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Microbial growth is the increase in...
in number of cells,not cell size TERM 2
Why is it important to understand the
conditions necessary for microbial growth?
DEFINITION 2 We want to encourage the good ones( fermentation, beer ,wine) and preventpathogenicpathogensfrom growing (foodspoilage) TERM 3
Heterotroph are?
DEFINITION 3 an organism that mustobtain carbon in an organic form made byother living organisms: proteins,carbohydrates, lipids and nucleic acids TERM 4
Autotroph are?
DEFINITION 4 organism that uses CO2, aninorganic gas, as its carbon source TERM 5
Inorganic nutrients are?
DEFINITION 5 atom or molecule that contains acombination of atoms other than carbon and hydrogen: metals and their salts (magnesium sulfate, ferricnitrate, sodium phosphate), gases (oxygen, carbondioxide) and water
Organic nutrients are?
contain carbon and hydrogen atomsand are usually the products of living things: methane (CH4), carbohydrates, lipids, proteins, andnucleic acids TERM 7
Phototroph are?
DEFINITION 7 use light as their primaryenergy source TERM 8
Chemotroph are?
DEFINITION 8 depend on 0xidationreductionreacitons of inorganic or organiccompounds for energy TERM 9
Metabolic Diversity Among Organisms (CH 5)
(Pages 142-145)
DEFINITION 9 Macronutrients required in large quantities; play principal roles in cell structure & metabolism Fig 5.28 proteins, carbohydrates Micronutrients or trace elements required in small amounts; involved in enzyme function & maintenance of proteinstructure manganese, zinc, nickel TERM 10
Physical Requirements for Growth
DEFINITION 10 Temperature pH Osmotic Pressure
Mesophiles (G = middle loving)
Optimum 25 to 40C Most microbes, most human pathogens, most culture incubators37C Psychrotrophs (G. feeder) Term used by food microbiologists Grow best at or above 20C but can grow at lowtemperatures Often responsible for spoilage of refrigerated food (4C) Mold mycelium, slime on food surfaces, or off-tastes andoff colors in foods. TERM 17
Thermophiles (G = heat loving) Facultative
Thermophiles
DEFINITION 17 Facultative Thermophiles Grow best above 45 but can grow at lower temperatures Common in Compost Heaps, surface soil, and cooler HotSprings TERM 18
Thermophiles (G = heat loving) Obligate
Thermophiles
DEFINITION 18 Obligate Thermophiles Cannot grow below 45 Optimum 50 to 60 Common in Hot Water Lines, Hot Springs TERM 19
Hyperthermophiles (Archae)
DEFINITION 19 Optimum > 80C Sulfuric hot springs, Hydrothermal deep ocean vents[box p.164-5] Strain 121 (Pyrococcus furiosus) is a recentlydiscovered Archae Polymerase chain reaction (PCR) grows in the autoclave 121C, survived 130Cfor 2 hrs.Fuel production,Industrial applications TERM 20
Physical Requirements for Growth
DEFINITION 20 pH Most bacteria grow between pH 6.5 and 8.5 Acidophiles can grow in acidic environments Fungi (molds and yeasts) grow between pH 5 and 6 Acidic foods such as pickles, cheese, sauerkraut/kimchee have lowenough pH to discourage growth of bacteria and most fungi Many microbes produce acid as a product of metabolism so mostculture media contains buffers to minimize or delay the resulting dropin pH Our stomach acid keeps us from getting sick from the majorityof bacteria, except a few. Which ones?
Our stomach acid keeps us from getting sick
from the majority of bacteria, except a few.
Which ones?
Heliobacter pylori, ecoli TERM 22
Physical Requirements for Growth Osmotic
pressure
DEFINITION 22 Microorganisms obtain most of their nutrients insolution from the surrounding water. Hypertonic environments, increase salt or sugar,cause plasmolysis (cells shrink = lose water) Salted fish, honey, and sweetened condensedmilk = preserved foods Some organisms have adapted: Extreme or obligatehalophiles require high osmotic pressure Facultative halophiles tolerate high osmotic pressure
