Microbial Growth (Lec. 4) Flashcards
Define psychrophile
reproduces the most in a cold environment
Define mesophile
reproduce the most at a human body temp
Define thermophile
reproduce the most at hot temperatures
Define alkaliphile
thrive the most in a basic environment
Define neutrophile
6.5-7.5 pH for bacteria and 5-6 for fungi
Define acidophile
thrive the most in an acidic environment
Define halophile
thrive the most in a salty environment
Define halotolerant
Don’t thrive in especially salty environments but can live there
Define aerobe
needs oxygen to live
Define anaerobe
don’t need oxygen to live
Define facultative anaerobe
reproduce the best with oxygen but that don’t need it to live.
Define obligate anaerobe
Cannot reproduce or live in an environment with oxygen
Define microaerophile
Need oxygen but at a lower concentration
Identify ways in which aerobes avoid damage by toxic forms of oxygen
Catalase turns hydrogen peroxide into water and oxygen
Define a biofilm and the stages of formation
A complex aggregate of multiple different types of bacteria (usually polymicrobial).
1. Attachment: adhesion of a few motile cells to a suitable solid surface
2. Colonization: growth, quorum sensing, and polysaccharide formation
3. Development: more growth and polysaccharides
4. Active dispersal: triggered by environmental factors such as nutrient availability
Identify one use of selective media
When you have polymicrobial samples to you use a selective media to kill off all the types you don’t want to study
Identify one use of differential media
To differentiate between different types of bacteria growing within one sample
Identify one use of enrichment media
To grow a small sample of bacteria to a certain level
Explain three direct methods of measuring cell growth
plate count, filtration, direct microscopic count
Plate count: serial dilution to decrease colony forming units to a level at which you can count them on a plate
Filtration: has to be a sample with not a lot of microbes in it
Direct microscopic count: placed on a grid, count average number of bacteria per viewing field
Explain one indirect method of measuring cell growth
Turbidity: a spectrophotometer measures the wavelength of light that passes through a tube of bacteria and the curvature is equal to the number of prokaryotes in the sample
