2.1 bacterial growth

how do most bacteria divide?

by binary fission leading to exponential growth

*growth and septum formation, division, repeat

line type for exponential growth arithmetic vs logarithmic plot

ari: curve to expo

log: staright line increasing

at what stage do nutrients run out?

entering stationary phase

what controls bacterial growth?

temp, nutrients, pH, oxygen

bacteria type that grows at lowest temperature?

psychrophiles

location: permafrost, glaciers, deep ocean, fridge

bacteria type that grows at second lowest temperature?

mesophiles

ex: human pathogens

bacteria type that grows at second highest temperature?

thermophiles

location: hot tubs, source of laundry enzymes

bacteria type that grows at highest temperature?

hyperthermophiles

sources of heat-stable enzymes for PCR

challenges and solutions for thermo and hyperthermophiles

challenges: protein denaturation, structural damage

solutions: heat-stable proteins, sat fa in membranes

challenges and solutions for psychrophiles

challenges: reduced enzyme activity and membrane fluidity

solutions: cyroprotectants inside cells, unsat fa in membrane

what does a typical minimal medium contain? CNSP

single carbon source and mineral salts:

• C: glucose, sucrose, lactose except photosyn bacteria

• mineral salts:

  • N: NH3, NO3-, amino acids

  • Sulfur: SO42-

  • Phosphorus: PO43-

  • cations and anions: Mg2+, Mn 2+, Ca2+, Zn2+, Fe2+, Cl-

do bacteria need vitamins?

yes and they can make them ex: in gut and we can use them too

which type of bacteria can grow in a minimal medium?

phototrophs

which type of bacteria canNOT grow in a minimal medium?

auxotrophs

• cannot syn important nutrient (aa, nucleotide bases, vitamins) and get it from enviro

• enviro must always have nutrient present

save energy

what are acidophiles?

bacteria that can grow pH< like mining areas, geothermal vents, acidic soils

what are neutrophiles?

bacteria that grow neutral ph (6-8) like most parts of the human body

what are alkaphiles?

bacteria that grow in pH>9 like in industrial plants, insect hinguts, soda lakes

what is the pH inside a cell regardless of external pH?

7

obligate aerobes

need oxygen to grow (close to water surafce)

obligate anaerobes

need oxygen free to grow (bottom of water)

facultative anaerobes

grow w/ or w/o oxygen

human pathogens are typically mesophilic acidophiles T or F

F mesophilic neutrophiles

how do bacteria make ATP?

respiration aka oxidative phosphorylation

fermentation aka substrate-level phosphorylation

respiration electron carriers:

NADH or FADH₂

genertaed during glycolysis and TCA cycle

respiration electron carriers are oxidized by (BLANK) to produce (BLANK)

oxygen; ATP

why do we need oxygen?

NADH + O₂ +ADP + Pi → NAD⁺ +H₂O + ATP

efficient way to produce energy from food a well

1 molecule of glucose gives 34 molecules of ATP

where does respiration happen gram neg?

periplasmic space

where does respiration happen gram pos?

outside the membrane

ETC consists of membrane-bound (BLANK)

oxidases (enzymes)

what are the CONSUMED reducing powers of the ETC?

NADH or FADH₂

provide electrons

What is the terminal electron acceptor in ETC?

O2; forms water

what is created through ETC?

proton gradient

what used proton motive force to make ATP?

ATP synthase

can respiration be anaerobic?

yes

how can respiration be anaerobic?

use different terminal electron acceptors like fumarate, NO3-, SO42-, S

• NADH + fumarate +ADP + Pi → NAD⁺ + succinate + ATP

• NADH + NO3- +ADP + Pi → NAD⁺ + NH3+ ATP

how does fermentation work?

ATP is synthesized by direct transfer of phosphate group from substrate x to ADP

O2 not needed

X +ADP → Y ATP

not efficient: 1 molecule glucose gives 4 molecules of ATP

what arre the PRODUCED reducing powers of fermentation?

NADH or FADH₂

bacteria that causes dental caries?

streptococcus mutans

• gram-pos coccus

• facultative anaerobe

• produces lots of acid

• makes sticky biofilm

why/how does S. mutans generate a lot of acid?

they lack gene to encoding proteins in ETC meaning it only utilizes fermentation for ATP generation which is not efficient, which produces a lot of acid (sucrose → fructose and glucose →glycolysis and lactic acid is formed) and can demineralize the enamel

why/how does S. mutans generate biofilm?

bacteria produces enzymes called glucosyltransferases that take glucose and make them into long-chain glucans which are sticky and help bacteria hold onto the surface of the tooth forming a biofilm (sucrose → fructose and glucose → long-chain glucans)