Utilization of Xenosiderophores by Burkholderia Cenocepacia

Abstract

urkholderia cenocepacia is a member of the Burkholderia cepacia complex (Bcc). B. cepacia is an aerobic organism, a gram-negative, non-fermenting bacillus. B. cepacia was initially identified by Walter Burkholder in the 1940s when he was investigating the "sour skin" condition of onion bulbs. Their massive genomes, composed of many replicons, endow them with remarkable metabolic enhancements and genotypic and phenotypic versatility. For instance, they naturally possess the ability to resist a variety of antibiotics. Many Bcc species are known to be highly useful in their native environment. In particular, certain Bcc strains can protect plants from fungal diseases. In contrast to its beneficial aspect, as in agriculture, B. cenocepacia is responsible for one of the deadly infections in people with cystic fibrosis (CF). The ability of some Bcc species to spread among CF patients and start epidemic outbreaks has been demonstrated. Compared to infections with Pseudomonas aeruginosa, Bcc species usually infect immunocompromised people rather than those with normal immune systems. One of the B. cenocepacia virulence factors is the production of siderophores. These molecules have a high affinity for iron which is essential for bacterial growth. B. cenocepacia strains can produce four different siderophores, with ornibactin and pyochelin being the most commonly produced ones. B. cenocepacia possesses outer membrane receptors that enable it to utilize siderophores for iron acquisition. In this study, previous work was done for a knockout mutation of the genes responsible for producing the two siderophores, ornibactin and pyochelin. That facilitates the aim of this research to test the ability of B. cenocepacia to take in siderophores produced by other microorganisms (xenosiderophores) by using suitable low-iron growth conditions with commercially obtainable siderophores. The results indicate that B. cenocepacia is able to utilize some of the tested xenosiderophores as an iron source for its growth.