Antibacterial efficacy of four selected medicinal plants against xanthomonas oryzae pv . oryzae

Mondal, A. K., Hasan, M. M., Ananya, S., Begom, M. M. and Islam, A.T.M. S. 2017. Antibacterial efficacy of four selected medicinal plants against Xanthomonas oryzae pv. oryzae. Bangladesh J. Plant Pathol. 33 (1&2): 37-42 Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae is an important disease of rice causes heavy yield losses. The bacterium was isolated and identified through different biochemical test and pathogenicity test. Methanol and aqueous Leaf extract of some plant leaves including Azadirachta indica (Neem), Citrus limon (Lemon), Annona squamosa (Ata) and Aegle marmelos (Bael) were evaluated for their antibacterial efficacy against the isolated pathogen using disc diffusion method. Water extracts (2.42 cm) of all the plant showed higher antibacterial efficacy against the tested bacterium compared to methanol extract (1.48 cm) and control (0.00 cm). Among medicinal plants, Neem leaf water extract showed the higher zone of inhibition (2.60 cm) than methanol extract (1.90 cm). Water extract of Ata leaf showed the higher zone of inhibition (2.57 cm), followed by methanol (1.67 cm). On the other hand, water extract of Bael leaf showed the higher zone of inhibition (2.47 cm) compared to methanol (1.70 cm)., Lemon water extract showed the maximum inhibition zone (2.13 cm) comparing to methanol (1.60 cm). MIC and MBC of water extract were found best at 62.5 μg/ ml using Neem and Ata leaf extract where Lemon and Bael leaf extract gave 125 μg/ ml. In cell viability test, all plants with water extract showed 100% cell death at 240 min time of exposure.