Inhibitory effect of marine algae collected from the Eastand West coast of India against luciferase andluminescence producing Vibrio harveyi

Abstract

This study explored the development of inhibitors from marine algae against luminescence disease causing Vibrio harveyi. Organic solvents such as ethyl acetate (EA) and methanol:chloroform (CM) were treated to extract compounds from marine algae such as Skeletonema costatum, Ulva fasciata and Kappaphycus alvarezii. Antagonistic effect of algae extracts was determined against marine V. harveyi. EA extract of S. costatum and U. fasciata at 300 µg showed maximum zone of inhibition (12.6 and 12.3 mm) against V. harveyi. Similarly, CM extract of S. costatum also showed maximum zone of inhibition (8.3 mm). When crude EA extract of S. costatumat 300 µg/ml was used for V. harveyi, the level of luciferase was reduced to three to seven counts per second (CPS) as compared to the control for 4 days as read by luminometer. 300 mg/ml of CM extract of U. fasciata, reduced the luciferase to 3 to 6 CPS. When EA extract of S. costatum at (300 µg/ml) was treated against V. harveyi, the luminescence was reduced 10 to 15 CPS. The CM extract from U. fasciatashowed reduction in the luminescence production (7 to 13 CPS). Considering the cumulative effect of anti-luminescence and anti-Vibrio activities, 300 mg of crude extract prepared from S. costatum in both solvents were confirmed as inhibitory to V. harveyi. Significant difference (p<0.05) was observed among the levels of luciferase and luminescence in all the extracts but S. costatum showed less. This study confirms that marine algae extracts can be used to control luminescent disease causing V. harveyi among the shrimp grow-out system and larviculture. Key words: Algae extracts, antagonism, Vibrio harveyi, anti-luciferase, anti-luminescence.