Gram-positive bacteria retain the crystal violet-iodine complex and stain purple, whereas gram-negative bacteria stain pink.
Catalase test is used to distinguish among Gram-positive cocci. Staphylococci are catalase-positive but Streptococci are catalase-negative.
Blood agar is an enriched medium which supports growth of gram-positive cocci and differentiates them on the basis of hemolysis (α, β, or γ).
Selective (against gram-positive bacteria) and differential culture medium (LF and NLF), commonly used for the isolation of enterics.
TSI test determines whether a gram-negative rod utilizes glucose, and lactose or sucrose fermentatively and forms hydrogen sulfide.
Bacteria can be grown in an artificial medium in the laboratory. Growth medium can be broth, agar or biphasic. Medica can be categorized based on functions.
