Micro- Chapter 6 Lecture

• macrobe growth= increase in size
• microbe growth= increase in cell number via binary fission (bacteria, protists, algae) or budding (yeast)

• -they are small 
• -they need small amounts of nutrients
• -they have diverse metabolisms
• -they can tolerate a wide variety of physical conditions

carbon, energy, and electrons/hydrogen ions

photoautotrophs- get energy from light and carbon from the environment

chemoautotrophs- get energy from chemicals and energy from the environment

photoheterotrophs- get energy from light and carbon from organic compounds

chemoheterotrophs- get energy and carbon from organic compounds

Temperature, PH, and Osmotic Pressure, and hydrostatic pressure

• temp plays an important role because it affects the 3D structure or biological molecules. Microbes have minimum, optimum, and maximum growth temperatures. 
• -cold causes slow growth
• -optimal is maximum growth
• -maximal causes denaturation to occur

psychrophiles (cold lovers): 0-15 degrees C

mesophiles (most pathogens): 20-40 degrees C, optimal is 37 degrees

thermophiles (warm lovers): 45-110 degrees C

H+ and OH- interfere with the hydrogen bonding of proteins and nucleic acids. A PH that the microbe doesn't like can destroy tertiary and quaternary protein structures and nucleic acid structures. 

Acidophiles (acid-lovers): PH 0.1-5.4

Neutrophiles: PH 5.4-8.0 (most human pathogens)

Alkaliphiles (base-lovers): PH 7-11.7

most microbes need water to dissolve enzymes and nutrients for metabolism. cells will eventually die without water although endospores and cysts can last a long time without it. 

water also effects osmotic and hydrostatic pressure

it determines the amount of pressure put on the cell's membrane due to the dissolved substances in the solution 

• hyperosmotic (hypertonic) environment- the substances are on the outside of the cell and cause the cell to shrink due to water loss=plasmalysis
• *used in food preservation
• *halophiles can live in extreme salty 

hypoosmotic (hypotonic) environment- substances are on the inside of the cell so the cell takes up water=turgid. this is for cells with cell walls. if the cell doesn't have cell walls, then the cell bursts.

bacteria can survive to a depth of 7000m. Barophiles actually require pressure to keep their tertiary structure. 

for each 10m of depth, water pressure increases by 1 atm pressure

CHONPS, trace elements (Zn, Mn, Ng, etc), and vitamins/growth factors

Carbon acts as an energy source an is a building block for cells (carbohydrates, etc)

nitrogen is used in amino acids, purines and pyrimidines

*nitrogen fixation- cyanobacteria and rhizobium can reduce N₂ into NH₃ which is an essential process to fertilize soil

in aerobic microbes (obligate aerobes), oxygen is the final electron acceptor of the electron transport chain. However, superoxide radials and peroxide anions of oxygen are also toxic. these toxic forms of oxygen cause cell damage and damage to lipids and proteins

Aerobes- metabolize aerobically; obligate require O2

Anaerobes- metabolize anaerobically; obligate are poisoned by O2

Facultative anaerobes- can metabolize aerobically and anaerobically

Aerotolerant anaerobes- metabolize anaerobically; can detoxify oxygen' poisonous forms

Microaerophiles- require oxygen levels from 2-10%; have a limited ability to deto

sulfur is for cysteine, methionine and coenzymes

needed for nucleic acids, ATP, and phospholipids

antagonistic- one organism harms or kills the other 

synergistic- both organisms cooperate to reap better benefits than if they were living alone (they are able to live separately) 

symbiotic- they live in close nutritional and/or physical contact and are interdependent on each other. they do not live apart.

complex relationships between organisms. they microbes operate differently as a group than they would independently.

bacteria respond to signals from each other and with new behaviors

• defined 
• complex
• selective
• differential
• anaerobic
• transport

refridgeration: 4 degrees C 

deep freezing: -70 degrees C

lyophilization (freeze drying)

• they grow by binary fission=the cell duplicates itself by splitting into two daughter cells. 
• *growth is logarithmic
• *their generation time is the time is takes the cells to double in number (20 minutes to us is 20 hours to them, for example)
• *all cells do not divide at the same time=non-synchronous, but they do all stay in the same growth phase

lag phase

log phase- growth at exponential rate (meaning, 2, 4, 8, 18, etc). this phase has a finite number because as bacterial increase in number, nutrients and depleted and waste accumulates. the limiting factor is the rate of energy production from ATP 

stationary phase- this is the leveling out phase. nutrition is limited, wastes may be at toxic levels, there isn't enough O2 and PH isn't at its optimal level. 

death/decline phase- too much waste, and not enough nutrition, cells begin to die.

Viable plate counts

Membrane filtration

Microscopic counts

Electronic counters

Most probable number

• turbidity- measuring with a spectrophotometer
•  (the metabolic products or the dry weight)