Established and abandoned tea (Camillia sinensis L.) rhizosphere: dominant bacteria and their antagonism.

Some parts of the Indian Himalayan region are covered by established and abandoned tea bushes. Rhizospheric soils of these plants were studied for bacterial dominance and antagonism. Representatives of Bacillus and Pseudomonas genera were found to dominate the rhizosphere of established and abandoned tea bushes, respectively. Amongst the isolated species Bacillus subtilis and Bacillus mycoides appeared to be closely associated with roots of established tea bushes while the rhizosphere of abandoned tea bushes was dominated by Pseudomonas putida. Four isolates of both B. subtilis and P. putida were selected on the basis of maximum antibacterial activity. The bacteriocin-like activity of B. subtilis and P putida strains was detected to be active over a range of temperature 0-50 degrees C and was sensitive to proteolytic enzymes. Incubation of indicator strains with different concentrations of bacteriocin-like substances confirmed their bactericidal activity. Various species of Bacillus and Pseudomonas behaved antagonistically amongst themselves due to the production of bacteriocins under in vitro conditions.