Microbial Control and Kinetics of Death

This set of vocabulary flashcards covers fundamental terminology of microbial control, kinetics of microbial death, and physical/chemical methods of control as described in the lecture notes.

Sepsis

Refers to bacterial contamination.

Asepsis

The absence of significant contamination.

Sterilization

The process of removing and destroying all microbial life, including highly resilient endospores.

Commercial Sterilization

A process that specifically targets the destruction of C. botulinum endospores in canned goods.

Disinfection

Destroying harmful microorganisms, usually on inanimate surfaces.

Antisepsis

Destroying harmful microorganisms specifically from living tissue.

Degerming

The mechanical removal of microbes from a limited area, such as using an alcohol swab before an injection.

Sanitization

Lowering microbial counts on eating utensils to safe public health levels.

Biocide (Germicide)

Treatments specifically designed to kill microbes.

Bacteriostasis

A method that inhibits growth rather than killing the microbes; it does not kill vegetative cells.

Thermal Death Point (TDP)

The lowest temperature at which all cells in a liquid culture are killed in $10\,\text{minutes}$.

Thermal Death Time (TDT)

The minimal time required for all bacteria in a liquid culture to be killed at a specific, set temperature.

Decimal Reduction Time (DRT or D-value)

The time, in minutes, required to kill $90\%$ of a population (a $1\text{-log}$ decrease) at a given temperature.

Autoclave

An effective tool that uses steam under pressure at $121^{\circ}\text{C}$ at $15\,\text{psi}$ for $15\,\text{mins}$ to kill all organisms and endospores.

Pasteurization

Heat treatments (such as $72^{\circ}\text{C}$ for $15\,\text{sec}$) that reduce spoilage and pathogens but do not sterilize the product.

Filtration

The process of passing liquid or gas through membrane filters (typically $> 0.22\,\mu\text{m}$) to sterilize heat-labile solutions.

Ionizing Radiation

Radiation types like X-rays or Gamma rays that ionize water to create reactive hydroxyl radicals and cause lethal mutations in DNA.

Nonionizing Radiation

Ultraviolet (UV) radiation that damages DNA by creating thymine dimers.

Disk-Diffusion Method

A standardized test where a chemical-soaked disk is placed on an inoculated plate to measure a Zone of Inhibition.

Zone of Inhibition

The area on an inoculated plate where bacteria cannot grow; a larger zone indicates a more effective compound against that specific microbe.

Heat-labile

Materials such as certain plastics or enzymes that are heat-sensitive and will be destroyed by high heat (like an autoclave).

$70\%$ Ethanol

A concentration of ethanol that is more effective as a bactericide than $100\%$ ethanol because water is required for protein denaturation.