Intraperiplasmic Predatory Bacteria: Diversity, Mechanisms, and Application as Alternatives to Antibiotics

Bdellovibrio bacteriovorus represents one of nature's most remarkable examples of obligate bacterial predation. This small, highly motile bacterium exhibits a biphasic life cycle alternating between a free-swimming attack phase and an intraperiplasmic growth phase within gram-negative prey bacteria. Recent advances have elucidated the molecular machinery coordinating prey recognition, invasion, and host manipulation, revealing sophisticated enzymatic arsenals and regulatory networks that orchestrate the predatory program. Transcriptomic studies demonstrate precise temporal control of lytic enzymes, nutrient acquisition systems, and developmental checkpoints throughout the life cycle. Bdellovibrio and related organisms occupy diverse niches, including soil, freshwater, and the mammalian gut, where they influence bacterial community composition through top-down predation. This ecological ubiquity, combined with inherent bactericidal activity, has generated considerable interest in therapeutic applications against multidrug-resistant pathogens, with encouraging results in animal infection models. In this article, we synthesize current understanding of predatory mechanisms, environmental roles, and biotechnological potential of Bdellovibrio while identifying key knowledge gaps: the regulatory logic governing life cycle transitions, molecular determinants of host range, and predator–prey population dynamics. Addressing these questions will advance both fundamental microbiology and antimicrobial innovation.