Firmicutes: Low G+C Gram-Positive Bacteria

Question 1

Peptidoglycan Structure differences

Answer 1

number of interpeptide bridges between glycan chains

Question 2

Endospore Production

Answer 2

• heat-resistant
• germinates in optimal growth conditions
• location and size used to identify bacteria

Question 3

Class Clostridia

Answer 3

• anaerobic
• endospore
• food spoilage

Question 4

Clostridium Stickland Process

Answer 4

• survive heat treatment of canned food
• fermentation, ATP produced
• forms: ammonium, H2S, fatty acids, amines

Question 5

Clostridium botulinum

Answer 5

botulism
respiratory muscle paralysis

Question 6

Clostridium tetani

Answer 6

• lockjaw
• affects nervous system
• painful muscle contractions

Question 7

Clostridium perfringens

Answer 7

• gas-gangrene and food poisoning
• toxins that cause necrosis

Question 8

Clostridium acetobutylicum

Answer 8

• butanol production
• useful

Question 9

2 Orders of Class Bacilli

Answer 9

• Bacillales
• Lactobacillales

Question 10

5

Genus Bacillus

Answer 10

• endospore
• chemoheterotrophic rods
• peritrichous flagella if motile
• aerobe / facultative aerobe
• catalase +

Question 11

antibiotics

Impact of Genus Bacillus

Answer 11

• bacitracin
• gramicidin
• polymyxin

Question 12

Bacillus anthracis

Answer 12

• anthrax
• skin ulcers
• in soil

Question 13

Bacillus cereus

Answer 13

• food poisoning
• β-haemolysis

Question 14

2 Useful Bacillus species

Answer 14

• Bacillus thuringiensis
• Bacillus sphaericus
• parasporal body in sporangium
• toxic to some insects

Question 15

Which Family does not superficially fit into the Order Bacillalles?

Answer 15

Family Staphylococcus

Question 16

6

Genus Staphylococcus

Answer 16

• facultative anaerobe
• non-motile
• cocci
• irregular clumps of cells
• oxidase -
• catalase +

Question 17

Staphylococcus epidermidis

Answer 17

wound infections

Question 18

Staphylococcus aureus

Answer 18

• abscesses, pneumonia
• food poisoning
• nose mucous membrane, skin and digestive system of warm-blooded animals

Question 19

2 Resistant S.aureus strains

Answer 19

• Meticillin RSA
• Vancomycin RSA
• Both are resistant to multiple drugs

Question 20

How is S.aureus distinguished from S.epidermidis?

Answer 20

presence of coagulase:
- causes blood plasma to gel
- β-haemolysis

Question 21

7

Order Lactobacillales

Answer 21

• grow together with yeast
• non-sporulating
• non-motile
• fermentation
• no cytochromes
• energy from sub-level phos
• facultative anaerobes

Question 22

Genus Lactobacillus

Answer 22

• rods
• no catalase
• not usually pathogenic

Question 23

Lactobacillus

Homolactic fermentation

Answer 23

EM pathway (lactic acid and energy)

Question 24

Lactobacillus

Heterolactic fermentation

Answer 24

phosphoketolase pathway (lactate and ethanol produced)

Question 25

Lactobacillus

Answer 25

- fermented foods and drinks - sometimes food spoilage

Question 26

Lactobacillus bulgaricus and Streptococcus thermophilus

Answer 26

flavour and aroma of yoghurt

Question 27

Genus Leuconostoc

Answer 27

- facultative anaerobe - cocci - pairs or in chains - no catalase or cytochromes - plants, silage and milk - heterolactic ferm: glucose to D-lactate and ethanol or acetic acid

Question 28

Impact of Genus Leuconostoca

Answer 28

- fermented foods and drinks - osmotolerant - food spoilage of high sugar foods

Question 29

Leuconostoc mesenteroides

Answer 29

produce dextran from sucrose

Question 30

Enterococcus, Streptococcus and Lactococcus

Answer 30

- closely related genera - chemoheterotrophic - mesophilic - non-sporulating

Question 31

Identification for Ent, Strep, Lacto

Answer 31

- ability to lyse red blood cells - serological studies: different cell wall antigens on different strains

Question 32

α-Haemolysis (Ent, Strep, Lacto)

Answer 32

- Streptococcus pneumoniae - greenish zone - incomplete haemolysis

Question 33

β-Haemolysis (Ent, Strep, Lacto)

Answer 33

- Streptococcus pyogenes - clear zone - complete haemolysis

Question 34

Streptococcus pyogenes

Answer 34

sore throat rheumatic fever

Question 35

Streptococcus mutans

Answer 35

tooth decay

Question 36

Streptococcus pneumoniae

Answer 36

pneumonia

Question 37

Lactococcus lactis

Answer 37

- useful - production of cheese