<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="country-region"><smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place"> Chemical defense in ascidians <i style="">Eudistoma viride</i> and <i style="">Didemnum psammathodes </i>in Tuticorin, southeast coast of India: Bacterial epibiosis and fouling deterrent activity </smarttagtype></smarttagtype>

Abstract

The culturable epibacterial abundance in the ascidians <i style="">Eudistoma viride</i> and <i style="">Didemnum psammathodes</i> was studied and correlated with their antifouling activity. The epibacterial abundance varied significantly between <i style="">E. viride</i> and <i style="">D. psammathodes</i>. The antibacterial assay of the crude extracts of the ascidians showed inhibitory activity against all the 20 biofilm bacteria. However, <i style="">E. viride</i> showed prominent antibacterial activity than that of <i style="">D. psammathodes</i> with an average inhibition zone of 29.1 mm. The comparison between epibacterial abundance and the antifouling activity showed an interesting significant negative correlation [-0.910 (P<0.001)]. Though the ascidians showed activity against all biofilm bacteria, the presence of epibacteria still on its surface could be attributed to their selective inhibition against certain bacteria due to chemical defense mechanism or the ascidians may exhibit a surface property suitable for particular epibacteria which may be symbiotic and contribute to the reduced abundance of other bacterial epibionts.