Microbiology (Tortora), Chapter 7

Front 1

Sterilization

Back 1

the removal or destruction of all forms of microbial life

Front 2

Commercial sterilization

Back 2

subjects canned food to only enough heat to destroy the endospores of Clostridium botulinum.

Front 3

Disinfection

Back 3

is the destruction of vegetative pathogens on a surface, usually with chemicals. Spores and viruses are not necessarily destroyed.

Front 4

Antisepsis

Back 4

the chemical disinfection of living tissue, such as skin or mucous membrane

Front 5

Asepsis

Back 5

the absence of pathogens on an object or area, as in aseptic surgery

Front 6

Degerming

Back 6

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

Front 7

Sanitization

Back 7

the reduction of microbial populations on objects to safe public health levels.

Front 8

-cide

Back 8

suffix indicates the killer of a specified organism

Front 9

biocide or germicide

Back 9

kills microorganisms

Front 10

fungicides

Back 10

kill fungi

Front 11

virucides

Back 11

kill viruses

Front 12

-stat

Back 12

indicates only that the substance inhibits for example-bacteriostasis

Front 13

Bacterial populations killed by heat or chemicals tend to die at a _______ rate

Back 13

constant

Front 14

The _____ ______ controls the passage of nutrients and wastes into and out of the cell. Damage to the ______ _____ causes leakage of cellular contents and interferes with cell growth

Back 14

plasma membrane

Front 15

Chemicals may denature proteins by reacting, for example, with disulfide bonds (or disulfide bridges), which give proteins their 3 dimensional active shape. Chemicals and radiation may prevent proper replication or functioning of _____ or ______

Back 15

DNA or RNA

Front 16

Thermal death point

Back 16

the lowest temperature required to kill a liquid culture of a certain species of bacteria in 10 minutes

Front 17

Thermal death time

Back 17

the length of time required to kill ALL bacteria in a liquid culture at a given temperature

Front 18

Decimal reduction time (D value)

Back 18

the length of time, in minutes required to kill 90% of the population of bacteria at a given temperature

Front 19

Moist Heat:
Boiling (100 C) kills vegetative forms of bacterial pathogens, many viruses, and fungi within 10 minutes.

Back 19

Endospores and some viruses survive boiling for longer times.

Front 20

Steam under pressure

Back 20

allows temperatures above boiling to be reached

Front 21

Autoclaves

Back 21

retorts, and pressure cookes are vessels in which high steam pressures can be contained. 121 C for 15 minutes. Moisture must touch all surfaces in order to bring about sterilization. Air must be completely exhausted from the container

Front 22

Pasteurization

Back 22

mild heating that is sufficient to kill particular spoilate or disease organisms without seriously damaging the taste of the product. Dairies use the phosphatase test to determine if products have been properly pasteurized

Front 23

High temperature, short-time pasteurization

Back 23

uses temperatures of at least 72 C for about 15 seconds to pasteurize milk

Front 24

Equivalent treatments

Back 24

the heat of 115 C acting on an organism for 70 minutes is equivalent to heat of 125 C acting on an organism for only 7 minutes; that is applying a higher temperature for a shorter time may kill the same number of microbes as a lower temperature for a longer time.

Front 25

Ultra-high-treatment (UHT)

Back 25

Milk can be sterilized and stored without refrigeration when given UHT)

Front 26

Dry sterilization:
Incineration, as in direct flaming, is efficient for limited purposes.

Hot air sterilization: as in an oven, requires higher temperatures (170 C) and longer times (2 hrs) to ensure sterilization

Back 26

Moist heat is generally more efficient

Front 27

Liquids sensitive to heat can be passed through a thin ______ ______ that has carefully controlled pore sizes to retain microorganisms

Back 27

membrane filter

Front 28

Operating theaters and special clean rooms receive air passed through ________

Back 28

high-efficiency particulate air filters (HEPA)

Front 29

Refrigerator temperatures (0C to 7 C) slow the metabolic rate of microbes, however, ________ species still grow slowly.

Back 29

psychrotrophic. Some organisms grow at temperatures slightly below freezing, but microbes at the usual temperatures of freezer compartments are completely dormant.

Front 30

________ ______ applied to liquid suspensions such as fruit juices can kill vegetative bacterial cells. Endospores are relatively resistant. An advantage is that flavors, colors, and nutrient values are preserved.

Back 30

High pressure.

Front 31

Ionizing radiation

Back 31

such as X rays, gamma rays, and high-energy electron beams carry high energy and break DNA strands. Ionizing radiation forms reactive hydroxyl radicals. Such radiation is used to sterilized pharmaceuticals.

Front 32

Ionizing radiation cont
irradiation is a type of cold sterilization.

Back 32

all ionizing radiation can penetrate liquids and most solid materials including our bodies.

Gamma rays are the most penetrating, followed by X-Ray while cathode rays are the least penetrating.

Front 33

Irradiated food does show a slight decrease in vitamin B1 levels. Radiation treatment results in the production of free radical oxidants (Which dissapear almost immediately)

Back 33

No food can be sold to consumers without clear labels that it has been irradiated. Radiation is used to reduce pathogens E. Coli and Salmonella in beef & chicken and the reduction of worms and insects on fruits and vegetables.

Front 34

Nonionizing radiation (UV rays):
UV does not penetrate as many materials as ionizing radiation because it has much lower energy. UV radiation is used to disinfect rather than sterilize.

Back 34

UV rays do not penetrate liquid well, but liquids can be treated with UV by spreading the liquid into a thin layer. Water treatment plant.

Front 35

Choosing a Microbial Chemical
1) Rapid action in low concentrations.
2) Solubility in water of alcohol and long-term staility
3) Boad-spectrum microbicidal action without being toxic to humans or animals.
4) Penetration of inanimate surfaces to sustain a cummulative or persistent action.

Back 35

5)Resistance to becoming inactivated by organic matter.
6) Noncorrosive or nonstaining properties
7) Sanitizing or deodorizing properties
8) Inexpensive and readily available.