Chapter 7 – Microbiology – Flashcards

cell wall - prevent cell from bursting PM - permeability DNA - proteins and enzymes

time of exposure cell wall type concentration of microbes concentration of antimicrobial temperature

they go under UHT (ultra high temperature) or steam

removal or destruction of all forms of microbial life heating is the most common form (dry/moist)

limited heat treatment used in canned food processing kills endospores of clostridium botulinum (obligate anaerobe)

- destruction of vegatative (non-endospore forming) microorganisms that may be harmful - may involve chemicals, UV light, steam, boiling water includes antiseptic

a disinfectant that is used on living tissue ex. hydrogen peroxide, hand sanitizer, iodine, mouth wash, baby wipes.

removal of microbes from a limited region generally involves mechanical removal

lower microbial counts on eating utensils high temperature washing or chemical disinfectant

-cide (to kill) -stat/stasis (stop/steady) limit growth - bacteriostatic

microbial contamination free of microbial contamination

longer

organic matter mixed with microbes lowers antimicrobial activity. ex- biofilms

number of microbes environmental influences time of exposure microbial characteristics

target plasma membrane by damaging lipids/proteins altering permeability target proteins by breaking bond (h+ or covalent) target DNA and RNA - for DNA replication and protein synthesis

thermal death point thermal death time decimal reduction time

lowest temperature in which all microbes in a solution are killed in 10 minutes

minimal length of time for all bacteria in a solution to be killed at a given temperature

time in minutes in which 90% of a bacterial population will be killed at a given temperature

(moist heat: autoclaving, pasteurization, uht) dry heat (incineration & flaming)

denaturing of proteins of breaking of H bonds

100C no pressure autoclaving is preferred if substance can tolerate it

for 10 minutes kills bacteria, viruses, and most fungi endospores and some viruses can still survive (20hours)

as pressure increases, so does temperature kills all organisms and endospores in 15 minutes if its directly in contact with steam - 121C

prions which are infectious proteins

moist heat that exposes microbes to high temperatures for a short time. still has microbes so not sterilized!

sterilizes allows storage of milk w/o refridgeration 140C for 4 seconds

not as effective as moist direct flaming incineration - burned to ashed hot air sterilization - item is placed in oven (170C for 2 hours)

a physical method of microbial control used to sterilize heat sensitive materials HEPA filters remove microbes greater than 0.3 um membrane filters 0.1 um - 0.45 um

high efficiency particular air vacuum, purifiers, operating rooms

refrigeration- causes psychrotrophs to grow more slowly freezing- microbes are dormant, not dead & freeze thaw cycles are harmful for bacteria because ice crystals disrupt membrane structures

alters molecular structures of carbs and proteins some fruit juice endospores are resistant to this

absence of water or lyophilization no growth or reproduction can remain viable for several years

high salt or sugar results in a hypertonic solution decreases moisture content

gamma rays (from radioactive substances), xrays, high energy electrons, ebeams ionize water that form hydroxyl radicals that attack DNA.

UV light which mutates DNA like hospitals and caffeteria

heat kills most vegetative pathogens in moisture containing foods

they are more detrimental

ionozing, nonionizing, microwave

use dilution test

is not serial dilution use 3 types of bacteria: 2 gram negs & 1 positive metal or glass cylinders dipped in bacteria cultures are dried and placed in disinfectant for 20 minutes at 10C cylinders are transferred to sterile liquid medium, incubated, and analyzed for growth

pseudomonas

inoculate an agar plate with bacteria using a cotton swab filter paper soaked with disinfectant is placed of agar check for zone around paper. larger the zone, more effective it is to disinfectant

used by lister in surgeries rarely used bc it irritates skin and it smells unpleasant used in throat bc local anesthetic

-derivatives of phenol &chemically altered to lower irritation - target lipid membranes and affect permeability

2 phenol molecules bridged together hexachlorophene (skin infections used in nurseries) triclosan (p. aeruginosa resistant bc overuse)

affect cell membranes chlorhexidine- microbial control on skin and mucous membranes, presurgical antiseptic

iodine and chlorine

i2 - impairs protein synthesis and alters cell membranes used mainly for skin and wound disinfection tincture - solution with alcohol iodophor - combined with organic molecule (dont stain and are less irritating on skin)

cl2 - germicidal activity caused by HOCl whcih diffuse easily through cell walls to inhibit enzyme function. strong oxidizing agen

H + Cl + HOCl

hypochlorites - calcium and sodium chlorine dioxide - kills anthrax endospores chloramines- chlorine and ammonia

kill bacteria and fungi (not endospores or nonenveloped viruses) denatures proteins, can disrupt membranes ex. ethanol (62-65%) and isopropanol

no must be mixed with water to break down protein and 100% will evaporate too fast

silver: (nitrate) put in babies eyes for infection mercury, copper: inhibits green algae, zinc: rooftops/mouthwash metal ions cause protein denature oligodynamic reaction - very small amounts of heavy metals exerting antimicrobial activity

soaps and detergents - degerming used to remove debris, microbes, dead cells, oils on surface quaternary ammonium compounds

chlorine gas

most widely used surface cleaners affect PM because its positive charge cationic detergents kill gram + bacteria, fungi, amoeba, viruses dont kill endospors or mycobacteria pseudomonas is resistant

soap and water aqueous zephiran 50% ethanol and 10% acetone tincture 70% ethanol and 30% water 1% iodine and 70% ethanol (tincture of iodine)

SO2 - sulfur dioxide sorbic acid and sodium benzoate calcium propionate sodium nitrate and sodium nitrite

wine making takes a llong time

soda and prevents molds from growing in acidic foods (cheese/soft drinks)

fungistat which is used to stop growth in break affect mold metabolism or PM

added to meat products to protect against botulism reaction in the body causes nitrosamine (reaction with amino acids) which is a carcinogen nitrate and nitrite can be converted to one another

causes lethargy and affects nervous system, gastrointestinal tract and it is caused by clostridium botulinum toxin

a type of disinfectant that is usally injected or injested nisin and natamycin- used in food preservation

cheese - prevents growth of endospore forming bacteria, present naturally in dairy products

cheese bc it is an antifungal antibiotic

used for embalming inactive proteins by forming covalent bonds with functional groups. formaldehyde and glutaraldehyde - less irritating and more effective sterilizng agent for killing endospores but take a long time.

chemicals that sterilize in a closed chamber like matresses in hospitals ex. ethaline oxide/chlorine dioxide

causes molecules to get oxidized ozone (o3) hydrogen peroxide benzoyl peroxide peracetic acid

o3 supplements chlorine in water disinfection

disinfects inanimate objects contact lens cleaners

acne treatment

very effective liquid chemical sterilant that does not residues so we can not be harmed. approved for washing fruits and veggies

prions endospores of bacteria mycobacteria cysts of protozoa vegetative protozoa gram negative fungi including most spores viruses without envelopes gram positive viruses with lipid envelopes