belongs to the Pseudomonas genus; 16S rRNA analysis as well as phylogenomic analysis has placed P. fluorescens in the P. fluorescens group within the genus, to which it lends its name. Pseudomonas fluorescens has multiple flagella. It has an extremely versatile metabolism, and can be found in the soil and in water. It is an obligate aerobe, but certain strains are capable of using nitrate instead of oxygen as a final electron acceptor during cellular respiration.
The rhizosphere is the narrow region of soil or substrate that is directly influenced by root secretions and associated soil microorganisms known as the root microbiome. Soil pores in the rhizosphere can contain many bacteria and other microorganisms that feed on sloughed-off plant cells, termed rhizodeposition, and the proteins and sugars released by roots, termed root exudates. This symbiosis leads to more complex interactions, influencing plant growth and competition for resources.
Bacteria (bækˈtɪəriə; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria play a vital role in many stages of the nutrient cycle by recycling nutrients and the fixation of nitrogen from the atmosphere.