Microbiology Lecture Notes: Microbes, Morphology, Growth, Asepsis, and Normal Flora

A complete set of vocabulary flashcards keying in on fundamental definitions, bacterial structures, growth characteristics, sterilization protocols, and human normal flora based directly on the lecture transcript.

Microbiology

The study of organisms that are so small that they cannot be seen with the naked eye, derived from the Greek words Mikros (small), bios (life), and logia or logos (study of).

Microbes

Living and non-living entities that are ubiquitous, meaning they are found everywhere.

Bacteriology

The specialized field of microbiology focused on the study of bacteria.

Virology

The specialized field of microbiology focused on the study of viruses.

Mycology

The specialized field of microbiology focused on the study of mycoses.

Parasitology

The specialized field of microbiology focused on the study of parasites.

Acellular infection agent

Infectious agents lacking cellular structure that cannot reproduce on their own and require a living host cell to survive and replicate.

Prions

Infectious protein molecules that cause rare, fatal diseases in humans and animals, such as Creutzfeldth-Jakob Disease (CJD) and Mad Cow disease (MCD).

Viruses

Acellular microbes smaller than bacteria that are obligate intracellular parasites and are not considered to be living.

Pellicle

The outer surface structure characteristic of eukaryotic protozoa.

Cyst

The infective stage of protozoa capable of infecting a susceptible host.

Trophozoites

The pathogenic state of protozoa.

Diatoms

Unicellular algae containing silicon-dioxide.

Dinoflagellates

Unicellular algae that serve as important members of the phytoplankton group.

Comparison of Bacteria and Fungi Characteristics

A comparative summary detailing cell types, ecosystem roles, optimal pH ($6.5\text{--}7.0$ vs. $4\text{--}6$), cell wall composition, membrane sterols, modes of nutrition, and methods of reproduction between bacteria and fungi.

Comparison of Algae and Plants Characteristics

A comparative summary detailing taxonomy, cellular structures, presence of vascular systems, habitat, organ differentiation, and reproductive methods between algae and plants.

Coccus

Spherical or round-shaped bacteria that can be arranged in pairs (diplococci), chains (streptococci), clusters (staphylococcus), groups of four (tetrad), or groups of eight (octad).

Bacillus

Rod-shaped bacterial organisms, some of which are short and resemble elongated cocci called coccobacilli.

Glycocalyx

An outer envelope structure composed of polysaccharide, polypeptide, or both; termed a capsule if strongly attached to the cell wall or a slime layer if loosely attached.

Peptidoglycan

The principal component of bacterial cell walls (also called murein or mucopeptide) providing rigid support, osmotic protection, and playing an important role in cell division.

Teichoic Acids

Major surface antigens present in Gram-positive cell walls that function in host attachment and tensile strength.

Lipid A

The lipid component of lipopolysaccharides in Gram-negative outer membranes responsible for endotoxin actions.

O antigen

The repeat unit of polysaccharide in Gram-negative cell wall outer membranes that is unique to each bacterial species and protects against the host immune system.

Periplasmic Space

The fluid-filled space between the outer membrane and inner plasma membrane in Gram-negative bacteria containing enzymes for molecular breakdown and antibiotic inactivation.

Mycolic acid

Large amounts of waxes forming the lipid-rich outer layer of acid-fast cell walls such as Mycobacterium tuberculosis.

Flagella

Bacterial organs for motility composed entirely of molecules of the protein subunit flagellin.

Ophotrichous

Flagellar arrangement characterized by a tuft of flagella at the end of the bacterium.

Pili (Fimbriae)

Bacterial surface structures made of pilin protein subunits that function in motility, adherence (common pili), or conjugation (sex pili).

Nucleoid

The region in prokaryotes where genetic material is packaged as a simple, circular, double-stranded DNA without a surrounding nuclear membrane.

Mesosomes

Extensions of the cytoplasmic membrane that function in cell division and serve as points of attachment for bacterial chromosomes.

Endospores

Highly resistant bacterial structures composed of dipicolinic acid that confer resistance to heat, drying, and radiation during hostile environmental conditions.

Sporulation

The process of spore production initiated when environmental conditions become detrimental to the bacteria.

Pathogens

Microorganisms known to cause disease, accounting for approximately $3\text{--}4\text{ absolute percentage points}$ (about $3$\%) of known microbes.

Autotrophs (Lithotrophs)

Organisms that utilize inorganic compounds as their sole source of carbon.

Heterotrophs (Organotrophs)

Organisms that make use of organic compounds as their carbon source.

Obligate Aerobes

Bacteria with an absolute requirement for O2 ($21$\% O2, $0.03$\% CO2) that contain dismutase enzymes to protect against toxic oxygen.

Obligate Anaerobes

Bacteria that grow only in the absence of free oxygen ($0$\% O2, $5\text{--}10$\% CO2, $80\text{--}90$\% N2, $5\text{--}10$\% H2) and lack superoxide dismutase, catalase, and cytochrome c oxidase.

Capnophiles

Microorganisms that require increased levels of CO2 ($5\text{--}10$\% CO2, $15$\% O2) for growth, such as Haemophilus and Neisseria.

Microaerophiles

Microorganisms that require a decreased or small amount of O2 ($5$\% O2, $10$\% CO2, $85$\% N2), such as Campylobacter and Helicobacter.

Thermophiles

Bacteria that grow best at temperatures higher than $40\text{--}45$ degrees Celsius ($40^\text{o}\text{C}$).

Mesophiles

Bacteria requiring an optimal growth temperature of $20^\text{o}\text{C}\text{--}40^\text{o}\text{C}$, including most medically important bacteria.

Psychrophiles

Bacteria requiring cold optimal growth temperatures of $10^\text{o}\text{C}\text{--}20^\text{o}\text{C}$, such as Listeria monocytogenes and Yersinia enterocolitica.

Halophiles

Bacteria requiring high salt concentrations for growth, including Vibrio species except Vibrio mimicus and Vibrio cholerae.

Lag Phase

The growth phase lasting $1\text{--}4\text{ hours}$ during which bacteria adapt to a new environment and display high enzymatic activity without immediate division.

Log Phase

The growth phase lasting about $8\text{ hours}$ where bacterial cells divide at a constant rate, are most metabolically active, and are most susceptible to antibiotics.

Stationary Phase

The growth phase marked by waste accumulation and nutrient depletion where the number of dying organisms equals the number of new organisms.

Decline Phase

The final growth phase where the number of dying organisms exceeds viable organisms, causing total population to decrease.

Decontamination

The process using physical or chemical means to remove, inactivate, or destroy pathogens on a surface or item.

Disinfection

The process using physical or chemical means to destroy pathogens on inanimate objects, excluding bacterial spores.

Sterilization

The process by which all microbial forms and pathogens are destroyed or removed, including spores.

Antiseptic

A chemical solution applied to living tissue (skin) that prevents microbial spread by inhibiting growth or destroying organisms.

Iatrogenic Infection

An infection acquired specifically during the course of undergoing diagnostic tests or therapeutic procedures.

Pasteurization

A heat sterilization method below $100^\text{o}\text{C}$ used for beverages and milk via conventional ($60^\text{o}\text{C}\text{--}65^\text{o}\text{C}$), flash ($72^\text{o}\text{C}$ for $15\text{ seconds}$), or UHT ($140^\text{o}\text{C}$ for $15\text{ seconds}$) protocols.

Tyndallization (Fractional Sterilization)

A method of exposing materials to live steam at $100^\text{o}\text{C}$ over consecutive days to sterilize culture media such as TCBS and selenite broth.

Autoclave

The most efficient physical sterilization method using steam under pressure at temperatures above $100^\text{o}\text{C}$ to destroy all microbial forms including spores.

Lyophilization

A freeze-drying process utilized in laboratories for the long-term preservation of microorganisms.

Microbial Ecology

The study of the relationship between microorganisms and their surrounding environment.

Resident Flora

Microorganisms that occupy a fixed area and permanently inhabit the body of a normal, healthy individual.

Transient Flora

Microorganisms that temporarily house or inhabit specific body sites without establishing permanent residence.

Lactobacillus acidophilus

Predominant resident vaginal flora that produces lactic acid to maintain acidic pH, preventing gonococcal infections.