Negative staining technique principle, procedure, results. The methylene blue stain is a simple technique, staining everything blue. Introduction observation of bacteria with conventional bright field microscopy yields relatively little useful information. Other stain techniques seek to identify various bacterial structures of importance. Gram stain the previous lab introduced simple staining techniques that enable microbiologists to observe the morphological characteristics of bacteria. Stains and dyes are frequently used in histology the study of tissue under the microscope and in the medical fields of histopathology, hematology, and cytopathology that focus on the study and diagnoses disease at a microscopic level. Distinguishes bacteria of two large and medically important groups. The gram stain procedure distinguishes between gram positive and gram negative groups by coloring these cells red or violet. Gram staining is a common technique used to differentiate two large groups of bacteria based on their different cell wall constituents. To learn the techniques of gram staining, nigrosin staining and koh test. Before you can create an account, you must have filled out the wgu application and paid the application fee. Gram staining helps to identify bacterial pathogens in specimens and cultures by their gram reaction gram positive and gram negative and morphology coccirod. Staining microscopic specimens microbiology lumen learning. In 1884, hans christian gram, a danish doctor, developed a differential staining technique that is still the cornerstone of bacterial identification and taxonomic division.
Staining is a technique used to enhance contrast in samples, generally at the microscopic level. To use and relate the gram stain to the study of bacterial cell morphology, and as an important step in the identification of a bacterial species. Some tests are used routinely for many groups of bacteria oxidase, nitrate reduction, amino acid degrading enzymes, fermentation or utilization of carbohydrates. Grams iodine acts as a mordant helps to fix the primary dye to the cell. The primary stain of this method is crystal violet, which. It was developed by danish microbiologist hans christian gram in 1884 as an effective method to distinguish between bacteria with different types of cell walls, and even today it remains one of the most frequently used staining techniques. Types of staining techniques used in microbiology and. A positive capsule stain requires a mordant that precipitates the capsule. The lab report assistant is simply a summary of the experiments questions, diagrams if needed, and data tables that should be addressed in a formal lab report. Gramnegative bacteria tend to exhibit lower fluorescence intensity than grampositive bacteria, because of their cell structure outer membrane impedes penetration of cfda. Some staining techniques involve the application of only one dye to the. View types of bacterial staining techniques pdf from biol 240l at university of waterloo. The staining procedures require the use of a mordant so that the stain adheres in layers to the flagella, allowing visualization.
Choose from 500 different sets of microbiology staining techniques flashcards on quizlet. Virology techniques introduction virology is a field within microbiology that encompasses the study of viruses and the diseases they cause. The acid fast bacteria have a waxy substance mycolic acid on their cell wall that makes them impermeable to staining procedures. The procedure is named for the person who developed the technique, danish bacteriologist hans christian gram. Learn microbiology staining techniques with free interactive flashcards. By counterstaining with dyes like crystal violet or methylene blue, bacterial cell wall takes up the dye. Bacteria and cells are visualised without enabling differentiation of bacteria according. Other stain techniques seek to identify various bacterial structures of. In the past, conventional identi fi cation of fungi relied on the combination of morphological and physiological properties. In recent years, morphological studies, supplemented with staining techniques and biochemical methods, still play an.
In the laboratory, viruses have served as useful tools to better understand cellular mechanisms. Cover different classification schemes for grouping bacteria, especially the use of the gram stain 2. Classification of bacteria basic microbiology online. However, the use of these dyes by themselves only stains fungal structures andor plant cell walls and provides no clear distinction between the fungal and plant cell walls. Introduction bacteria are too small to see without the aid of a microscope. Gram stain or gram staining, also called grams method, is a method of staining used to distinguish and classify bacterial species into two large groups. To be visible on a slide, organisms that stain by the gram method must be present in concentrations of.
Flagella stain principle, procedure and result interpretation. Already available was a staining method designed by robert. Histologic staining options available include, but are not limited to. Capsules appear colourless with stained cells against dark background. Other bacteria lose the stain and take on the subsequent methylene blue stain blue. Hence staining techniques are used to produce colour contrast. Stains may be used to define biological tissues highlighting. The most widely used staining procedure in microbiology is the gram stain, discovered by the danish scientist and physician hans christian joachim gram in 1884. Gram staining is a differential staining technique that differentiates bacteria into two groups. The steps of the gram stain procedure are listed below and illustrated in table 1. Types of bacterial staining techniquespdf types of. Capsules are fragile and can be diminished, desiccated, distorted, or destroyed by heating. Staining simply means coloring of the micro organisms with the dye that emphasizes and elucidate different important structures of microorganisms including bacteria, virus, protozoa and etc. Staining techniques in microbiology linkedin slideshare.
Live bacteria do not show the structural detail under the light microscope due to lack of contrast. Gram stain is a very important differential staining techniques used in the initial characterization and classification of bacteria in microbiology. Kits are available commercially, or formulas for reagents are listed in appendix b. The most useful staining procedure in medical microbiology. Fixation of clinical materials to the surface of the microscope slide either by heating or by using methanol. Some staining techniques utilize these differences to stain the bacteria differently. Bacterial classification, structure and function introduction the purpose of this lecture is to introduce you to terminology used in microbiology. Bacteria vary in certain physiological and biological properties. Different bacteria stain differently to a common staining procedure.
This staining technique is used to demonstrate the presence of acid fast bacilli. When this secretion remains loose and undemarcated it is called a slime layer and when it is organized into a sharply defined structure it is called as capsule. When the bacteria is stained with primary stain crystal violet and fixed by the mordant, some of the bacteria are able to retain the primary stain and some are. New staining technique for fungalinfected plant tissues. It is almost always the first test performed for the identification of bacteria.
Gram stain protocols american society of microbiology. Gram stain developed in 1884 by hans gram, a danish microbiologist. Crystal violet may also be used as a simple stain because it dyes the cell wall of any bacteria. In microbiology the concept of staining is very important because it highlights the structures of microorganisms allowing them to be seen under a microscope. Objectives to learn the technique of smear preparation. The purpose of this lesson is to provide a general overview of laboratory techniques used in the. The gram stain is a differential method of staining used to assign bacteria to one of two groups grampositive and gramnegative based on the properties of their cell walls.
Bacteria have an affinity to basic dyes due to acidic nature of their protoplasm. The name comes from the danish bacteriologist hans christian gram, who developed the technique gram staining differentiates bacteria by the chemical and physical properties of their cell walls. If this is your first attempt to access the mywgu portal, you need to create an account before you can sign in. Some staining techniques, such as the gram and ziel neelsen stains, although of great diagnostic value because of their differential staining properties for specific bacteria, reveal little. Method of staining used to distinguish and classify bacterial species into two large groups. Grampositive bacteria gramnegative bacteria provides useful information for disease treatment. In negative staining technique, an acidic stain such as nigrosin, india ink, eosin or congo red is used in which the bacterial culture or the specimen is mixed well and then spread over the microscopic glass slide to form a thin smear. Such staining methods are called differential staining methods, these include gram staining and acid fast staining. A capsule in bacteria is the result of amorphous viscid secretion released by the bacteria. The gram stain and differential staining journal of. While some eucaryotes, such as protozoa, algae and yeast, can be seen at magnifications of 200x400x, most bacteria can only be seen with x magnification.
Acid fuchsin is a magenta red acid dye that is largely used for plasma staining whereas basic fuchsin is a magenta basic dye largely used to stain the nucleus the technique is also referred to as acid fast staining. Asm journals are the most prominent publications in the field, delivering uptodate and authoritative coverage of both basic and clinical microbiology. Capsule staining principle, reagents, procedure and result. Gram staining is the common, important, and most used differential staining techniques in microbiology, which was introduced by danish bacteriologist hans christian gram in 1884. The previous lab introduced simple staining techniques that enable microbiologists to observe the morphological characteristics of bacteria. Types of different staining techniques of microorganisms. Staining of bacterial cells objective to learn the techniques of smear preparation, gram staining, nigrosin staining and correlating the results of gram staining with koh test. Gram stain pure strain cultures to determine whether gram negative or gram positive. Classic gram staining techniques involve the following steps. Identifying bacteria using gram, acidfast and spore. To prevent the bacteria from washing away during the staining steps, the smear may be chemically or physically fixed to the surface of the slide. A wet mount technique is used for staining bacterial flagella, and it is simple and useful when the number and arrangement of flagella are critical to the identification of species of motile bacteria. Staining techniques in microbiology a presentation by g. Most bacteria are identified and classified largely on the basis of their reactions in a series of biochemical tests.
Make a thin film of the material on a clean glass slide, using a. This test differentiate the bacteria into gram positive and gram negative bacteria, which helps in the classification and differentiations of microorganisms. Pdf staining techniques and biochemical methods for the. Routine methods of staining of bacteria involve dying and fixing smears procedures that kill them. Make a thin film of the material on a clean glass slide, using a sterile loop or swab for viscous specimens. Gram staining detects a fundamental difference in the cell wall composition of bacteria. The name comes from the danish bacteriologist hans christian gram, who developed the technique. In gram positive bacteria, the crystal violet dye iodine complex combines to form a larger molecule which precipitates. In this exercise, bacterial endospores will be visualized by special staining techniques.
953 49 1005 670 5 715 1530 602 910 1481 939 500 1545 941 388 258 1017 706 519 476 1110 201 104 269 468 198 640 1214 553 1056