Week #3 Microbial Nutrition & Growth

Microbial Growth

An increase in the number of cells rather than an increase in size.

Requirements for Microbial Growth

Microbes need to synthesize cell components like nucleic acids, proteins, lipid membranes, and cell walls.

Sources Needed for Growth

Microbes require sources of carbon, energy, and electrons to grow and multiply.

Microbial Grouping

Microbes are categorized into four basic groups based on their carbon and energy sources.

Core Chemicals for Growth

Essential chemicals include nucleotides, amino acids, phospholipids, and sugars derived from macronutrients.

Trace Elements

Micronutrients like copper, zinc, manganese, and molybdenum are essential for enzyme function.

Capnophiles

Microbes that require higher concentrations of carbon dioxide and low oxygen levels for growth.

Reactive Oxygen Species (ROS)

Byproducts of aerobic metabolism that can damage cell structures.

Protective Enzymes

Superoxide dismutase (SOD) and catalase help microbes eliminate the toxic effects of ROS.

Catalase Test

A laboratory test used to differentiate bacterial species based on catalase production.

Temperature Categories

Microbes are categorized based on their optimal growth temperature (psychrotrophs, mesophiles, etc.).

Growth Temperature Effects

Minimum, maximum, and optimum growth temperatures affect microbial metabolism.

pH Effects on Growth

Neutrophiles, acidophiles, and alkalinophiles have different optimal pH ranges for growth.

Osmotic Pressure

The pressure exerted on bacterial cells by their environment, affecting their growth.

Obligate Halophiles

Microbes that require high salt concentrations for growth.

Biofilms

Complex structures formed by microbes in mixed communities that can impact human health.

Pure Cultures

Culturing microbes in isolation from mixed communities for study and identification.

Aseptic Techniques

Methods used to prevent contamination during microbial culture.

Clinical Specimen Collection

Proper collection and handling of specimens to avoid contamination and ensure accurate diagnosis.

Quadrant Streaking

A technique used to isolate bacterial species from clinical specimens.

Serial Dilutions

A method for quantifying microbial populations by diluting specimens before plating.

Selective Media

Media that inhibit the growth of some organisms while promoting others.

Differential Media

Media that allow for the differentiation of organisms based on specific characteristics.

Fastidious Bacteria

Bacteria that require specific nutrients or conditions for growth.

Anaerobic Cultures

Techniques and media used to culture obligate anaerobes that cannot tolerate oxygen.

Bacterial Preservation

Methods like refrigeration, deep-freezing, and lyophilization to store bacterial cultures.

Binary Fission

The asexual reproduction process by which bacterial cells divide.

Generation Time

The time required for a bacterial population to double in number.

Microbial Growth Curve

Phases of growth observed in a closed system, including lag, log, stationary, and death phases.

Direct Methods of Measuring Growth

Techniques like direct microscopic counts and viable plate counts.

Indirect Methods of Measuring Growth

Techniques like turbidity measurements using a spectrophotometer.