Bacteria Growth And Physiology Flashcards
What is growth and what doesn’t contribute to growth
- orderly increase in the sum of all components of an organism
- not due to water uptake or lipid and saccharide deposits at membrane
How do bacteria multiply
What is a culture
- through binary fission of a single bacteria to make up a population
- a group of bacteria making up a population originating from a single cell
What is binary fission
-division of a single parent into 2 identical progeny with identical genetic material and you can’t differentiate between parent and progeny
Describe the process of binary fission
How is fission initiated
-fission initiated when there is an increase in cellular components until it reaches critical mass
- DNA replicated by mitosis to produce 2 identical sets of chromosomes
- cell elongation
- septum forms so parent can form into daughter
- completion of septum with distinct cell walls
- cell separates
List 3 ways to grow bacteria
1 colonies
2 turbidity
3 biofilm formation
Describe colony bacterial growth
- developed on solid medium
- macroscopic product of 20-30 cell divisions from a single cell
Describe turbidity bacteria growth
- transformation of a clear broth ( liquid ) medium to a turbid suspension of 10^7-9 cells per mL
- spectrometry used to measure number of cells in medium
How so biofilm formation done
-bacterial growth is spread thinly ( 300-400um ) over a thing inert surface
What does single bacteria become and what is the progeny covered in in biofilm
/becomes complex community of progeny covered in membrane called glycocalyx
What is purpose or glycocalyx in bacteria , it’s significance and how to bacteria communicate in biofilm
-protects community of progeny from the environment
/through complex telecommunication system called quorum sensing
List and describe the steps in biofilm formation
1 planktonic phase
-cells mobile and still coming together
2 irreversible attachment sessile state
-become fixed on one place at surface and form colonies and glycocalyx layer
3 growth and microcolony formation
-continued growth and glycocalyx formation
4 maturation
-reached full state
5 dispersed
-colony cells leaves culture and find new surface attach to
List infections associated with biofilm formation
1 infective endocarditis
2 streptococcus viridans on heart valve
3 pseudomonas aeruginosa lung infection
4 staphylococcus aureus on catheters
What type of growth is shown in fluid culture medium and how is it expressed
- in fluid culture medium bacteria displays a uniform growth curve
- expressed in log numbers of viable bacteria over time
How is bacteria growth determined
-fixed volume of liquid medium ( culture batch ) is inoculated with bacteria and number of viable cells per mL is determined periodically and plotted
What does growth curve show and list its 4 phases
-shows fundamental insight to genetics and physiology of bacteria replication
1 lag phase
2 exponential / log
3 stationary
4 death phase
Describe lag phase , what occurs and what determines length
- part of graph is straight
- cells still adapting to new environment
- as they adapt enzymes and nutrients and intermediates for growth are accumulated until they reach feasible amounts
- length of phase depends on species ability to adapt
Describe exponential phase , what occurs and what stops the phase
- line increase exponentially
- cells Dividing at constant rate
Phase stops if
1 one or more nutrients are depleted
2 lack of biological space
3 toxic metabolites accumulate and Inhibit growth
Describe stationary phase , what occurs
- line is straight
- growth slows down and reaches max and stabilizes
- production of secondary metabolites occur such as spores and antibiotics
- spores genes activated
Describe death phase , what occurs
- line drops exponential
- irreversible loss of ability to reproduce
- viable cells population decrease exponentially
- release of spores and toxins and cells are autolyzed
Significance of growth curve
- helps to know which phase produces antibiotics
- used to explain what is happening in body during infection
Describe long and short exponential growths and bacteria associated
1 short
- small # of bacteria initiate deadly disease as they can proliferate fast
- symptoms are acute
2 long
-slow division leading to chronic infection eg tuberculosis bacillus
Describe what happens to bacteria inside body tissue
- bacteria stressed
- populations rarely fully viable
- may cease growth but continued synthesis to adapt to stress
Effects of non growing bacteria
- immunologic
- sporulation and toxin release
- production of spores and toxins
What does bacteria need energy for
1 establish proton motive force - potential energy derived from
Passage of protons across a membrane
2 allow macromolecule synthesis
List 3 mechanisms to generate metabolic energy
1 fermentation
2 photosynthesis
3 respiration
Describe fermentation
-enzymatic process in which pyrophosphate bond is donated to ADP by a phosphorylated metabolic intermediate
How are metabolic intermediates for fermentation formed and characteristics
- metabolic rearrangement of a fermentable substrate such as glucose or lactose
- elemental composition of fermentation product identical to those of substrate
Example of fermentation pathway
-fermentation of glucose using Embden-Meyerhof pathway yielding ATP and lactic acid
What is respiration
List alternate oxidants
Chemical reduction of oxidant ( 02 electron acceptor ) through a series of specific electron carriers in membrane to establish a proton motive force across membrane
-CO2, sulfate or nitrate
Two types of electron donors and example
1 inorganic ( lactic acid )
2 organic ( H2 )
Describe photosynthesis
-cells with pigment called chlorophyll trap sunlight and use the energy to photochemically create reductant and oxidant to produce O2 and organic matter
Categorize microbes based on energy source
1 phototrophs- use light to drive metabolic processes
2 chemotrophs - use organic or inorganic elements
3 lithotrophs - inorganic only
4 organotrophs / chemoorganotrophs - organic only
List groups of elements, the types and functions
Synthesis of structural components
/ C, N , O , P , S and H
-synthesis of lipids, proteins, carbohydrates and nucleic acids
Other cellular functions
- K : actives enzymes / maintain osmolality
- Ca2 and Mg : cofactor
- Fe : electron transfer during redox reactions
Trace elements
-Cu , Zn , Mn : activates and stabilizers of various enzymes
Categorize microbes based on carbon source and reductant method of C
1 autotrophs : do not need Organic nutrients for growth
-use photosynthesis to reduce CO2 and water expense
2 chemolitrotrophs : use inorganic substrates as reductant ( H2 or thiosulfate ) and CO2 as carbon source
3 heterotrophs : organic C which can be assimilated eg glucose
Importance or nitrogen and it’s dry mass , it’s % in air and stability
- mass nucleic acids , proteins
- 5%
- 80% in atomosphere
- highly stable due to N-N triple bond
How do all microbes assimilate N2
-pathways has end product as NH3
Categorize microbes based on N2 assimilation and explain
1 nitrogen fixation - directly break N2 and is assimilated as NH3
2 ammonification- deaminates aas such as glutamine and glutamate to acquire NH3
3 assimilatory nitrate / nitrite reduction - reduction of nitrate / nitrite to NH3
Importance of sulphur and can it be used in element form
-cellular function, cell wall , structure of coenzymes
/no
How does microbes assimilate sulfur
1 autotrophic oxidize sulfur to sulfate
2 most reduce S to H2S ( salmonella )
3 some assimilate H2S from growth medium
Use of phosphate and how assimilated
- make nucleic acids , ATP and coenzymes such as NAD and NADP
- make techoic acid and some capsular polysaccharides are phosphorylated
-assimilated always as free inorganic phosphate
How are trace elements provided and how is Fe taken up , what are siderophores and role of plasmid derived siderophores
- Tap water or contaminates of other medium ingredients
- Fe taken and forms insoluble hydroxides at neutral pH facilitated by siderophores
- siderophores are compounds that chelate iron and promote its transport as a soluble complex
- major role in invasiveness of some pathogens
What are growth factors and how obtained
-organic compounds needed for growth but cells can’t make them on eir own
/obtain from environment
List environmental factors taken into bacterial growth account
/pH
- temperature
- aeration
How do microbes regulate internal pH
-pumping Protons into and out of cell
Classify microbes based on pH tolerance and put ranges
1 alkaliphiles
-regulate internal 9.5 over external of 9-11
2 neutrophiles
-maintains internal of 7.5 over external of 5.5-8.5
3 acidophiles
-maintain internal of 6.5 over external of 1-5
Describe temp against growth graph
- lowest temp that will not support growth but won’t kill bacteria
- growth increases exponentially as temp increases
- reach optimum , highest rate of growth
- beyond optimum rate decrease fast
- highest temp recorded that wont support growth but won’t kill
- beyond cell is disintegrated
Categorize microbes based on temp and put ranges and short description
1 psychrophile
- range -5 to 15
- found at arctic and Antarctica
2 psychrotrophs
- range 20-30 but can also grow at as low as -5
- important in food spillages eg listeria monocytogenes
3 mesophile
- range 30-37
- body temp optimal for mesophiles
4 thermophiles
- range 50-60
- not found in people as body temp to low
- found in hot springs
5 hyperthermophiles
- range well above boiling point
- exist at higher pressure under water volcanoes
How do microbes tolerate upper end range of temp and describe
- heat shock response
- transient synthesis of HSP to stabilize heat sensitive proteins and deals with denatured ones
What is sterilization with heat and cold shock phenomena
/use of excessive heat to kill microbes
/killing of microbes by rapid cooling
What is aeration and how do all organism depend on it
By product of aerobic metabolism and dangers of it
- atmosphere condition
- all organisms use oxidation to transfer energy to compounds that participate in their biochemical processes
- Peroxide and superoxide
- Fe can generate OH radical wc can damage any biological macromolecules
How does bacteria protect against aerobic by products and describe how they do it
1 superoxide dismutase
-catalyze superoxide( 02-) and hydrogen reaction to form oxygen and water
2 catalyse
-catalyze peroxide breakdown to water and oxygen
Categorize microbes based on aeration and presence of enzymes and test tube location
1 obligate aerobes
-both enzymes present ,require O2 for growth and close to surface of tube
2 obligate anaerobes
-no enzyme , require complete absence of 02 and bottom of tube
3 aerotolerant anaerobes
-superoxide dismutase only , do need O2 but can grow in it and scattered all over tube
4 facultative anaerobes
-both enzymes present , can grow with or without O2 and scattered all over
5 micro anaerobes
-small amount of enzyme , require minimal amounts of O2 ( 2-10%) any more is inhibitory and found in middle of tube just under surface
6 capnophiles
- require increased CO2 to grown
- eg Neisseria species
How do microbes tolerate change in external osmolality and ionic conc
- uptake of K ions
- opening and closing ion and anion voltage gates
Categorize Microbes based on salt needs and explain briefly
1 nonhalophile
-growth dependent on no or little salt.
2 halotolerant
-will grow in absence of presence of not extreme levels salt
3 halophile
-needs high conc of salt to grow properly
4 extend halophile
-needs excessive amounts of salt to grow properly
What is an osmophile
-bacteria which requires high conc of sugar in environments to grow
List the important human pathogen optimum conditions
1 mesophile temp
2 pH 7.4-7.6 ( neutrophile )
3 heterotrophs
4 mostly facultative anaerobes ( or any O2 requirement )
