Chapter 3: Microbial Growth Flashcards
physical requirements
temperature, pH, osmotic pressure
chemical requirements
carbon, nitrogen, sulfur, phosphorous, oxygen, trace elements, organic growth factors
psychrophiles
cold loving
psychrotrophs
grow betweeen o and 20-30 degrees C
cause food spoilage
mesophiles
moderate temperature loving
thermophiles
heat loving, optimum growth 50-60 degrees C
hyperthermophiles
optimum growth above 80 degrees C
hydrothermal vents
most bacteria grow between pH of
6.5 and 7.5
molds and yeasts grow between pH of
5 and 6
acidophiles grow in pH of
acid pH
hypertonic environment
more solute outside cells
plasmolysis
cell shrinking due to high osmotic pressure
extreme/obligate halophiles require high
osmotic pressure (high salt)
facultative halophiles tolerate
high osmotic pressure
why is carbon required
backbone of organic molecule
why is nitrogen required
component of proteins, DNA, RNA, ATP
why is sulfur required
in amino acids, thiamine, biotin
why is phosphorous required
used in DNA, RNA, ATP; found in cell mambranes
why are trace elements required
inorganic elements required in small amounts usually as enzyme cofactors
what trace elements are needed
iron, copper, molybdenum, zinc
obligate aerobes
need oxygen
facultative anaerobes
grow via fermentation or anaerobic respiration without oxygen
obligate aerobes
unable to use oxygen and harmed by it
aerotolerant anaerobes
tolerate but cannot use oxygen
microaerophiles
require oxygen concentration lower than air (21%)
bacteria from lowest to highest in terms of oxygen
obligate aerobes, aerotolerant annaerobes, microaerophiles, facultative anaerobes, obligate anaerobes
organic growth factors
organic compounds obtained from environment
types of organic growth factors
vitamins, amino acids, purines, pyrimidines (vitamins are inorganic)
biofilms
microbial communities that form slime of hydrogels that adhere to surfaces
bacteria communicate cell to cell via
quorum sensing
benefits to biofilms
share nutrients to increase growth and reproduction, shelter bacteria from harmful environment, 1000x resistance to microbicide
culture medium
nutrients prepared for microbial growth, most common is agar
sterile
no living microbes
inoculum
introduction of microbes into a medium using sterile pipet, loop, or swab
culture
microbes growing in or on a culture medium
agar
complex polysaccharide used as solidifying agent for culture media for petri plates
chemically defined media
exact chemical composition is known used to grow fastidious organisms which require many growth factors
complex media
extracts and digests of yeasts, meats, and plants, chemical composition varies batch to batch
difference betweeen nutrient broth and nutrient agar
broth is liquid, agar is solid
reducing media
used for cultivation of anerobic bacteria
reducing media contains
sodium thioglycolate that combine O2 to deplete it - heated to drive oxygen off
capnophiles
microbes require high CO2 conditions; create CO2 packet using candle jar
BSL 1
no special precuations, basic teaching lab
BSL 2
lab coat, gloves, eye protection