Microbial Nutrition and Ecology Study Notes

Nutrition

The process by which chemical compounds (nutrients) are acquired from the environment to sustain life.

Bioelements

Basic requirements for life including carbon, hydrogen, oxygen, phosphorus, potassium, nitrogen, sulfur, calcium, iron, sodium, chlorine, magnesium.

Essential nutrients

Substances (elements or compounds) that an organism must obtain from its environment.

Macronutrients

Nutrients required in large quantities that play principal roles in cell structure and metabolism, such as proteins and carbohydrates.

Micronutrients

Trace elements required in small amounts, involved in enzyme function and maintenance of protein structure (e.g., manganese, zinc, nickel).

Organic nutrients

Nutrients that contain carbon and hydrogen atoms, usually produced by living organisms (e.g., carbohydrates, lipids).

Inorganic nutrients

Atoms or molecules that contain a combination of atoms other than carbon and hydrogen (e.g., metals, salts, gases).

Growth factors

Essential organic nutrients that an organism cannot synthesize and must obtain from the environment.

Heterotroph

An organism that must obtain carbon in an organic form made by other living organisms, such as proteins and carbohydrates.

Autotroph

An organism that uses CO2, an inorganic gas, as its carbon source, not nutritionally dependent on other living things.

Photoautotrophs

Organisms that produce oxygen and use chlorophyll as the primary pigment for photosynthesis.

Chemoautotrophs

Organisms that survive entirely on inorganic substances; includes methanogens that produce methane gas.

Saprobes

Free-living microorganisms that feed on organic debris from dead organisms.

Facultative parasite

An organism that can be an opportunistic pathogen and can grow in the absence of a host.

Active transport

A process that requires energy and carrier proteins to move substances against their concentration gradient.

Passive transport

Movement of substances across a cell membrane that does not require energy, following concentration gradients.

Diffusion

The net movement of molecules from an area of higher concentration to an area of lower concentration.

Osmosis

The diffusion of water across a selectively permeable membrane.

Isotonic Solution

A solution where water concentration is equal inside and outside the cell, resulting in equal rates of diffusion.

Hypotonic Solution

A solution where there is a net diffusion of water into the cell, causing it to swell.

Hypertonic Solution

A solution that causes water to diffuse out of the cell, resulting in cell shrinkage.

Neutrophiles

Microorganisms that grow best at a pH between 6 and 8.

Acidophiles

Microorganisms that thrive in acidic environments with low pH.

Alkalinophiles

Microorganisms that grow in alkaline environments with high pH.

Symbiosis

A close nutritional relationship between organisms that can be mutualistic, commensalistic, or parasitic.

Mutualism

A type of symbiosis where both partners benefit and may be obligatory or non-obligatory.

Parasitism

A relationship where a parasite derives benefits at the expense of a host organism.

Binary fission

The process by which bacterial cells divide, leading to population growth.

Exponential growth

A phase of maximum growth during which the population increases rapidly under optimal conditions.

Growth curve

A predictable pattern of population growth in a laboratory setting, consisting of lag, exponential, stationary, and death phases.

Generation time

The time required for a complete fission cycle, during which the population doubles.