| Burkholderia gladioli | |
|---|---|
Scientific classification | |
| Domain: | Bacteria |
| Kingdom: | Pseudomonadati |
| Phylum: | Pseudomonadota |
| Class: | Betaproteobacteria |
| Order: | Burkholderiales |
| Family: | Burkholderiaceae |
| Genus: | Burkholderia |
| Species: | B. gladioli |
| Binomial name | |
| Burkholderia gladioli (Zopf 1885) Yabuuchiet al. 1993 | |
| Type strain | |
| ATCC 10248 CCUG 1782 CFBP 2427 CIP 105410 DSM 4285 HAMBI 2157 ICMP 3950 JCM 9311 LMG 2216 NBRC 13700 NCCB 38018 NCPPB 1891 NCTC 12378 NRRL B-793 | |
| Synonyms | |
Pseudomonas gladioliSeverini 1913 | |
Burkholderia gladioli is a species ofaerobicgram-negativerod-shapedbacteria[1] that causes disease in both humans and plants. It can also live insymbiosis with plants and fungi[2] and is found in soil, water, the rhizosphere, and in themicrobiome of many animals. It was formerly known asPseudomonas marginata.
Burkholderia gladioli synthesizes several inhibitory substances, among themgladiolin,bongkrek acid,enacyloxin,arsinothricin, andtoxoflavin.[3][4][5][6] Those molecules might participate in antagonistic interactions with other microbes in the environment where they grow.[7] Onepathovariety, growing oncoconut pulp, produces themitochondria disruptingtoxinbongkrek acid which can cause fatal poisoning in humans.
The members of the genusBurkholderia were formerly classified asPseudomonas, butBurkholderia was one of the seven genera that arose whenPseudomonas was divided based onrRNA differences.[8]Burkholderia gladioli is closely related to, and often mistaken for, a member of theBurkholderia cepacia complex. This includes ten closely related species, which are all plant pathogens.
Burkholderia gladioli is divided into severalpathovars:[9]
The genus Burkholderia is named after scientistWalter H. Burkholder, who discovered an organism linked to disease in the skin of onions.[11]
Gladioli refers to the plant genusGladiolus, which is grown ornamentally around the world, and where the fungus can cause rot.[12] The flower is named gladiolus "little sword" from gladius "sword", due to the shape of the leaves.
Burkholderia are motile, Gram negative rods that may be straight or slightly curved. They are aerobic, catalase positive, urease positive, nonsporeformers. They grow onMacConkey agar, but do not ferment the lactose.Burkholderia gladioli can be distinguished from the otherBurkholderia because it is oxidase negative[1]B. gladioli is indole negative, nitrate negative, and lysine decarboxylation negative.[13]
On the molecular level, PCR can be used to distinguish between the differentBurkholderia species. According to Furuya et al., the ribosomal RNA gene is highly conserved and universally distributed in all living things, and therefore difference in the DNA sequences between 16S and 23S rRNA genes can be used to differentiate between the species.[14]
Theprimers used for the amplification of the 16S to 23S region in theB. gladioligenome are as follows: GLA-f 5'-(CGAGCTAATACCGCGAAA)-3' and GLA-r 5'-(AGACTCGAGTCAACTGA)-3' Using these primers for PCR results in an amplicon of approximately 300 bp.[14]
All members of the genusBurkholderia have multireplicon genomes. They are able to keep "essential housekeeping" genes on the largest chromosome. This largest chromosome has a single origin of replication. The gene order and GC composition is conserved as well. Members ofBurkholderia are able to capture and retain foreign DNA. The foreign DNA can be detected by looking for atypical GC context areas. One of the first foreign DNA segments detected this way encoded for virulence.[1]
TheB. gladioli genome consists of 6 major holders of genetic information: two chromosomes and four plasmids. The entire genome amounts to 9.06 Mb (Million Bases) with 89.64% of the genome – including non-coding regions – on the two chromosomes.[15]
All species of the genusBurkholderia – except forB. mallei – display a form of motility when suspended within liquid. Being Gram-Negative,B. gladioli will not be stained by the Crystal Violet – Iodine complex, but will be counter stained red by Safranin. The optimal growth temperature on a Nutrient Agar plate is 30–35 °C. The GenusBurkholderia (includingB. gladioli) shows a remarkable amount of diversity of metabolism of carbohydrates and other organic compounds.B. gladioli is able to more acids than is typical for its genus.
| Test type | Test | Characteristics |
|---|---|---|
| Colony characters | Size | |
| Type | Round | |
| Color | Pale Yellow | |
| Shape | ||
| Morphological characters | Shape | Slightly Bent Rods |
| Physiological characters | Motility | + |
| Growth at 6.5% NaCl | ||
| Biochemical characters | Gram staining | - |
| Oxidase | d | |
| Catalase | ||
| Oxidative-Fermentative | ||
| Motility | + | |
| Methyl Red | ||
| Voges-Proskauer | ||
| Indole | ||
| H2S Production | ||
| Urease | ||
| Nitrate reductase | ||
| β-Galactosidase | ||
| Hydrolysis of | Gelatin | + |
| Starch | - | |
| Casein | ||
| Utilization of | Glycerol | |
| Galactose | + | |
| D-Glucose | + | |
| D-Fructose | + | |
| D-Mannose | + | |
| Mannitol | + |
B. gladioli has been identified as a plant pathogen inonions,gladiolus,iris, and together withBurkholderia glumae affect therice. It was originally described to have caused rot of gladiolus corms. The bulbs can become water soaked and decay.
Some other common symptoms of infected plants can be seen in the leaves. The leaves contain brown lesions, and they may become watersoaked. Other symptoms are the wilting and/or rot of roots, stems, and petals.B. gladioli has also been identified as the causative agent in leaf-sheath browning in gladiolas and onions. Sometimes, the whole plant decays.[2]
One widespread plant disease caused byB. gladioli is called scab. It can be seen on gladiolus corms as water-soaked brown spots, outlined in yellow. Eventually, they can become hollow and surrounded by scabs. If the scabs fall off, they leave behind cavities or lesions.[16]
B. gladioli in humans is anopportunistic pathogen that is an important agent forhospital-associated infections. It has recently appeared as a severe pathogen in patients withcystic fibrosis, causing severe pulmonary infections.[2] Though it is still a fairly uncommon pathogen, its presence is associated with a poorprognosis. It has also colonized the respiratory tracts of patients with granulomatous disease. In lungtransplant patients, infection can be fatal as patients have developedbacteremia and sterile wound infections as a result.[17]
Tempe bongkrèk, a variation oftempeh prepared with coconut, is susceptible toB. gladioli pathovar.cocovenenans contamination. Contaminatedtempe bongkrèk can contain lethal amounts of highly toxicbongkrek acid andtoxoflavin.[citation needed]
B. gladioli was implicated in the2015 deaths of 75 people, inMozambique, who had consumed a home-brewed beer made from corn flour that was contaminated with the bacterium.[18]
A 3-year long study period of neonatal and nosocomial sepsis yielded 14 patients (out of approximately 3784) with isolated positive colonies ofB. gladioli from blood cultures. During this time, symptoms of the sepsis caused by theB. gladioli infection included congenital leukemia, pneumonia, and several other respiratory malfunctions. A mortality rate of 7% is linked to theB. gladioli infections present during the time of study.[19]
The primary system responsible for the disease caused byBurkholderia gladioli is atype two secretion pathway.[20] An experiment performed by Chowdhury and Heinemann revealed that six strains ofB. gladioli that were avirulent still contained the capacity for mushroom growth inhibition without having the characteristics of mushroom tissue degradation. This led the two to believe the genetic factors that cause the microbe to have the ability to generate the cavity disease within an organism can be separated from the factors that inhibit mycelium growth within said mushrooms.[20]
Gladiolin, a novelmacrolide produced byB. gladioli strain BCC0238, was found to have promisingantibiotic activity againstMycobacterium tuberculosis in a 2017 study; the compound, which inhibitsRNA polymerase, is structurally and functionally similar toetnangien, a macrolide synthesised by the bacteriumSorangium cellulosum which has also demonstrated potency againstMycobacterium, but is more unstable than gladiolin. In the study, gladiolin was found to have low mammaliancytotoxicity and good activity againstM. tuberculosis isolates, suggesting that it may be a useful starting point in developing new antibiotics to treat multidrug resistanttuberculosis infections.[21]