Untitled Quiz

Microbial Temperature Classifications

• Optimum Growth Temperature: Ideal temperature for microbial growth.
• Minimum Growth Temperature: Lowest temperature for survival and replication.
• Maximum Growth Temperature: Highest temperature for microbial growth.

Lake Whillans Exploration

• Expected limited life due to cold, nutrient-poor conditions.
• Discovered a rich diversity of microbial life.

Deep-Sea Vents

• Host extreme heat-loving bacteria, surviving at temperatures up to 340 °C.

Mesophiles

• Thrive in moderate temperatures between 20 °C and 45 °C.
• Includes important human microbiota and pathogens like E. coli and Salmonella.

Psychrotrophs (Psychrotolerant)

• Prefer cooler temperatures ranging from 4 °C to 25 °C.
• Common in temperate climates and responsible for spoilage in refrigerated food.

Psychrophiles (Cold-loving organisms)

• Grow at 0 °C and below, optimal around 15 °C.
• Typically do not survive above 20 °C.
• Found in permanent cold environments like deep ocean waters and are crucial decomposers in cold climates.

Thermophiles (Heat-loving organisms)

• Optimal growth between 50 °C and 80 °C.
• Do not grow at room temperature.
• Commonly located in environments like hot springs and compost piles, with examples including Thermus aquaticus and Geobacillus spp.

Hyperthermophiles

• Thrive at temperatures between 80 °C and 110 °C, with some surviving above 121 °C.
• Identified in extreme environments such as hydrothermal vents, with examples like Pyrobolus and Pyrodictium.

Adaptation to Extreme Temperatures

• Low Temperatures: Cause loss of membrane fluidity, ice damage, slowed chemical reactions, and rigid proteins prone to denaturation.
• High Temperatures: Result in protein and nucleic acid denaturation, increased fluidity disrupting metabolism.
• Applications of these temperature effects include sterilization and pasteurization.

Psychrophiles' Protein Characteristics

• Flexible proteins with fewer stabilizing bonds.
• Utilize antifreeze proteins and unsaturated lipids to maintain membrane fluidity.
• Slower growth rates compared to mesophiles; can endure freezing and are stable with glycerol storage at -80 °C.

Thermophiles' and Hyperthermophiles' Macromolecule Differences

• Elevated ratio of saturated lipids limits membrane fluidity, enhancing survival at high temperatures.
• DNA shows higher guanine-cytosine content for stability.
• Proteins feature additional bonds and modified amino acids for increased resistance to denaturation.