Chapter 6= Microbial Growth

Examples of; Solvent, Solute, and Solution

* Solvent= Water
* Solute= Sodium chloride or Amino acids
* Solution= Saline or Complex media

Encourage growth of different microbes:

\-Research of pathogens

\-Biotechnology(food)

\-Genetic Engineering= recombinant DNA, Vaccines, Hormones

Requirements for Growth

1. Physical requirements= environment microbe goes into to grow
2. Chemical requirements= atoms and molecules, nutrients the microbes will need to build up molecules and get energy.


1. -Provide conditions to allow the bacteria to continue to metabolize, replicate.

Physical Requirements for Growth: Temperature

Every species of microbe has optimal temperature= where it grows at its fastest rate.

\-Every microbe has temperature range= range of temps where you get least some growth occurring.

* Have minimum and maximum
* 5 types of temp requirement: Psychrophiles, Psychrotrophs, Mesophiles, Thermophiles, and Hyperthermophiles.

Psychrophiles

Cold-loving microbes, in polar regions

\-Optimal temp= 10℃

\-Temp range= -10-20℃

Psychrotrophs

Will grow in room temp, spoiling food, grow at -4℃, refrigerator temp.

\-Optimal temp= 22℃

\-Temp range= 0-30℃

Mesophiles

Normal flora outside/inside body. human pathogens

\-Optimal temp= 37℃- body temp

\-Temp range= 10-50℃

Thermophiles

Hot areas, Hot springs

\-Optimal temp= 60℃

\-Temp range= 40-70℃

Hyperthermophiles

Extreme hot environments, boiling water, hot springs, ocean floor= hydrothermal vents

\-Optimal temp= 90-100℃

\-Temp range= 70-110℃

Physical requirements for Growth: pH

A measure of the relative concentration of hydroxide ions compared to hydrogen ions relates to liquid water.

\-PH Scale= higher the hydrogen ion concentration, the lower the number.

* Acidic= Higher concentration of hydrogen ions, less hydroxide ions- 1-5pH
* Neutral= Same amount of hydrogen and hydroxide ions, living things tend to prefer, 7pH, 6-8
* Basic= High concentration of hydroxide ions, less hydrogen ions, 9-14 pH

3 Basic classifications of pH requirements for growth

1. **Acidophile**= Acid loving, low pH, __**Optimal pH= 3, pH range= 1-5.5**__
2. **Neutrophile**= Percer neutral pH, moderate pH, __**Optimal pH=7, pH range= 5.5-8.5**__
3. **Alkaliphile**= Love basic pH, High pH, __**Optimal pH= 9.5, pH range= 7.5- 11.5**__

Physical requirements for Growth: Osmotic pressure

Osmosis= Diffusion of water across a membrane

\-Comparing two solutions= to each other, separated by a membrane.

\-Solution= Solvent + Solute

* Isotonic, Hypotonic, Hypertonic

\-Osmosis goes from Hypotonic solution to Hypertonic

Diffusion

passive transport, no energy input, molecules move from 1 area of high concentration to low concentration

* More down a concentration gradient, will continue to move to low concentration until equilibrium reaches equilibrium

Equilibrium

no concentration gradient

Isotonic

has same solute concentration as the other solution

\-No osmosis. Outside and inside cell are same concentration.

Hypotonic

lower solute, higher water concentration

Hypertonic

higher concentration of solute, lower water

Type of environment that bacterial cells need in order to function…

\-Water= so proteins have 3D structure to have correct hydrogen bonding, and for metabolism

Osmotic pressures: 3 types

1. **Isotonic solution**= equal in and out cell
2. **Hypotonic solution**= has less solute outside compared to inside.
3. **Hypertonic solution**= has more solute outside the cell compared to the inside cell

Isotonic solution

equal concentration of solute and water.

\-No osmosis, survive very well.

Hypotonic solution

Less solute outside environment compared to inside cell. Environment is ___, water will move into cell.

\-Bacterial cells will only survive if cell wall has not been weakened or damaged, will osmotic lysis.

Hypertonic solution

More solute outside cell compared to inside cell.

Environment is ____, cell/cytoplasm hypotonic

\-Water will move outside cell, lose water and cytoplasm will shrink= Plasmolysis.

* Cause death of bacterial cell.Physical requirements for Growth:

Physical requirements for Growth

The purpose is to keep bacteria metabolizing, bacteria are able to Anabolism and Catabolism and then its ability to get energy= ATP

* Reproduce its molecules and go through processes like cell growth, cell division
* Dependent on bacterium has functional enzymes= cannot survive
* When producing media, need to make sure media has correct pH= neutral pH, has correct osmotic pressure= slightly hypotonic
* Put media into incubator which takes into account temp requirements

Chemical Requirements for Growth

Type of nutrients that bacteria need to be able to build larger macromolecules(proteins) that will act as enzyme or replicate DNA when cell goes through cell division

* Anabolic and Catabolic= release ATP, Nitrogen, Carbon, Oxygen, Hydrogen
* Macronutrients and Micronutrients

Macronutrients

Microbes need larger amounts of nutrients

\-Main atoms required in relatively large amounts for bacteria to function

* Carbon, Nitrogen, Phosphorous, and Sulfur

Carbon

All living things are ____ based

\-Organic molecules= molecules that contain high concentration/amount of ____

\-Makes up basic skeleton of cell Macromolecules in all living things.

\-____Skeleton; vary in length, may have double bonds and vary in location, arranged in rings, may be unbranched or branched.

Nitrogen

Essential for some macromolecules, organic molecules

\-Essential for; Structure of Nucleotides, and Amino acids

Phosphorous

Important for; Nucleotides, sugar phosphate backbone in DNA, for ATP.

Sulfur

Found in 2 amino acids= Cysteine, Methionine, and involved in disulfide bonds that can form in protein structure help prevent proteins from denaturing found in bacteria that live in high temps.

Micronutrients

Nutrients needed in very small amounts

* $**Growth Factor**$= $Organic molecules$= Carbon containing. **Coenzyme**
* $**Trace Elements**$= $Inorganic molecules-$ different types of metals. **Cofactor**

Oxygen

Is toxic to living cells

\-4.5 billion years ago= before life existed in atmosphere= no O2

\-1st cells to evolve where Autotrophs= Photosynthetic cells

\-No course of Organic Molecule on planet, self feeders.

\-Oxides= oxygen interacts with water is toxic for cells.

Antioxidants

Able to neutralize oxides which will protect our DNA from being mutated. Prevent cancer

* Enzymes that can detoxify oxides

Oxygen requirements

1. Do the cells $**contain enzymes to detoxify the oxides**$ that are produces by oxygens
2. Do cells actually $**use oxygen as part of their Carbohydrate metabolism= Aerobic, Anaerobic, or Fermentation**$

Obligate Aerobes

Oxygen required

\-Aerobic growth

* Growth occurs only where high concentrations of oxygen have diffused into medium
* Growth at top

Facultative Anaerobes

More growth in presence of oxygen

\-Aerobic and Anaerobic growth

* Growth is best where most oxygen is present, still some growth at bottom but mostly a top.

Obligate Anaerobes

Only Anaerobic growth

* Growth occurs only where there is No Oxygen

Aerotolerant Anaerobes

Only Anaerobic growth

* Grow with or without oxygen.
* Growth occurs evenly; oxygen has no effect= have enzymes that detoxify oxides

Microaerophiles

Only Aerobic growth

* Oxygen required in low concentration.
* Have low levels of enzymes to detoxify oxides. Very sensitive to high levels of concentration
* Will grow in middle since can only get small amounts of oxygen

Differential Media

Media that will change color or cause the bacteria to change color.

\-Enable you to tell difference between different types of bacteria

* Ex; Blood agar

Selective Media

Stop/slow growth of unwanted microbes; encourage desired microbes only allow certain microbes to grow

\-inhibits the growth of certain types of bacteria, and allows the growth of other types.

* Ex: PEA Agar= inhibits/stops the growth of Gram(-) bacteria. Gram(+) will grow well

Reducing media

used to grow obligate anaerobes

\-Ex: Thioglycolate media= in pares ability of oxygen to diffuse through media

* Determine oxygen requirement

Types of culturing bacteria

1. Chemically defined
2. Complex
3. Reducing
4. Selective
5. Differential
6. Enrichment

Enrichment

Has extra growth factors

* Nutrients are used for fastidious bacteria(hard to grow)
* Similar to selective media but designed to increase numbers of desired microbes.

Chemically Defined

Growth of Chemoautotrophs and Photoautotrophs; Microbiology

* Know every component in media, distilled water.

Complex

Growth of most Chemoheterotrophic organisms, made of extracts

Binary Fission

Process by which bacterial cells divide

* When bacteria cells are put in optimal conditions= Physically and chemically requirements are met for growth
* Enzymes are able to function and cells can metabolize and divide

Logarithmic Growth

Population of bacteria will grow, every generation

* Will double their numbers= start-1, next generation have- 2= 4=8=16=32
* Most bacteria will double in their numbers every 20 minutes when in optimal situation.

Bacterial Growth Curve

When population of bacteria is placed in conducive environment, where all physical and chemical requirements are met, Population of bacteria will grow specific phases


1. Lag phase
2. Log phase
3. Stationary phase
4. Death phase

Lag phase

bacteria are introduced to the environment, with no increase in a number of bacteria. Bacteria adjusting.

* 1st

Log Phase

bacteria are replicating at fastest rate, increasing number

* 48 hours
* 2nd

Stationary phase

bacteria still dividing, now have significant amount dying, waste products produced.

* 3rd

Death phase

bacteria are dying. more bacteria dying then less replication

* 4th

Nutrition Classification

All organisms= Energy source

\-Chemical= Chemotrophs= Carbon source= Organic or Inorganic(CO2) Compounds

* Organic compound= Chemoheterotrophs
* Inorganic compound(CO2)= Chemoautotrophs

or

\-Light= Phototrophs= Carbon souce= Organic or Inorganic(CO2) compounds

* Organic Compond= Photoheterotrophs
* Inorganic compound(CO2)= Photoautotrophs