Microbiology for Beginners

Equipment Essential for Microbiology Laboratory

Equipment Essential for Microbiology Laboratory

There are many must-have types of equipment used in the microbiology laboratory. Some of them are inoculating loops, microscopes, and many more.

Gel Filtration Chromatography

Gel Filtration Chromatography

Gel Filtration Chromatography separates the samples based on the molecular size and shape of specimen present in them.

Phase Contrast Microscope

Phase Contrast Microscope

Phase contrast microscope is a modified version of bright field microscope that helps in visualizing cells or objects without staining.

Thin Layer Chromatography

Thin Layer Chromatography

The chromatography using thin layers of adsorbent held on a glass plate is known as thin layer chromatography. It has stationary and the mobile phase.

Chromatography: An Overview

Chromatography: An Overview

Chromatography is a separation technique that uses a stationary and mobile phase to separate the mixture.

Types of Microscopes and Their Uses

Types of Microscopes and Their Uses

There are two types of microscope: light microscope and electron microscope. Light microscope uses visible light and electron microscope uses beam of electrons as a source of illumination.

Which Probiotics to Use?

Which Probiotics to Use?

A number of commercial providers are marketing various probiotic products. With so many options choosing a probiotic can be confusing.

Working Mechanism of Light Microscope

Working Mechanism of Light Microscope

Light projects through an opening in the stage. Then the projected light hits the object and enters the objective lens. Resolution is the ability of a lens to distinguish two adjacent points as distinct and separate.

Parts of Microscope and Their Functions

Parts of Microscope and Their Functions

Microscope is a piece of laboratory optical equipment that is used to magnify small things that are too small for the details to be seen by the naked eye.

Microbial Jargons and Their Meaning

Microbial Jargons and Their Meaning

Jargon refers to technical vocabulary that is specific to a particular profession or field.

Microorganisms with Probiotic Properties

Microorganisms with Probiotic Properties

Species of Lactobacillus and Bifidobacterium are most commonly used as probiotics. Other are Saccharomyces boulardii, Streptococcus, etc.

Probiotics, Prebiotics and Health Benefits

Probiotics, Prebiotics and Health Benefits

Prebiotics are complex carbohydrates that escape digestion in the upper gastrointestinal tract and are available for microorganisms living in the colon.

Cell Wall–Deficient Bacteria

Cell Wall–Deficient Bacteria

Although most prokaryotes cannot survive in nature without their cell walls, some do so naturally. For example, mycoplasma and thermoplasma.

Nutritional Types of Bacteria

Nutritional Types of Bacteria

Organisms that can utilize radiant energy (sunlight) are called phototrophs. Chemotrophs are organisms that can harvest energy from chemicals.

Archaea: Characteristics, Similarities, Differences with Bacteria

Archaea: Characteristics, Similarities, Differences with Bacteria

Archaea is a group of phylogenetically related prokaryotes distinct from Bacteria and known for tolerance to physiochemical extremes.

Normal Flora of the Skin-Skin Microbiome

Normal Flora of the Skin-Skin Microbiome

Human skin is home to billions of diverse bacteria, archaea, fungi, and viruses with bacteria making up the vast majority

Bacterial Quorum Sensing

Bacterial Quorum Sensing

Quorum sensing (QS) is a bacterial cell-cell signaling mechanism that helps them to adjust gene expressions based on requirements.

Electron Microscope: Principle, Types, Applications

Electron Microscope: Principle, Types, Applications

Electron microscope is a type of microscope with high resolving power, that uses electrons instead of visible light to illuminate the object.

Fluorescence Microscope: Principle, Types, Applications

Fluorescence Microscope: Principle, Types, Applications

Fluorescence microscopy is widely used in diagnostic microbiology (diagnosis of tuberculosis, trichomoniasis) and in microbial ecology.

Radiation Sterilization: Types, Mechanism, Applications

Radiation Sterilization: Types, Mechanism, Applications

Sterilization and decontamination in the medical supplies (surgical supplies, vaccines, and drugs) is done using radiation sterilization.

Disinfection: Methods and Uses

Disinfection: Methods and Uses

Disinfection is a process whereby pathogenic organisms, but not necessarily all microorganisms or spores, are destroyed.

pH Requirements of Microorganism

pH Requirements of Microorganism

Most microorganisms grow best around neutral pH values (6.5 - 7.0), but some thrive in extreme pH conditions (pH10).

Gram-Positive Bacilli (Rods) and Diseases

Gram-Positive Bacilli (Rods) and Diseases

Gram-positive bacilli are a diverse group of bacteria responsible for variety of infections such as gas-gangrene, tetanus, anthrax, etc.

Psychrophiles, Mesophiles, Thermophiles

Psychrophiles, Mesophiles, Thermophiles

Psychrophiles can grow at 0°C, mesophiles have optimum temperature near 37°C, and thermophiles grow best at 50-60°C.

Preparation of Gram stain Reagents

Preparation of Gram stain Reagents

Reagents are primary stain (crystal violet), mordant (iodine), decolorizer (ethanol or acid-alcohol), and counterstain (safranin or dilute carbol-fuchsin).

Lab Diagnosis of Intestinal Parasitic Infections

Lab Diagnosis of Intestinal Parasitic Infections

Detection of the parasites or their particular stages (ova/egg, cyst, larva or trophozoite) in the stool specimen is diagnostic.

SEM vs. TEM Electron Microscopy

SEM vs. TEM Electron Microscopy

SEM provides detailed images of the surfaces of cells whereas TEM provides details about internal composition, morphology, crystallization.

Spread Plate Technique: Principle, Procedure, Results

Spread Plate Technique: Principle, Procedure, Results

Bacterial culture method for estimating the viable bacterial count after serial dilutions (when required).

Most Probable Number (MPN) Test: Principle, Procedure, Results

Most Probable Number (MPN) Test: Principle, Procedure, Results

The most probable number (MPN) is a statistical serial dilution method for estimating viable numbers of bacteria present in a food or water sample.

Carbohydrate Fermentation Test: Uses, Principle, Procedure, Results

Carbohydrate Fermentation Test: Uses, Principle, Procedure, Results

It tests for the presence of acid and/or gas produced from carbohydrate fermentation. and is useful in differentiating among bacterial groups or species.

Microbes with Good and Bad Smell

Microbes with Good and Bad Smell

Odor of colonies of bacteria may help in their identification but sniffing culture plates is not a good idea and you may contract a disease.

Pour Plate Method: Procedure, Uses, (Dis) Advantages

Pour Plate Method: Procedure, Uses, (Dis) Advantages

One of the best methods to determine the number of bacteria present per mL of liquid broth/specimen.

Capsule Stain: Principle, Procedure, Results

Capsule Stain: Principle, Procedure, Results

The best way to visualize capsule is to stain the background using an acidic stain and to stain the cell itself using a basic stain.

Streak Plate Method: Principle, Procedure, Uses  

Streak Plate Method: Principle, Procedure, Uses  

Routine method for the isolation of bacteria from clinical specimen or for obtaining individual isolated colonies from a mixed culture.

Simple Staining: Principle, Procedure, Uses

Simple Staining: Principle, Procedure, Uses

Any basic dye such as methylene blue, safranin, or crystal violet can be used to color the bacterial cells. Not performed routinely in a diagnostic lab.

Taenia solium vs. Taenia saginata 

Taenia solium vs. Taenia saginata 

Taeniasis is caused by both Taenia solium and Taenia saginata but only infections with Taenia solium may cause cysticercosis. Find out why

Staphylococcus vs. Micrococcus

Staphylococcus vs. Micrococcus

Micrococcus is lysostaphin and furazolidone resistant, bacitracin sensitive and microdase positive. Find the results of Staphylococcus.

Difference Between Prokaryotic Cell and Eukaryotic Cell

Difference Between Prokaryotic Cell and Eukaryotic Cell

Eukaryotic cells contain a nucleus with a nuclear membrane enclosing multiple chromosomes, while prokaryotic cells have a single chromosome.

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Key Phrases Used in Microbiology Lab Reports

Some famous and notorious people, a microbiologist must know  (Part-1)

Some famous and notorious people, a microbiologist must know (Part-1)

Buffy Coat: Definition, Preparation, Uses  

Buffy Coat: Definition, Preparation, Uses  

Buffy coat suspension is a concentrated leukocyte suspension which contains WBCs and platelets.

Endospore Staining: Principle, Procedure, Results

Endospore Staining: Principle, Procedure, Results

In Schaeffer-Fulton`s method, primary stain-malachite green is forced into the spore by steaming the smear, safranin is counterstain.

Microbiology Laboratory Safety Rules and Procedure

Microbiology Laboratory Safety Rules and Procedure

Safety in a microbiology laboratory is important in the prevention of infection because virulent and/or potentially pathogenic microorganisms are cultured (grown) there. 

Robert Koch and Koch’s postulates

Robert Koch and Koch’s postulates

Robert Koch is also known as the 'Father of Clinical Microbiology.' Koch's postulate provided guidelines to identify the causative agent of an infectious disease.

Catalase test: Principle, Procedure, Results, Uses

Catalase test: Principle, Procedure, Results, Uses

Catalase test is used to distinguish among Gram-positive cocci. Staphylococci are catalase-positive but Streptococci are catalase-negative.

Enterobacteriaceae Family: Common Characteristics

Enterobacteriaceae Family: Common Characteristics

Enterobacteriaceae is a family of gram-negative rods which are catalase positive and oxidase negative.

What are the roles of Medical Microbiologist?

What are the roles of Medical Microbiologist?

Medical microbiologists working in reference laboratories might be devoted to carrying out research in a particular gene whereas the microbiologist working in a general diagnostic laboratory are confined to routine laboratory works.

Modified Kirby-Bauer Disc Diffusion Method

Modified Kirby-Bauer Disc Diffusion Method

Modified Kirby-Bauer disc diffusion test method is a reference method to test the susceptibility of a bacterial isolate in a clinical laboratory.

Gram-Positive vs. Gram-Negative Bacteria

Gram-Positive vs. Gram-Negative Bacteria

Gram positive bacteria appear purple and gram-negative bacteria appear pink when stained by Gram-staining methods.

Types of Staining Techniques Used in Microbiology

Types of Staining Techniques Used in Microbiology

Based on the types and number of dyes used, staining can be categorized simple stain, negative stain, impregnation methods and differential stain.

List of interesting infectious diseases and reason behind their funny name

List of interesting infectious diseases and reason behind their funny name

Biosafety Levels and Agents of Disease

Biosafety Levels and Agents of Disease

There are four risk groups (RG1-RG4, RG1 being lowest risk) and four bio-safety levels (BSL-1 to BSL-4). BSL-4 is maximum containment.

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Common Cause of Bacteremia and Sepsis

Most common cause are E. coli, S. aureus, Salmonella, Klebsiella pneumoniae, S. pnuemoniae and H. influenzae.

Henrietta Lacks and Origin of HeLa Cells

Henrietta Lacks and Origin of HeLa Cells

Why is common cold so common?

Why is common cold so common?

Common cold, also known simply as a cold, is a self-limiting viral infection of the upper respiratory tract.

Why Viral Nucleic acid (Genome) is unique?

Why Viral Nucleic acid (Genome) is unique?

Nobel Prizes for Research in Microbiology and Immunology

Nobel Prizes for Research in Microbiology and Immunology

Nobel prize in Physiology and Medicine-2020 was given to three different virologist for the discovery of Hepatitis C virus.

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Extracellular and Intracellular Bacteria

Obligate intracellular bacteria cannot be grown in artificial media (agar plates/broths) in laboratories but requires viable eukaryotic host cells.

Microbiologists Just Want to Have Fun

Microbiologists Just Want to Have Fun

Bacterial Growth Curve: Phases, Significance

Bacterial Growth Curve: Phases, Significance

Typical growth curve of microorganisms in a closed system consists of distinct phases called lag phase, log phase, stationary phase, and death phase.

Biosafety level 2 (BSL2) guidelines for teaching laboratories

Biosafety level 2 (BSL2) guidelines for teaching laboratories

BSL2 is suitable for organisms that pose a moderate individual risk and low community risk for infection.

Oxygen Requirements for Pathogenic Bacteria

Oxygen Requirements for Pathogenic Bacteria

Microorganisms can be classified as obligate aerobes, facultative, microaerophilic, aerotolerant and obligate anaerobes based on their oxygen requirements.

Size, Shape, Arrangement of Bacteria

Size, Shape, Arrangement of Bacteria

Bacteria exist in four basic morphologies: cocci; rod-shaped cells, or bacilli; spiral-shaped cells, or spirilla; and comma-shaped cells, or vibrios.

Amazing world of Microbes: Some Unbelievable Facts

Amazing world of Microbes: Some Unbelievable Facts

Career Opportunities for Microbiologist

Career Opportunities for Microbiologist

Motility Patterns of Bacteria

Motility Patterns of Bacteria

Motility patterns of Gram-negative bacteria are also used for their identification. Most of the Gram-positive bacteria are non-motile.

Peptidoglycan: Structure, Function

Peptidoglycan: Structure, Function

Peptidoglycan consists of carbohydrate backbone composed of alternating units of NAG and NAM molecules attached through β-1,4-glycosidic bonds.

Cytoplasmic Granules in Bacteria

Cytoplasmic Granules in Bacteria

Concentrated deposits of certain substances which are presented/located in the cytoplasm of certain bacteria.

Teichoic Acid: Structure, Functions

Teichoic Acid: Structure, Functions

Teichoic acids are fibers of glycerol phosphate or ribitol phosphate and is located in the cell-wall of gram-positive bacteria.

Lipopolysaccharide (LPS) Layer

Lipopolysaccharide (LPS) Layer

Lipopolysaccharide (LPS) layer also called the outer membrane is the outermost layer present in the cell wall of gram-negative bacteria.

Bacterial Pili (Fimbriae): Types, Functions

Bacterial Pili (Fimbriae): Types, Functions

Pili or fimbriae are hair-like filaments that help pathogen in adherence to host cells. Sex pili play role in conjugation.

Flagella: Structure, Arrangement, Function

Flagella: Structure, Arrangement, Function

Flagella are long, whiplike appendages that move the bacteria toward nutrients and other attractants

Bacterial Spores: Structure and Spore-Forming Bacteria

Bacterial Spores: Structure and Spore-Forming Bacteria

Bacterial spores are highly resistant, dormant structures formed in response to adverse environmental conditions

Bacterial Capsule: Importance, Capsulated Bacteria

Bacterial Capsule: Importance, Capsulated Bacteria

Capsule is a gelatinous layer covering the bacterium and is a major virulence factor of S. pneumoniae, H. influenzae, etc.

Why Microbiology is the Most Interesting Subject

Why Microbiology is the Most Interesting Subject

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Funny Name of Microorganisms

Coagulase Test: Principle, Procedure, Results

Coagulase Test: Principle, Procedure, Results

Coagulase test detects clumping factors and bound coagulase and differentiates Staphylococcus aureus (positive) from CoNS (negative).