Strain-specific predation of Bdellovibrio bacteriovorus on Pseudomonas aeruginosa with a higher range for cystic fibrosis than for bacteremia isolates

Abstract

This work aimed to evaluate the predatory activity of Bdellovibrio bacteriovorus 109J on clinical isolates of Pseudomonas aeruginosa selected from well-characterized collections of cystic fibrosis (CF) lung colonization (n = 30) and bloodstream infections (BSI) (n = 48) including strains selected by genetic lineage (frequent and rare sequence types), antibiotic resistance phenotype (susceptible and multidrug-resistant isolates), and colony phenotype (mucoid and non-mucoid isolates). The intraspecies predation range (I-PR) was defined as the proportion of susceptible strains within the entire collection. In contrast, the predation efficiency (PE) is the ratio of viable prey cells remaining after predation compared to the initial inoculum. I-PR was significantly higher for CF (67%) than for BSI P. aeruginosa isolates (35%) probably related to an environmental origin of CF strains whereas invasive strains are more adapted to humans. I-PR correlation with bacterial features such as mucoid morphotype, genetic background, or antibiotic susceptibility profile was not detected. To test the possibility of increasing I-PR of BSI isolates, a polyhydroxyalkanoate depolymerase deficient B. bacteriovorus bd2637 mutant was used. Global median I-PR and PE values remained constant for both predators, but 31.2% of 109J-resistant isolates were susceptible to the mutant, and 22.9% of 109J-susceptible isolates showed resistance to predation by the mutant, pointing to a predator–prey specificity process. The potential use of predators in the clinical setting should be based on the determination of the I-PR for each species, and the PE of each particular target strain.

Improvement of the Antibacterial Activity of Phage Lysin-Derived Peptide P87 through Maximization of Physicochemical Properties and Assessment of Its Therapeutic Potential

“…Except for the few less susceptible strains, a relatively low variability was observed in the magnitude of the killing effect (ranging between 4–6 logs). While it would not be unexpected that the origin of isolates determines susceptibility [ 19 ], our results showed no significant differences in susceptibility between the strains from different sources ( Figure 4 b), as also shown for other phage-derived antimicrobials [ 20 ].…”

Outer Membrane Porin F in E. coli Is Critical for Effective Predation by Bdellovibrio

“…This was not the case for all the other bacterial species tested, however, indicating that other surface components act as receptors in those prey and suggesting that individual BALO strains possess a never-before-realized diversity in their prey recognition machinery, one that allows them to attach to and recognize diverse prey strains. While these results fit the scope of published data showing that BALOs have quite different and preferential activities against given prey (26)(27)(28), even when obtained from the same locale, future work in identifying these additional prey surface components and their roles in predation rates should be pursued.…”

Bdellovibrio’sPrey-Independent Growth is Fuelled by Amino Acids as a Carbon Source

“…B. bacteriovorus 109J was routinely grown at 30ºC in Hepes buffer (25 mM Hepes amended with 2 mM CaCl 2 ·2H 2 O and 3 mM MgCl 2 ·3H 2 O, pH 7.8) or DNB liquid medium (consisting of 0.8 g L −1 NB (Difco™) (supplemented with 2 mM CaCl 2 ·2H 2 O and 3 mM MgCl 2 ·3H 2 O) with Pseudomonas putida KT2440 as prey[24, 25]. To remove the prey, the co-cultures were filtered twice through a 0.45 μm filter (Sartorius).…”

“…Predator viability was counted as plate forming units per milliliter (pfu mL -1 ). It was calculated from a culture performing serial dilution from 10 −1 to 10 −7 in Hepes buffer and developing on the lawn of prey after 48-72 h of incubation at 30°C by using the double layer method[24, 25]. Briefly, 0.1 mL of the appropriate dilution was mixed with an additional 0.5 mL of prey cell suspension of P. putida KT2440 pre-grown in NB and prepared in Hepes buffer OD 600 10, vortexed and plated on DNB solid medium.…”