Which of the following is late lactose fermenter ?
Ans. is 'd' i.e., Shigella sonnei Lactose fermenters produce pink/bright red colonies on MacConkey's agar , while lactose non-fermenters produce pale colonies :Lactose fermenters (rapid) : These are Coliforms, e.g. Escherichia, Klebsiella and Enterobacter aerogenes.Late lactose fermenters (slow): These are Shigella Sonnei, Serratia, Citrobacter, Arizona, Providencia and Ervinia.Non-lactose fermenters : Shigella except Shigella Sonnei, Salmonella, Proteus
E coli
Klebsiella
Salmonella
Shigella sonnei