Multiple Vibrio fischeri genes are involved in biofilm formation and host colonization

Abstract

Biofilms are increasingly recognized as the predominant form for survival in the environment for most bacteria. The successful colonization of Vibrio fischeri in its squid host Euprymna tasmanica, involves complex microbe-host interactions mediated by specific genes that are essential for biofilm formation and colonization. In the present investigation, structural and regulatory genes were selected to study their role in biofilm formation and host colonization. We have mutated several genes (pilT, pilU, flgF, motY, ibpA and mifB) by an insertional inactivation strategy. Results demonstrate that structural genes responsible for synthesis of type IV pili and flagella are crucial for biofilm formation and host infection. Moreover, regulatory genes affect colony aggregation by various mechanisms including alteration of synthesis of transcriptional factors and regulation of extracellular polysaccharide production. These results reflect the significance of how genetic alterations influence communal behavior, which is important in understanding symbiotic relationships.

Ecological Diversification of Vibrio fischeri Serially Passaged for 500 Generations in Novel Squid Host Euprymna tasmanica

“…Perhaps symbionts in E. tasmanica are selected for better host tissue attachment and elevated stress tolerance (more sticky and hardy), while those in E. scolopes are evolutionarily honed for chemotaxis (more nimble locomotion and elevated nutrient sensitivity). Biofilm formation is positively correlated in many host-associated vibrios with colonization potential, immunity avoidance, and eukaryotic cell attachment in hosts [57–59]. Biofilms are known to increase bacterial survival against environmental stress [58–61].…”

A genomic comparison of 13 symbiotic Vibrio fischeri isolates from the perspective of their host source and colonization behavior

“…For instance, type-4 pili (T4P) are a class of surface structures often associated with pathogenic or beneficial microbial colonization of host tissue (Craig et al, 2004;Dulla et al, 2012), and 10 distinct T4P gene clusters have been identified in V. fischeri strain ES114 (Ruby et al, 2005). Some of these putative pilus proteins (that is, MshA, PilT and PilA2) have been linked previously to the colonization process Ariyakumar and Nishiguchi, 2009;Chavez-Dozal et al, 2012). As expected, these pili are encoded in the genomes of all the light organ-derived strains (Table 2).…”

Comparative analysis of quantitative methodologies for Vibrionaceae biofilms

“…We also selected mutant Vibrio fischeri strains (from the ETJB1H isolate) that have been reported to be defective in biofilm formation (Ariyakumar and Nishiguchi 2009; Chavez-Dozal et al 2012). Mutant strains had interruptions in genes responsible for: (a) twitching motility and pilus assembly (Δ pilT , Δ pilU , Δ mshA ; Ariyakumar and Nishiguchi 2009; Chavez-Dozal et al 2012), (b) flagellum assembly and functionality (Δ flgF , Δ motY ; Chavez-Dozal et al 2012), (c) stress responses such as heat shock (Δ ibpA ) and magnesium-dependent induction (Δ mifB ; Chavez-Dozal et al 2012). …”

“…Aliquots of each Vibrio isolate (200 µL) were added to individual wells on a flat-bottom, polystyrene 96-well microtitre plate (Corning, Sigma Aldrich CLS3628, St. Louis, MO) and incubated for 24 h under conditions previously described (Chavez-Dozal et al 2012). After incubation, planktonic (those not forming biofilms) cells were removed by briskly shaking the plate and attached cells were washed three times with sterile media.…”

“…CV was then quantified by solubilizing with 95% ethanol and optical density (A 562 ) readings were recorded at 562 nm for each biofilm in individual wells. For the XTT assay, planktonic cells were removed and plates washed as previously described (O’Toole 2011; Ariyakumar and Nishiguchi 2009; Chavez-Dozal et al 2012). Metabolic activity was measured by the XTT reduction assay (Pierce et al 2010).…”