Microbiology terms - L
- lactic acid bacteria
- A group of gram-positive, non-sporing bacteria which carry out a lactic acid
fermentation of sugars. It includes species of Lactobacillus, Leuconostoc,
Pediococcus and Streptococcus.
- lactic acid fermentation
- A type of fermentation carried out by lactic acid bafcteria in which sugar
(e.g. lactose, glucose, pentose) are converted either entirely (or almost
entirely) to lactic acid (homolactic fermentation) or to a mixture of lactic acid
and other products (heterolactic fermentation).
- lag phase
- The period after inoculation of a population before growth begins.
- latent virus
- A virus present in a cell, yet not causing any detectable effect.
- leaching
- Removal of valuable metals form ores by microbial action.
- leukocidin
- A substance able to destroy phagocytes.
- leukocyte
- A white blood cell, usually a phagocyte.
- lichen
- A fungus and an alga (or a cyanobacterium) living in symbiotic association.
- lipid
- Water-insoluble organic molecules important in structure of the cytoplasmic
membrane and (in some organisms) the cell wall. See also phospholipid.
- lipopolysaccharide (LPS)
- Complex lipid structure containing unusual sugars and fatty acids found in
many gram-negative Bacteria, and constituting the chemical structure of the
outer layer.
- lithotroph
- In reference to energy source (electron donor) - An organism which uses an
inorganic substrate (such as ammonia, hydrogen) as an electron donor in
energy metabolism. There are two types of lithotrophs: chemolithotroph and
photolithotroph. Compare with autotroph, heterotroph, organotroph, and
phototroph.
- lophotrichous
- Having a tuft of polar flagella.
- lower respiratory tract
- Trachea, bronchi, and lungs.
- luminescence
- Production of light.
- Lyme disease
- A tick-borne disease which affects humans and other animals. Lyme disease
was named after a place called Lyme in Connecticut, USA, where this
disease was first recognized and has rapidly become the most prevalent
tick-borne disease in the United States. Lyme disease is caused by a
spirochete named Borellia burgdorferi which is carried in and transmitted
to human by the deer tick called Ixodes dammini although it can also be
spreat by other ticks such as the common dog (wood) ticks. The initial
symptoms of Lyme disease include an acute headache, backache, chills, and
fatigue and often a large rash at the biting site. Lyme disease can be easily
treated with the antibiotics such as tetracycline or penicillin. However
delayed or improper treatment may lead to the infection of the central
nervous sytem by the spirochete and result in visual disturbances, facial
paralysis or seizures.
- lymph
- A clear yellowish fluid found in the lymphatic vessels that carries various
white (but not red) blood cells.
- lymphocyte
- A white blood cell involved in antibody formation or cellular immune
responses.
- lymphokine
- Substance secreted from T lymphocytes which stimulates the activity of
other cells.
- lysin
- An antibody that induces lysis.
- lysis
- Repture of a cell, resulting in loss of cell contents.
- lysogen
- A prokaryote containing a prophage. See also temperate virus
- lysosome
- A cell organelle containing digestive enzymes.
Compiled by Tsute Chen, Converted by Ben Hoyt