Effect of mangrove plant (Sesuvium portulacastrum) extract against Vibrio harveyi during shrimp larviculture

The present study aimed at finding a potential antagonistic activity of the leaves of mangrove plant Sesuvium portulacastrum against pathogenic Vibrio harveyi during shrimp larviculture. Crude extract obtained from the leaves of mangrove plant S. portulacastrum was screened for its antagonistic activity against V. harveyi and the minimum inhibitory concentration was determined. Crude extract was characterized for its phytochemical composition by GC-MS and FTIR analysis. The antagonistic activity of S. portulacastrum crude extract was tested against V. harveyi during Penaeus monodon larviculture. MIC of S. portulacastrum extract was 100 µg against 1×10^sup 8^CFUml^sup -1^of V. harveyi. When V. harveyi was cultured in Luria Bertani broth with crude extract of S. portulacastrum (100 µg ml^sup -1^) the growth and its virulence factors became weak. The cumulative percentage on mortality of postlarvae was 54% in 30 days, whereas control tank showed 67% mortality. Differences in reduction on the cumulative percentage mortality in the treatment tank was 13% as compared to control. Using statistical analysis, significant differences (P