Endophytic populations were isolated from 2400 segments of Oryza sativa collected from Bhadra River Project Area, Southern India during December 2005 (Winter) and April 2006 (Summer). Overall colonization rates from surface sterilized tissues were 40.3% in roots and 25.83% in leaves during winter season, 20.15% in roots and 8.66% in leaves during summer season. Nineteen different fungal taxa, a Streptomyces sp. and bacterial species were isolated. Streptomyces sp., Chaetomium globosum, Penicillium chrysogenum, Fusarium oxysporum and Cladosporium cladosporioides were dominant endophytes in this study. Frequency of colonization between the sites, seasons and rice varieties were found to differ significantly. Dual culture studies revealed that C. globosum, P. chrysogenum and Streptomyces sp. are suitable candidates for extraction of biologically active compounds. Rice harbors many endophytic organisms and some of them have antagonistic properties against fungal pathogens.

In the present study the ethanol extract of the aerial part of Andrographis paniculata was prepared and evaluated for antimicrobial activity against eleven bacterial strains by determining minimum inhibitory concentration and zone of inhibition. Minimum inhibitory concentration values were compared with control and zone of inhibition values were compared with standard ciprofloxacin in concentration 100 and 200 μg/ml. The results revealed that, the ethanol extract is potent in inhibiting bacterial growth of both Gram-negative and Gram positive bacteria.

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