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Modern Identification Methods of Bacteria

Raheesa M Khatib, Veena and Neelamma Konanavar

The early diagnosis of disease is essential to reduce the diseases from the stage of seedlings to harvest in order to grow healthy crop to get maximum yield. Detection of bacteria is tracing of plant pathogenic bacteria in or on plant material, especially when they occur latently, without causing symptoms. But identification means isolation, characterization and naming of bacteria. It is an important step in the diagnosis of bacterial infection and the taxonomic studies. There is no exclusive or reliably simple method of identifying pathogen and the disease they cause. The traditional identification methods are visual inspection of pathogen in situ or in vitro in pure culture by microscopic examination stain reaction, colony characters, oxygen requirement, physiological characters biochemical characters and serological methods. The identification by bacteriophage technique can be considered as both traditional as well as modern. Less specificity and less discrimination at species and strain level is the drawback of the conventional identification methods. In recent years completely newer identification techniques have been developed. This is mainly due to the development in molecular biology, unraveling the structure and function of microorganism. Knowledge of the composition and the place of structural elements in microorganism has made the real finger printing methods possible such as special serological methods like Immuno-electrophoresis, Monoclonal antibodies, Immunogold labeling. Identification by separation of bacterial components using chromatographic techniques (FAA Analysis by Gas chromatography), separation of bacterial protein (PAGE). The nucleic acid based identification methods are more important because it is purely on genetic basis. Fluorescent In situ Hybridization (FISH), developed by Christoph Lengauer, based on the DNA-DNA hybridization. RFLP based on the Southern hybridization. One of the important development in genomic studies is the discovery of PCR by Kary Mullis in 1985. The PCR based identification methods are RFLP-PCR, PFGE, RAPD,REP-PCR, AFLP, Real Time PCR and BIO-PCR at tracer level infection by the bacteria, especially important for quarantine.