Applying Staining Techniques to View and Identify Bacteria

Abstract The main objective of this experiment was to identify different bacteria by simple staining, negative staining and Gram staining. In order to observe each bacterial cell, the bacteria were aseptically transferred to a glass slide and then observed with an oil microscope using an optical microscope. From the laboratory, E. coli and B. megaterium were Gram negative, B. subtilis and Streptococcus mutans were determined to be Gram positive. Introduction The purpose of this experiment was to observe various characteristics of bacteria by applying various staining techniques.

Gram stain is an examination to identify bacteria by cell wall composition. It was named after Hans Christian Gram who developed technology in 1884. Bacteria are first stained with a purple dye that specifically binds peptidoglycan of complex structure of amino acids and sugars on the cell wall. This is followed by a series of steps for ultimately removing unbound or loosely bound crystal violet. The cells are then stained with a second red dye called crocin. Gram-positive bacteria are stained purple because cell walls are rich in peptidoglycan. On the other hand, gram negative bacteria with two cell walls look red. The outer layer of lipid does not bind strongly to crystal violet and the dye is easily washed out during the dyeing process.

Danish microbiologist Hans Christian Joachim Gram has developed a way to distinguish bacteria by a reaction different from staining. The procedure for applying Gram stain was as follows: bacteria were stained with purple dye and treated with gram solution (1 part iodine, 2 parts potassium iodide and 300 parts water). Later, when ethanol is added to the medium, the bacteria retain the blue color of the original dye or become red shades. Blue bacteria are identified as gram positive and red bacteria as gram negative

Gram positive bacteria are classified according to their rotation color after chemicals called Gram stain. Gram-positive bacteria were stained blue when applied to staining. Other bacteria stain red. They are called Gram negative. Gram-positive bacteria and gram-negative bacteria have different cell walls, so the staining is different. They also cause different kinds of infections, and different kinds of antibiotics work for them. Gram positive bacteria are increasingly tolerant to antibiotics. For example, methicillin-resistant Staphylococcus aureus (MRSA) bacteria are resistant to most penicillin-related antibiotics. Methicillin is penicillin. MRSA strains usually contain infections obtained in medical institutions and may cause infections (regional infections) obtained outside the medical institution.