Stress Tolerance and Virulence-Related Roles of Lipopolysaccharide in Burkholderia glumae

Abstract

The lipopolysaccharide (LPS) composed of lipid A, core, and O-antigen is the fundamental constituent of the outer membrane in gram-negative bacteria. This study was conducted to investigate the roles of LPS in Burkholderia glumae, the phytopathogen causing bacterial panicle blight and seedling rot in rice. To study the roles of the core oligosaccharide (OS) and the Oantigen region, mutant strains targeting the waaC and the wbiFGHI genes were generated. The LPS profile was greatly affected by disruption of the waaC gene and slight reductions were observed in the O-antigen region following wbiFGHI deletions. The results indicated that disruption in the core OS biosynthesis-related gene, waaC, was associated with increased sensitivity to environmental stress conditions including acidic, osmotic, saline, and detergent stress, and to polymyxin B. Moreover, significant impairment in the swimming and swarming motility and attenuation of bacterial virulence to rice were also observed in the waaC-defective mutant. The motility and virulence of O-antigen mutants defective in any gene of the wbiFGHI operon, were not significantly different from the wild-type except in slight decrease in swimming and swarming motility with wbiH deletion. Altogether, the results of present study indicated that the LPS, particularly the core OS region, is required for tolerance to environmental stress and full virulence in B. glumae. To our knowledge, this is the first functional study of LPS in a plant pathogenic Burkholderia sp. and presents a step forward toward full understanding of B. glumae pathogenesis.

Pectobacterium parmentieri SCC 3193 Mutants with Altered Synthesis of Cell Surface Polysaccharides Are Resistant to N4-Like Lytic Bacteriophage ϕA38 (vB_Ppp_A38) but Express Decreased Virulence in Potato (Solanum tuberosum L.) Plants

“…The phage-resistant P. parmentieri mutants, while having altered polysaccharide synthesis, also expressed various phenotypes that are likely not directly related to phage-resistance but apparently contribute to their environmental fitness. Other studies of mutants with defects in LPS have revealed their role in resistance to different stresses [ 67 , 68 ]. Likewise, mutations resulting in alternations of the LPS structure were found to be associated with the altered ability to form biofilm and/or to survive under various abiotic stresses [ 68 ].…”

Genomics-Driven Activation of Silent Biosynthetic Gene Clusters in Burkholderia gladioli by Screening Recombineering System

“…The hot CYMG-0.5% agar and hot CYMG-0.25% agar (15 mL) was poured into Petri dishes for swarming assay and swimming assay, respectively [ 28 , 32 ]. The plates were dried.…”

Identification of a Cupin Protein Gene Responsible for Pathogenicity, Phage Susceptibility and LPS Synthesis of Acidovorax citrulli

“…For example, mutations in LPS biosynthesis-related genes of Salmonella enterica resulted in the loss of its virulence ( Kong et al, 2011 ). Similarly, mutation of genes involved in the synthesis of the core oligosaccharide (OS) of LPS, resulted in clear reduction in the virulence of Burkholderia glumae that causes bacterial panicle blight and seedling rot in rice ( Lee et al, 2019 ). Since PMI is involved in the production of intermediates used for the synthesis of the OS of LPS, our data coincide with these previous data.…”