Microbial Growth I - Vocabulary Flashcards

Key vocabulary terms and definitions from the Microbial Growth I notes, covering history, culturing basics, environmental factors, and microbial physiology.

Antonie van Leeuwenhoek

Father of Microbiology; used a self-made microscope to observe ‘little animalcules’ and described protists, sperm cells, and bacteria.

Yersinia pestis

Bacterium that caused the Black Death; responsible for massive mortality in 14th-century Europe.

Robert Koch

German physician who proved bacteria cause disease and formulated Koch’s postulates; developed early growth media.

Bacillus anthracis

Bacterium isolated from dead animals; causes anthrax and used by Koch to demonstrate infection leads to disease.

Mycobacterium tuberculosis

Bacterium isolated by Koch; causative agent of tuberculosis.

Koch’s Postulates

Four criteria linking a microbe to a disease: presence in diseased hosts, isolation in pure culture, reproduction of disease in a healthy host, and re-isolation from the diseased host.

Petri dish

Shallow circular plate used to culture microbes; named after Richard Petri.

Agar

Solidifying agent for growth media derived from algae; higher melting point than gelatin; microbes cannot digest it.

Fannie Hesse

Developed the use of agar from algae to solidify culture media.

Helicobacter pylori

Bacterium that causes peptic ulcers; its role was proven by Marshall and Warren, earning a Nobel Prize.

Barry Marshall

Australian physician who proved H. pylori causes peptic ulcers through self-experimentation in support of Koch’s postulates.

Peptic ulcer

Ulcer in the stomach or duodenum associated with H. pylori infection.

Osmotic pressure

Solute concentration effects on water movement; influences microbial growth; organisms can be osmophiles or osmotolerant.

Osmophiles

Organisms that require high osmotic pressure for growth.

Osmotolerant

Organisms that can grow across a wide range of salt or sugar concentrations.

Water activity (Aw)

Amount of water available to cells; growth requires Aw around 0.9–1.0; fungi tolerate lower Aw than bacteria.

Isotonic solution

Solution with the same solute concentration inside and outside the cell; cells maintain shape.

Hypotonic solution

Lower external solute concentration; water enters cell, may cause swelling or lysis.

Hypertonic solution

Higher external solute concentration; water exits cell, causing plasmolysis.

Halophiles

Organisms that require high salt (NaCl) for growth; often adapted via membrane/cell wall changes.

Haloarchaea

Archaea adapted to extremely saline environments; many inhabit hypersaline waters and can appear red due to carotenoids.

Halobacterium

Example of haloarchaea; thrives in very high-salt environments such as the Dead Sea.

Psychrophiles

Organisms with optimum growth around 15°C; can grow at 0–20°C; often from polar regions; membranes remain fluid at low temperatures.

Psychrotrophs

Organisms that prefer 20–30°C but can grow at 0–30°C; common in refrigerated food spoilage.

Mesophiles

Organisms with optimum growth 20–45°C; include most human pathogens.

Thermophiles

Organisms with optimum growth 55–65°C; can survive 45–100°C; found in compost, hot springs, and deep-sea vents.

Hyperthermophiles

Organisms with optimum growth 80–115°C; mostly archaea; highly heat-tolerant enzymes.

Acidophiles

Organisms that prefer acidic environments (pH roughly 1.0–5.5).

Neutrophiles

Organisms that prefer near-neutral pH (approximately pH 5.5–8.0).

Alkalophiles

Organisms that prefer alkaline environments (pH roughly 8.5–11.5).

Obligate anaerobes

Organisms that cannot tolerate oxygen and must be grown in anaerobic environments.

Coliform bacteria

Group of bacteria (e.g., E. coli) used as indicators of fecal contamination in water.

Desulfovibrio

An anaerobic bacterium that reduces sulfates and grows without oxygen.

Clostridium

Genus of obligate anaerobic bacteria important in medical and environmental contexts.

Methanococcus

Methanogenic archaea; anaerobes that produce methane.

Macro-nutrients

Major nutrients required in larger amounts (e.g., carbon, nitrogen, phosphorus, potassium, calcium, magnesium, iron).

Micro-nutrients (trace elements)

Nutrients needed in trace amounts (e.g., zinc, manganese, nickel) essential for enzyme function.

Chemoautotroph

Energy derived from inorganic molecules; carbon fixed from CO2.

Photoautotroph

Energy derived from light; carbon fixed from CO2.

Chemoheterotroph

Energy and carbon derived from organic molecules.

Photoheterotroph

Energy derived from light; carbon derived from organic molecules.

Anabolism

Biosynthesis; the build-up of complex molecules from simpler ones.

Catabolism

Breakdown of molecules to release energy for cellular activities.

Oxygen as final electron acceptor

In aerobic respiration, oxygen acts as the final electron acceptor in the electron transport chain.