Variability of cell surface hydrophobicity among Pasteurella multocida somatic serotype and Actinobacillus lignieresii strains

Abstract

Pasteurella multocida possesses a characteristically gram-negative ultrastructure, yet its inability to grow in the presence of hydrophobic compounds and the general penicillin susceptibility of genera making up the family Pasteurellaceae suggest a cell envelope having atypical permeability properties. The cell surface hydrophobicity properties of strains representing 15 of the 16 somatic serotypes of P. miltocida and three strains of ActinobaciUlus lignieresii were assessed with hydrocarbon adherence and hydrophobic interaction chromatographic assays. These methods revealed surface hydrophobicity to vary dramatically among strains in both species. No direct correlation was observed with species, growth rate, or susceptibility to the antibiotics oxytetracycline (polar), polymyxin B (amphiphilic), or novobiocin (nonpolar) as measured with MIC determinations. All strains were susceptible to the antibiotics, although A. lignieresii was significantly less susceptible than P. multocida to novobiocin. These data suggest that cell surface hydrophobicity in P. multocida may be influenced by the type of lipopolysaccharide present but is not directly related to permeability of the antibiotics examined. The wide diversity of hydrophobic properties exhibited by strains of both P. multocida and A. lignieresii precludes the use of this parameter as a taxonomic aid.

Disparate properties of Burkholderia multivorans and Pseudomonas aeruginosa regarding outer membrane chemical permeabilization to the hydrophobic substances novobiocin and triclosan

“…multivorans environmental strain ATCC 17616 and clinical CGD isolate CGD2 were provided by Dr. Adrian Zelazny (NIH-NIAID, Bethesda, MD). All cultures were maintained under cryoprotective conditions at -80˚C [ 20 ] to provide inocula for working cultures which were cultivated on Difco Mueller Hinton Agar (MHA; Beckton Dickinson Co., Sparks, MD). Starter cultures were prepared by inoculating Difco Mueller Hinton Broth (MHB; Beckton Dickinson Co.) with cells from working cultures as described previously [ 20 ].…”

“…Minimal inhibitory concentrations (MICs) were determined using a modified conventional macrobroth two-fold dilution bioassay [ 11 , 20 ] with MHB as diluent. MHB stock solutions of novobiocin sodium (Sigma-Aldrich Co., St Louis, MO), rifamycin SV (Sigma-Aldrich Co.), and polymyxin B sulfate (Sigma-Aldrich Co.) were prepared to desired concentrations, filter sterilized (0.22 μm Fisherbrand Syringe Filter; Thermo Fisher Scientific Inc., Pittsburgh, PA), and stored at 4°C until needed.…”

Susceptibility of compound 48/80-sensitized Pseudomonas aeruginosa to the hydrophobic biocide triclosan

“…All strains were maintained as cryopreserved stock cultures at À 80 1C (Darnell et al, 1987) and cultivated on Mueller Hinton medium (MHA; Difco Laboratories, Detroit, MI) plates for 18 h at 37 1C to obtain working cultures. Starter cultures were prepared by inoculating 125-mL screwcapped flasks, each containing 20 mL of sterile Mueller Hinton broth (MHB; Difco Laboratories), with cells from working cultures and incubating for 12-15 h at 37 1C with rotary aeration (180 r.p.m.)…”

“…The susceptibilities of all the test strains to triclosan and selected hydrophobic antibiotics were determined using a standard macrobroth two-fold serial dilution bioassay (Darnell et al, 1987) with either MHB or MHB plus compound 48/80 (10.0 mg mL À1 ) as a diluent. Stock solutions of triclosan were prepared by first solubilizing in ethanol (95%), and then diluting to the desired final concentration in sterile MHB.…”

Identification of genes involved in biosynthesis of Actinobacillus pleuropneumoniae serotype 1 O-antigen and biological properties of rough mutants

“…Cultures were incubated at 37°C with rotary aeration at 180 rpm in a model G24 Environmental Incubator Shaker (New Brunswick Scientific, Edison, NJ, USA) until late-exponential phase for cell surface hydrophobicity assays and until an OD 620 = 0.10 for cell surface charge assays. Cell surface hydrophobicity 30 Labrie, Rioux, Wade, Champlin, Holman, Wilson et al was measured by assessing the degree to which wild-type and mutant strains were able to partition into n-hexadecane (Sigma) using the method of Rosenberg et al 23 as modified by Darnell et al 24 The only differences were that cells were harvested and washed using centrifugation for 12 min at 12,000 g at 4°C, and that assay mixtures consisted of 1 ml n-hexadecane added to 4 ml cells standardized to an OD of 0.5 at 620 nm. Cell surface electrostatic charge properties were assessed on the basis of zeta potential values.…”