Inhibition of exoprotease enzyme production in Aeromonas hydrophila quorum sensing system due to methanol extract of fresh and dried galangal rhizome (Alpinia galanga)

Abstract

Novitasari Y, A Pangastuti, R Rakhmawati. 2012. Inhibition of exoprotease enzyme production in Aeromonas hydrophila quorum sensing system due to methanol extract of fresh and dried galangal rhizome (Alpinia galanga). Biofarmasi 14: 51-61. Motile Aeromonas septicemia disease is one of the factors causing the failure of fish farming. The disease is caused by Aeromonas hydrophila. One of the virulence factors of A. hydrophila is an exoprotease. Exoprotease enzyme molecules are controlled by N-butanoyl-Lhomoserine lactone (C4-HSL), which is a signal molecule in quorum sensing system. One of the natural resources that have the potential to inhibit the experiment of exoprotease enzyme is Galanga rhizomes (Alpinia galanga L.). The rhizomes contain the active compound groups including flavonoids, phenols, and terpenoids. The purposes of this research were to determine the inhibition of A. hydrophila exoprotease enzyme production by methanol extracts of fresh and dried rhizomes and the optimal concentration to inhibit the production of exoprotease enzyme. Exoprotease enzyme activity was measured qualitatively by the diameter of clear zone on LB supplemented by skim milk and quantitatively by spectrophotometric method. The methanol extracts of fresh and dried rhizomes were added to A. hydrophila culture. The growth, exoprotease activities protein concentration were measured every 2 hours for 10 hours. The test results were analyzed by univariate analysis with significance level of 0.05. The results showed that methanol extract of fresh rhizome was more effective in reducing the activity of A. hydrophila exoprotease. 8% methanol extract of fresh rhizome significantly reduced the activity of A. hydrophila exoprotease without inhibiting the growth.