Common Duckweed (Lemna minor) Is a Versatile High-Throughput Infection Model For the Burkholderia cepacia Complex and Other Pathogenic Bacteria

Abstract

Members of the Burkholderia cepacia complex (Bcc) have emerged in recent decades as problematic pulmonary pathogens of cystic fibrosis (CF) patients, with severe infections progressing to acute necrotizing pneumonia and sepsis. This study presents evidence that Lemna minor (Common duckweed) is useful as a plant model for the Bcc infectious process, and has potential as a model system for bacterial pathogenesis in general. To investigate the relationship between Bcc virulence in duckweed and Galleria mellonella (Greater wax moth) larvae, a previously established Bcc infection model, a duckweed survival assay was developed and used to determine LD50 values. A strong correlation (R2 = 0.81) was found between the strains’ virulence ranks in the two infection models, suggesting conserved pathways in these vastly different hosts. To broaden the application of the duckweed model, enteropathogenic Escherichia coli (EPEC) and five isogenic mutants with previously established LD50 values in the larval model were tested against duckweed, and a strong correlation (R2 = 0.93) was found between their raw LD50 values. Potential virulence factors in B. cenocepacia K56-2 were identified using a high-throughput screen against single duckweed plants. In addition to the previously characterized antifungal compound (AFC) cluster genes, several uncharacterized genes were discovered including a novel lysR regulator, a histidine biosynthesis gene hisG, and a gene located near the gene encoding the recently characterized virulence factor SuhBBc. Finally, to demonstrate the utility of this model in therapeutic applications, duckweed was rescued from Bcc infection by treating with bacteriophage at 6-h intervals. It was observed that phage application became ineffective at a timepoint that coincided with a sharp increase in bacterial invasion of plant tissue. These results indicate that common duckweed can serve as an effective infection model for the investigation of bacterial virulence factors and therapeutic strategies to combat them.

A general protein O‐glycosylation system within the Burkholderia cepacia complex is involved in motility and virulence

“…Several virulence models, including Galleria mellonella, Dictyostellium discoideum , and mice have been utilized to characterize virulence attenuation following inactivation of bacterial glycosylation systems (Coyne et al ., ; Guerry et al ., ; Taguchi et al ., ; Iwashkiw et al ., ). Lemna minor (Common duckweed) has been established as an infection model for several pathogens, including P. aeruginosa and S. aureus (Zhang et al ., ), and recently this model was adapted to investigate Bcc virulence mechanisms (Thomson and Dennis, ). Here, we utilized the duckweed model to compare LD 50 of the different B. cenocepacia strains (Fig.…”

“…The G. mellonella wax worm model was initially developed to compare the relative virulence of Bcc strains (Seed and Dennis, ). Duckweed, originally established as an infection model for gauging virulence of S. aureus and P. aeruginosa (Zhang et al ., ), has recently been adapted as a Bcc infection model; correlation between the virulence of Bcc strains within this plant host and the wax worm model has been observed (Thomson and Dennis, ). Several Bcc virulence factors have been explored in the context of plant and insect models (Uehlinger et al ., ).…”

“…This figure is available in colour online at wileyonlinelibrary.com. including P. aeruginosa and S. aureus (Zhang et al, 2010), and recently this model was adapted to investigate Bcc virulence mechanisms (Thomson and Dennis, 2013).…”

Aerosol Phage Therapy Efficacy in Burkholderia cepacia Complex Respiratory Infections

“…Some of these phages had been shown to be active against B. cenocepacia in Galleria mellonella and Lemna minor infection models (Table 1) (35,45). In the current study, the phages were evaluated for their ability to be repeatedly propagated to high titers of Ն10 9 PFU/ml and to retain lytic activity in the mouse model.…”

Quantification of type VI secretion system activity in macrophages infected with Burkholderia cenocepacia

“…Also, B. cenocepacia can be transmitted from patient to patient (Drevinek & Mahenthiralingam, 2010). B. cenocepacia is pathogenic in several plant and non-mammalian animal infection models (Khodai-Kalaki et al, 2015;Thomson & Dennis, 2013;Uehlinger et al, 2009;Vergunst et al, 2010) and can survive intracellularly within epithelial cells (Burns et al, 1996;Sajjan et al, 2006), macrophages (Lamothe et al, 2007;Martin & Mohr, 2000;Saini et al, 1999) and amoebae (Lamothe et al, 2004;Marolda et al, 1999).…”