Lecture 7 Effect of Environment on Bacterial Growth

Question 1

A. to F.

Answer 1

A. Entry of nutrients into the cell
B. Effects of nutrient concentration on bacterial growth rate
C. Utilization of nutrient that do not enter the cell
D. Effects of temperature on bacterial growth
E. Effects of solute on bacterial growth
F. Gaseous requirements of bacteria

Question 2

A. Entry of nutrients into the cell

Process by which chemical substances called NUTRIENTS are acquired from the environment
Used in cellular activities

Answer 2

Nutrition

Question 3

A. Entry of nutrients into the cell

_ _ must be provided to an organism
(_, _, _, _, _, _)

Answer 3

Essential nutrients (C, N2, O2, H2, P, S)

Question 4

A. Entry of nutrients into the cell

2 categories of Essential Nutrients:
1. _ or trace elements - required in small amounts; involved in enzyme function and maintenance of protein structure
2. _ - required in large amounts; play principal role in cell structure and metabolism

Answer 4

2 Categories of Essential Nutrients:
1. Micronutrients or trace elements
2. Macronutrients

Question 5

A. Entry of nutrients into the cell

Controls passage of nutrients into the cell

Answer 5

Cytoplasmic (cell) membrane

Question 6

A. Entry of nutrients into the cell

Cytoplasmic (Cell) Membrane
- _
- _ _ - only relatively small, non-polar materials can move through the lipid bilayers (lipids, O, CO2, and alcohol)
- water-soluble materials like glucose, amino acids, and electrolytes need some assistance to cross the membrane

Answer 6

• Semi-Permeable
• Selectively Permeable

Question 7

A. Entry of nutrients into the cell

2 parts of a phospholipid bilayer

Answer 7

• Hydrophilic head
• Hydrophobic tail

Question 8

A. Entry of nutrients into the cell

Comprises the cell membrane, cell wall, and outer membrane if present

Answer 8

Cell envelope

Question 9

A. Entry of nutrients into the cell

Cell Envelope
_ _ _ - peptidoglycan cell wall, plasma membrane, cytoplasm
_ _ _ - outer membrane, periplasmic space, inner membrane

Answer 9

Gram + bacteria
Gram - bacteria

Question 10

A. Entry of nutrients into the cell

Cell Envelope
Embedded within are _:
- channels/transporters to facilitate movement of specific molecules
- maintain internal environment
- cell signaling
- protection

Answer 10

Proteins

Question 11

A. Entry of nutrients into the cell

Uptake of Nutrients
_ _ _:
- _ _ - plays a role in regulating the passage of solutes (dissolved in a solution)
- semi-permeable and selectively permeable
- no proteins in _ _ are known to pump solutes across it although some activity facilitate passage

Answer 11

Gram - bacteria
- Outer Membrane

Question 12

A. Entry of nutrients into the cell

Uptake of Nutrients
- _ _ - peptidoglycan, cytoplasmic membrane (active transporters, single membrane efflux pumps)
- _ _ - (LPS) outer membrane (OM diffusion pore, OM general porin), peptidoglycan, cytoplasmic membrane (active transporters, SM efflux pumps, RND efflux)

Answer 12

• Gram +
• Gram -

Question 13

B. Effect of nutrient concentration on bacterial growth rate

Movement of particles from an area of higher concentration to an area of lower concentration

Answer 13

Diffusion

Question 14

B. Effect of nutrient concentration on bacterial growth rate

The difference in concentration of a substance across a space

Answer 14

Concentration Gradient

Question 16

B. Effect of nutrient concentration on bacterial growth rate

Types of Diffusion

Answer 16

A. Passive Diffusion (Simple Diffusion)
B. Facilitated Diffusion
C. Active Transport
D. Group Translocation

Question 17

B. Effect of nutrient concentration on bacterial growth rate

Types of Diffusion
_ _ - a process in which molecules from a region of higher concentration moves to one of lower concentration
- occurs when there are regions of the membrane through which a particular solute can pass freely
e.g. movement of O into cells and CO2 out of cells (without requiring energy)

Answer 17

A. Passive Diffusion

Question 18

B. Effect of nutrient concentration on bacterial growth rate

Types of Diffusion
_ _ - diffusion in and out of the cell of certain compounds
- is mediated by specific membrane proteins collectively known as PERMEASES or CARRIER PROTEINS or CHANNEL PROTEINS
- no energy input

Answer 18

B. Facilitated Diffusion

Question 19

B. Effect of nutrient concentration on bacterial growth rate

Types of Diffusion
_ _ - vital process that uses cellular energy to move molecules across cell membrane against concentration gradient
- facilitated by specialized carrier proteins
- primary and secondary

Answer 19

C. Active Transport

Answer 20

C. Active

Question 21

B. Effect of nutrient concentration on bacterial growth rate

Types of Diffusion
Active Transport
_ _ _ - directly uses energy from ATP hydrolysis to move substances
- ATP-binding casette (ABC) transporters
- Maltose ABC transporter in E. coli

Answer 21

Primary Active Transport

Question 22

B. Effect of nutrient concentration on bacterial growth rate

Types of Diffusion
Active Transport
_ _ _ - uses energy stored in an electrochemical gradient (from primary acrive transport) to move other substances
- proton motive force (PMF) or ion gradients
- symporters (lactose transport) and antiporters (Na+/H+ antiporter)

Answer 22

Secondary Active Tranpsport

Question 23

B. Effect of nutrient concentration on bacterial growth rate

Types of Diffusion
Active Transport
Secondary Active Transport
_ _ _ - an electrochemical gradient of protons (H+ ions) across cell membrane
- provides energy for various cellular processes
- generated by electron transport chain (ETC)
- drives ATP synthesis, active transport and motility in bacteria

Answer 23

Proton Motive Force

Question 24

B. Effect of nutrient concentration on bacterial growth rate

Types of Diffusion
_ _ - the transported molecule is chemically modified during transport
- a cascade of enzymes and phosphorylation events
- uses phosphoenolpyruvate (PEP) as an energy source
- E. coli via PEP-dependent phosphotransferase system (PTS)

Answer 24

D. Group Translocation

Question 25

B. Effect of nutrient concentration on bacterial growth rate Simple Compaison of Transport Systems Passive Diffusion, Facilitated Diffusion, Active Transport, Group Translocation Property - Carrier mediated, Transport speed, Against concentration gradient, Specificity, Metabolic energy, Solute modified during transport

Answer 25

PFAG Carrier mediated - + + + Transport speed slow rapid rapid rapid Against concentration gradient - - + NA Specificity - + + + Metabolic energy - - + + Solute modified during transport - - - +

Question 26

B. Effect of nutrient concentration on bacterial growth rate Other forms to transport molecules _ _ _ - uptake from environment in Gram - bacteria resembling endocytosis - release similar exocytosis for communication and pathogenesis; secretion systems to transport molecules

Answer 26

Outer membrane vesicle (OMV)

Question 27

C. Utilization of nutrients that do not enter the cell Utilization of Substrates that Cannot Pass the Cell Membrane _ - some macromolecules such as starch, cellulose, or RNA; highly charged small molecules such as nucleotides -> cannot pass the cell membrane but can be used as substrates for growth

Answer 27

Exoenzymes

Question 28

C. Utilization of nutrients that do not enter the cell Utilization of Substrates that Cannot Pass the Cell Membrane Characteristics of Exoenzymes - _ while inside the cell - upon release from the cell, they become _

Answer 28

- inactive - active

Question 29

D. Effects of temperature on bacterial growth _ - most important factor that determines the rate of growth, multiplication, survival and death of all microorganisms - rate of enzyme reaction increases with higher _

Answer 29

Temperature

Question 30

D. Effects of temperature on bacterial growth Temperature - _ _: Minimum, Optimum, Maximum - _ _ of a particular microbial species may vary: stage in the life cycle of the microorganism, nutritional content of the medium

Answer 30

Cardinal Temperatures

Question 31

D. Effects of temperature on bacterial growth Temperature - _ temperatures damage microbes by denaturing enzymes, transport carriers, and other proteins - microbial membrane are disrupted by _ temperatures

Answer 31

- high - extreme

Question 32

D. Effects of temperature on bacterial growth Temperature - as the incubation temp is _, enzymatic reactions inside the cell proceed at _ rates and growth rates _ until cells reach the minimum temp at which growth is possible - temperatures _ _ _ growth temp cause no damage; on the contrary, _ temp preserves microorganisms

Answer 32

- lowered; slower; decreased - below the minimum; cold

Question 33

D. Effects of temperature on bacterial growth 1. At the very low temp, metabolic rates are very slow and cells will survive for long period 2. As temp rises, enzymatic reactions inside the cell proceed at faster rate and growth also becomes more rapid until optimum growth rate is achieved 3. Just above that temperature, proteins, DNA, RNA, and other critical cell components become irreversibly denatured and growth rate falls rapidly to zero 4. Subsequent increase in temp may kill the microorganism

Answer 33

Effects

Question 34

D. Effects of temperature on bacterial growth _ - the lowest temp at which organisms grow _ - highest growth rate _ - the highest temp at which growth occurs

Answer 34

Minimum Optimum Maximum

Question 35

D. Effects of temperature on bacterial growth 30 degrees C Range _ - membrane gelling _ - enzyzme reactions at maximum rate _ - protein denaturation

Answer 35

Minimum Optimum Maximum

Question 36

D. Effects of temperature on bacterial growth Three Classifications of Bacteria according to Growth Temperature _/_ - able to grow at 0 degrees C or lower but they grow best at higher temps (-20-10 degrees C) - extremophilic organisms that are capable of growth and reproduction in low temps - found in places that are permanently cold e.g. oilar regions and deep sea - genera Pseudomonas, Flavobacterium, Alcaligenes

Answer 36

A. Psychrophiles/Cryophiles

Question 37

D. Effects of temperature on bacterial growth Three Classifications of Bacteria according to Growth Temperature _ - grow best in moderate temps - temp range (20-45 degrees C) - most microorganism are _ - body temp pathogenic to human (37 degrees C) - lower part: saprophytic bacteria, fungi, algae, protozoa - upper part: parasitic microorganisms of humans and animals - E. coli, Streptococcus pneumoniae

Answer 37

B. Mesophiles

Question 38

D. Effects of temperature on bacterial growth Three Classifications of Bacteria according to Growth Temperature _ - heat-loving microorganisms - grow best at temp above 45 degrees C - growth minimum is usually around 45 degrees C but the optimum is between 50-80 degrees C - most are prokaryotic which may be found in volcanic areas, compost peeats, hot springs - Thermus aquaticus, Geogemma barrosii

Answer 38

C. Thermophiles

Question 39

D. Effects of temperature on bacterial growth Three Classifications of Bacteria according to Growth Temperature _ - thrive in extremely hot environment - temp range: 80-113 degrees C - cell membrane contains high levels of saturated fatty acids to retain its shape at high temps - Sulfolobus solfataricus, Methanococcus jannaschii, Thermotoga

Answer 39

D. Hyperthermophiles

Question 40

E. Effects of solute on bacterial growth _ which consists of 80-90% of a cell, influences growth beyond its role in cellular metabolism and nutrition, through osmotic pressure and hydrostatic pressure

Answer 40

H2O

Question 41

E. Effects of solute on bacterial growth _ _ - the force with which water moves through the cytoplasmic membrane from a solution containing a low concentration of dissolved substances (solute) to one containing a high solute concentration

Answer 41

Osmotic Pressure

Question 42

E. Effects of solute on bacterial growth Bacteria based on Osmotic Requirement _ - grow in solution of increased osmolarity - microorganisms adapted to environments with high osmotic pressures such as high sugar concentrations _ - grow in solution of increased salt concentration - a type of extremophile organism - name comes from Greek word for "salt-loving"

Answer 42

Osmophiles Halophiles

Question 43

E. Effects of solute on bacterial growth _ - shrink _ - normal _ - burst

Answer 43

Hypertonic Isotonic Hypotonic

Question 44

E. Effects of solute on bacterial growth _ _ _ _ - detected only for growth at the expense of certain specific C and energy sources - ex. Enterobacter aerogenes require sodium for growth on citrate - bacteria of marine origin, most moderate halophiles and extreme halophiles require sodium for growth on citrate

Answer 44

Sodium Requirement of Bacteria

Question 45

E. Effects of solute on bacterial growth Sodium Requirement of Bacteria - in all of these organisms, sodium plays a number of different roles, all indespensable to the maintenance of cellular function - _ _ - assures correct function of transport mechanism - extreme halophiles - a high concentration of NaCl is essential in order to maintain both stability and catalytic activity of enzymes

Answer 45

- Marine bacteria - Extreme halophiles

Question 46

E. Effects of solute on bacterial growth _ _ - pressure exerted on the cells by the movement of water resting on top of them _ - pressure-dependent microbes - organisms that need a high-pressure environment in order to grow - deep- sea environment (ocean floors, deep lakes-pressure exceed 380 atm)

Answer 46

Hydrostatic Pressure Barophiles/Piezophiles

Question 47

E. Effects of solute on bacterial growth Effects of pH on Bacterial Growth _ - the negative logarithm of hydrogen ion concentration - microbial growth is strongly affected by the pH of the culture medium

Answer 47

pH

Question 48

E. Effects of solute on bacterial growth Effects of pH on Bacterial Growth Drastic variations of cytoplasmic pH -> Disruption of plasma membrane -> Enzyme activity, Membrane transport protein activity -> _

Answer 48

Inhibition

Question 49

E. Effects of solute on bacterial growth Effects of pH on Bacterial Growth _ - grow between pH 0-5.5 _ - pH 5.5-8 _ - pH 8-14

Answer 49

Acidophile Neutrophile Alkaliphile

Question 51

E. Effects of solute on bacterial growth Effects of pH on Bacterial Growth _ _ for microbial growth - middle of pH range from pH 6-8 _ _ - min pH 4, max pH 9 _ and _ - broader pH, optimum pH 5-6

Answer 51

Optimum pH Most bacteria Molds and yeasts

Question 52

F. Gaseous requirements of bacteria 1. In order to cultivate microbial cells in the laboratory, the _ _ _ must be present 2. Some gases are used in cellular metabolism, others may have to be excluded from a culture because they are _ to the cells 3. _ and _ are the 2 principal gases that affect the growth of microbial cells

Answer 52

1. proper gas atmosphere 2. toxic 3. O and CO2

Question 53

F. Gaseous requirements of bacteria _ - organisms that can survive and grow in an oxygenated environment - standard air atmosphere (21%) - Mycobacterium and Legionella _ - microorganisms which may be poisoned by O - cannot grow in an air atmosphere - do not use O

Answer 53

A. Aerobes B. Anaerobes

Question 54

F. Gaseous requirements of bacteria B. Anaerobes _ _ - can tolerate low concentrations of O - highly O tolerant (Clostridium perfringens) - moderately O tolerant (Clostridium tetani) _ _ - killed by brief exposure of O (Methanobacterium and Methanospirillum)

Answer 54

- Tolerant Anaerobes - Strict Anaerobes

Question 55

F. Gaseous requirements of bacteria _ _ - anaerobic bacteria that do not require O for growth although may use it for energy production if available - under anaerobic conditions may obtain energy by a metabolic process called _ - members of Family Enterobacteriaceae such as E. coli and many yeast like Saccharomyces cerevisciae

Answer 55

C. Facultative Anaerobes - fermentation

Question 56

F. Gaseous requirements of bacteria _ - can use O - cannot withstand the level of O present in the air (21%) and usually grow best at O levels between 1-15% - limited tolerance to O is due to high susceptibility to superoxide radicals and hydrogen peroxide - Campylobacter jejuni

Answer 56

D. Microaerophiles

Question 57

F. Gaseous requirements of bacteria _ _ - O is used by aerobic and facultative anaerobic organisms because its strong oxidizing ability makes it an excellent electron acceptor - during _, O was reduced resulting to production of toxic and highly reactive intermediates (ROS)

Answer 57

Oxygen Toxicity - Respiration

Question 58

F. Gaseous requirements of bacteria Oxygen Toxicity _ _ _ _ _ 1. Oxygen inactivation of enzymes 2. Damage due to toxic derivatives of oxygen

Answer 58

Factors Implicated in Oxygen Toxicity

Question 59

F. Gaseous requirements of bacteria Toxic Derivatives of Oxygen (Derivatives | Functions) 1. _ _ - addition of a single electron to an O molecules -> damage to cells -> inactive cell components 2. _ _ - can destroy viral cell components 3. _ _ - most reactive chemical substance -> damage the cell 4. _ _ - very powerful oxidant; alteration of our genetic material to the promotion of cytotoxicity

Answer 59

1. Superoxide radical 2. Hydrogen peroxide 3. Hydroxyl radicals 4. Singlet oxygen

Question 60

F. Gaseous requirements of bacteria Protective Mechanisms (Substance/Compound | Functions) 1. _ - catalyzes the oxidation of organic compound by H2O2 -> reduced to H2O H2O2 + reduced substrate --perioxidase-> 2H2O + oxidized substrate 2. _ _ - acts as quenchers of singlet O and protects the cell from photooxidative death

Answer 60

1. Perioxidase 2. Carotenoid pigment

Question 61

F. Gaseous requirements of bacteria Protective Mechanisms (Substance/Compound | Functions) 3. _ _ - catalyzes conversion of superoxide radicals to O2 and H2O2 2O2- + 2H+ --superoxide dismutase-> O2 + H2O2 4. _ - decomposes hydrogen peroxide H2O2 --catalase-> 2H2O + O2

Answer 61

3. Superoxide dismutase 4. Catalase