Antimicrobial compounds from marine halophytes for silkworm disease treatment

Abstract

Forty-five crude methanolic extracts from 23 marine halophytes were screened against five bacterial and two fungal saprophytic pathogens of diseased silkworm Bombyx mori. Amongthirty-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 againstProteus vulgaris (11 mm dia) and the seagrass species of Syringodium isoetifolium showed maximum inhibition against P. vulgaris (9 mm dia). The solar saltern cyanobacteriumPhormidium 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. isoetifoliumshowed complete reduction in the bacterial and fungal viable counts within 3 h of exposure. Key words: Mangroves, Bombyx mori, seaweed, sea grass, time kill assay herbal disinfectants, cyanobacteria.