Functional analysis of phenazine biosynthesis genes in Burkholderia spp.

Authors: HENDRY, SAMUEL - University Of Southern Mississippi; STEINKE, STEPHAN - Technical University Of Braunschweig; WITTSTEIN, KATHRIN - Helmholtz Centre For Environmental Research; ADEWUNMI, YETUNDE - University Of Southern Mississippi; SAHUKHAL, GYAN - University Of Southern Mississippi; ELASRI, MOHAMED - University Of Southern Mississippi; Thomashow, Linda; Weller, David; MAVRODI, OLGA - University Of Southern Mississippi; BLANKENFELDT, WULF - Helmholtz Centre For Environmental Research; MAVRODI, DMITRI - University Of Southern Mississippi

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2021
Publication Date: 5/11/2021
Citation: Hendry, S., Steinke, S., Wittstein, K., Adewunmi, Y., Sahukhal, G., Elasri, M., Thomashow, L.S., Weller, D.M., Mavrodi, O., Blankenfeldt, W., Mavrodi, D. 2021. Functional analysis of phenazine biosynthesis genes in Burkholderia spp.. Applied and Environmental Microbiology. 87. Article e02348-20. https://doi.org/10.1128/AEM.02348-20.
DOI: https://doi.org/10.1128/AEM.02348-20

Interpretive Summary: Some Burkholderia bacteria produce colored antibiotics called phenazines that contribute to the survival and competitiveness of producers of such compounds, but knowledge of their synthesis and roles in Burkholderia is lacking. Our research focused on phenazine biosynthesis pathways of Burkholderia lata and related species of worldwide origin. Most of these bacterial strains were members of the B. cepacia (Bcc) complex, but the capacity to synthesize phenazines was also present among isolates of the B. pseudomallei group and the plant pathogen B. glumae. Our findings suggest that the phenazine biosynthetic pathway in Burkholderia has a complex evolutionary history that likely involved horizontal gene transfer among several distantly related groups of organisms. We analyzed mutants of B. lata, which helped to identify phenazines produced by species of the Bcc group and to characterize the role of some of the biosynthesis genes in these bacteria. Our functional studies failed to link phenazine production with the capacity of Burkholderia to carry out certain deleterious activities, but at the same time revealed a link between the presence and amount of phenazines and the dynamics of biofilm growth in the laboratory.

Technical Abstract: Burkholderia encompass a group of ubiquitous Gram-negative bacteria that include numerous saprophytes as well as species that cause infections in animals, immunocompromised patients, and plants. Some species of Burkholderia produce colored, redox-active secondary metabolites called phenazines (Phz). Phenazines contribute to competitiveness, biofilm formation, and virulence in the opportunistic pathogen Pseudomonas aeruginosa, but knowledge of their diversity, biosynthesis, and biological functions in Burkholderia is lacking. To bridge this gap, we focused on phenazine pathways of B. lata and related species of worldwide origin. Most Phz+ strains were members of the B. cepacia (Bcc) complex, but the capacity to synthesize phenazines was also present among isolates of the B. pseudomallei clade and the plant pathogen B. glumae. Our findings suggest that the phenazine biosynthetic pathway in Burkholderia has a complex evolutionary history that likely involved horizontal gene transfers among several distantly related groups of organisms. We analyzed isogenic mutants and plasmid deletion derivatives of B. lata, which helped to identify phenazines produced by species of the ubiquitous Bcc group and to characterize the role of phenazine-modifying genes in the synthesis of 4,9-dihydroxyphenazine-1,6-dicarboxylic acid dimethylester. Our functional studies failed to link the production of phenazines with the capacity of Burkholderia to kill fruit flies and rot onions, but at the same time revealed a link between the presence and amount of phenazines and the dynamics of biofilm growth in flow cell and static experimental systems.