An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; however, most of the endophyte/plant relationships are not well understood. Some endophytes may enhance host growth, nutrient acquisition and improve the plant's ability to tolerate abiotic stresses, such as drought and decrease biotic stresses by enhancing plant resistance to insects, pathogens and herbivores. Although endophytic bacteria and fungi are frequently studied, endophytic archaea are increasingly being considered for their role in plant growth promotion as part of the core microbiome of a plant.
The Burkholderiaceae are a family of bacteria included in the order Burkholderiales. It includes some pathogenic species, such as Burkholderia mallei (glanders) and Burkholderia pseudomallei (melioidosis). This family was found to be enriched in scale-eating pupfish guts, even after being fed a common laboratory diet, suggesting it may aid in scale-digestion.
Paenibacillus is a genus of facultative anaerobic, endospore-forming bacteria, originally included within the genus Bacillus and then reclassified as a separate genus in 1993. Bacteria belonging to this genus have been detected in a variety of environments, such as: soil, water, rhizosphere, vegetable matter, forage and insect larvae, as well as clinical samples. The name reflects: Latin paene means almost, so the paenibacilli are literally "almost bacilli". The genus includes P. larvae, which causes American foulbrood in honeybees, P. polymyxa, which is capable of fixing nitrogen, so is used in agriculture and horticulture, the Paenibacillus sp. JDR-2 which is a rich source of chemical agents for biotechnology applications, and pattern-forming strains such as P. vortex and P. dendritiformis discovered in the early 90s, which develop complex colonies with intricate architectures as shown in the pictures:
Paenibacillus polymyxa, also known as Bacillus polymyxa, is a Gram-positive bacterium capable of fixing nitrogen. It is found in soil, plant tissues, marine sediments and hot springs. It may have a role in forest ecosystems and potential future applications as a biofertilizer and biocontrol agent in agriculture.
Pseudomonas lini is a fluorescent, Gram-negative, rod-shaped bacterium isolated from rhizospheric soil in France. The type strain is CFBP 5737, though there are also eight other strains known. This bacterium has also been isolated from endophytic tissues of lodgepole pine trees growing on gravel mining sites with potential to perform biological nitrogen fixation and plant growth promotion.
Pseudomonas migulae is a fluorescent, Gram-negative, rod-shaped bacterium isolated from natural mineral waters in France. This bacterium has also been isolated from endophytic tissues of lodgepole pine trees growing on gravel mining sites with potential to perform biological nitrogen fixation and plant growth promotion. Based on 16S rRNA analysis, P. migulae has been placed in the P. fluorescens group.
Paraburkholderia phymatum is a species of bacteria that is capable of symbiotic nitrogen fixation with the legumes Machaerium lunatum and Mimosa pudica. Recently, the genome was sequenced. It consists of two chromosomes, a megaplasmid, and a plasmid hosting the symbiotic functions.
Paraburkholderia phytofirmans is a species of bacteria. They have been reported to colonize endophytic tissues of hybrid spruce and lodgepole pine with a strong potential to perform biological nitrogen fixation and plant growth promotion.
Paraburkholderia sacchari is a species of bacteria in the phylum Pseudomonadota. It was isolated in the 1990s from sugarcane crop soil, and later identified as a new bacterial species, originally named as Burkholderia sacchari. Paraburkholderia sacchari was found to be capable of creating and accumulating polyhydroxyalkanoates (PHA) by incorporating different monomers. This strain was subject of a number of genetic and bioproccess engineering studies conducted worldwide aiming to establish PHA production from different substrates, especially using agro-industrial byproducts.
Caballeronia sordidicola is a species of bacteria which has been reported to perform biological nitrogen fixation and promote plant growth
Paraburkholderia tuberum is a species of bacteria that is capable of symbiotic nitrogen fixation with the legume Aspalathus carnosa.
Paraburkholderia heleia is a gram-negative, nitrogen-fixing, aerobic, non-spore-forming, rod-shaped bacterium from the genus Paraburkholderia and the family Burkholderiaceae which was isolated from the Chinese water chestnut Eleocharis dulcis in acid sulfate soil areas of Vietnam. Colonies of Burkholderia heleia are pale yellow.
Caballeronia humi is a Gram-negative, aerobic, non-motile bacterium from the genus Burkholderia and the family Burkholderiaceae which was isolated from peat soil in Russia.
Caballeronia telluris is a bacterium from the genus Caballeronia and the family Burkholderiaceae.
Caballeronia terrestris is a bacterium from the genus Burkholderia and family Burkholderiaceae.
Caballeronia udeis is a bacterium from the genus Caballeronia and family Burkholderiaceae which has been reported to perform biological nitrogen fixation and promote plant growth
Paraburkholderia monticola is a Gram-negative, short-rod-shaped and aerobic bacterium from the genus Paraburkholderia which has been isolated from soil from the Gwanak Mountain in Korea.
Paraburkholderia rhizosphaerae is a bacterium from the genus of Paraburkholderia which has been isolated from rhizosphere soil in Daejeon in Korea.
Caballeronia is a genus of bacteria from the family of Burkholderiaceae which has been reported to perform biological nitrogen fixation and promote plant growth
Paraburkholderia elongata is a Gram-negative bacterium belonging to the genus Paraburkholderia. The type strain is P. elongata 5NT, which was isolated from the Arnot research forest, near Van Etten, New York, using agar medium supplemented with soil-extracted, solubilized organic matter. The same isolation effort and methodology led to the isolation of P. solitsugae 1NT. P. elongata was named after its tendency to form elongated, filamentous cells when grown in concentrated growth media. Phosphate concentration was found to regulate the conditional filamentation of P. elongata, resulting from the accumulation of intracellular polyphosphate.
