Module 4: Microbial Nutrition, Growth, and Ecology

Vocabulary flashcards covering microbial nutrition, growth phases, environmental factors, and ecological relationships from Module Four.

Nutrition

The process by which organisms obtain nutrients.

Nutrients

Chemical substances that are required for growth.

Macronutrients

Nutrients that are required in large amounts.

Micronutrients

Nutrients required in small amounts, often referred to as trace elements.

Essential nutrients

Substances that the organism cannot produce and must be supplied in their diet.

Growth factors

Organic substances, such as amino acids or vitamins, that an organism requires for metabolism but cannot synthesize.

Generation time

The time it takes for a whole population to double; also called doubling time.

Binary fission

An asexual reproduction process in bacteria where cells elongate, replicate their chromosome, and pinch into two identical daughter cells.

Closed system

An environment for bacterial growth where no additional nutrients are added and no waste is removed.

Lag growth phase

The initial period on a growth curve with no increase in population as bacteria adjust to their new environment.

Logarithmic (log) phase

The phase of rapid growth and division occurring under optimum conditions with high nutrients and low waste.

Stationary phase

The phase where the death rate equals the division rate due to nutrient depletion and waste buildup.

Death (decline) phase

The final growth phase where nutrients are minimal and waste products are at a maximum, causing cells to die.

Biofilms

Highly structured microbial communities that form a slime layer on the surface of objects.

Planktonic cells

Free-swimming cells in solution that initiate biofilm formation by attaching to a surface.

Sessile

The state of cells once they have attached to a surface and begun to colonize.

EPS

Extracellular polymeric substances; the extracellular material released by microorganisms to form the biofilm matrix.

Psychrophile

Cold-loving organisms with an optimum temperature between $0\,^{\circ}C$ and $20\,^{\circ}C$.

Psychrotroph

Organisms that prefer temperatures between $4\,^{\circ}C$ and $25\,^{\circ}C$ and are responsible for food spoilage in refrigerators.

Mesophile

Middle-temperature loving organisms that grow between $20\,^{\circ}C$ and $45\,^{\circ}C$, including human pathogens.

Thermophile

Heat-loving organisms that prefer hot temperatures from $50\,^{\circ}C$ to $70\,^{\circ}C$.

Superoxide dismutase

An enzyme in aerobic organisms that breaks down the highly reactive superoxide anion ($O_2^-$).

Catalase

An enzyme that breaks down toxic hydrogen peroxide ($H_2O_2$) into oxygen and water.

Obligate (strict) anaerobe

An organism that cannot live in the presence of oxygen, as oxygen is lethal to it.

Facultative anaerobe

An organism that can live without oxygen but grows better when oxygen is present.

Obligate aerobe

An organism that must have oxygen in its environment to survive.

Aerotolerant

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

Microaerophile

An organism that requires small amounts of oxygen in its environment.

Capnophile

An organism that requires low oxygen levels but high carbon dioxide ($CO_2$) content.

Thioglycolate broth

A medium used in the laboratory to determine the oxygen requirements of bacteria.

Acidophile

Organisms that prefer to grow at a pH below $5.5$.

Alkalophile

Organisms that prefer to grow at a pH between $8$ and $10.5$.

Neutrophile

Organisms that grow best between pH $6$ and $8$, including most human pathogens.

Osmosis

The diffusion of water from an area of high water concentration to low concentration.

Osmotic pressure

The push against the cell wall caused by water rushing into the cell.

Osmophile

Organisms that thrive in environments with high solute concentrations.

Halophile

A specific type of osmophile that loves and requires a high salt environment.

Photosynthesis

The process by which organisms capture sunlight energy to build chemical bonds in sugar molecules.

Barotolerant

Organisms that can survive under increased atmospheric pressure.

Barophiles

Organisms that require high pressure to grow, such as those found on the ocean floor.

Population

A group composed of organisms belonging to the same species.

Community

A group made up of multiple populations of different species living and interacting together.

Symbiosis

The interaction between various species or populations in a particular environment.

Commensalism

A symbiotic relationship where one species benefits and the other is unaffected.

Amensalism

A relationship where one species harms another while remaining unaffected itself.

Mutualism

A symbiotic relationship where both species involved benefit from the interaction.

Neutralism

A relationship where species coexist without any positive or negative effect on each other.

Parasitism

A relationship where one species benefits at the expense of a harmed host.

Autotroph

An organism that obtains its carbon from inorganic carbon dioxide ($CO_2$).

Heterotroph

An organism that obtains its carbon from organic compounds like sugar.

Photoautotroph

An organism that derives energy from light and carbon from $CO_2$.

Chemoautotroph

An organism that derives energy from inorganic compounds and carbon from $CO_2$.

Chemoheterotroph

An organism that derives both its energy and carbon source from organic compounds.

Photoheterotroph

An organism that derives energy from sunlight but uses organic compounds for its carbon source.

Saprobe

A type of chemoheterotroph that feeds on dead or decaying organic matter.