bios 352 week 4

normal growth conditions

sea level

temp

neutral ph

outside normal growth conditions

extremophiles

why is temp regulation important?

-enzymes have optimal temp for function

-high temps destroy proteins

-low temps solidify membranes

psychrophiles

-enzymes adapt to function in cold temp

-membrane remains semifluid

thermophiles

enzymes are adapted to function in hot temp

more of a rigid structure

optimal growth temp

The temperature range at which an organism grows most efficiently, balancing enzymatic activity and structural integrity.

minimum growth temp

lowest can grow

maximum temp rate

The highest temperature at which an organism can survive and grow before enzymatic activity declines.

obligate aerobe

requieres O2

microaerophile

requires o2 at low concentrations

microaerophile

requires o2 at low conc

strict anaerobe

o2 is toxic

facultative anaerobe

does not require o2

aerotolerant

grows equally well with or without o2

clostridium tetani

a strict anaerobic bacterium that causes tetanus, producing neurotoxins.

deep dead tissue with no oxygen supply

obligate aerobes tube

cells at the top

obligate anaerobes tube

cells at the bottom

facultative anaerobes tube

cells throughout the tube, able to grow with or without oxygen. (mainly at top)

aerotolerant anaerobes tube

cells throughout the tube

microaerophiles tube

middle of tube compactly packed

neutralophiles

ph 5-8

acidophiles

ph 0-5.55

alkaliphiles

ph 8-10.5

barophiles

organisms that thrive at high pressure, typically found in deep-sea environments.

halophiles

thrive in salt conditions

halotolerant

tolerate high salt and can survive outside it

Workflow

Specimen collection -> Culturing ->
Biochemical, Microscopy and Molecular
testing -> Antimicrobial susceptibility
testing -> Final Identification

pure culture media

a medium that contains only one type of organism, allowing for the growth and study of individual species.

all purpose media

a type of growth medium that supports the growth of various types of microorganisms without being selective.

specialized media

fastidious organisms

chemically defined media

is a growth medium formulated with precise chemical composition, allowing the growth of specific organisms by providing essential nutrients.

complex media

a type of growth medium that contains a mixture of complex organic substances, providing nutrients for a wide range of microorganisms.

selective media

is a type of growth medium that allows the growth of specific organisms while inhibiting the growth of others, often through the addition of inhibitors or nutrients.

differential media

is a type of growth medium that distinguishes between different types of organisms based on their biochemical properties, often by visible changes in the medium.

emb agar eosin methylyne blue

A selective and differential medium used to isolate and identify gram-negative bacteria, particularly E. coli, through color changes.

Strong lactose fermentation in emb agar

dark purple to green

weak lactose fermentation in emb agar

brown to pink

msa agar mannitol salt agar

A selective medium for isolating Staphylococcus species, especially Staphylococcus aureus, which ferments mannitol, leading to a color change in the medium.

mannitol fermentation

yellow

no mannitol fermentation

pink to red colonies

blood agar

A growth medium that supports the cultivation of various bacteria and differentiates them based on their hemolytic properties.

beta hemolytic blood agar

clear zones, complete lysis

alpha hemolytic blood agar

cloudy, partial lysis

gamma hemolytic

no change, no lysis

catalase test

differentiates staphylococcus (+) vs steptococcus (-)

coagulase test

test that differentiates Staphylococcus aureus (+) from other Staphylococcus species (-).

oxidase test

identifies oxidase positive bacteria

indole test

detects the capability of bacteria to hydrolyze tryptophan to indole

tsi (triple sugar iron) test

a differential test that examines a bacterium's ability to ferment sugars and produce hydrogen sulfide, using three sugars (glucose, lactose, and sucrose) and phenol red as a pH indicator.

tsi (triple sugar iron) test meanings

yellow- can use several carbs

yellow butt- can only use glucose

black- has produced h2s

red- no fermentation

bacterial endospores

most resistant

prozoan cysts and oocysts

resistant to disinfectants

mycobacterium species

waxy outer membrane

pseudomonas species

can grow in some disinfectants

non eveloped viruses

lack lipid envelope

number of microbes

fraction of population dies during given time

decimal reduction time

time required to kill 90% of population under specific conditions

bls-1 level of infection

fewest precautions

bls-2 level of infection

moderate risk of infection

bls-3 level of infection

extreme risk, fatal diseases requiring multiple precautions and special controls.

sterilization

killing and removal of all living organisms from inanimate objects (endospores)

disinfection

killing and removal of most/all organisms from inanimate objects (not endospores)

antisepsis

killing and removal of most/all pathogens from the surface of living tissues

sanitation

reducing the microbial population to safe levels

heat physical control

dry heat

moist heat

pasteurization

dry heat

method of sterilization using high temperatures without moisture to kill or inhibit microbial growth.

moist heat

most effective

boiling does not sterilize

pasteurization

heating at high tempts for short times (not all organisms are killed)

autoclaving

destroys endospores

temp higher than boiling point of water by using steam under pressure.

freezing

low temp

refrigeration slows growth

freezing stops growth

once thawed, microbial cells can grow

filtration of fluids

membrane filters

filtration of air

high-efficiency particulate air (hepa) filters

ionizing

gamma rays

xrays

produces oxygen species

ultaviolet

damages dna

poor penetrating power

sterilants/sporicides

substances that eliminate all forms of microbial life, including spores. They're used in sterilization processes for medical instruments and equipment. oxidizes primary metabolites.

high level disinfectants

cant destroy endospores

struggle with biofilms (bleach)but are effective against viruses and bacteria.

denatures proteins through oxidation

intermediate level disinfectants

cant destroy some non eveloped viruses and all endospores

denatures proteins by dehydration

low level disinfectants

cant destroy all viruses, bacteria, fungi, or endospores

not biofilm effective

alters some membrane proteins

not effective against some gram negatives

alcohol

level:intermediate

denatures proteins and dissolved lipids

halogens

high level

oxidizes cellular components, denatures enzymes, disrupts membrane

phenolics

level :intermediate

use: household disinfectants

mode of action :denatures proteins

aldehydes

example:formaldehyde

high level

sterilization of medical instruments

mode of action: cross links proteins and dna making them inactive