Cultivation of Microorganisms

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Questions and Answers

The process of propagating organisms by providing the proper environmental conditions is known as ______.

cultivation

Microorganisms need ______ to synthesize macromolecules and maintain essential chemical gradients.

metabolic energy

When cultivating microorganisms, factors like nutrients, pH, temperature, and ______ must be controlled.

aeration

Fermentation, respiration, and photosynthesis are the three major mechanisms for generating ______.

<p>metabolic energy</p> Signup and view all the answers

The plating method involves placing a limited number of cells in or on a ______ medium.

<p>gelled</p> Signup and view all the answers

Agar, a polysaccharide extracted from red algae, is an ideal ______ agent for most microbial media.

<p>gelling</p> Signup and view all the answers

The dilution method reduces the density of microorganisms in a sample through ______ dilution.

<p>serial</p> Signup and view all the answers

In the natural environment, the population of microorganisms is roughly ______.

<p>constant</p> Signup and view all the answers

The survival of any microbial group within its environment is determined by the maintenance of a pool of living ______ and by successful competition for nutrients.

<p>nutritional deprivation</p> Signup and view all the answers

Growth is the regular increase in the sum of all components of an ______.

<p>organism</p> Signup and view all the answers

In unicellular microorganisms, such as bacteria, growth involves the ______ of cells.

<p>duplication</p> Signup and view all the answers

The bacterial growth curve represents the population dynamics of bacteria growing in a closed system, also known as a ______ culture.

<p>batch</p> Signup and view all the answers

The ______ phase is when bacteria adapt to their environment and prepare for active division.

<p>lag</p> Signup and view all the answers

During the ______ phase, cells divide at a constant rate, resulting in exponential population growth.

<p>exponential</p> Signup and view all the answers

The maximum stationary phase occurs when growth rate slows due to nutrient depletion and ______ accumulation.

<p>waste</p> Signup and view all the answers

During the decline or death phase, nutrients are exhausted, and toxic waste products accumulate leading to a decline in the number of living ______.

<p>cells</p> Signup and view all the answers

Flashcards

Microbial survival

Microbial survival relies on nutrient competition and deprivation management.

Growth in organisms

Growth is the regular increase in mass or size of all components of an organism.

Unicellular growth

In unicellular organisms, growth means cell duplication, increasing population size.

Bacterial growth curve

A growth curve showing bacterial population changes in a closed system over time.

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Lag phase

Initial phase where bacteria adapt to the environment with increased metabolic activity but no cell division.

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Exponential phase

Phase of rapid cell division and maximum metabolic activity resulting in exponential population growth.

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Maximum stationary phase

Phase where growth rate slows; new cells equal dying cells, stabilizing the population size.

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Decline phase

Final phase where nutrients are depleted, and cells die at an exponential rate; some may form spores.

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Cultivation of microorganisms

The process of propagating organisms by creating suitable environmental conditions.

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Metabolic energy mechanisms

Three main ways to generate energy: fermentation, respiration, photosynthesis.

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Nutritional demands

Microorganisms have diverse nutritional requirements and energy sources.

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Isolation of microorganisms

Separating a single microorganism to grow in pure culture without others.

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Plating method

Technique where single cells grow into separate colonies on solid medium.

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Dilution method

Serially diluting a sample to isolate single microorganisms in pure culture.

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Factors for growth control

Critical elements include nutrients, pH, temperature, aeration, and salt.

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Microbial survival in nature

Microbial populations balance growth with death, maintaining a constant ecosystem.

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Study Notes

Cultivation of Microorganisms

  • Cultivation is the process of growing microorganisms by providing suitable environmental conditions.
  • Microorganisms need metabolic energy to synthesize macromolecules and maintain chemical gradients.
  • Nutrients must be in a usable form.
  • Factors like nutrients, pH, temperature, aeration, salt concentration, and ionic strength influence growth.
  • Three major metabolic energy mechanisms are fermentation, respiration, and photosynthesis.

Cultivation Methods

  • Two key aspects for cultivation are the choice of a suitable medium and isolation of bacteria in pure culture.
  • Fundamental goals in microbiological cultivation include:
    • Obtaining a crop of specific cells.
    • Determining the number and type of organisms in a sample.
    • Isolating a specific organism from a source.
  • Isolation in pure culture involves isolating a single cell from other cells to maintain isolated progeny.

Plating Method

  • If a small number of cells are placed on a gel medium, each cell will grow into a discrete colony.
  • Agar, an acidic polysaccharide from red algae, is a good gelling agent for microbal media.

Dilution Method

  • Reduces the density of microorganisms in a sample through serial dilution.
  • Diluted sample is plated or inoculated to isolate single cells.
  • Single cells grow into pure colonies.
  • Samples from each dilution are plated or streaked on solid media.

Survival of Microorganisms in the Natural Environment

  • The population of microorganisms in the biosphere is roughly constant; growth is counterbalanced by death.
  • Survival depends on maintaining a pool of living organisms and successful nutrient competition.

Meaning of Microorganism Growth

  • Growth means a regular increase in the organism's components (size or mass).
  • In unicellular organisms, growth results in an increase in the number of individuals.

Bacterial Growth Curve

  • The bacterial growth curve showcases the population dynamics in a closed system (batch culture).
  • The curve shows the changes in the number of living cells over time.
  • The curve has distinct phases: lag, exponential, stationary, and death.

The Lag Phase

  • Bacteria adapt to the new environment.
  • Increased metabolic activity, but little to no cell division.
  • Duration depends on the organism and environmental conditions.
  • Key processes include synthesis of enzymes, proteins, and other molecules for growth.

The Exponential Phase

  • Cells divide at a constant rate, leading to exponential population growth.
  • Each generation, the population roughly doubles.
  • Bacteria are highly metabolically active and sensitive to antibiotics.
  • Key processes include DNA replication, protein synthesis, and active metabolism.

The Stationary Phase

  • Growth rate slows due to nutrient depletion and waste accumulation.
  • Number of new cells equals the number of dying cells.
  • Population size stabilizes.
  • Key processes include adjusting metabolism to stress conditions and secondary metabolite production.

The Death Phase

  • Nutrients are exhausted and toxic waste accumulates.
  • Cells die at an exponential rate.
  • Some bacteria form spores or enter a dormant state.
  • Key processes include lysis and breakdown of cellular structures in dead cells.

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