Where bodily cells cordinate their movments based on

chemicals in their eviorment. Petrichous bacteria

use a combination of run and tumble motions to move.

-sugars

-amino acids

-oxygen

-Hydrophobic amino acids

-organic salts

-heavy metals

-Acids(benzoic acid)

Bacteria divide by binary fission. A septum forms and dives into two bacteria.

The bacteria grow exponentially.

(bacterial growth)

What is a:

 lag phase?

log phase?

stationary phase?

death phase?

long term stationary phase?

Lag phase=Bacteria are preparing to grow

Log phase= Bacteria grow exponentially

Stationary phase+ Nutrients run out and waste products build up

Death phase=Bacteria death occurs at and exponential rate

Long term stationary phase= The # of bacterium decline slowly

To measure bacteria growth. It counts cells directly

under a microscope.

What is a spectrophotometer used for?

What is plating?

measure abosorbance at O.D. 590 

Range= 1x 10⁷ -1 10¹⁰

Plating= can detect living cells

Sterilization=kills all microbes

Disinfection=remove microbes from non living tissue

Antiseptics- remove microbes from  living tissue

Bactericide=chemical that kills bacteria

Bacteriostatic=prevents growth of bacteria but doesnt kill them

Ecolie stop growing at 45 degrees C and die at 55.

-90% die after 24 secs at 60 C.

What is the D-value?

What is thermal death time?

Time it takes to kill 90% of bacteria

Thermal death time is the time it takes to 

What is pasteurization?

What is flash pasteurization?

What is ultra high temp sterilization?

What is autoclave?

Pasteurization = 63 -66 degrees C for 30 min

Flash pasteruzation=71 C for 15 secs

Ultra high temp sterilization= 150 C for 1 to 3 secs

Auto clave= Steam and pressure usually 121 C for 15 min

Bacterial D values:

Salmonella?

Staphylococcus?

Clostridium perfringens?

Clostridium botulinum?

Salmonella = 24 secs at 60 C

Staphylococcus=5 min at 60 C

Clostridium perfringens=- 5 min at 90 C

Clostridium botulinum=13 secs at 121 C

(Endospore structure)

What is the core wall?

What is the cortex?

What is the spore coat?

What is exsporium?

Core wall = cell wall of the spore

Cortex= Weakly cross linked peptidoglycan and DPA on surface of cell

Spore coat = dense protein layer

Exosporium = Thin outer coating

Its non pathogenic.

-The most studied gram positive bacterium

-lives in soil

-one strain used to make natto

- Found in soil

-causes anthrax

-produces a toxin that can kill cells

-potential to use as a biological weapon

-spores have to be 2-5 micrometers

-Anaerobic, but spores can surivie in air

-Causes gangrene

-can infect wound tissue

-Causes tetanus

-Produces mutiplle toxins during formation. These cause muscle paralysis.

-Potential proble with home canned food.

1) apply heat(pasteurization, Ultra high pasteurization, autoclave, cooking)

2) Consume immediately 3)Desication(remove H₂O) (bacteria requre water to digest food)

4)Fermentation= allow one organism to consume the food and secrete anti microbial products(examples include bread, alcoholic beverages, dairy products, soy sauce and chocolate)

 5)raise osmolarity(increase solute concentration) 6) increase acidity(decrease in ph makes it difficult to grow. 

1) yeast formation

2)lactic acid fermentation

3)acetic fermentation

Modern Methods of bacterial Control

1) asepsis-avoid contamination

2)decrease temp(refrigeration only slows microbial growth while freezing forms crystals in the cytoplasm and ruptures the cell wall.(not all bacteria)

3)anti microbial chemicals

Sodium Nitrite(meat), Sulfites(wine), Sorbic acid(cake mix) Benzoic acid(cereal) Propionic acid

4) radiation 

5) filter sterilization=Membrane with opening to small for microbes to pass.

6) antibiotics 

-ca survive 5000 gy of radiation(5 gy would kill a human)

Has specialized DNA repair mechanisms,and multiple copies of genomes.

1) enaymatic reactions

2) oxidation

3) Microbes

-Molecular oxygen is somewhat toxic and can be partially reduced to form reactive  O₂ species.(super-oxide and hydrogen peroxide)

-Dead organisms can no longer produce antioxidants to prevent Oxidative damage.

-Lipids in meats and other food products can become oxidised.

1) keep oxygen concentration low

-below 20% in atmosphere and

-3 to 5% cellular levels

-Microbes spoil food by consuming it and excreting products that make it unpalatable

-different process from food poisoning(contaminated with pathogens)

Food spoilage of dairy products?

What is the sour taste?

What else occurs?

What is bitter taste?

1) sour taste  is from lactic and acetic acid production by bacteria

2)Denaturation-Proteolysis of casein and decreased PH.

3) Bitter tase- Protein degradation

Food spoilage of meat?

What is rancid taste?

What is the smell?

What do fish contain?

-The rancid taste is oxidation of lipids in meat. The lipids are produced by bacteria.

-The smell  is degradation of amino acids to make sulfides and amines.

- Fish contain trimethylamine oxide and convert it to trimethylamine when fish spoils.

1) use of endogenous organinc molecules as an electron donor

2)Growth of microbes to make food

3)industrial growth of microorganisms

* bacteria are grown in fermentors

- Food additives such as:(Vitamins(b₁₂ and C)),essential amino acids and xanthin gum(thickening agent found in ice cream)

-Pharmaceuticals 

-Chemicals(acetone)

-Fertilizers

-Pesticides

What is fixed cycle fermentation? 

What is continuous cycle fermentation?

-Fixed Cycle= ingrediants and microbes added. The cycle ends when processing is finished.

-Continous Cycle= ingreidients and H₂O are continually added for microbes

-microbes must be monitored

-if replicated too fast they can break the fermentor

-too slow there is no product

-producing a lot of bacteria generally translates to not a lot of product.

What are common models for studying Microbial aging?

What is replicative life span?

What is Chronological life span?

-Yeast are common models for studying aging.

- Replicative Life Span= Time non dividing yeast cells can life after nutrients are removed.

-Chronological life span= Time non-dividing yeast cells can life after nutrients removed.

*Homologous of genes that exstend life span in yeast also exstend life span in mice.

-usually live in running water

-two forms exsits the stalked cell and the motile swarmer cell

-Immobilized E.Coli were tracked for nine generations

-Cells with an older pole reproduced at a slightly slower rate.