test two lec 9 part 2 Flashcards
what has a direct effect on cells macromolecular structures
concentration of H+ or hydronium ions
extreme concentrations of hydronium or hydroxide ions in a solution will limit growth of what type of phile
mesophile
living cells tolerate a grater range in environmental concentration of what than of virtually any other chemical substance
hydrogen ions
the charges on amino and carboxyl groups within a protein contribute to what
the intramolecular bonds that govern protein shape and protein activity
what optimal pH
5 to 8.5
can the intracellular pH of microbe be different than environment
yes
what about the membrane that allows bacteria to regulate internal pH
membrane is impermeable to protons
if there are large differences between intra and extracellular pH, this could lead to what on microbes
leakage of protons either directly or via proteins
what can accelerate leakage of hydrogen ions in membrane
weak acids
this causes the internal pH to acidify
what are the three classes of organisms that are differentiated by pH
neutralophiles
acidophiles
alkaliphiles
what is the pH for neutralophiles
5 to 8
where do you find neutralophiles
human pathogens
can the neutralophiles fluctuate their pH
yes
they do this to maintain their metabolism
stay within .5 of external pH
what is the pH for acidophiles
0 to 5
acidophiles are mostly
chemoautotrophs bc they oxidize reduced metals and generate strong acids
acidophiles have what kind of membrane
tetrether lipids which decrease proton permeability, allow for growth
what is the pH for alkaliphiles
9 to 11
where are alkaliphiles found
soda lakes
what makes alkaliphiles special
contain cytoplasmic enzymes that have ordinary optima pH so cells have surface barriers that sequester cytoplasmic enzymes from high extracellular pH
what is in an alkaliphile membrane that helps with pH
hexosamines in peptidoglycan
high level of diether lipids that help from proton leakage
Na+/H+ antiporters: bring in protons and Na+ released
what can microbes do if placed in conditions below optimum
exchange extracellular K+ for intracellular H+ when internal pH becomes too low
what molecules can microbes use to change pH
amino acid decarboxylases and deaminases
drain protons from cell
microbes also possess an emergency global response system which does what
acid tolerance or acid resistance by protein levels increasing when others decrease
when is oxygen toxic to cells
cells that do not have enzymes capable of efficiently destroying the reactive oxygen species
anaerobes
how can oxygen damage cells
damage RNA, DNA, proteins and lipids
what enzymes do aerobic organisms have that help fight reactive oxygen species
superoxide deaminase
catalase
peroxidase
what are strict aerobes
an organism that performs aerobic respiration and can only grown in the presence of oxygen
oxygen is terminal electron acceptor
what are strict anaerobes
an organism that does not grow in the presence of oxygen
dies in response to oxygen due to ROS
strict anaerobes use what type of mechanism
fermentation
anaerobic respiration
what are facultative anaerobes
an organism that can grow in either the presence or absence of oxygen
what are aerotolerant anaerobes
an organism that does not use oxygen for metabolism but can grow in the presence of oxygen
contain enzymes to protect from ROS
what are microaerophiles
organisms that require oxygen at a concentration lower that that of the atmosphere, but unable to grow in high oxygen environments
decreased levels of enzymes
microaerophiles are also what
capnophiles
what are capnophiles
bacteria that require increased concentrations of carbon dioxide and some are pathogenic
how do you culture anaerobes in lab
oxygen removing techniques
what is oxygen removing technique
degassing media and including special reducing agents or enzyme systems
what are some oxygen removing techniques
anaerobe jar: O2 removed by palladium plus H2
anaerobe chamber with airlock system and glove ports: O2 removed replaced with N2
what are oligotrophs
organisms with a high rate of growth at low solute concentrations
what are oligotrophic conditions
low nutrient concentrations (1 to 5 mg C/L)
what do oligotrophs have on their membrane
prothecae
what are prothecae
thin extensions of membrane and cell well that expand the surface area of cell and increase nutrient transport capacity
what gene systems are affected when nutrients decline
growth rate slows, daughter cells become smaller
starvation elicits what response
starvation response
what happens during starvation response
enzymes are produced to increase efficiency of nutrient gathering and protect cell macromolecules from damage
cells begin to make and store glycogen
what triggers the starvation response
accumulation of small signal molecules such as cAMP or guanosine tetraphosphate
during starvation response, when cells growing on nutrient deprived agar what happens
cells form colonies and intricate shapes that help population cope to food stress
what is eutrophication
the sudden infusion of large quantities of a formerly limiting nutrient
what is a downfall of eutrophication
unrestricted growth consumes other nutrients to a degree that threatens the existence of competing species
static does what to growth
inhibits
cidal does what to growth
kills cells
germicidal does what
kills pathogens but not spores
sterilization
process by which all living cells, spores and viruses are killed/destroyed
disinfection
killing or removal of disease producing organism from inanimate surfaces
does not necessarily result in sterilization
pathogens killed but not all microbes
antisepsis
killing or removal of pathogens from the surface of living tissues
sanitation
reducing the microbial population to safe levels and usually involves both cleaning and disinfecting an object
what factors influence the efficacy of given chemical agent
presence of organic matter
kinds of organisms present
corrosiveness
stability, odor, and surface tension
how does presence of organic matter affect efficacy of chemical agent
chemical will bind, lowering agents effectivenes
how does corrosiveness affect efficacy of chemical agent
shouldnt damage surface or skin
what are some commercial disinfectant and antiseptics
ethanol
iodine
chlorine
ethylene oxide
what are surfactants
detergents
how do surfactants work
hyrdophobic and hydrophilic ends will emulsify fat into water
cationic: gain access to neg charge bacterial cell and disrupt membranes
anionic: not anitmicrobial but help with mechanical removal
how do low molecular weight aldehydes in disinfectants
formaldehyde
combine with and inactivate proteins and nucleic acids
what are antibiotics
chemical compounds synthesized by one microbe that kill or inhibit the growth of other microbial species
what does penicillin do
mimics part of bacterial cell wall and prevents bacterial cell wall formation
bactericidal
what do antibiotics target
protein synthesis
DNA replication
cell membranes
bacteria can attack same species but wont attack itself bc
alters its own receptors
how can bacteria develop resistance to disinfectants and antibiotics
alter fatty acid synthesis protein
produce membrane spanning multidrug efflux pumps
biofilms
what are the five physical agents that kill microbes
high temp pasteurization cold filtration irradiation
how does high temp work with killing microbes
moist heat, water penetrates cells
how to kill spores
high pressure and temp such as a steam autoclave
what is pasteurization
the heating of food at a temp and time combination that will kill Coxiella burnetti
what does pasteurization not want to do
kill all microorganisms in food just reduce the viable pathogens
how is cold used in killing microbes
low temps slow down growth and preserve strains
helps with storage of cultures: glycerol
how does glycerol store strains
prevent production of ice crystals that can pierce cells
what is lyophilization
freeze drying
quick freezing at low temp to prevent formation of ice crystals, apply vacuum to remove water, cells store as powder
how does filtration work
micropore filters with pore size of .2 micrometers to remove microbial cells but not viruses
can remove cells without heat
can air be sterilized by filtration
yes
laminar flow biological safety cabinet
how does irradiation work for killing microbes
UV light
gamma rays, electron beams, x-rays
when is UV light used
to sterilize surface
poor penetrating power
what has high penetrating power
gamma rays, electron beams, x-rays
what is used to irradiate foods and other heat sensitive items
gamma rays, electron beams and x-rays
what happens with microbes and radiation
water and other intracellular molecules absorb energy and form chemicals that damage DNA and scramble genetic info
what are some variables of microbes to radiation
size of DNA
rate at which they can repair damaged DNA
takes a higher dose for frozen food contaminated with microbes
what is the worlds toughest bacterium
Deinococcus rediodurans
what can deinococcus rediodurans survive
high amounts of uv radiation cold dehydration acidity vacuum conditions
what os s[ecial about deinococcus rediodurans
ability to repair damaged DNA in less than 24 hours
has been genetically engineered for use in bioremediation
what is biocontrol
the use of one microbe to control the growth of anothre
what are probiotics
contain certain microbes that, when ingested, aim to restore balance to intestinal flora
what is phage therapy
aims to treat infectious disease with virus targeted to the pathogen
