Nutritional Factors that Influence Microbial Growth
Nutritional Factors that Influence Microbial Growth To live/reproduce, all living things need: An energy source A source of Carbon Food Sunlight – phototroph Iron etc- chemotroph If reduced form of chemical, organism can use it as energy Organic-chemoorganotroph Inorganic – chemolithotroph Organic cmpds- heterotroph CO2- autotrophs
Nitrogen fixation- make into organic form that humans can use
N is often a limiting nutrient in the environment Meaning.. an ingredient to make cells. Low amount relative to the need
Look at table 4.4
Cyanobacteria- blue-green algae – in sun light, cells begin to smell and happens because excess phosphorous
Cultivating Bacteria in the Laboratory- chemoorganoheterotrophs
Complex vs defined media
Glucose salts- minimum ingredients Ecoli needs to grow
Ecoli can use glucose as sole energy- “minimal medium “
Brain break- what type of medium is blood agar- COMPLEX
Differential vs selective vs differential AND selective media
Differential- ingredient added that can be changed by certain bacteria in a recognizable way Blood agar Hemolysis Alpha- green Beta- yellow surrounding strep throat
Selective Hemolytic Ingredient added that inhibits growth f many unwanted organisms Antibiotic-containing medium
Selective and differential MacConkey agar – gram neg that ferment lactose Bile salts + dye Inhibits all but GNR that typically reside in the intestine Lactose + pH indicator Lactose fermenters are reddish
Halotolerant- salt tolerant Staphylococcus aureus is haloterant. Based on this info which should be incorporated into a medium designed to isolate the bacterium ? –SALT
Table 4.6 – know what info means MACONKEY AGAR/BLOOD AGAR- know
In general bacteria grow faster than yeasts which grow faster than molds
Intrinsic Factors Water availability pH nutrients biological barriers antimicrobial chemicals
Extrinsic
Nitrogen fixation- make into organic form that humans can use
N is often a limiting nutrient in the environment Meaning.. an ingredient to make cells. Low amount relative to the need
Look at table 4.4
Cyanobacteria- blue-green algae – in sun light, cells begin to smell and happens because excess phosphorous
Cultivating Bacteria in the Laboratory- chemoorganoheterotrophs
Complex vs defined media
Glucose salts- minimum ingredients Ecoli needs to grow
Ecoli can use glucose as sole energy- “minimal medium “
Brain break- what type of medium is blood agar- COMPLEX
Differential vs selective vs differential AND selective media
Differential- ingredient added that can be changed by certain bacteria in a recognizable way Blood agar Hemolysis Alpha- green Beta- yellow surrounding strep throat
Selective Hemolytic Ingredient added that inhibits growth f many unwanted organisms Antibiotic-containing medium
Selective and differential MacConkey agar – gram neg that ferment lactose Bile salts + dye Inhibits all but GNR that typically reside in the intestine Lactose + pH indicator Lactose fermenters are reddish
Halotolerant- salt tolerant Staphylococcus aureus is haloterant. Based on this info which should be incorporated into a medium designed to isolate the bacterium ? –SALT
Table 4.6 – know what info means MACONKEY AGAR/BLOOD AGAR- know
In general bacteria grow faster than yeasts which grow faster than molds
Intrinsic Factors Water availability pH nutrients biological barriers antimicrobial chemicals
Extrinsic