Prevention of Acyl homoserine lactone (AHL) mediated biofilm formation by selected flora of Andaman & Nicobar Islands

Abstract

<span style="font-size:9.0pt;font-family:" times="" new="" roman";mso-bidi-font-family:"times="" roman""="" lang="EN-US">Acyl homoserine lactones (AHL) are inter-cellular signal molecules and it controls the population density dependent growth behavior of bacteria in a biofilm. The AHL mediated biofilm formation and its inhibition was evaluated using methanol (MeOH), ethyl acetate (EtOAc), n-butanol (n-BuOH) and aqueous (H₂O) fractions of 12 marine flora of Andaman and Nicobar Islands with fouling <i style="mso-bidi-font-style:normal">Vibrio </i>sp., isolated from root surface of mangrove. <span style="color:black;mso-font-kerning:12.0pt;mso-bidi-font-weight: bold;mso-bidi-font-style:italic">The 12 fractions were assayed for inhibition of AHL promoted biofilm formation of <i>Vibrio </i>sp. and the results showed that seven fractions possess AHL inhibitory potential. The extracts of mangroves <i><span style="color:black;mso-font-kerning:12.0pt;mso-bidi-font-weight: bold">Avicennia marina</span></i><span style="color:black;mso-font-kerning: 12.0pt;mso-bidi-font-weight:bold;mso-bidi-font-style:italic">, <i>Rhizophora mucronata</i> and macroalgae <i><span style="color:black;mso-font-kerning:12.0pt;mso-bidi-font-weight: bold">Sargassum ilicifolium, Actinotrichia fragilis</span></i><span style="color:black;mso-font-kerning:12.0pt;mso-bidi-font-weight:bold; mso-bidi-font-style:italic">, <i>Amphiroa anceps </i>and <i>Padina tetrastromatica </i>had anti-biofilm activity at least in one of the four solvent fractions. Out of these, EtOAc<span style="color:black;mso-font-kerning:12.0pt; mso-bidi-font-weight:bold;mso-bidi-font-style:italic"> fraction of <i>Padina tetrastromatica</i> (60% inhibition at 50 µg) showed higher inhibition on AHL mediated antibiofilm activity. The concentration dependent (10 - 200 µg) study of this fraction showed that there was a significant reduction in biofilm formation by increase in concentration with an IC₅₀ (50 % inhibitory concentration) of 4<span style="color:black;mso-font-kerning:12.0pt;mso-bidi-font-weight:bold; mso-bidi-font-style:italic">0 µg. Thus it was concluded that the AHL mediated biofilm inhibitory compound from <i>Padina tetrastromatica</i> can be used for the development of anti-quorum sensing antifoulants.

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