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43 Cards in this Set
- Front
- Back
microbial growth is the increase of ___ of cells
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number
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lowest temperature at which a specie can grow
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minimum growth temperature
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temperature at which a specie will grow best (fastest growth rates)
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optimum growth temperature
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highest temperature at which a specie will grow
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maximum growh temperaure
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-cold-loving microbes
-grow between 0-30 C -cause food spoilage -grow very well in fridge temps |
psychrotrophs
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-moderate temp
-pathogen growth -cause infection -body temp |
mesophiles
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-archaea, hot-springs
-heat resistant -endopore -survive food treatment -organic compost |
thermophiles
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most bacteria grow between pH __ and __
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6.5-7.5
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molds and yeasts grow at a ph between __ and __
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5-6
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___ grow in acidic environments
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acidophiles
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___ bacteria survive pH of 1 (drain water, coal mines, oxidize sulfur)
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chemoautotrophic
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___ ___ adapt to high salt environments, require high osmoic pressure
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extreme/obligate halophiles
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___ ___ do not require high salt concentration; tolerate high osmotic pressure
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facultative halophiles
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there are four elements require in large amount by microbes:
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carbon nitrogen
sulfur phosphorus |
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-structural backbone
-chemotrophs use organic __ sources -photo-autotrophs use CO2 by photosynthesis |
carbon
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-in amino acids and proteins
-most bacteria decompose proteins -some bacteria use ammonium ions (NH4) ir nitrate ion (NO3-) -few bacteria use N2 in nitrogen fixation |
nitrogen
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-in amino acids, vitamin such as thiamine/biotin
-most bacteria decompose proteins -some bacteria use sulfate ions (SO4 2-) or hydrogen sulfide |
sulfur
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-important for synthesis of nucleic acid: DNA, ATP, RNA, and cellular membranes
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phosphorus
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O2 boosted to higher-energy state
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singlet oxygen
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__ are essential organic compounds that cannot be synthesized by the organism; must be obtained from the environment
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organic growth factors
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___ ar bacteria living in a community to form slime on teeth, rcoks, fish; mor efficient levels of survival
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biofilms
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___ are nutrients prepared for microbial growth
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culture mediums
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no living microbes
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sterile
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introduction of microbes into medium
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inoculate
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microbes growing in/on culture medium
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culture
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-complex polysaccharide
-used as soldifying agent -generally not metabolized by microbes -liquifies at 100C, solidifies at ~40C |
agar
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exact chemical compostition is known
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chemically defined media
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motly used for heterotrophic organisms; do not know exact amount of chemical compostition
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complex media
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-reducing media
-contain chemicals sodium thioglycolate & oxyrase that combine to dissolve O2 and ultimately deplete O2 |
anaerobic culture methods
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-designed to encourage growth of certain types or organisms/inhibit others
-suppress unwanted microbes and encourage desired |
selective media
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-contain indicators
-makes it easier to distinguish colonies of different microbes |
differential media
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encourages growth of desired microbe
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enrichment media
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___ contains only one species or strain
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pure culture
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__ is a population of cells arising from a single cell or spore or form a group of attached cells
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colony
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a colony is often called a ___
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colony forming unit
CFU |
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___ can be done to preserve for short-term storage of bacteria
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refrigeration
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___ can be used to preserve a pure culture in glycerol and quick freeze at -50C to -95C
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deep freezing
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preservation- freeze-drying
frozen at -54C to -72C dehydrated in a vacuum |
lyophilization
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-binary fission (most)
-few by budding -conidiospores (actinomycetes) -fragmentation of filaments |
reproduction of prokaryotes
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lag phase
eponential/log phase stationary stage death/logarithmic decline |
acclimatize
cells grow rapidly deaths=births deaths > cells |
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-plate counts
-filtration -MPN -direct microscopic count -dry weight |
direct methods of measuring microbial growth
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-turbidity
-metabolic activity -dry weight |
indirect ways of measuring microbial growth
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number of bacteria/ml=
number of cells counted ----------------------------------- volume of area counted |
direct microscopic count
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