Burkholderia gladioli is a species of aerobic gram-negative rod-shaped bacteria that causes disease in both humans and plants. It can also live in symbiosis with plants and fungi and is found in soil, water, the rhizosphere, and in many animals. It was formerly known as Pseudomonas marginata.
Burkholderia gladioli synthesizes several inhibitory substances, among them gladiolin, bongkrek acid, enacyloxin, and toxoflavin. Those molecules might participate in antagonistic interactions with other microbes in the environment where they grow. One pathovariety, growing on coconut pulp, produces the respiratory toxin bongkrek acid which can cause fatal poisoning in humans.
Nomenclature
The members of the genus Burkholderia were formerly classified as Pseudomonas, but Burkholderia was one of the seven genera that arose when Pseudomonas was divided based on rRNA differences. Burkholderia gladioli is closely related to, and often mistaken for, a member of the Burkholderia cepacia complex. This includes ten closely related species, which are all plant pathogens.
Burkholderia gladioli is divided into several pathovars: B. gladioli pv. gladioli causes gladiolus rot B. g. pv. alliicola causes onion bulb rot B. g. pv.agaricicola causes soft rot in mushrooms B. g. pv. cocovenerans (sometimes written as cocovenenans) spoils coconut pulp
Etymology
Burkholderia - Named after the scientist (bacteriologist) that discovered an organism linked to disease in the skin of onions.
Gladioli - Small sword, of a lily; used within botany.<ref>{ { cite web | title = Species burkholderia gladioli | access-date = 22 February 2022 | url = https://lpsn.dsmz.de/species/burkholderia-gladioli | work = LPSN - List of Prokaryotic names with Standing in Nomenclature | publisher = DSMZ-German Collection of Microorganisms and Cell Cultures GmbH }}</ref>
IdentificationBurkholderia are motile, Gram negative rods that may be straight or slightly curved. They are aerobic, catalase positive, urease positive, nonsporeformers. They grow on MacConkey agar, but do not ferment the lactose. Burkholderia gladioli can be distinguished from the other Burkholderia because it is oxidase negative B. gladioli is indole negative, nitrate negative, and lysine decarboxylation negative.
On the molecular level, PCR can be used to distinguish between the different Burkholderia 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.
The primers used for the amplification of the 16S to 23S region in the B. gladioli genome 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 300bp.
All members of the genus Burkholderia 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 of Burkholderia 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.
The B. 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.
Characteristics
All species of the genus Burkholderia - except for B. 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 degree Celsius. The Genus Burkholderia (including B. 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.
Pathology
In plantsB. gladioli has been identified as a plant pathogen in onions, gladiolus, iris, and together with Burkholderia glumae affect the rice. It was originally described to have caused rot of gladiolus corms. The bulbs can become water soaked and decay.