DMP 712 Bact Exam 1 Nutrition and Growth and Metabolism Sections 2 and 3 Roberts
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- Two major nutritional groups
- autotrophs heterotrophs
-
Autrotroph
-energy from:
-carbon from: -
-energy from: sunlight or inorganic substrates
-carbon from: CO2 -
Heterotroph
include:
obtain energy from:
obtain carbon from:
nutritional requirements in: -
include: all pathogenic microbes
obtain energy from: reduced carbon cpds (carbs)
obtain carbon from: reduced carbon cpds (carbs)
nutritional requirements in: host tissues except for Fe - Gropus of Bacteria based on ability to use 02 (4)
-
aerobes: require O2 for growth
anaerobes: grow only w/o 02 (strict rapidly killed by 02, vs aerotolerant)
facultative (anaerobes): will grow w or w/o O2
microaerophilic: grow only at lower %02 levels - Toxic end products formed in presence of oxygen (2)
-
hydrogen peroxide (H2O2)
superoxide anion (O2-) - Enzymes to detoxify toxic end products
-
Catalase: 2H202 --> 2H20
Superoxide dismutase: 202- --> H202 + 02 - Relationship of CO2 on Bacterial Growth
- CO2 required for growth of all bacteria
- CO2 needed for which bacterial reactions?
- biosynthetic (fatty acid biosynthesis)
- What CO2 level needed for bacteria?
- Greater than atmospheric CO2 needed for some pathogens (supply with CO2 incubator or candle jar)
- 3 Temperature Ranges of Bacterial Growth
-
1) Psychophiles
2) Mesophiles
3) Thermophiles -
Psychophiles
range (temp)
obligate (location)
facultative (temp, association) -
range: 0-25C
obligate - found in snow fileds and polar ice caps
facultative - grow best 25-30C, often associated with food spoilage, can contaminate vaccines and IV solns -
Mesophiles
range (temp)
optimum (temp)
importance -
range: 15-45C
Optimum 30-37C
Includes most pathogens -
thermophiles
(range) - range 35-70C
- Most pathogens grow best at pH:
- 6.8-7.2
- Cardinal points of pH (3) and definition
-
Growth range defined by cardinal points
1) minimum pH - no growth below pH
2) maximum pH - no growth above pH
3) Optimum pH - point where best growth occurs -
Pathogens grow best at __________ pressure equal to __________ saline.
____ mM NaCl
Exception -
osmotic pressure
physiologic saline
150 mM NaCL
some halotolerant grow up to 7.5 % NaCl -
Bacterial growth
method
description -
Method: binary fission
Description: cell doubles in mass and divides into two equal daughter cells - Generation time
- amount of time for cell number to double (depends on species, growth medium and growth temperature)
- Measurement of growth (3)
-
1) change in turbidity using spectrophotometer
2) dilutions and plate counts of viable cells
3) coulter counter - count bacteria-sized particles - yields total counts - Bacterial Growth curve phases (4) picture?
-
1) lag
2) exponential (log)
3) stationary
4) death -
Phase of Bacterial growth (lag)
2pts -
1) period of atdaptation to new environment
2) little or no increase in cell numbers -
Phase of Bacterial growth (exponential or log)
1 pt - cells double at a constant rate
-
Phase of Bacterial growth (stationary)
2pts -
1) nutrients become depleted or metabolic waste products accumulate
2) growth occurs - balanced by cell death -
Phase of Bacterial growth (death)
1pt - numbers of viable cells decrease
- Four main components of bacteriological growth media
-
1) peptones
2) infusions and extracts
3) agar
4) fermentable sugar - Four main components of bacteriological growth media (peptones)
- acidic or enzymatic hydrolysates or proteins, usually casein
- Four main components of bacteriological growth media (infusions and extracts) (1pt, 3 examples)
-
water soluble fractions - crude source of nutrients
-meat
-plants
-yeast (source of vit B) - Four main components of bacteriological growth media (agar)
- solidifying agent (1.5%)
- Types of Bacteriological Media (3)
-
1) enrichment media
2) selective media
3) differential media -
Types of Bacteriological Media (enrichment)
importance: - favors growth of a microbe present in low numbers
-
Types of Bacteriological Media (selective)
contains:
favors:
inhibits: -
contains: chemicals such as 7.5% NaCl, detergents and heavy metals
favors: growth of one organism
inhibits: growth of other organisms in specimen -
Types of Bacteriological Media (Differential media)
contains: - contains: indicators to identify bacteria e.g. blood or dye
- Metabolism defn
- Chemical Reactions in Living Cells
- Catabolic pathways characteristics (3pts)
-
1) produce ATP
2) Oxidative - remove H's and e's from nutrients
3) produce intermediates - Anabolic pathways characteristics (3pts)
-
1) require ATP
2) Reductive (use H's supplied by NADH and NADPH)
3) Start with intermediates - Number of Stages of Fermentation?
- 2
-
First step of Fermentation:
Primary pathway of Fermentation
Embden-Meyerhof net yield:
Entner-Doudoroff net yield:
Pentose Phosphate net yield: -
Primary pathway of Fermentation: convert glucose to pyruvate Embden-Meyerhof net yield: 2ATP 2NADH/glucose
Entner-Doudoroff net yield: 1ATP + 1NADH
Pentose Phosphate net yield: OATP, NADPH, 4 and 5 C sugars - Second step of Fermentation
- forms alcohols, acids and other
- Respiration # of Stages?
- 3
- First step of Respiration
- primary pathway, same as fermentation: glucose --> pyruvate
- Second step of respiration
- Oxidation of pyruvate via TCA cycle --> 1ATP, 4NADH 1 FADH2
- Third Step of Respiration
-
ETS
1 NADH yields 3 ATPs
1 FADH2 yeilds 2 ATPs - Electron Transport System associated with:
- bacterial cell membrane
- Electron Transport System description
- Electrons passed through ETS in a stepwise fashion and energy released is used to generate ATP - due to different oxidation or reduction potentials
- Electron Transport System carriers and transfer molecules (3)
-
1) Flavoproteins (contain cofactors derived from riboflavin)
2) Coenzyme Q / ubiquinones
3) Cytochromes (cofactor is porphryin - Fe complex) -
Glycolysis Produces:
TCA cycle produces:
Total: -
Glycolysis produces:
2 ATP
(2 NADH =) 6ATP
TCA cycle produces:
(4NADH = ) 12ATP
(1FADH = ) 2ATP
(1GTP = ) 5ATP
Total:
2 pyruvates/glucose:
38 ATP -
Integration of Anabolism and Catabolism
Biosynthetic reactions in cells require what 2 things? - ATP and NADPH
-
Integration of Anabolism and Catabolism
Define: amphibolic pathway: - direction of pathway depends on needs of cell for pathways that produce energy as well as biosynthetic intermediates
-
Triple Sugar Iron (TSI) Agar Reactions
Detects: - Detects: fermentation of 3 sugars: lactose and sucrose at 1% and glucose at 0.1%
- TSI possible fermentation patterns: (3)
-
Bacteria ferment:
1) none of the sugars
2) only glucose
3) glucose and one or both of the other sugars - TSI metabolism describe on slant and butt
-
slant: aerobic metabolism
butt: anaerobic metabolism - TSI detects what other than fermentation?
- Hydrogen sulfide production
-
Interpretation of TSI Reactions:
yellow butt, red slant -
acid butt, alkaline slant
catabolism of only glucose --> lactic acid since butt is anaerobic. acid makes butt yellow
growth on peptones raises pH on slant -
Interpretation of TSI Reactions:
yellow/yellow -
acid butt and acid slant
10 fold higher concentration of the other sugars resuls in significantly more acid if either/or both are catabolized -
Interpretation of TSI Reactions:
red/red -
alkaline butt and alkaline slant
-no utilization of sugars
-degredation of peptones aerobically and anaerobically