Inhibitory Activity of Allium chinense G. Don. Extracts to Prodigiosin Synthesis by Serratia Marcescens

: Bawang Batak ( Allium chinense G. Don.) is one of native medicinal plants utilized as spices in North Sumatera, Indonesia. The plant is known to exhibit antimicrobial activities against several bacterial pathogens. Prospect of finding a new mechanism in combating bacterial infection through quorum-sensing inhibition is an alternative way yet promising strategy to the overuse of antibiotics. The aim of this study is to obtain the optimum concentration of methanolic (MeOH) and ethyl acetate (EtOAc) extracts of A. chinense as quorum-sensing inhibitors to prodigiosin synthesis by S. marcescens. The inhibition of prodigiosin synthesis is observed visually and measured in absorbance value (A 534 ) compared to control. The results showed that both extracts did not inhibit the growth of tested strain based on optical density (OD 600 ) among tested concentrations. The higher the concentration of MeOH and EtOAc extracts, the less synthesis of prodigiosin by S. marcescens in the concentration of 0.3% (w/v) at the end of incubation period (30h). The results showed that MeOH and EtOAc extract may be studied thoroughly for its possibility as quorum-sensing inhibitor following further parameters in the future.