CHAPTER 7 MICROBIAL GROWTH

What requitements are needed for microbial Growth?

Physical and Chemical

Physical Requirement are?

1. Ph

2. temp

3. osmotic pressure (water moves from are of high concentration to low)

4. hydrostatic pressure (depth)

Chemical Requirement/ NUTRIENTS are?

1. Carbon

2. nitrogen

3. oxygen

4. sulfur

5. phosphor and trace elements

6. Trace elements

Most Micorbes love what temp?

37 degrees Celsius which is human temp

HOW DOES high medium and low temp affect the microbe interactions?

High temp: Kills bacteria cells and denatures proteins

Increased temp: Speeds up enzymatic reaction and microbial growth

Low temp: Slows down growth and enzyme reaction hence refrigerating food.

Microbes can be group based off their temp survival ranges what are they ?

1. Psychrophiles: Love the cold (-20 to 10 degrees Celsius)

2. Psychrotrophs: Food borne illness related (0-30 degrees Celsius) [example: Listeria]

3. Mesophiles: Moderate loving (10-50 degrees Celsius) (common human pathogens, live in animals)

4. Thermophiles: Heat loving (40-75 degree Celsius)

Microbes have what type of temp ranges in response to temp?

Minimum range that support growth

Maximum range that supports growth

Optimal range that has the most growth of the microbes.

How can the PH of solutions be adjusted?

Use proton pumps or Enzymes

Microbes can be grouped based on their Ph ranges what are these groups?

1. Neutrophiles: PH of 7-7.4

2. Acidophiles: PH of 1-5 [example: LACTOBACILLUS ACIDOPHILUS ]

3. Alkaliphile Ph > 8.5 [example: Vibrio Cholerae]

Optimal PH of each group of ph dependent growth microbes are?

7 for Neutrophiles

3 for Acidophiles

<9 for Alkaliphiles

What is Osmotic Pressure in High sal/ suagr CONDITIONS and what is the process called?

1. In high salt/ sugar conditions the water moved out of the microbe to the environment [process is called plasmolysis

2. the plasma membrane moves from the cell wall and the bacteria cannot grow.

Affect of plasmolysis on Microbe?

Can lead to prevention of microbial growth.

Can lead to cell death but some can adapt and survive

Microbes can be grouped based on their survival in high Salt conditions what are these groups and it what conditions do they grow ? Examples? Amount of toleration by each group?

1. Obligate Halophiles- can survive high salt conditions, tolerate 35% of salt concentration, they need it to grow [example: Vibrio Species ]

2. Facultative Halophiles - Can survive in both low and high salt conditions, tolerate 20% salt concentration [example Staphylococcus Aureus]

Hydrostatic Pressure Increases with what in terms of water?

It increases with Depth

Microorganism that can withstand extreme H Pressure?

Barophiles

What are Facultative Anaerobes?

organisms that can use oxygen when present but can grow without it.

Organisms can be based on their Carbon Source to grow what are they? How do they acquire carbon for growth?

1. Heterotrophs: Get carbon from catabolizing organic molecules [lipids, proteins, sugars,]

2. Autotrophs: Get carbon, from inorganic source and use carbon fixation to convert the inorganic carbon to organic carbon

Organisms can e categroized based on the source they use for enegry what are they? What sources do they use for energy

1. Chemotrophs: Use redox reduction to acquire energy use both inorganic and organic chemicals [anaerobic , aerobic Respiration and Fermentation]

2. Phototrophs: Use light as an energy source