Effectiveness of tannins extract from leaf guava (Psidium guajava L) on the growth and damage of cell morphology Escherichia coli

This study aims to determine effectiveness of tannins extracted from guava leaf (Psidium guajava L) on the growth and damage cell morphology of Escherichia coli. The method used for qualitative analysis with the tannins are formed by the intensity of the color is blackish green FeCl3 compounds. In the quantitative analysis of tannins used variations of organic solvent (ethanol with a concentration of 30%, 50%, 70%). Levels of tannins in the sample solution was calculated with Tannates Acid Equivalent (EAT). Test of antimicrobial activity using agar diffusion method, while bacterial cell damage test using SEM (scaning electron microscopy). The best solvent to extract the highest levels of tannins with Ethanol 30% by value of tannin levels 2,351mg /g. The results showed that the extract tannins can inhibit the growth and destroy bacteria by reacting with the cell membrane of E. coli. Damage to the cell membrane of E. coli can prevent the entry of food ingredients or nutrients that are necessary for bacteria to generate energy as a result of bacteria will experience growth retardation and even death. Tannin compounds including polyphenols, these compounds can inhibit bacteria by destroying the bacterial plasma membrane is composed of 60% protein and 40% lipid which is generally in the form of phospholipids. In the cell membrane of tannin will react with proteins to form hydrogen bonds so that the protein will be denatured, but it can also react with tannins contained phospholipids in cell membranes, resulting in tannin will damage the cell membrane of E. coli.