Microbial Growth Requirements: Temperature, pH, Osmotic Pressure, and Nutrients

What are the five groups of microbes classified based on temperature range?

Psychrophiles, Mesophiles, Thermophiles, Hyperthermophiles, and Psychrotrophs.

What are the physical requirements for microbial growth?

Temperature, pH, and osmotic pressure.

What is the importance of osmotic pressure to microbial growth?

It affects cell turgor and can lead to plasmolysis in hypertonic environments.

What is the optimum growth temperature for thermophiles?

Typically found in hot springs and organic compost piles.

What defines hyperthermophiles?

They have an optimum growth temperature greater than 80°C.

What pH range do most bacteria grow best in?

Between pH 6.5 and 7.5.

What pH range do molds and yeasts prefer for growth?

Between pH 5 and 6.

How do buffers function in growth media?

They minimize pH changes in the culture media.

What are acidophiles?

Microbes that grow in acidic environments.

What is the effect of hypertonic environments on cells?

They cause plasmolysis as water moves out of the cell.

What are obligate halophiles?

Microbes that require high salt concentrations, up to 30% NaCl.

What are facultative halophiles?

Microbes that can tolerate high salt concentrations (2-10% NaCl).

What is the role of carbon in microbial growth?

It serves as the structural backbone of organic molecules.

What is the difference between chemoheterotrophs and autotrophs?

Chemoheterotrophs use organic molecules for both carbon and energy, while autotrophs use CO2 as their carbon source.

What is the significance of nitrogen for microbes?

It is a component of proteins, DNA, and ATP.

What role does sulfur play in microbial metabolism?

It is used in amino acids, thiamine, and biotin.

What is phosphorus used for in microbial cells?

It is found in DNA, RNA, ATP, and phospholipids.

What are trace elements?

Inorganic elements required in small amounts, such as iron, copper, molybdenum, and zinc.

What are obligate aerobes?

Microbes that require oxygen for growth.

What is the difference between facultative anaerobes and obligate anaerobes?

Facultative anaerobes can grow with or without oxygen, while obligate anaerobes are harmed by oxygen.

What are aerotolerant anaerobes?

Microbes that tolerate oxygen but cannot use it.

What do microaerophiles require?

They require oxygen concentrations lower than that of air.