Antimicrobial activity test of ethanol extracts of bangle rhizomes (Zingiber montanum) against fish-decomposing bacteria Pseudomonas sp. and Vibrio sp.

Fish spoilage often occurs if not handled properly. Fish are prone to spoilage due to their high water content. Several natural antimicrobial alternatives have begun to be used to slow down spoilage in fish. Bangle rhizome (Zingiber montanum) is a traditional medicinal plant utilized by the community due to its secondary metabolites, such as flavonoids, alkaloids, saponins, and essential oils, which have potential antibacterial properties. This study aims to determine the antimicrobial activity of bangle rhizome ethanol extract against Pseudomonas sp. and Vibrio sp., which are pathogenic bacteria in fishery products.
Objective: The purposes of this study is to determine the antimicrobial activity of bangle rhizome Zingiber montanum ethanol extract against Pseudomonas sp. and Vibrio sp., to identify the optimal concentration of the bangle rhizome ethanol extract as antimicrobial, and to identify the types of secondary metabolites contained in the bangle rhizome that exhibit antimicrobial activity.
Results: The test results showed that in the well diffusion antimicrobial test, the best results were obtained at the highest concentration, namely 100%, with an average inhibition zone diameter of 6.83 mm for Pseudomonas sp. and 5.8 mm for Vibrio sp. Meanwhile, in the antimicrobial microdilution test, the highest inhibition percentage was observed at a concentration of 80%, with 2.07% for Pseudomonas sp. and 1.27% for Vibrio sp.