What is gram positive and gram negative?

Answer 1

Gram-positive is a result of the Gram staining technique, developed by Danish scientist Hans Christian Gram (1853 - 1938).

Bacteria can have two types of cell walls. Gram-Positive bacteria have a relatively thick layer of peptidoglycan. Gram-negative bacteria have a much thinner layer of peptidoglycan.

There are 4 basic steps to a Gram-staining.

# The smear is flooded with a primary stain (such as crystal violet). This generally ends up staining all cells within the smear. # The smear is rinsed to remove excess dye, and a mordant such as an iodine solution is flooded onto the smear. A mordant is a substance that increases the affinity of cellular components for a dye.

# The smear is rinsed again, removing all excess dye. The smear is then briefly washed with a 95% alcohol or a alcohol-acetone mixture. This mixture acts as a decolorizing agent. If the color is washed away then you are dealing with a Gram-negative bacteria (thin layer of peptidoglycan).

# A counterstain is applied to the rest of the smear as a contrasting color to the now colorless Gram-negative bacteria (typically the red dye safranin). The Gram-positive bacteria remains violet because the dye was never decolorized because of the thick peptidoglycan cell wall.

The gist of this is that Gram-positive bacteria will absorb the dye within their thick peptidoglycan cell wall component and resist the effects of decolorizing alcohol. Gram-negative bacteria will easily lose the dye from their thin peptidoglycan component of the cell wall. The significance of this test allows Microbiologists, Doctors, etc to fight the bacteria with certain specific antibiotics.

Answer 2

gram positive bacteria are those which shows positive test to gram staining and which shows negative test are gram negative bacteria.firstly bacteria are stained with crystal violet stain and after that bacteria are treated by alcohol or other destained solution . if bacteria are destained then these are Gram negative if not then these are gram positive. for visualisation gram negative further stained by safaranine dye.