Chapter 9: Microbial Growth

A set of vocabulary flashcards focusing on key terms and definitions related to microbial growth, including methods of reproduction, growth phases, metabolic products, and environmental influences.

Binary Fission

A method of prokaryote reproduction where one cell divides into two, and population doubles each division.

Exponential Growth

Population growth where the number of cells doubles at each division.

Generation Time

The time it takes for a microbial population to double.

Divisome

A structure formed by proteins that activates to produce a peptidoglycan cell wall during cell division.

Lag Phase

The initial phase of the growth curve where the number of cells does not increase as bacteria synthesize required enzymes.

Log Phase

The phase of the growth curve where cells divide at a constant rate and are most sensitive to antibiotics.

Stationary Phase

The phase in the growth curve where microbial growth rate slows and primary metabolite production occurs.

Death Phase

The phase in the growth curve where the number of live cells decreases due to nutrient depletion.

Primary Metabolites

Compounds produced during the growth phase essential for bacterial growth and development.

Secondary Metabolites

Compounds produced during the stationary phase not required for primary metabolism, often serve ecological roles.

Viable Cell Count

A count of cells capable of multiplying, typically ascertained using plate counts.

Most Probable Number (MPN)

A statistical estimate of cell concentration in a very dilute original sample, using dilution series.

Turbidity

Cloudiness of a culture which is proportional to the concentration of microbial cells present.

Halotolerant

Microorganisms that can withstand up to 10% salt concentration.

Halophiles

Microbes that require high salt concentrations for growth.

Nutritional Diversity

Variation in the types of nutrients that different microbial species can utilize for energy.

Autoinducers

Chemical signals used by bacteria for quorum sensing to coordinate group behaviors.

Biofilm

A community of microorganisms encased in a polysaccharide matrix, often adhering to surfaces.

Chemostat

An open culture system that maintains continuous growth by adding fresh medium and removing waste.

Aseptic Technique

Methods used to prevent contamination when culturing microbial cells.

Culture Medium

A nutrient solution used to support microbial growth, which can be liquid or solid.

pH Influence on Microbial Growth

Most microbes prefer a neutral pH around 7, with some adapted to acidic or alkaline environments.

Nutritional Factors

Include major elements like carbon and nitrogen required for cell components and growth.

Phototrophs

Organisms that obtain energy from sunlight for growth.

Chemotrophs

Organisms that derive energy by extracting it from chemical compounds.

Complex Media

Culture media composed of various ingredients whose exact composition is variable.

Selective Media

Media designed to inhibit the growth of certain species while promoting others.

Differential Media

Media that contains substances that allow for the identification of microbial species based on biochemical reactions.

Microaerophilic

Microorganisms that require lower levels of oxygen than are present in the atmosphere.

Obligate Anaerobes

Microorganisms that cannot survive in the presence of oxygen.

Capnophiles

Microorganisms that thrive in environments with elevated levels of carbon dioxide.

Environmental Factors

Parameters such as temperature and water availability that influence microbial growth.