PowerPoint 5 - Microbial Growth

Microbial Growth

Refers to the growth of a bacterial population, not individual microorganisms.

Binary Fission

A common mechanism of cell replication in bacteria, which is a form of asexual reproduction.

Colony

A visible mass of microorganisms originating from a single mother cell.

Cytokinesis

The process during cell division that separates the cytoplasm of the parental cell into two daughter cells.

Origin of Replication

The location on a circular chromosome where DNA replication begins.

Terminus

The point at which DNA replication ends on a chromosome.

FtsZ Protein

A protein that directs the process of cytokinesis in bacterial cell division.

Divisome

A complex structure formed during cell division that activates peptidoglycan synthesis.

Generation Time

The time required for a population to double in number.

Doubling Time

The time it takes for the bacterial population to double through one round of binary fission.

Exponential Growth

A phase where the cell population increases rapidly as a result of successful binary fission.

Lag Phase

The initial phase of the growth curve where cells prepare for division.

Log Phase

The exponential growth phase where cells are actively dividing.

Stationary Phase

The phase of growth where the number of new cells equals the number of dying cells.

Death Phase

The phase where the number of dying cells exceeds the number of new cells.

Chemostat

A culture vessel used to maintain specific growth rates in a laboratory.

Plate Count

A method for measuring viable bacteria by counting colonies that grow on agar plates.

Colony-Forming Units (CFUs)

A term used to express the number of viable bacterial cells in a sample.

Serial Dilution

A method used to reduce the concentration of a culture for accurate cell counts.

Spread Plate Method

A technique for counting colonies by spreading a diluted sample over an agar surface.

Pour Plate Method

A method of counting bacteria by mixing diluted samples with warm agar.

Filtration

A technique to count bacteria when the expected quantity is low, often used for water samples.

Most Probable Number (MPN) Method

A statistical method used to estimate the number of microbial cells in a sample.

Direct Microscopic Count

A method that involves counting cells in a measured volume on a microscope slide.

Petroff-Hausser Chamber

A specific slide designed to facilitate counting of bacterial cells.

Fluorescence Staining

A technique used to differentiate between live and dead cells in a sample.

Coulter Counter

An electronic device that counts cells in a liquid by measuring changes in resistance.

Biofilms

Structured communities of microorganisms that attach to surfaces and contain complex ecosystems.

Extracellular Polymeric Substances (EPS)

A matrix secreted by biofilm organisms that helps protect and structure the community.

Quorum Sensing

The process by which bacterial cells communicate and coordinate activities based on population density.

Inducers

Signaling molecules used in quorum sensing that trigger specific gene expression in bacteria.

Obligate Aerobes

Bacteria that require oxygen to survive.

Obligate Anaerobes

Bacteria that cannot survive in the presence of oxygen.

Facultative Anaerobes

Bacteria that can thrive in both aerobic and anaerobic environments.

Aerotolerant Anaerobes

Organisms that do not use oxygen but are not harmed by its presence.

Microaerophiles

Bacteria that require a lower concentration of oxygen than what is present in the atmosphere.

Neutrophiles

Microbes that grow best at a near-neutral pH, typically between 6.5 and 7.5.

Acidophiles

Organisms that thrive in acidic environments, typically below pH 5.55.

Alkaliphiles

Microbes that grow best in alkaline environments, typically between pH 8.0 and 10.5.

Mesophiles

Organisms that grow optimally at moderate temperatures, generally between 20°C to 45°C.

Thermophiles

Microbes that thrive at higher temperatures, usually between 50°C and 80°C.

Psychrophiles

Microorganisms that grow optimally at cold temperatures, typically below 15°C.

Halophiles

Microorganisms that thrive in high salt concentrations.

Barophiles

Microbes that require high pressure for growth.

Algal Blooms

Rapid growth of algae often caused by nutrient runoff, particularly nitrogen and phosphorus.

Culture Media

Prepared nutrient solutions used to grow microorganisms.

Selective Media

Type of media that inhibits the growth of some microorganisms while promoting the growth of others.

Differential Media

Media that allows differentiation between microorganisms based on color change.

Agar

A gelatinous substance derived from algae used as a thickener in culture media.

Blood Agar

A type of differential medium used to detect hemolytic activity of bacteria.