QsvR and OpaR coordinately repress biofilm formation by Vibrio parahaemolyticus

Abstract

Mature biofilm formation by Vibrio parahaemolyticus requires exopolysaccharide (EPS), type IV pili, and capsular polysaccharide (CPS). Production of each is strictly regulated by various control pathways including quorum sensing (QS) and bis-(3′–5′)-cyclic di-GMP (c-di-GMP). QsvR, an AraC-type regulator, integrates into the QS regulatory cascade via direct control of the transcription of the master QS regulators, AphA and OpaR. Deletion of qsvR in wild-type or opaR mutant backgrounds altered the biofilm formation by V. parahaemolyticus, suggesting that QsvR may coordinate with OpaR to control biofilm formation. Herein, we demonstrated both QsvR and OpaR repressed biofilm-associated phenotypes, c-di-GMP metabolism, and the formation of V. parahaemolyticus translucent (TR) colonies. QsvR restored the biofilm-associated phenotypic changes caused by opaR mutation, and vice versa. In addition, QsvR and OpaR worked coordinately to regulate the transcription of EPS-associated genes, type IV pili genes, CPS genes and c-di-GMP metabolism-related genes. These results demonstrated how QsvR works with the QS system to regulate biofilm formation by precisely controlling the transcription of multiple biofilm formation-associated genes in V. parahaemolyticus.

Environmental magnesium ion affects global gene expression, motility, biofilm formation and virulence of Vibrio parahaemolyticus

“…CV staining assay was performed similarly as previously described [ [43] , [44] , [45] , [46] , [47] ]. Briefly, the bacterial seed was diluted 50-fold into 2 ml HI broth or HI broth supplemented with 55 mM Mg 2+ in a 24-well cell culture plate, and then incubated at 30 °C with shaking at 150 rpm for 12 h. Planktonic cells were collected for detection of OD 600 values.…”

“…Colony morphology assay was performed similarly as previously described [ 44 ]. Briefly, 2 μl of bacterial seed was taken to spot on an HI plate or HI plate supplemented with 55 mM Mg 2+ , and then statically incubated at 37 °C for 24 h.…”

“…Intracellular c-di-GMP level was similarly quantified as previously described [ 44 , 48 ]. Briefly, the bacterial seed was diluted 1000-fold into 5 ml HI broth supplemented with 0 and 55 mM MgCl 2 , respectively, and then incubated at 37 °C with aeration to an OD 600 value of 1.5.…”

“…CPS phase variation was similarly detected as previously described [ 44 ]. Briefly, a small portion of bacterial seeds was streaked onto a HI plate or HI plate supplemented with 55 mM MgCl 2 , followed by incubated at 37 °C for 24 h.…”

Breaking barriers: The potential of nanosystems in antituberculosis therapy

“…Significant reduction in intracellular MTB accumulation in macrophages BALB/C mice, via oropharyngeal aspiration 31.25 μg/g body weight Both CS-PLGA@GL and free β-glucan increased specific cytokine levels in male CD1 mice. However, free β-glucan only matched the nanoparticle effect at higher concentration [ 247 ] Cellulase and Levofloxacin-loaded Composite Nanoparticle (CL@LEV-NPs) 196.2 ± 2.89 Enhanced anti-biofilm effects when combined with ultrasound due to ROS generation BALB/c mice, 5 mg/kg CL@LEV-NPs facilitated the removal of biofilms from subcutaneous implants in BALB/c mice post-BCG infection and reduced local inflammation [ 248 ] PeptoMicelles 98–100 Micelle stability and low potency against Mycobacterium marinum Intravenous administration 180 mg/kg Comparable efficacy to free drug in C3HeB/FeJ mouse model. Safety confirmed in zebrafish larva model [ 249 ] RIF-loaded iron oxide nanoparticles with polyacrylic Acid polyethylene glycol coating and mannose functionalization (Rif@IONPs-PAA-PEG-MAN) 20–22 Rif@IONPs-PAA-PEG-MAN showed high biocompatibility with minimal cytotoxicity and were preferentially internalized by MTB-infected macrophages, involving mannose receptor interaction, endocytosis, micropinocytosis, and phagocytosis pathways.…”