WEEK 3 PART 2: BACTERIAL CELL STRUCTURE, PHYSIOLOGY, METABOLISM AND GENETICS Flashcards
pH required for bacteria to grow
7.0 and 7.5
Required temperature for Psychrophiles/Cryophiles
0 degrees Celsius to 20 degrees Celsius
Required temperature for Mesophiles
20 degrees Celsius to 45 degrees Celsius
Required temperature for Thermophiles
50 degrees Celsius to 60 degrees Celsius
Requires oxygen for growth
Obligate aerobes
Most clinically significant bacteria and can grow either with or without oxygen. Ex: Enterics
Facultative anaerobes
Bacteria that cannot grow in the presence of oxygen. Ex: Clostridium & Bacteriodes
Obligate anaerobes
Bacteria that can survive in the presence of oxygen but do not use oxygen for metabolism. Ex: Propionibacterium acnes
Aerotolerant anaerobes
Bacteria the requires a reduced level of oxygen (2 to 10%) for growth. Ex: Campylobacter and Treponema
Microaerophiles
Bacteria that requires extra carbon dioxide (5 to 10%). Ex: Neisseria gonorrhea, Streptococcus pneumoniae and Hemophilus influenzae
Capnophiles
Bacteria that requires high salt concentrations or hypertonic environments (30% salt. Ex: Staphylococcus aureus, and Vibrio spp.
Obligate halophiles
Bacteria that do not require high salt concentrations but grows in 2% to 15% salt concentration.
Facultative halophiles
Time required for one cell to divide into two cells.
Generation Time (Doubling time)
Phase where there is little or no cell division; intense metabolic activity. Also known as Adjustment Phase
Lag Phase
AKA “Exponential growth phase”; cell begins to divide; active cellular reproduction with constant minimum generation time; cells are at their most active state.
Log (Logarithmic) Phase
Phase where growth rate slows down (# of new cells = # of microbial deaths = population stabilizes period of equilibrium.
Stationary Phase
Phase where logarithmic decline; number of deaths exceeds the number of new cells formed.
Death Phase
used to estimate the number of bacteria
Direct counting under the microscope
growing dilution of colony-forming units per milliliter (CFU/mL)
Direct plate count
the density (cloudiness or turbidity) of bacterial culture in log phase can be correlated to CFU/mL of the culture. Method used in AST (Aspartate Aminotransferase)
Density measurement
Metabolism. Utilization of a variety of substrates as carbon sources
Anabolism
Metabolism. Production of specific end products from various substrates.
Catabolism
Two mechanisms of Carbohydrate utilization
Fermentation and Respiration
A mechanism of Carbohydrate utilization. An aerobic process of energy production. End product - ATP
Respiration (oxidation)
A mechanism of Carbohydrate utilization. An anaerobic process of energy generation. End product - mixtures of lactate, butyrate, ethanol, and acetoin.
Fermentation
What are the THREE MAJOR BIOCHEMICAL PATHWAYS used by bacteria to break down glucose to pyruvic acid
EMP GLYCOLYTIC, PENTOSE PHOSPHATE, ENTNER-DUODOROFF PATHWAY
Major pathway in conversion of glucose to pyruvate. Anaerobic process. Bacteria members of Enterobacteriaceae. End product - 2 molecules of pyruvic acid
EMBDEN-MEYERHOF-PARNAS GLYCOLITIC PATHWAY