Lecture 4: Microbial Nutrition

auxotrophy

consuming essential nutrients that the cell cannot synthesize

photo-

obtains energy through light

chemo-

obtains energy through chemicals (eating other food)

auto-

obtains carbon from CO2

hetero-

obtains carbon organically (eats other things for food)

litho-

obtains electrons inorganically

organo-

obtains electrons organically

saprobe

eats dead/decaying matter

macronutrients

nutrients needed in large quantities: carbs, fats, proteins

micronutrients

K, Na, ca, Mg, Fe, Zn

diffusion

movement of a molecule from a higher to lower density/concentration

osmosis

diffusion of water through a selectively permiable membrane

• iso, hypo, hypertonic

psychrophiles

cardinal temp -20 - 15. (can live below freezing). can survive in refrigerated food!

psychrotroph

cardinal temp 4-36 ish (second coldest)

mesophile

cardinal temp 10-50. most medically important microbes are these because their optimum temperature is close to human body temp.

thermophile

cardinal temp 45-80. second hottest

extreme thermophile

cardinal temp 68-130. the hottest

aerobe

needs o2

anaerobe

hates o2, don ‘t use it, don’t tolerate it (mostly)

facultative organism

can use o2, but don’t need it

aerotolerant anaerobe

don’t care if o2 is there

microaerophile

likes a lil bit of o2

physical factors besides temperature and oxygen that microbes must contend with?

gases, pH, osmotic pressure. also radiation, barometric pressure

capnophile

organism that thrives in CO2 rich environments. neisseria, brucella, steptococcus pneumoniae

acidophile

organism that thrives in acid. mold and yeast commonly spoil pickles

alkaliphile

organism that thrives in alkaline. proteus can neutralize urine and infect urinary system

osmophile

organism that lives in high solute concentration

halophile

organism that lives in high concentration of salt

obligate halophile

require at least 9% NaCl, grow optimally at 25%

facultative halophile

do not usually reside in salt environment, but resistant to salt.

commensalism

one organism benefits, the other is unaffected (mostly)

parasitism

one organism is benefitted, host is harmed

mutualism

symbiosis where microbes live closely together, both are benefitted

synergism

organisms work together to achieve a common goal. example: biofilms!

differences in bacteria that grow in biofilms from planktonic bacteria

genes, behavior, environment response

binary fission

main method of bacterial division

parent enlarges —> duplicate chromosome —> pull cell envelope together at middle —> cell wall forms complete septum

doubling time

the time it takes for a full fission cycle, each generation the population increases 2x

lag phase

population isn’t growing, before it grows

exponential growth phase

population is actively growing, keeps doubling

stationary phase

population stays the same as more cells grow but also start to die off

death phase

more cells die than can be replaced

viable plate count

counting based off the visible colonies

optical density (turbidity) measurement

counting based on opacity of solution, indicating greater amount of microbes

fluid thioglycollate medium

medium that has a little bit of agar, separates microbes based on oxygen requirements, reacting with oxygen so that it can only penetrate the top of the tube

catalase

enzyme produced by oxygen favoring organisms that turns H2O2 into H2O and O, causing oxygen bubbles to form

quorum sensing

bacteria secrete chemicals to recruit other organisms for biofilms, activates different genes to stop free swimming and call everyone to settle together. pseudomonas aeruginosa — cystic fibrosis

reasons that biofilms are hard to eradicate

glycocalyx is not dissolvable by water, lateral gene transfer allows fast anti-antibiotic evolution, prevents detatchment of cells

staphylococcus aureus

facultative halophile bacteria that lives on the skin and causes infection

listeria

psychotroph bacteria that lives in food. causes listeriosis, which can lead to fever and flu-like symptoms, as well as eventually meningitis. (idk if we have to know THAT much but i wanted to know)

symbiotic

relationship where at least one organism is obligated to another

nonsymbiotic

relationship where neither organism is obligated to the other, optional relationship.

antagonism

an organism seeks to destroy another organism, organisms are in conflict with one another

turbidometry

measuring bacterial growth by observing how turbid (opaque) the solution is