Lecture 5 Flashcards
What are the physical requirements for growth?
temperature
pH
osmotic pressure
What are the chemical requirements required for growth?
- carbon
- nitrogen, sulfur, phosphorous
- trace elements
- oxygen
- organic growth factors
What are the 3 main points in temperature for growth?
- minimum growth temperature
- optimum growth temperature
- maximum growth temperature
What are psychrophiles?
- temperature
- location found
- adaptations
cold-loving organisms
- -20C to 10C
- Antarctic/Arctic regions or deep ocean or permafrost
- specialized enzymes and cellular membranes that remain fluid and functional at low temperatures
Why are psychrophiles important?
cold-adapted industrial processes
- biotechnology
What are psychrotrophs?
- temperature
- location found
- results in what?
- cold-loving
- 0C to 30C
- variety of environments like refrigerator
- causes food spoilage
What are mesophiles?
- temperature
- location found
- importance
- moderate temperature loving
- 30C to 40C
- soil, water, human body, compost piles
- important for fermentation, digestion, decomposition
What are thermophiles?
- temperature
- location found
- adaptations
- heat-loving
- 50C to 60C
- hot springs, geothermal areas, compost heaps
- specialized enzymes and cellular structures to maintain stability and functionality
Why are thermophiles valuable?
production of biofuels and other biotechnological applications
What are hyperthermophiles?
- temperature
- location found
- anything more than 80C (sometimes more than 100C)
- hydrothermal vents on ocean floor, hot springs, geysers
What are the steps on a bacterial growth graph?
1) Lag phase: no growth
2) Exponential phase: growing more
3) Stationary phase: the peak; maximum amount
4) Death phase: cells dying
What are acidophiles?
bacteria growing in acidic environments
What are alkaliphiles?
bacteria growing in basic environments
What is an example of alkaliphiles?
Bacillus alcalophilus
What is plasmolysis?
caused by high osmotic pressure
What are extreme or obligate halophiles?
bacteria that grow in high osmotic pressure
What are facultative halophiles?
bacteria that can exist in high osmotic pressure
What are trace elements? Give some examples.
inorganic elements required in small amounts
- enzyme cofactors
- iron, copper, zinc
What is organic growth? Give some examples.
organic compounds from the environment
- vitamins, amino acids, purines, pyrimidines
What are biofilms and their purpose?
form slime/hydrogels that stick to surfaces
- share nutrients
- shelter bacteria from harmful environmental factors
Where is biofilm found?
digestive system and sewage treatment systems
What is culture medium?
nutrients prepared for microbial growth
What does it mean to be sterile?
no living microbes
What is inoculation?
introduction of microbes into a medium
What is a culture?
microbes growing in a culture medium
Who created aseptic technique?
Louis Pasteur
What is aseptic technique?
prevents contamination and maintaining sterility
What are the essential tools in aseptic technique?
- autoclave
- biological safety hood
- bunsen burner
What temperatures does agar solidify and liquefy?
- solidifies at 40C
- liquefies at 100C
What are capnophiles?
microbes that require high CO2 conditions
- candle jar
What are the biosafety levels?
BSL-1: no special precautions
BSL-2: lab coat, gloves, goggles
BSL-3: biosafety cabinets to prevent airborne transmission
BSL-4: sealed, negative pressure, HEPA filters
What is selective media?
suppresses unwanted microbes and contains inhibitors to suppress growth
What is differential media?
allows distinguishing of colonies of different microbes on the same plate
Can media be both selective and differential?
yes
What is enrichment culture?
encourages the growth of a desired microbe by increasing very small numbers of a desired organisms
- Sabouraud Dextrose Agar
What is a pure culture?
contains only one species or strain
How do we isolate pure cultures?
streak plate method
How do we preserve bacterial cultures?
- deep-freezing: -50C to -95C
- lyophilization (freeze-drying): -54C to -72C and dehyrated
What is binary fission?
prokaryotic cell reproduction by division into two daughter cells
What is budding?
asexual reproduction as a protuberance from a parent cell to a daughter cell
What are conidiospores?
fungi
- actinomycetes
- fragmentation of filaments
What are the steps of binary fission?
1) Cell elongates and DNA is replicated
2) Plasma membrane begins to constrict and new wall is made
3) Cross-wall forms, completely separating the two DNA copies
4) Cells separate
How do you ensure the right number of colonies on a plate?
Serial dilution
What is filtration?
solution passed through a filter that collects bacteria
- then transferred to a petri dish to grow colonies
What is the most probably number method?
multiple test tubes
- count positive tubes
- compare to statistical table
What is the direct microscopic count method?
average number of bacteria per viewing field is calculated
- uses Petroff-Hausser cell counter
What is turbidity?
measurement of cloudiness with a spectrophotometer
What is metabolic activity?
amount of metabolic product is proportional to the number of bacteria
What is dry weight?
bacteria are filtered, dried, and weighed
- used for filamentous organisms
