Predatory bacteria Bdellovibrio: survival strategy

Predatory potentials of novel Bdellovibrio isolates against multidrug-resistant and extremely drug-resistant bacterial pathogens of animals and plants

Bdellovibrio and like organisms (BALOs) predate on Gram-negative bacteria selectively, which holds promise as an alternate to combat against multidrug-resistant bacterial pathogens. In this study, two Bdellovibrio strains designated MPR17 and MPR18 were isolated from water samples by double-layer agar technique using P. fluorescens as prey and investigated for their predatory potentials against six pathogenic Gram-negative, MDR and XDR bacteria. Both the BALOs preyed on all the tested bacteria including P. syringae, B. glumae, V. parahaemolyticus, P. mirabilis, M. bovis, and A. schindleri with different killing rates. Against A. schindleri, Bdellovibrio sp. MPR18 produced a maximum of 2.11 × 107 PFU/ml, but MPR17 did not produce any detectable PFUs. TEM analysis of predator-prey interactions recorded different life stages including attachment, bdelloplast formation, prey lysis, and release. Morphologically, both the Bdellovibrio isolates MPR17 and MPR18 were small vibrioid in shape with a long single polar flagellum and measured of about < 500 nm diameter in size, suggesting that they are the smallest ever described Bdellovibrio. Predatory activity was further assessed in liquid co-cultures that evidenced time-dependent decrease in the prey cell density from 24 h with significant reduction at 72 h with different degrees of predation with respective prey bacteria. Bdellovibrio sp. MPR17 and MPR18 exhibited strong bacteriolytic activity in liquid cultures, which was equivalent to the bactericidal activities of standard antibiotics especially for M. bovis (99%), P. syringae (90%) and A. schindleri (90%). The findings of this study signify the potential of novel Bdellovibrio sp. MPR17 and MPR18 as a biocontrol agent with multiple host range to eradicate different MDR and XDR bacterial infections, which could contribute positively for resolving the crisis of antimicrobial resistance.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-025-04230-8.

Bdellovibrio and like organisms: current understanding and knowledge gaps of the smallest cellular hunters of the microbial world

Almost sixty years ago, Bdellovibrio and like organisms (BALOs) were discovered as the first obligate bacterial predators of other bacteria known to science. Since then, they were shown to be diverse and ubiquitous in the environment, and to bear astonishing ecological, physiological, and metabolic capabilities. The last decade has seen important strides made in understanding the mechanistic basis of their life cycle, the dynamics of their interactions with prey, along with significant developments towards their use in medicine, agriculture, and industry. This review details these achievements, identify current understanding and knowledge gaps to encourage and guide future BALO research.

Effect of copper sulfate on Bdellovibrio growth and bacteriolytic activity towards gibel carp-pathogenic Aeromonas hydrophila

The use of bdellovibrios has been regarded as an alternative to control multidrug-resistant pathogens and fish bacteriosis. However, scarce information is available on the potential of bdellovibrios in the presence of copper sulfate, which is an algicide widely used to treat cyanobacterial blooms in aquaculture. In the present study, the effects of copper sulfate at sublethal and lethal levels (0.1 and 1.0 mg·L^-1) on Bdellovibrio sp. strain BDF-H16 were evaluated. The growth of Bdellovibrio sp. strain BDF-H16 was significantly promoted by both concentrations of copper sulfate, but less so by the lethal concentration. The bacteriolysis of gibel carp-pathogenic Aeromonas hydrophila by Bdellovibrio sp. strain BDF-H16 was also stimulated by copper sulfate in both solid and liquid media. However, Bdellovibrio sp. strain BDF-H16 with 0.1 mg·L^-1 copper sulfate clearly inhibited infection of gibel carps by A. hydrophila better than Bdellovibrio sp. strain BDF-H16 with 1.0 mg·L^-1 copper sulfate did.