the smooth part of the cell wall make it to get stain
Yogurt contains mostly lactic acid bacteria, which are Gram-positive bacteria. This means they will stain purple under a Gram stain.
Bacteria are gram positive or gram negative. Serratia happens to be a gram negative bacteria. They appear pink on a gram stain. Gram positive bacteria stain to a purple color on a gram stain. We can classify and ID bacteria using their gram stain and shape. Some antibiotics only work on gram negative bacteria and some only work on gram positive bacteria. It helps a doctor know which antibiotic to use.
Gram negative bacteria (pink gram stain) contain no outer cell membrane, while gram positive bacteria (purple gram stain) do contain an outer cell membrane. Gram negative and positive bacteria can respond differently to antibiotics. Many only work on only one of the two bacteria types. A gram stain is also the first step in identifying a bacteria, dividing bacteria into two large and distinct groups.
gram staining differentiates between gram negative and gram positive bacteria by showing different colors. it shows blue or purple like color for gram positive bacteria and red color for gram negative bacteria. where as simple stain gives the same color to all the types of bacteria. hence it is difficult to differentiate between them.
Bacteria stain either gram-positive or gram-negative based on the presence or absence of a cell wall. Viruses do not pick up a gram stain.
Gram-positive bacteria retain the crystal violet stain and appear purple when stained with Gram's stain, because the thick peptidoglycan layer in their cell wall traps the dye. On the other hand, Gram-negative bacteria do not retain the crystal violet stain and appear red or pink after the addition of a counterstain like safranin, due to their thin peptidoglycan layer which is unable to retain the dye.
Streptococcus pyogenes is gram positive bacteria.
Crystal violet is the primary stain in the Gram's stain procedure, used to color all bacteria cells purple. This helps differentiate between Gram-positive bacteria (which retain the violet color) and Gram-negative bacteria (which lose the violet color when decolorized with alcohol).
Gram-positive bacterium are those that are stained dark blue or violet by Gram Staining. This is in contrast to Gram-Negative Bacterium, which cannot retain the crystal violet stain, instead taking up the counter-stain and appearing red or pink. Gram-positive organisms are able to retain the crystal violet stain because of the high amount of peptidoglycan in the cell wall. Gram-positive cell walls typically lack the outer membrane found in Gram-negative bacteria.
After the addition of mordant in the Gram stain, gram-negative bacteria will appear red or pink under the microscope. This is because the mordant helps to fix the crystal violet stain to the cell wall of gram-positive bacteria, making it harder for the decolorizer to remove it from the thicker peptidoglycan layer of gram-positive bacteria.
If iodine is not applied, both the gram-positive and gram-negative stains will appear to be gram-negative. The iodine acts as a mordant that helps to fix the crystal violet stain in the gram-positive bacteria, making them appear purple. Without iodine, the crystal violet stain can be easily washed out of both gram-positive and gram-negative bacteria, resulting in a pink or red color.
You do not " get " them, but gram positive bacteria are gram positive because their cell wall is of sufficient thickness and properly constructed to hold the Gram stain. They have one thick wall of peptidoglycan that holds the stain against being washed away. Gram negative bacteria have two thinner walls which allow the stain to be washed away, basically.