chapter 4 - culturing microbes and effects of microbial growth Flashcards
What are the macronutrients needed for microbes?
- carbon
- nitrogen
- oxygen
- hydrogen
- phosphorus
- sulfur
What are the micronutrients needed for microbes?
- boron
- cobalt
- copper
- iron
- manganese
- molybdenum
- nickel
- selenium
- tungsten
- vanadium
- zinc
What are the different types of culture media?
- complex medium: readily used to grow a range of bacteria
- defined medium: require prior knowledge of nutrition requirement of microbes
- selective media: contains compounds that selectively inhibit growth of some microbe but not others
- differential medium: contains indicator usually a dye that detects metabolic reactions
- enrichment medium: contains the addition of specific compounds necessary to enhance the growth of fastidious
What is colony morphology?
visible characteristics used to identify microorganisms
Explain the aseptic technique for transferring liquid culture
- flame loop
- tube cap removed
- flaming tube tip
- sterlized loop enters tube
- tube is reflammed
- tube is recapped and steps repeat
Explain the aseptic technique for streaking a petri plate
- loop is sterilized and loophole of inoculum is removed from tube
- initial streak is worked in well in one corner of the agar plate (at angles to first streaks)
- showing colonies after incubation
How is spectrophotometric measurement of microbial growth?
optical density is defined as the negative of the logarithm of the transmission
What is growth?
increase in the number of cells
What is binary fission?
cell division following enlargement of a cell to twice original size
What is septum?
partition between dividing cells, pinches off between two daughter cells
What is generation time?
time required for microbial cells to double in number
What are the four types of phases in growth curve?
- lag phase: interval between inoculation of a culture and beginning of growth
- exponential phase: doubling at regular intervals
- balanced growth cells are metabolically identical, rates vary, continues until no longer sustain growth - stationary phase: growth rate of population is zero
- decline phase: total number decreases due to cell death
How to calculate generation time
g = time / number of generation during the period
What is chemostat culture?
continuous culture where volume of culture medium is added at same rate as spent medium is removed.
steady state: when cell number nutrient, waste remain constant
What is planktonic growth?
growth of free-floating/free-swimming cells in liquid suspension
