Role of Anaerobiosis in Capsule Production and Biofilm Formation in Vibrio vulnificus

Abstract

Vibrio vulnificus, a pervasive human pathogen, can cause potentially fatal septicemia after consumption of undercooked seafood. Biotype 1 strains of V. vulnificus are most commonly associated with human infection and are separated into two genotypes, clinical (C) and environmental (E), based on the virulence-correlated gene. For ingestion-based vibriosis to occur, this bacterium must be able to withstand multiple conditions as it traverses the gastrointestinal tract and ultimately gains entry into the bloodstream. One such condition, anoxia, has yet to be extensively researched in V. vulnificus. We investigated the effect of oxygen availability on capsular polysaccharide (CPS) production and biofilm formation in this bacterium, both of which are thought to be important for disease progression. We found that lack of oxygen elicits a reduction in both CPS and biofilm formation in both genotypes. This is further supported by the finding that pilA, pilD, and mshA genes, all of which encode type IV pilin proteins that aid in attachment to surfaces, were downregulated during anaerobiosis. Surprisingly, E-genotypes exhibited distinct differences in gene expression levels of capsule and attachment genes compared to C-genotypes, both aerobically and anaerobically. The importance of understanding these disparities may give insight into the observed differences in environmental occurrence and virulence potential between these two genotypes of V. vulnificus.

Impact of hypoxia on gene expression patterns by the human pathogen, Vibrio vulnificus, and bacterial community composition in a North Carolina estuary

“…As production of these polysaccharides is metabolically expensive, there must be a key ecological role for their production in the estuarine environment, especially under hypoxic stress. Consistent with our previous in vitro results, the expression of wzb was decreased during conditions where oxygen was limited; however, the second CPS type and EPS production did not follow that trend [Phippen and Oliver, 2015b].…”

“…We investigated a variety of genes involved in multiple categories, including capsular polysaccharide (CPS)/exopolysaccharide (EPS) production, motility and attachment, global gene regulation, putative virulence factor production, stressosome formation, and general metabolism (Figure ). Many of these genes have been previously shown to be differentially regulated by V. vulnificus in response to environmental and host stressors and/or those that have been implicated in virulence [ Bisharat et al , ; Phippen and Oliver , , ; Williams et al , ].…”

“…Invasion from the GI tract, production of lipopolysaccharide and flagella, and upregulation of key colonization factors are known to be facilitated by exposure to anoxia in vivo by Salmonella , Escherichia coli , and V. cholerae , respectively [ Jones et al , ; Lamas et al , ; Liu et al ., ; Xu et al , ]. We have previously shown that anoxia leads to a translucent colony phenotype and decreased biofilm formation by V. vulnificus , due to the downregulation of genes involved in capsule production and type IV pilus formation in vitro [ Phippen and Oliver , , ]. In situ gene expression by V. vulnificus has been investigated thoroughly in response to both temperature and salinity, and during entry into the viable but nonculturable state [ M. K. Jones et al ., ; Smith and Oliver, , ].…”

The Effect of the Environmental Temperature on the Adaptation to Host in the Zoonotic Pathogen Vibrio vulnificus

“…In regard to biofilm, temperature did not affect its formation, unless in the conditions assayed. In fact, some studies reported that this process is controlled by iron, among other external factors (Phippen and Oliver, 2015;Pajuelo et al, 2016;Chodur and Rowe-Magnus, 2018) (Figure 7).…”

Stress Response of Vibrio parahaemolyticus and Listeria monocytogenes Biofilms to Different Modified Atmospheres

“…Rutherford et al (2007) also found differences in the amount of Listeria on shrimp which were stored in air, vacuum, and map packaging (100% CO 2 ) at 3, 7, and 10 • C. Moreover, V. parahaemolyticus and L. monocytogenes could form bacterial biofilms to survive on food processing surfaces under anaerobiosis or aerobiosis (Voidarou et al, 2011;Valimaa et al, 2015;Perez-Ibarreche et al, 2016;Song et al, 2016). In an early study, the biofilm formation of Vibrio vulnificus was reduced due to the lack of oxygen (Phippen and Oliver, 2015). However, Salmonella spp.…”