Effectiveness of predatory bacterium Bdellovibrio bacteriovorus in combination with Pseudomonas fluorescens and Lactobacillus acidophilus as candidates for in vitro anticolibacillosis.

Abstract

Background: Bdellovibrio bacteriovorus has stood out since its initial discovery because of its exceptional capacity to feed on other Gram-negative bacteria. Since this specific "predatory bacterium" may be used as both a probiotic and an antibiotic, research on it has expanded in response to the growing issue of Antimicrobial Resistance (AMR). It is necessary to investigate the relationship between B. bacteriovorus and other Gram-negative bacteria, as well as the presence of Gram-positive bacteria, in the same environment to determine whether or not these factors have an impact on their ability as predators.

Aim: This study aimed to assess the effectiveness of the combination of the predatory bacterium B. bacteriovorus with Pseudomonas fluorescens and Lactobacillus acidophilus as potential candidates for in vitro anticolibacillosis.

Methods: The method employed Escherichia coli ATCC 15144 as the prey, while B. bacteriovorus 109 J ATCC 15143 was used as the predator, combined with P. fluorescens and L. acidophilus as the nutrient sources of the predator. In the challenge experiment, a ratio of the bacterial combination was used to optimize predation to E. coli of 10⁷ PFU/10⁵ CFU per ml.

Results: The study showed that the combination of B. bacteriovorus with P. fluorescens and L. acidophilus after 24 hours of in vitro incubation at 37^°C increased the predatory bacteria count by tenfold, effectively reducing the E. coli population. However, in the absence of Gram-negative bacteria as a nutrient source, the predator population gradually declined.

Conclusion: The combination of B. bacteriovorus as a predatory bacterium with P. fluorescens and L. acidophilus is an effective candidate for in vitro anticolibacillosis.