Authors: LALITA LAKHRAN , NARESH KUMAR AND Dr. R.R. AHIR
Department of Plant Pathology, S.K.N. University of Agriculture, Jobner, Jaipur(Raj.)India 303328
Bdellovibrio is a genus of Gram negative bacteria with the ability to parasitize and kill other Gram negative bacteria. It first describe by Stalp and Stark (1963). Bdellovibrio appears as a comma- shaped motile rod, o.3-0.5 by 0.5- 1.4μm in size with a scarcely visible flagellum. They exhibit lytic activity on Gram negative bacteria of Pseudomonadaceae and Enterobacteriaceae. They attack on Agrobacterium, Erwinia , Pseudomonas and Rhizobium. There are no bdellovibrios reported on gram positive bacteria. Bdellovibrio are obligate aerobes.
- Bdellovibrio parasitized other Gram negative bacteria by entering into their periplasmic space and breading of biosynthesis of biopolymers( Protein, NA etc.). of their host. After entering the periplasmic space of its host. The bdellovibrio bacterium forms a structure known as “ Bdelloplast”. This bdelloplast is created as the host cell is modified to become spherical in shape. Inside the bdelloplast, the singular large flagella of the predatory Bdellovibrio is lost. Which modified both predetors and pray’s cells. The predetors cell on remain dormant at this stage without affecting the variability of the host. In most cases bdellovibrio devours its pray’s and moves on because of this bdellovibrio can be considered as bacterial predetors in addition to parasite. It found in river water and soil. Three species: Bdellovibrio stolpii, B. starri and B. bacteriovorus.
- Extracxellular: A Saprophytic and host independent form, predatory non growing phase.
- Intercellular: Parasitic and host dependent form, spiral or non – flagellated cells or flagellated maturencells, reproductive phase.
Life cycle: It includes following stages:
- Attachment : First, the bacterium attached itself to the host’s outer membrane using a hook like extension which breaks down the outer cell wall through the release of certain enzymes.
- Penetration: Attachement is followed by penetration into the periplasm and repair of injury done to the cell membrane.
- Growth and development : Once the bacterium is inside the periplasm, it introduces hydrolytic enzymes into the host cytoplasm. This enhances the bacterium’s food supply by making the inner membrane of the host cell “ leaky”. The bacterium then grows and onces it has exhausted all the resources in the host cell, it divides into as many as 15 motile cells.
- Lysis of host cell: The weakened host cell lyses, releasing progeny of bdellovibrio bacteria, which are then ready to find new prey to attack. This life cycle takes up to 3-4 hours.
- Biological control of pathogens.
- Water purification.
- Biofilm/ an aggeregate of microbial control. Biofilm is defined as communities of microorganisms attached to a surface.
The ability of Bdellovibrio strongly support the concept of using B.bacteriovorus for treatment of disease-related biofilms and particularly, periodontal infections. This attribute is clearly beneficial with an antibiotic resistant strain. BALOs as biological control agents in environmental as well as medical microbiological settings. BALOs fail to completely kill their prey, even at high predator to prey ratios. However, resistance is due to a plastic phenotype rather than permanently genetically encoded and to date, completely resistant mutant prey has not been isolated. They are found strongly associated with natural biofilms and recent studies have shown that effective predation occurs in these naturally occurring bacterial communities.
About Author / Additional Info: