Chapter 6: Microbial Growth

Question 1

Psychrophiles

Answer 1

• cold loving organism

Question 2

types of psychrophiles

Answer 2

• true
• psychrotrophic / faculatative

Question 3

True psychrophiles

Answer 3

• can grow at 0 degrees
• optimum = 15 degrees
• cannot grow at 20-25 degrees
• non pathogenic

Question 4

Psychrotrophic / faculatative psychrophiles

Answer 4

• can grow at 0 degrees
• optimum at 20-30 degrees
• cannot grow at 30 degrees
• pathogenic
• causes food (spoilage mild, odour, slimy)

Question 5

Mesophile

Answer 5

• medium loving organisms
• can grow at 25- 40 degrees
• optimum = 37 degrees
• cannot grow at 50 degrees
• pathogen

Question 6

types of themophilic organisms

Answer 6

• true
• hyperthermophiles

Question 7

true thermophilic organism

Answer 7

• cannot grow below 45 degrees
• optimum at 50-60 degrees
• maximum at 70-80 degrees
• non pathogenic

Question 8

Hyperthermophilic

Answer 8

• cannot grow below 45 degrees
• optimum at 50-60 degrees
• maximum at 110-121 degrees
• non pathogenic

Question 9

Optimum Ph is typically at

Answer 9

6.5 - 7.5

Question 10

If a bacteria goes past the optimal ph the bacteria cell wall will

Answer 10

denature

Question 11

Denaturation

Question 12

Hypertonic solution effect on the cell

Answer 12

• water moves out of the cell (shrinks)
• plasmolysis

Question 13

isotinic solution

Answer 13

• no net movement of water

Question 14

Hypotonic solution effect on the cell

Answer 14

• water moves into the cell (swells)
• if cell burst called osmotic lysis

Question 15

Obligate Aerobes

Answer 15

• only aerobic growth
• growth occurs where large amount of oxegen difuses into the medium
• contains enzymes catlayse and SOD (nutrilixes toxic forms of oxegen)
• most bacteria

Question 16

Obligate anaerobic

Answer 16

• only anaerobic growth
• growth occurs where there is no oxygen
• lacks enzymes that neutralize toxic form of oxygen
• harmed by oxygen

Question 17

example of obligate anaerobic bacteria

Answer 17

• clostridium species

Question 18

Faculatative anaerobic

Answer 18

• uses oxygen when available for fast growth
• when unavailable uses anaerobic of fermentation (slow growth)
• variable ATP

Question 19

Example of falculatative aerobic bacteria

Answer 19

• samonella, e-coli

Question 20

Aerotolerant anaerobes

Answer 20

• tolerate oxygen but choose not to use it
• obligate fermetators

Question 21

Example of aerotolerant anaerobes

Answer 21

lactobacillus

Question 22

Microaerophile

Answer 22

• aerobic
• uses oxegen in lower concentrations (2-10%)
• produce small amount of SOD

Question 23

example of microanerophile bacteria

Answer 23

• helicobacteria (ulcers)
• Campylobacteria jejuni (gastroenteritis)

Question 24

toxic forms of oxygen include

Answer 24

1. singlet oxegen
2. superoxide free radicles
3. peroxide anion
4. hydroxyl radical

Question 25

Singlet oxygen

Answer 25

• normal oxygen that has been boosted to a higher- energy state and is extremely radioactive

Question 26

Superoxide free radicles

Answer 26

• toxically caused by instability (steals electrons)
  O2- + O2- +2H = 2 H2O2 + O2

Question 27

Perioxide anion

Answer 27

2 H2O2 —— enzyme: catalase —–> 2 H2O + O2

or

H2O2 + 2H —Enzyme: peroxilase —> 2 H2O

Question 28

Hydroxyl Radical

Answer 28

(OH)
- most reactive
- formed by cellular cytoplasm by ionizing raditation

Question 29

Biofilm development

Answer 29

• queron sensing allows microbes

Question 30

Culture medium

Answer 30

• nutrients prepared for microbial growth

Question 31

Sterile

Answer 31

• no living microbes

Question 32

Inoculum

Answer 32

• introductions of microbes in (nutrient broth) / (agar plate) medium

Question 33

Agar

Answer 33

• complex polysaccaride
• used as a solidifying agent for culture media in peri plates
• is not metabolized by microbes

Question 34

what temp does agar liquify at

Answer 34

100 degrees

Question 35

What temp does agar remain solid at

Answer 35

37 degrees

Question 36

Selective media is made up of

Answer 36

bismuth sulphile agar

Question 37

Selective media is used to

Answer 37

• supress unwanted microbes and encourage desired microbes
• used to grow organism Samonella typhus (typhoid fever)

Question 38

Differential media is made up of

Answer 38

blood agar

Question 39

Deferential media is used to

Answer 39

• distinguish colonies of diffrent microbes
• used to grow streptococcus pyogenes (causes strep throat)
• has clear zome and hemolysis of RBC’s

Question 40

Selective and differential media is made up of

Answer 40

• manitol salt agar

Question 41

Selective + differntial media is used to

Answer 41

• grow streptococcus auxeus (skin infections, toxic shock syndrom, food poisoning
• has yellow zone

Question 42

Steps in Binary Fisson

Answer 42

1. cell elongates and DNA is replicated
2. cell wall and membrane begin to constrict
3. cross wall forms, completely separating the two DNA copies
4. cells seperates

Question 43

Lag phase

Answer 43

• intense activity preparing populaton for growth

Question 44

Log phase

Answer 44

• logrithmic; exponetial
• increase in population

Question 45

Generation time formula

Answer 45

(60mins x hours) / (number of generations)

Question 46

Examples of log phase

Answer 46

• use of antibiotics
• radiation
• antiseptic

Question 47

Stationary phase

Answer 47

• period of equalibrium
• microbial dealth balance production of new cells

Question 48

Dealth phase

Answer 48

• population is decreasing at a logarithmic rate