Salmonella Shigella Agar

culturing techniques efficiently identify

bacterial strains based on their growth requirements

How does the salmonella shigella agar medium work

it restricts certain gram-positive strains while permitting the growth of specific gram-negative strains

what does the SSA contain

peptone, lactose, and essential micronutrients

what acts as selective agents

bile salts and brilliant green dye

the pH indicator turns

red when pH drops below 6.8

what is the drop in pH caused by

lactose fermentation of escherichia coli

what does salmonella use as a carbon source

peptone, it does not ferment sugar

what else is used in SSA to aid in identification

ferric acid and sodium thiosulfate - they are reducible sulfur sources

most salmonella strains produce

hydrogen sulfide which turns medium black

shigella lacks the

enzymes for sulfur reduction, so it maintains its original color