Abstract

S. Ravi Kumar*, G. Ramanathan, M. Subhakaran and S. Jacob Inbaneson

Forty-five crude methanolic extracts from 23 marine halophytes were screened against five bacterial and two fungal saprophytic pathogens of diseased silkworm Bombyx mori. Among thirty-four mangrove samples screened for antibacterial activity, the leaf extract of Rhizophora mucronata showed maximum inhibitory activity against Staphylococcus aureus (20 mm dia.). The seaweed species of Padina tetrostomatica showed maximum inhibitory activity against Proteus vulgaris (11 mm dia) and the seagrass species of Syringodium isoetifolium showed maximum inhibition against P. vulgaris (9 dia). The solar saltern cyanobacterium Phormidium fragile exhibits higher inhibitory activity against P. vulgaris (17 mm dia). The growth of fungal pathogens of Aspergillus niger was highly inhibited by S. isoetifolium (15 mm dia) and Padina tetrostomatica (13 mm dia) respectively compared with the other extracts. It is also noted that 16x concentration of the leaf extract of R. mucronata and S. isoetifolium showed complete reduction in the bacterial and fungal viable counts within 3 h of exposure.