Gram-positive and gram negative bacteria stain differently in a gram stain test because of the difference in their cell wall composition. The other bacterial cells that stain purple or blue are called gram-positive bacteria. This is because they take up the stain of the counterstain after being decolorized. After the gram staining process, the gram negative bacteria stain red or pink. Gram-negative bacteria are classified based on the color they turn after this gram staining process. The application of a primary stain (crystal violet)ĭuring this process, it is the cell wall structure that affects the ability of the bacterial cell to retain or lose the crystal violet stain used in the Gram staining procedure.The gram staining procedure involves 4 consecutive steps which include: Therefore, the two main features that differ the structure of gram positive bacteria from gram-negative bacteria include the thickness of the peptidoglycan layer and the presence or absence of the outer lipid membrane. This difference is due to the presence or absence of an outer lipid membrane. This differential staining method is based on the distinct differences in the structure and composition of the bacterial cell wall. The gram staining response of bacterial cells is an empirical criterion making gram positive bacteria and gram negative bacteria the two types of bacteria. Mechanism of the Gram stain test for bacteria classificationĪccording to the gram stain test, bacteria are traditionally divided into two groups:- gram-positive and gram-negative. Lysozyme is an antimicrobial enzyme produced by animals that form part of the immune system. These gram negative bacteria examples are of medical significance because their outer membrane protects them from lysozyme, detergents and many antibiotics (including penicillin). Common gram negative bacteria representative species include the model organism, Escherichia coli, and many pathogenic bacteria, such as Chlamydia trachomatis, Pseudomonas aeruginosa, and Yersinia pestis. Photo credit: These organisms can be found in virtually all environments on Earth that support life. Gram negative bacteria stain pink or red in a gram stain test The cell envelope of the gram negative bacteria cell is made up of a thin peptidoglycan cell wall incorporated between an inner cytoplasmic cell membrane and an outer membrane. Gram-negative bacteria are characterized by their cell envelopes. At the end of the gram stain, gram negative bacteria stain pink/ red while gram positive bacteria stain purple or blue. The Gram staining procedure in microbiology is a differential staining technique used to differentiate bacterial cells into gram-positive or gram-negative bacteria based on the differences in their cell wall components. Gram negative bacteria vs gram positive bacteria.What is the difference between gram positive and gram negative bacteria?.Why gram-negative bacteria are more harmful.Examples of gram negative bacteria antibiotics used for treatment include:.List of gram negative bacteria and their diseases.List of gram negative bacteria examples.Outer membrane of gram negative bacteria.Characteristics of gram negative bacteria.Mechanism of the Gram stain test for bacteria classification.
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