Ch 7: Microbial Nutrition Flashcards
What are macronutrients
Required in relatively large quantities: CHNOPS
What are the three general categories of essential nutrients for microbes
Macronutrients, micronutrients, organic growth factors
What are micronutrients
Required in small quantities; trace elements
What are organic growth factors
Cannot be synthesized by the cell from either nutrient and must be obtained from their food or environment. Example: vitamins
How are microbes classified
Based on how they get their carbon and energy
What are autotrophs
Get their carbon in the form of CO2 in the atmosphere
Two types of autotrophs
Photoautotroph and chemoautotroph
What does a photoautotroph use as the energy source
Light energy; photosynthesis
What does a chemoautotroph use as its energy source
Inorganic molecules
Where do heterotrophs get their carbon and energy from
Other organic molecules
Chemoheterotrophs
Use organic molecules produced by other organisms as their energy source. Glycolysis, respiration, fermentation
Two types of chemoheterotrophs
Saprobe and parasite
Saprobe
Source is dead organisms; free living, don’t require host; type of chemoheterotroph
Parasite
Source is live organisms, use a living host; type of chemoheterotroph
Passive transport
Random movement of molecules, ions, from areas of high conc to areas of low conc,no ATP required
Moves with the conc gradient
Three types of passive transport
Simple diffusion, osmosis, facilitated diffusion
Simple diffusion
Random movement of solutes, high to low
Osmosis
Diffusion of water; hi to low conc
Facilitated diffusion
Diffusion that requires a carrier membrane protein
Active transport
Directional movement of molecules, ions from areas of low to high conc; ATP and membrane protein pumps are required. Moves against the conc gradient
Solid agar
Polysaccharide derived from seaweed, melts at 100°C and resolidify at 42°C. Poured at 45 to 50°C
Chemically defined agar
Reproducible in the lab by using an exact formula; synthetic
Chemically undefined agar
Unable to be reproduced in the lab by using an exact formula; extracts
General purpose media
Will grow a broad spectrum of bacteria; ex: TSA or TSB
Selective media
Contains one or more agents that inhibit the growth of certain microbes and therefore encourages another or allows it to grow; Ex: salt agar and MacConkey agar
Differential media
Allows multiple types of microbes to grow, but are designed to display visible differences among the microbes. Ex: Mannitol salt agar, MacConkey agar, fermentation broths
Enrichment media
Contains complex organic substances or growth factors that a certain species must have in order to grow. Ex: blood agar
Cardinal temperature range
The range of temperature for growth of a certain microbe: has a minimum, maximum, & optimum
Psychrophile
Likes cold; two types obligate and facultative
Which Psychrophile grows slower in cold
Facultative Psychrophile
Mesophile
Likes warm: optimum 20 to 40°C
Thermophile
Likes hot: optimum greater than 45°C
Three categories of microbes based on oxygen use
Those that use O and can detoxify it; those that can neither use O nor detoxify it; those that do not use O but can detoxify it
Two toxic byproducts of oxygen use
Superoxide Ion and hydrogen peroxide
Two enzymes to detox The toxic byproducts of oxygen use
Superoxide dismutase and catalase
What does superoxide dismutase do
Converts superoxide ions into hydrogen peroxide
Does catalase do
Converts hydrogen peroxide into water and oxygen
Aerobe
Can use oxygen as the final electron acceptor in cellular respiration
Obligate aerobe
Must use oxygen, cannot grow without it
Facultative anaerobe
Can use an alternative acceptor if O is unavailable can switch to fermentation; does not require oxygen and can grow without it
Microaerophile
Requires small amounts of O (2-10%); do not grow in regular atmospheric levels of O of 20%
Anaerobe
Cannot use oxygen as the final electron acceptor use alternate acceptors
Obligate anaerobe
Will die if exposed to oxygen, lack detox enzymes, must either use fermentation or anaerobic respiration
Aerotolerant anaerobes
Obligate fermenters: do not use oxygen and can survive and grow to a limited extent in it. Must use fermentation only
Thioglycollate
Reacts with oxygen to create anaerobic conditions; reduces the O/R potential of the media
Resazurin
Red dye which is an indicator of oxygen
What grows best in acid, neutral, or basic environments
Acidophiles, neutrophiles, & alkaliphiles
Grows best in a hypertonic environment
Osmophile; ex: sugar or salt
Halophiles
grows best in a hypertonic environment due to excess salt
Xerophiles
grows best in a hypertonic environment due to lack of water
Three classes of aerobes
Obligate aerobe, facultative anaerobe, microaerophile
Two classes of anaerobes
Obligate anaerobe, aerotolerant anaerobe
Define obligate
Exist in a very narrow niche, rigid in requirements
Define facultative
Exist in a wide niche, flexible in requirements
Barophile
Grow best upon being exposed to higher than normal atmospheric pressure
Binary fission
Cell division in prokaryotes
What types of cells will tolerate and sometimes grow well in a hypertonic environment and why
Large cocci because of low surface area to volume ratio
Doubling time or generation time
Amount of time required for a population to double
Describe the lag phase
Recovery phase, little to no growth during this phase
Describe the exponential phase
Rapid period of growth
Three factors that cause growth to stop
Using up the nutrients available, increased waste production, crowded
stationary phase
Cryptic growth is occurring. Number of live cells produced equals number of cells dying
Describe the growth curve of a batch culture
Inverted “U” with four separate phases
Describe the growth curve of a maintenance culture
Remains in stationary phase indefinitely
Sensors that measure the chemistry or turbidity of a maintenance culture are called
Chemostat and turbidostat
SPC
Standard plate count; written in standard notation
Ex: 1.92 X 10^8 cells/ml
