Question

Determine if the below are gram (+) or gram (-) or both:

Teichoic Acid

Periplasmic Space

Outer membrane

Lipopolysacharride

Peptidoglycan

Capsule

Answer 1

Teichoic Acid - Gram (+)

Periplasmic Space - Gram (-)

Outer membrane - Gram (-)

Lipopolysacharride - Both (present in very high concentration

in Gram negative bacteria, and almost

none in Gram positive bacteria )

Peptidoglycan - Both ( it is thin and single layerd in Gram

negative bacteria and thick multi layerd in

Gram positive bacteria).

Capsule - Both (mainly Gram negative bacteria)

Additional information :

Gram positive bacteria give postive result in gram straining (retained the stain of crystal violet), and appear purple under light microscope.

Example : B. Antrhacis.

Gram negative bacteria give negative result in gram straining (counter stained by safranin), and appear red or pink under light microscope.

Example : E. Coli.