Name: gram and acid-fast staining methods
Uploaded: 2025-06-12T09:26:11.000Z
Duration: 1 min 26 s
Channel: JoVE

K12 Standards

new-york-state-science-learning-standards

New York State Science Learning Standards

Middle School

Earth and Space Sciences

Space Systems

MS-ESS1-1

Differential Staining Technique

A coloração diferencial distingue os microrganismos com base nas propriedades da parede celular, auxiliando na identificação e classificação bacteriana. A coloração de Gram classifica as bactérias como gram-positivas ou gram-negativas por sua capacidade de reter o cristal violeta após a descoloração do álcool. Uma fina mancha de cultura microbiana é espalhada em uma lâmina, seca ao ar e fixada por calor. O esfregaço é corado com cristal violeta, lavado com água e tratado com iodo, formando um complexo cristal violeta-iodo. O álcool é usado para descolorir esse esfregaço até que o escoamento esteja claro, seguido de um enxágue com água. As bactérias Gram-positivas retêm a mancha roxa devido à sua espessa camada de peptidoglicano. Em contraste, as bactérias gram-negativas perdem a mancha roxa à medida que o álcool rompe a membrana externa e lava o complexo cristal violeta-iodo. A safranina é usada para contrabalançar as bactérias gram-negativas de rosa, enquanto as bactérias gram-positivas permanecem roxas. A coloração álcool-ácido resistente detecta Mycobacterium espécie, cujas paredes celulares cerosas e ricas em ácido micólico resistem à descoloração. As bactérias ácido-resistentes retêm carbol fucsina

técnica de coloração diferencial

A colora&#231;&#227;o diferencial &#233; uma t&#233;cnica microbiol&#243;gica essencial que explora varia&#231;&#245;es nas estruturas da parede celular para classificar e identificar microrganismos. Ela facilita a distin&#231;&#227;o entre bact&#233;rias, auxiliando em aplica&#231;&#245;es diagn&#243;sticas e de pesquisa. Duas das t&#233;cnicas de colora&#231;&#227;o diferencial mais amplamente utilizadas s&#227;o a colora&#231;&#227;o de Gram e a colora&#231;&#227;o &#225;cido-resistente, ambas baseadas em diferen&#231;as qu&#237;micas e estruturais nas paredes celulares bacterianas.
T&#233;cnica de Colora&#231;&#227;o de Gram
A colora&#231;&#227;o de Gram diferencia as bact&#233;rias com base na composi&#231;&#227;o de suas paredes celulares, classificando-as como gram-positivas ou gram-negativas. Esta t&#233;cnica come&#231;a com a prepara&#231;&#227;o de um esfrega&#231;o bacteriano fixado ao calor, que &#233; inicialmente corado com violeta cristal. Em seguida, adiciona-se iodo, formando um complexo violeta cristal-iodo que fica retido na parede celular. O tratamento subsequente com um descolorante &#224; base de &#225;lcool remove esse complexo das bact&#233;rias gram-negativas, mas n&#227;o das gram-positivas. A diferen&#231;a reside na espessa camada de peptideoglicano das bact&#233;rias gram-positivas, que ret&#233;m a colora&#231;&#227;o roxa. Por outro lado, as bact&#233;rias gram-negativas possuem uma camada de peptideoglicano mais fina e uma membrana externa que &#233; desestruturada pelo &#225;lcool, resultando na perda da colora&#231;&#227;o roxa. Aplica-se ent&#227;o a safranina como corante de contraste, fazendo com que as bact&#233;rias gram-negativas adquiram colora&#231;&#227;o rosa, enquanto as gram-positivas permanecem roxas.
T&#233;cnica de Colora&#231;&#227;o &#193;cido-Resistente
A colora&#231;&#227;o &#225;cido-resistente &#233; especialmente &#250;til para identificar esp&#233;cies do g&#234;nero Mycobacterium, cujas paredes celulares ricas em &#225;cido mic&#243;lico resistem &#224; colora&#231;&#227;o convencional e &#224; descolora&#231;&#227;o. Nesse procedimento, aplica-se um corante vermelho, a carbolfucsina, a um esfrega&#231;o fixado ao calor, frequentemente com aquecimento, para facilitar a penetra&#231;&#227;o do corante no m&#233;todo de Ziehl-Neelsen. Em seguida, utiliza-se uma solu&#231;&#227;o de &#225;lcool &#225;cido para remover o corante das c&#233;lulas n&#227;o &#225;cido-resistentes. As bact&#233;rias &#225;cido-resistentes, devido &#224;s suas paredes celulares cerosas, ret&#234;m a colora&#231;&#227;o vermelha, ao passo que as c&#233;lulas n&#227;o &#225;cido-resistentes s&#227;o coradas com azul, geralmente com azul de metileno. Vale destacar que o m&#233;todo de Kinyoun, uma varia&#231;&#227;o da colora&#231;&#227;o &#225;cido-resistente, n&#227;o requer aquecimento para a aplica&#231;&#227;o da carbolfucsina.
Ambas as t&#233;cnicas de colora&#231;&#227;o s&#227;o ferramentas indispens&#225;veis para a identifica&#231;&#227;o microbiana, diagn&#243;stico cl&#237;nico e determina&#231;&#227;o de interven&#231;&#245;es terap&#234;uticas apropriadas. Por exemplo, bact&#233;rias gram-negativas frequentemente apresentam maior resist&#234;ncia a certos antibi&#243;ticos devido &#224; presen&#231;a de sua membrana externa, tornando sua identifica&#231;&#227;o cr&#237;tica para um tratamento eficaz. Compreender essas t&#233;cnicas &#233; fundamental para a microbiologia e a pr&#225;tica cl&#237;nica, permitindo uma identifica&#231;&#227;o precisa e auxiliando na escolha dos antibi&#243;ticos adequados.

Técnica de Coloração Diferencial

A colora&#231;&#227;o diferencial &#233; uma t&#233;cnica microbiol&#243;gica essencial que explora varia&#231;&#245;es nas estruturas da parede celular ...

Education

JoVE Core

Microbiology

Microbiologia

Unit

Unidade

Introduction to Microbiology

Introdução à Microbiologia

KEY TERMS AND CONCEPTS

TERMOS E CONCEITOS-CHAVE

gram and acid-fast staining methods

Gram and acid-fast staining methods help scientists tell bacteria apart by looking at their cell walls. These differential stains are important in microbiology because they support identification, diagnosis, and research. They use structural and chemical differences in bacterial cell walls to separate microorganisms into clear groups.

Gram staining classifies bacteria as gram-positive or gram-negative. A heat-fixed bacterial smear is first stained with crystal violet, and iodine is added to form a crystal violet-iodine complex. Alcohol then acts as a decolorizer. It removes the complex from gram-negative cells but not from gram-positive cells.

The reason for this difference is the cell wall structure. Gram-positive bacteria have a thick peptidoglycan layer, which holds the purple stain. Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane. Alcohol disrupts that outer membrane, so the purple stain is lost. Safranin is then used as a counterstain. It turns gram-negative bacteria pink while gram-positive bacteria stay purple.

Acid-fast staining is used to identify Mycobacterium species. These bacteria have mycolic acid-rich cell walls, which resist normal staining and decolorization. Carbolfuchsin, a red dye, is applied to a heat-fixed smear. In the Ziehl-Neelsen method, heat is often used to help the dye enter the cell. Acid-alcohol then removes the stain from non-acid-fast cells.

Acid-fast bacteria keep the red stain because their waxy cell walls hold it. Non-acid-fast cells lose the red dye and are counterstained blue, usually with methylene blue. A related method, the Kinyoun stain, does not use heat for carbolfuchsin application. Both gram staining and acid-fast staining are essential for microbial identification, clinical diagnostics, and choosing the right treatment. Gram-negative bacteria can be more resistant to some antibiotics because of their outer membrane, so identifying them can guide therapy.

Gram and Acid-Fast Staining Methods

history of microbiology

Microbiology's Key Discoveries Over Time

Microbiology is the study of microorganisms, and its history is shaped by major discoveries about life at the microscopic level. Since the 17th century, new tools and experiments have changed how scientists understand microbes and their effects on medicine, agriculture, and industry. The early foundations of microbiology began with better microscopes and careful observation. In 1665, Robert Hooke examined thin slices of cork with a crude microscope and described the small boxlike spaces he saw.

two-dimensional microscopy in microbiology

two-dimensional-microscopy-in-microbiology

Microscopy Methods for Viewing Microbes

Two-dimensional microscopy helps scientists view microbes and cells in a single focal plane. It is widely used in biological and medical research because it shows cellular and subcellular structures with different levels of contrast and detail. Each method has its own strengths, so the best choice depends on the specimen and the question being studied. Bright-field microscopy is the most common form of light microscopy. It uses transmitted light that passes through the specimen, and stains are...

three-dimensional microscopy in microbiology

three-dimensional-microscopy-in-microbiology

Live and Deep Cell Imaging Methods

Three-dimensional imaging methods help scientists see cell structures with more detail. In microbiology, Differential Interference Contrast Microscopy, or DIC, and Confocal Scanning Laser Microscopy, or CSLM, are two important tools. They each solve different imaging problems and give useful views of cells and tissues. DIC microscopy improves contrast in transparent, unstained samples. It works by turning phase differences, which come from changes in refractive index inside cell structures,...

simple staining technique

Staining Microbes for Shape and Arrangement

Simple staining helps reveal the size, shape, and arrangement of microorganisms under the microscope. It uses one dye to color the whole cell. That creates strong contrast between the cells and the background. A careful preparation step comes first. A small drop of microbial culture is spread on a clean glass slide to make a thin smear. The smear is air-dried and then heat-fixed, which means it is briefly passed over a flame. Heat fixation keeps the cells attached to the slide. It also helps...

differential staining technique

Gram and acid-fast staining methods help scientists tell bacteria apart by looking at their cell walls. These differential stains are important in microbiology because they support identification, diagnosis, and research. They use structural and chemical differences in bacterial cell walls to separate microorganisms into clear groups. Gram staining classifies bacteria as gram-positive or gram-negative. A heat-fixed bacterial smear is first stained with crystal violet, and iodine is added to...

special staining techniques

Bacterial Stains for Capsules, Spores, Flagella

Special bacterial stains help reveal capsule, endospore, and flagella structures that standard microscopy cannot show clearly. These stains improve how microbiologists identify bacteria and understand features linked to disease and classification. They are also useful in diagnosis and research because they expose key parts of bacterial cells. Capsule staining is a negative staining method that makes the capsule visible. A bacterial capsule is an outer layer that can act as a virulence factor,...

key techniques in microbiology

Aseptic Methods for Microbial Cultures

Aseptic methods help keep microbial cultures clean, safe, and accurate in the laboratory. These practices reduce contamination and protect both researchers and the microbes being studied. They are important in clinical, industrial, and research settings where sterility matters. Laboratory sterility starts with cleaning tools and surfaces. Scientists sterilize equipment with heat or chemicals and disinfect work areas before handling cultures. They also work near an open flame or inside a...

types of microorganisms

Microorganism Groups and Their Roles

Microorganisms are tiny life forms and particles that can be grouped by structure. Cellular microorganisms include bacteria, archaea, fungi, protozoa, and algae. Viruses are acellular, which means they are not made of cells. Bacteria are prokaryotic organisms, so they do not have a nucleus. They can be rod-shaped, spherical, or spiral-shaped. Bacteria live in soil, water, and human-associated places like the gut. Some, such as Escherichia coli and Streptococcus, are important in health and...

environmental applications of microorganisms

environmental-applications-of-microorganisms

Microbes in Ecosystems and Pollution Control

Microorganisms help keep ecosystems balanced by recycling carbon, nitrogen, and phosphorus. They also support sewage treatment, bioremediation, and biofuel production. These roles make microbes important in both natural and human-made systems. In the carbon cycle, microorganisms break down dead organic matter. During aerobic respiration, they release carbon dioxide. Photosynthetic organisms then use that carbon dioxide to make organic compounds, which helps close the carbon loop. Microbes are...

microorganisms in agriculture and food industry

microorganisms-in-agriculture-and-food-industry

How Microbes Improve Farming and Food

Microbes improve farming and food production by helping plants grow, protecting crops, and making foods such as bread, yogurt, and pickles. These tiny organisms support soil fertility, pest control, fermentation, and food preservation. They are a key part of sustainable agriculture and food safety. In agriculture, nitrogen-fixing bacteria turn nitrogen from the air into ammonia, which plants can use to build amino acids and proteins. Rhizobium lives with plant roots, while Azotobacter is...

microorganisms in medicine and therapeutics

microorganisms-in-medicine-and-therapeutics

Microbes in Vaccines and Gene Therapy

Microbes in vaccines and gene therapy help modern medicine prevent disease and treat genetic disorders. Scientists use the biological properties of microorganisms to support public health, improve immune protection, and make therapeutic products. These uses also include gut health and antibiotic production. Live attenuated vaccines use weakened pathogens, such as the measles, mumps, and rubella (MMR) vaccine. They act like a natural infection and can trigger cellular, humoral, and mucosal...

key terms and concepts

Learn how Gram staining and acid-fast staining identify bacteria by cell wall structure, from crystal violet to carbolfuchsin, for diagnostics and treatment.

Gram and Acid-Fast Staining Methods | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

Weather and Climate

MS-ESS2-5

MS-ESS2-6

Minnesota Academic Standards in Science

Earth and Space Science

1.1.1 Earth’s Place in the Universe

3.1.1

4.2.2

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

Earth's Place in the Universe

8-ESS1-3

Earth's Systems

6-ESS2-5

Earth and Human Activity

7-ESS3-5

8-ESS1-1

8-ESS1-2

6-ESS2-6

Punnett Squares

Punnett squares are a tool used in genetics to predict the possible traits an offspring might inherit from its parents. Developed by Reginald Punnett,

Differential staining is an essential microbiological technique that exploits variations in cell wall structures to classify and identify microorganisms. ...

Special Staining Techniques

Specialized staining techniques play a vital role in microbiology by enabling the visualization of specific bacterial structures that remain undetectable ...

Environmental Applications of Microorganisms

Microorganisms play a pivotal role in maintaining ecosystem balance by recycling essential elements such as carbon, nitrogen, and phosphorus, as well as ...

Microorganisms in Agriculture and Food industry

Microorganisms play a crucial role in agriculture and the food industry, contributing to soil fertility, crop protection, and food production. Their ...

Prokaryotic vs. Eukaryotic Cells

Prokaryotic and eukaryotic cells represent two fundamental types of cellular organization, differing significantly in structure, complexity, and function. ...

Microbial Morphologies 

Bacterial and archaeal cells exhibit remarkable diversity in shape and structure, critical in their adaptability and functionality. Among bacteria, the ...

Develop and use a model of the Earth-Sun-moon system to describe the cyclic patterns of lunar phases, eclipses of the Sun and moon, and seasons. [Clarification Statement: Examples of models could include physical, graphical, or conceptual models.]

Develop and use a model to describe the role of gravity in the motions within galaxies and the solar system. [Clarification Statement: Emphasis for the model is on gravity as the force that holds together the solar system and Milky Way galaxy and controls orbital motions within them. Examples of models could include physical models (such as a model of the solar system scaled using various measures or computer visualizations of elliptical orbits) or conceptual models (such as mathematical proportions relative to the size of familiar objects such as students' school or state).] [Assessment Boundary: Assessment does not include Kepler's Laws of orbital motion or the apparent retrograde motion of the planets as viewed from Earth.]

MS-ESS1-2

Analyze and interpret data to determine scale properties of objects in the solar system. [Clarification Statement: Emphasis is on the analysis of data from Earth-based instruments, space-based telescopes, and spacecraft to determine similarities and differences among solar system objects. Examples of scale properties could include the sizes of an object's layers (such as crust and atmosphere), surface features (such as volcanoes), and orbital radius. Examples of data could include statistical Information, drawings and photographs, and models.] [Assessment Boundary: Assessment does not include recalling facts about properties of the planets and other solar system bodies.]

MS-ESS1-3

What are Fossils?

Fossils are like nature’s time capsules. They are the remains or traces of plants and animals that lived long ago, sometimes millions of years ago. Th

How Fossilization Creates Fossils

Fossils are the preserved remains or traces of ancient organisms. They provide evidence of past life and environments. Fossilization is a rare process

Types of Fossilization - I

Fossils form in different ways depending on environmental conditions and the type of organism. Some fossils preserve hard parts like bones and shells,

Types of Fossilization -II

Fossils can form in different ways depending on how an organism is buried and preserved. Some fossils keep much of their original structure, while oth

Earth History and Clues from Fossils

Fossils are like nature’s time capsules. They hold clues about what Earth was like long before people existed. Some fossils show what ancient plants a

Principles of Relative Dating - I

Stratigraphy is the study of rock layers (strata) and their formation over time. It plays a key role in relative dating, helping geologists determine 

Principles of Relative Dating-II

Scientists use geological principles to determine the relative ages of rock layers and uncover Earth’s history. Two key concepts that help geologists 

Determining Relative Ages

Geologists determine the relative age of rock layers to understand Earth's history and the sequence of past events. Relative dating does not provide a

Geologic Time Scale - I

The geologic time scale is a system scientists use to organize Earth's long history into different time periods. It helps geologists understand major 

Geologic Time Scale-II

The geologic time scale helps scientists understand Earth's history by organizing it into different time periods. The Mesozoic and Cenozoic Eras are t

Tree Rings, Ice Cores, and Varves

Scientists use natural records such as tree rings, ice cores, and varves to study past climate conditions. These records reveal temperature, precipita

wegener-and-the-continental-drift-hypothesis

Wegener and the Continental Drift Hypothesis

In the early 1900s, Alfred Wegener, a German scientist, proposed the Continental Drift Hypothesis, the idea that Earth’s continents were once joined t

Construct a scientific explanation based on evidence from rock strata for how the geologic time scale is used to organize Earth's 4.6-billion-year-old history. [Clarification Statement: Emphasis is on how analyses of rock formations and the fossils they contain are used to establish relative ages of major events in Earth's history. Examples of Earth's major events or evidence could include very recent events or evidence (such as the last Ice Age or the earliest fossils of Homo sapiens) to very old events or evidence (such as the formation of Earth or the earliest evidence of life). Examples of evidence could include the formation of mountain chains and ocean basins, the evolution or extinction of particular living organisms, or significant volcanic eruptions.] [Assessment Boundary: Assessment does not include recalling the names of specific periods or epochs and events within them, radiometric dating using half-lives, and defining index fossils.]

MS-ESS1-4

Gram and Acid-Fast Staining Methods

Description

Transcript

Tags

More videos by Standards