Physical Control of Microbial Growth Flashcards

A set of vocabulary-style flashcards covering the definitions, methods, and conditions used for the physical control of microbial growth as presented in the lecture notes.

Sterilization

The absolute destruction of all life forms on an object.

Disinfection

The destruction of vegetative pathogens but not necessarily endospores or viruses; intended to reduce or inhibit growth.

Antisepsis

Chemical disinfection of skin, mucous membranes, or other living tissue.

-cide

A suffix for a chemical agent that rapidly kills microbes but not endospores.

-stasis

A suffix indicating that microbial growth and multiplication are inhibited.

Asepsis

The absence of pathogens from an object or area.

Degerming

The removal of transient microbes from the skin by mechanical cleansing or the use of an antiseptic.

Sanitization

The reduction of pathogens on eating utensils to safe public health levels by mechanical cleansing or chemicals.

Decontamination

The treatment of an object or surface to make it safe to handle.

Standard Autoclave Conditions

Sterilization at $121\,^\circ C$ and $15\,PSI$ for $15\,minutes$.

Geobacillus stearothermophilus

The biological indicator (formerly called Bacillus stearothermophilus) used to test for sterility by using its spores.

High-temperature short-term (HTST) pasteurization

Also known as flash pasteurization; involves heating at $72\,^\circ C$ for $15\,seconds$ followed by rapid cooling.

Ultrahigh-temperature (UHT) sterilization

Heating at $140$ to $150\,^\circ C$ for $1$ to $3\,seconds$.

Tyndallization

Fractional steam sterilization involving heating at $90{\text{--}}100\,^\circ C$ for three consecutive days with incubation at $37\,^\circ C$ in between.

Hot-air sterilization

A dry heat method involving an oven at $160$ to $170\,^\circ C$ for $2$ to $3\,hours$.

Incineration

The physical destruction of microorganisms by burning at $500\,^\circ C$, used for solid wastes.

Moist Heat Effects

Mechanism of action including the degradation of nucleic acids, denaturation of enzymes and essential proteins, and disruption of cell membranes.

Dry Heat Effects

Mechanism of action involving the oxidation of cell constituents and denaturation of proteins.

Deep freezing

Rapid cooling of a pure culture in suspension liquid to $-50\,^\circ C$ to $-95\,^\circ C$, effective for several years of preservation.

Lyophilization (freeze drying)

A preservation method where material is frozen at $-54\,^\circ C$ to $-72\,^\circ C$ and dehydrated in a vacuum.

Depth filters

Filters made of fibrous or granular materials (like diatomaceous earth or unglazed porcelain) bonded into a thick layer with small diameter twisting channels.

Membrane filters

Porous membranes made of synthetic materials such as cellulose acetate, cellulose nitrate, polycarbonate, or polyvinylidene fluoride.

HEPA filters

High-efficiency particulate air filters used for air filtration in environments like biosafety cabinets.

Ionizing radiation

Very short wavelength, high energy radiation (X-rays, Gamma rays) that causes death by destroying DNA, disrupting hydrogen bonds, and oxidizing double bonds.

Non-ionizing radiation

Short wavelength UV rays ($220{\text{--}}300\,nm$) that cause mutation or death through the formation of thymine dimers; most absorbed by DNA at $260\,nm$.

High intensity pulsed electric field treatment

A non-thermal control method involving exposure to an electric field of $15{\text{--}}20\,kV/cm$ for milliseconds, leading to electroporation.