Published by Australian Academy of Science
Glossary | When bugs have you on the run

antibiotic. A substance produced by bacteria or fungi that destroys or prevents the growth of other bacteria and fungi. Antibiotics are not effective against viruses.

bacteriocin. A small, naturally occurring protein produced by one species of bacterium that effectively protects it from competing organisms. Different bacteria produce different bacteriocins.

fermentation. The breakdown of organic molecules into simpler substances in the absence of oxygen. The process of fermentation can give rise to acids producing a lower pH.

gamma rays. The shortest wavelength of electromagnetic radiation. For more information see Gamma waves (NASA,USA).

pathogen. An organism capable of causing a disease.

pH. The pH scale is used to measure the strength of acids and bases (or alkalis). The acid strength in the human stomach is about pH 2. Alkalis such as caustic soda and basic household cleaners have a pH of about 12 to 14. Neutral is pH 7, (ie, neither acidic or alkaline). The scale is logarithmic, so pH 4 is ten times as acidic as pH 5 and pH 2 is ten times as acidic as pH 3, and so on. For more information see About soil pH (National Aeronautics and Space Administration, USA).