NaCl promotes antibiotic resistance by reducing redox states in Vibrio alginolyticus

Abstract

Summary The development of antibiotic resistance in Vibrio alginolyticus represents a threat to human health and fish farming. Environmental NaCl regulation of bacterial physiology is well documented, but whether the regulation contributes to antibiotic resistance remains unknown. To explore this, we compared minimum inhibitory concentration (MIC) of V. alginolyticus cultured in different media with 0.5%–10% NaCl, and found that the MIC increased as the NaCl concentration increased, especially for aminoglycoside antibiotics. Consistent with this finding, internal NaCl also increased, while intracellular gentamicin level decreased. GC–MS‐based metabolomics showed different distributions of pyruvate cycle intermediates among 0.5%, 4% and 10% NaCl. Differential activity of enzymes in the pyruvate cycle and altered expression of Na(+)‐NQR led to a reducing redox state, characterized by decreased levels of NADH, proton motive force (PMF) and ATP. Meanwhile, NaCl negatively regulated PMF as a consequence of the reducing redox state. These together are responsible for the decreased intracellular gentamicin level with the increased external level of NaCl. Our study reveals a previously unknown redox state‐dependent mechanism regulated by NaCl in V. alginolyticus that impacts antibiotic resistance.

Reduced redox‐dependent mechanism and glucose‐mediated reversal in gentamicin‐resistant Vibrio alginolyticus

“…PDH, KGDH and SDH were measured as previously described (Yang et al, 2018a). In brief, the overnight bacteria were diluted 1:100 in M9 medium with or without 5 mM glucose in a shaker bath at 30 C for 6 h. Samples were collected and adjusted the OD 600 to 1.0.…”

“…Phage therapy and antibacterial peptides attack bacterial cells directly (Pires et al, 2017;Zhang et al, 2017). Whereas the antibiotic-dependent method could be achieved through an antibiotic resistance-reverting molecule or an antibiotic sensitizer to enhance antibiotic killing efficacy (King et al, 2014;Gupta et al, 2014;Peng et al, 2015b;Su et al, 2015;Yao et al, 2016;Su et al, 2018;Yang et al, 2018a;Ye et al, 2018). The antibiotic sensitizers such as inhibitors inhibit enzymatic activity that degrades antibiotics or inhibit the efflux pump and thereby maintain the intracellular level of antibiotics (Gupta et al, 2014;King et al, 2014).…”

The characteristics of antibiotic resistance and phenotypes in 29 outer‐membrane protein mutant strains in Aeromonas hydrophila

“…About 10 mg of bacterial protein was separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and then transferred to the polyvinylidene fluoride (PVDF) membranes in transfer buffer (Bio-Rad, 1X Tris/Glycine buffer) for Western blotting as previously described (Yang et al, 2018). Briefly, PVDF membranes were blocked in phosphate-buffered saline containing 0.1% (v/v) Tween 20 (PBST) and 5% (w/v) skim milk for 2 h at room temperature, then incubated overnight with a rabbit/mouse primary antibody at a 1:1000 dilution at 4 C. After washing with PBST, the membranes were incubated with horseradish peroxidase-conjugated goat anti-rabbit or mouse antibody (ComWin, Beijing, China) at a 1:5000 dilution for 1 h at room temperature.…”

Malate enhances survival of zebrafish against Vibrio alginolyticus infection in the same manner as taurine

“…Bacterial disease outbreak is a significant constraint to the development of the aquaculture sector. Besides vaccination and antibiotic approaches [8,10,33,34], alternative strategies are being developed to control bacterial diseases [20,35,36]. These include the specific killing of pathogenic bacteria (bacteriophages and inhibition of chromosome II replication in vibrios), growth inhibition (short-chain fatty acids and polyhydroxyalkanoates), inhibition of virulence gene expression (interfering with the regulation of virulence factor expression and specifically inhibiting a certain virulence factor), and reprogramming of the antibioticresistant metabolome (reverting bacterial antibiotic resistance to uptake antibiotics) [35,37,38].…”