Lecture 5 Flashcards by Joanne Huynh

What are the physical requirements for growth?

temperature
pH
osmotic pressure

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What are the chemical requirements required for growth?

carbon
nitrogen, sulfur, phosphorous
trace elements
oxygen
organic growth factors

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What are the 3 main points in temperature for growth?

minimum growth temperature
optimum growth temperature
maximum growth temperature

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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

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Why are psychrophiles important?

cold-adapted industrial processes
- biotechnology

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What are psychrotrophs?
- temperature
- location found
- results in what?

cold-loving
0C to 30C
variety of environments like refrigerator
causes food spoilage

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What are mesophiles?
- temperature
- location found
- importance

moderate temperature loving
30C to 40C
soil, water, human body, compost piles
important for fermentation, digestion, decomposition

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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

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Why are thermophiles valuable?

production of biofuels and other biotechnological applications

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What are hyperthermophiles?
- temperature
- location found

anything more than 80C (sometimes more than 100C)
hydrothermal vents on ocean floor, hot springs, geysers

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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

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What are acidophiles?

bacteria growing in acidic environments

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What are alkaliphiles?

bacteria growing in basic environments

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What is an example of alkaliphiles?

Bacillus alcalophilus

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What is plasmolysis?

caused by high osmotic pressure

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What are extreme or obligate halophiles?

bacteria that grow in high osmotic pressure

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What are facultative halophiles?

bacteria that can exist in high osmotic pressure

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What are trace elements? Give some examples.

inorganic elements required in small amounts
- enzyme cofactors
- iron, copper, zinc

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What is organic growth? Give some examples.

organic compounds from the environment
- vitamins, amino acids, purines, pyrimidines

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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