[Also known as lactic-acid bacteria] - Lactobacilli (sing. lactobacillus) are anaerobic, Gram-positive microorganisms found in the gut or mucosa of mammals. They are primarily used in the manufacture of dairy products (cheese, yoghurt, kefir, etc.).
Abbr. of lethal dose (which see).
The LD value can be specified more precisely via an index number. LD 90 is the dose which eliminates on average 90% of an (e.g.) bacterial population.
The family of Legionella bacteria (scientific name Legionellaceae) contains more than 48 known species as well as numerous subgroups. They are water-dwelling Gram-negative aerobic bacteria that are potentially pathogenic for humans. Since they require still or recirculated water in the 25-50°C range for optimal growth, they are found primarily in air washers, cooling towers, dead pipes, water tanks and shower heads. Legionella are easily and effectively inactivated at even very low UVC doses.
Lethality describes the ratio of deaths to survivals after a dose of radiation, infection or illness - in other words, the mortality rate. It is therefore a measurement of hazard or risk.
Light is the colloquial name given to that portion of the electromagnetic spectrum lying in the 380-780 nm spectral range. This is the range that is visible to the naked human eye, with the limit values varying depending upon source. Consequently, the unfortunately common designation of ‘UV light’ is a contradiction in terms, and, strictly speaking, inaccurate.
[Abbr. for logarithm] - Although the term ‘log’ is the usual abbreviation for base-10 logarithms, the mathematically correct term here is lg.
We speak here of decadic logarithms.
In biology, bacterial reduction is indicated in log stages. A log reduction of X therefore means a reduction by X log stages starting from a given population. For example, the reduction by 1 log stage means a reduction of 90%, since only 10 have survived from the original population of 100 (= 10 x 10).
see also log reduction - In biology, each log stage describes the reduction of a population by a (further) power of ten: in other words, 1 log stage = 90%, 2 log stages = 99%, 3 log stages = 99.9%, etc.
The logarithm is an important mathematical function serving to illustrate significantly increasing series of numbers. The logarithm is the inverse operation of the power function ax = b, i.e. x = logb(a) (that is, logarithm of a to base b). This means that if a = 10x, then x = lg a.