Biochemical tests o Used to identify bacteria. Can they ferment lactose? No Yes Can they use Can they use citric acid as their citric acid as their sole carbon source? sole carbon source? No Yes No Yes Shigella: Salmonella: Escherichia Do they Produces lysine Generally produce decarboxylase. produces H2S acetoin? No Yes Citrobacter Enterobacter Figure 10.8Biochemical tests Figure 10.8 • Used to identify bacteria