Research Associate, Department Of Biotechnology, Karunya University, Karunya Nagar, Coimbatore-641114. Dr. D. Patric Raja,
Reader, Department of Plant Biology & Biotechnology, St. Xavier’s College (Autonomous) Palayamkottai- 629002 Tamil Nadu, India.
Received: 2008 February 13
Published: 2008 March 17
Abstract: Seaweeds are the most inexhaustible source of bioactive organic chemicals unlike the flowering plants, seaweeds are the least investigated and exploited group. Hence more attention is given to exploit these untapped resources in various ways. Preliminary studies on the biological activity of four different species of marine algae Caulerpa viz. Caulerpa scallpelliformis (R.Br) Weber van Bosse, Caulerpa crassifolia (C. Ag) J.Ag, Caulerpa sertularioides (Gmelin) Howe and Caulerpa racemosa (Forsk) Weber Van Bosse were carried out. Among the four species, Caulerpa scallpelliformis, Caulerpa crassifolia and Caulerpa sertularioides showed antibacterial activity. Paper chromatographic studies of the methanolic extracts showed the presence of 2 to 4 fluorescent compounds in different solvents. Antibacterial activities of the extract were assayed by paper disc diffusion method. The test bacteria were Bacillus subtilis, Staphylococcus aureus, Staphylococcus saprophyticus, Klebseilla pneumoniae and Escherchia coli. The effect of methanolic extracts of Caulerpa species on seed germination and vigour index of the following crops were studied through seed treatment. Vigna mungo (L.) Hepper., Vigna radiate (L.) Wilczek Var.radiata., Lablab purpureus (L.) Sweet Var.purpureus., Abelmoschus esculentus (L.) Moench., Sesbania grandiflora (L.)Poir. Out of the four Caulerpa species tested for antibacterial activity, three showed activity against one or more bacteria. Among the three, broadest bacterial spectra’s was exhibited by Caulerpa crassifolia. Different concentrations of Caulerpa extract used for seed treatment showed negative effect on seed germination and vigour index of seedlings, expect Vigna mungo (L.). Caulerpa extracts delayed germination. Further investigations are necessary to identify the chemical nature of fluorescent compounds observed in the present investigation.