IA. General Microbiology | 2. Bacterial metabolism. The growth and reproduction of bacteria. Flashcards
I. Bacterial metabolism
1. What is Bacterial Metabolism?
How bacteria gets energy and nutrients
I. Bacterial metabolism
2. What are the main types of Bacterial Metabolism?
- Heterotrophic
- Autotrophic
- Phototrophic
I. Bacterial metabolism - Heterotrophic
3A. What are characteristics of Heterotrophic?
- Heterotrophic bacteria
depend on preformed food for nutrition - Energy yielding catabolic reaction: transferring electrons from one molecule to another to produce ATP
- Some metabolize sugars and carbohydrates to produce energy – require enzymes to degrade polysaccharides into usable sugar units
I. Bacterial metabolism - Heterotrophic
3B. How does heterotrophic bacteria use carbohydrates?
- Sugars – produce energy via fermentation and respiration
(Carbohydrates used in glycolysis and pentose phosphate pathways in eukaryotic cells)
I. Bacterial metabolism - Heterotrophic
3C. How does fermentation happen in heterotrophic bacteria?
Fermentation → anaerobic process that takes places in the absence of any external electron acceptor.
- Sugar is broken down into smaller organic molecules → catabolic rxn that results in the formation of ATP
- Result in production of large quantities of organic end products and relatively small out of energy per glucose molecule consumed
- Variety of fermentation pathways and this helps ID the bacteria by their end products
I. Bacterial metabolism - Heterotrophic
3D. How does Respiration happen in heterotrophic bacteria?
Respiration → more energy is available through this process
■ Electrons from molecules of sugar are transferred to another inorganic molecule
■ Aerobic respiration uses oxygen as the final electron acceptor — sugar broken down and 38 ATP per molecule of glucose
■ Anaerobic conditions use inorganic molecules (nitrate, sulfate, carbon dioxide) as the final electron acceptor. Lower yield than aerobic respiration, but still higher than fermentation
I. Bacterial metabolism - Autotrophic
4A. What are the features of autotrophic bacteria?
- Autotrophic bacteria are capable synthesizing their food from simple inorganic nutrients
I. Bacterial metabolism - Autotrophic
4B. How do Autotrophic bacteria carry out metabolism?
- Use light energy through photosynthetic pigment and convert to ATP
- Synthesize all their cell constituents using carbon dioxide as the carbon source - most common way is through the Calvin Cycle and the acetyl-CoA pathway.
- Depends on the ability of the cell to carry out photosynthesis or aerobic respiratory metabolism – maintain carbon fixation
I. Bacterial metabolism - Autotrophic
4C. What is Calvin cycle?
● Calvin cycle is the reaction of ribulose 1,5-bisphosphate with carbon dioxide, yielding two molecules of 3-phosphoglycerate, a precursor to glucose.
I. Bacterial metabolism - Phototrophic
5A. What are phototrophs?
- Phototrophs are organisms that carry out photon capturing to produce complex organic compounds such as carbohydrates) and acquire energy
I. Bacterial metabolism - Phototrophic
5B. How do phototrophs carry out metabolism?
● Requires electrons to be available to replace electrons that are consumed during biosynthetic rxns
● Electrons are passed through an electron transport chain, with the generation of energy by formation of a proton gradient and concomitant ATP synthesis.
II. Cultivation of bacteria
1. What is cultivation of bacteria?
Multiplying microorganism by letting them reproduce in predetermined culture media under controlled laboratory conditions
● Bacteria grow and divide by binary fission → population growth
● Optimal environment → cell count grows exponentially
● Generation time → until the cell mass doubles normally 20-40 mins except mycobacteria (20hrs)
II. Cultivation of bacteria
2. Make bacteria growth curve
II. Cultivation of bacteria
3. What is the requirement of bacteria growth?
- Physical: Temp, Atmosphere, pH, Osmotic P
- Chemical: Culture medium
II. Cultivation of bacteria - Physical Aspects
4A. What are the 4 physical aspects of bacteria cultivation?
- Temperature
- Atmosphere
- pH
- Osmotic pressure
II. Cultivation of bacteria - Physical Aspects
4B. Describe temperature, a physical aspect of bacteria cultivation
● Psychrophiles - cold loving (< 20°C)
● Mesophiles - moderate loving
(20-40°C)
● Thermophiles - heat loving (> 40°C)
II. Cultivation of bacteria - Physical Aspects
4C. Describe Atmosphere, a physical aspect of bacteria cultivation
● Aerobic - need O2 to grow
● Anaerobic - do NOT need O2 to grow
● Obligate aerobic → NEED O2 to survive
● Obligate anaerobic → cannot survive in the presence of O2
● Facultative Anaerobic → can grow w/out O2, but if O2 present they can use it
● Microaerophilic → need low [O2]
● Aeroteolerant → cannot use O2 but are not harmed by it
=> Microbes that use O2 produce more than energy than those that do not use it
II. Cultivation of bacteria - Physical Aspects
4D. Describe pH, a physical aspect of bacteria cultivation
● Acidophiles: <5.5
● Neutrophiles: 5.5 - 8 (most bacteria)
● Alkaliphiles: >8
II. Cultivation of bacteria - Physical Aspects
4D. Describe Osmotic P, a physical aspect of bacteria cultivation
● Most bacteria need isotonic solution → cytoplasm in most bacteria has a greater osmolarity than its environment
● Hypertonic media → water will leave cell = plasmolysis
● Isotonic media → bacteria are in equilibrium with their environment
II. Cultivation of bacteria - Chemical Aspects
5. What does culture medium contain?
Culture Medium contains:
- Water
- Source of carbon and energy
- Source of nitrogen
- Trace elements
- Buffer sol’n
- Growth factors and agar (polysaccharide extracted from marine algae)
II. Cultivation of bacteria - Chemical Aspects
6. What are the 3 types of culture media?
- Consistency
- Nutritional Components
- Functional Use
II. Cultivation of bacteria - Chemical Aspects
7A. Classify the culture media based on consistency
a. Liquid media (bouillon)
→ bacteria grows uniformly producing general turbidity
(cloudiness) - no agar
b. Semi-solid media
→ soft and show bacterial movement - 0.5% agar is added
c. Solid Media
→ petri dish that contains a growth medium used to culture
II. Cultivation of bacteria - Chemical Aspects - Culture media (consistency)
7B. What are the features of Liquid media (bouillon)?
Liquid media (bouillon)
→ bacteria grows uniformly producing general turbidity
(cloudiness) - no agar
II. Cultivation of bacteria - Chemical Aspects - Culture media (consistency)
7C. What are the features of Semi-solid media?
Semi-solid media → soft and show bacterial movement - 0.5% agar is added
