Microbial Growth: Constraints, Extremophiles, and Growth Phases

What is the replication time for V. natriegens?

Less than 10 minutes.

What is the potential cell multiplication of a single microbe in 24 hours?

Over 10^12 cells.

How does replication time in macroorganisms compare to microbes?

Macroorganisms take days to years, while some microbes replicate in minutes.

What are intrinsic constraints on microbial growth?

Genome size, metabolism, and cell physiology.

What are extrinsic constraints on microbial growth?

Abiotic factors like temperature, pH, salinity, nutrients, and biotic factors like microbe interactions.

What temperature range do most microbes thrive in?

20-40 °C.

What pH range is optimal for most microbial growth?

6.5-7.5.

What is the salinity range that most microbes can tolerate?

0.5-1.0%.

What are extremophiles?

Microbes that can grow in extreme environmental conditions.

What adaptations allow thermophiles to survive high temperatures?

Lipid and protein chemistries adapted for thermal stability.

What is the significance of GDGTs in extremophiles?

They form stable monolayers in membranes at high temperatures.

What is the role of heat- and cold-adapted chaperones in extremophiles?

They maintain structural stability of proteins at temperature extremes.

What are piezophiles?

Microbes that live in high-pressure environments, such as deep ocean biospheres.

What is the generation time (g) in microbial growth?

The time from one generation to the next, also known as doubling time.

What is exponential growth in microbes?

A population grows in a manner proportional to 2^n, where n is the number of generations.

What assumptions are made in exponential growth models?

Constant generation time, unlimited resources, and binary fission for all microbial domains.

How does generation time (g) relate to growth rate (k)?

g is inversely proportional to k; k = log10(Nt/N0)/0.301t.

What phases do microbes experience during growth?

Lag, log (exponential), stationary, and death phases.

What occurs during the lag phase of microbial growth?

Cells prepare for growth by detecting their environment and synthesizing cellular components.

What characterizes the log phase of microbial growth?

Cells grow at the maximum growth rate possible under specified conditions.

What happens during the stationary phase of microbial growth?

Growth rate equals death rate due to resource depletion and waste accumulation.

What defines the death phase in microbial growth?

Death rate exceeds growth rate.

What is the role of D. radiodurans in biotechnology?

Used in cosmetics and for its DNA damage response capabilities.

How is Taq polymerase significant in molecular biology?

It is a thermostable DNA polymerase used in PCR assays.

What is the commercial significance of microalgae like C. cohnii?

Used in the production of DHA supplements.

What environmental pressures can affect microbial growth?

Temperature, pH, salinity, nutrients, and interactions with other microbes.

What adaptations do piezophiles have for high-pressure environments?

Similar adaptations to those found in psychrophiles, including lipid fluidity.