Microbial Growth & Nutrition Concepts

Growth & Nutrition

• The presentation is about bacterial growth and nutrition.
• Learning objectives include understanding ATP, various microbial metabolisms, bacterial cell division, and population growth.

Energy

• ATP is an energy-carrying molecule.
• It's composed of three structures.
• Energy is stored within the bonds between phosphates.
• ATP becomes ADP through a condensation reaction.
• Processes like replication, growth, motility, and active transport require energy.

Energy Sources

• Organisms are categorized as phototrophs or chemotrophs, depending on their energy source.
• Phototrophs obtain energy from light.
• Chemotrophs obtain energy from chemical compounds.

Autotrophs & Heterotrophs

• Autotrophs (producers) create their own food from raw materials using energy.
• They are typically photosynthetic.
• Heterotrophs (consumers) cannot make their own food and obtain nutrients by consuming other organisms (phototrophs or other heterotrophs).

Types of Metabolism

• Metabolism is categorized based on energy and carbon sources.
• Chemoheterotrophs utilize organic compounds as both energy and carbon sources.
• Phototrophs use light as an energy source, and obtain carbon from CO2.
• Chemoautotrophs obtain energy from inorganic compounds and carbon from CO2.
• Photoautotrophs and photoheterotrophs use light as an energy source, where one uses CO2 and the other uses an organic compound.

Fermentation

• Fermentation is an ancient process that breaks down starch and sugars without oxygen.
• This anaerobic process produces ATP and end products like alcohol, lactic acid, etc.
• Fermentation is used in various food production (bread, alcohol, yogurt).

Bacterial Growth in the Lab

• The factors that affect bacterial growth, in the lab or in nature, include solid vs. liquid media, temperature, nutrients, selective media, acidity (or alkalinity).

Bacterial Growth Stages

• A typical bacterial growth curve can be divided into lag phase, exponential growth phase, stationary phase, and death phase.

Bacterial Growth Requirements

• For bacterial growth, essential components are temperature, pH, nutrients, oxygen, and water.

Bacterial Adaptation Strategies in various conditions

• Organisms like psychrophiles thrive in cold, permanently cold environments, while thermophiles endure permanently hot environments.
• Mesophiles are those that thrive in moderate environments.
• Acidophiles can adapt to thrive in highly acidic environments
• Alkaliphiles live in highly basic environments.

Oxygen Requirement

• Obligate aerobes need oxygen for growth, facultative aerobes can grow with or without oxygen, and obligate anaerobes can only grow without oxygen and can be harmed by its presence.
• Microaerophiles can grow in low oxygen environments

Osmotic Effects

• Water availability is vital for bacterial growth, including avoiding dryness and solute availability.
• Halophiles tolerate high salt concentrations, while nonhalophiles do not.

Prokaryotic Cell Division

• Bacteria divide through a process called binary fission.

Generation Time

• Generation time is the time it takes for a bacterium to divide and thus to double. It varies depending on the organism and environmental factors.
• Shorter generation times are seen in optimal environments with nutrients readily available.

Dormancy States

• Endospores are highly resilient structures formed by some bacteria for survival in stressful environments.
• Persisters are dormant cells with reduced metabolism and resistance to antibiotics.