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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/06/01 16:26:40」(JST)

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Gnotobiosis (from Greek roots gnostos 'known' and bios 'life') is a condition in which all the forms of life present within an organism can be accounted for. Typically gnotobiotic organisms are germfree or gnotophoric (having only one contaminant).

Gnotobiotic animals

A gnotobiotic animal is an animal in which only certain known strains of bacteria and other microorganisms are present. Technically, the term also includes germ-free animals, as the status of their microbial communities is also known.^[1] However, the term gnotobiotic is often incorrectly contrasted with germ-free.

Gnotobiotic animals (also 'gnotobiotes' or 'gnotobionts') are born in aseptic conditions, which may include removal from the mother by Caesarean section and immediate transfer of the newborn to an isolator where all incoming air, food and water is sterilized.^[2] Such animals are normally reared in a sterile or microbially-controlled laboratory environment, and they are only exposed to those microorganisms that the researchers wish to have present in the animal. These gnotobiotes are used to study the symbiotic relationships between an animal and one or more of the microorganisms that may inhabit its body. This technique is important for microbiologists because it allows them to study only a select few symbiotic interactions at a time (see Scientific control), whereas animals that develop under normal conditions may quickly acquire a microbiota that includes hundreds or thousands of unique organisms.

Animals reared in a gnotobiotic colony often have poorly developed immune systems, lower cardiac output, thin intestinal walls and high susceptibility to infectious pathogens.^[2]

Such animals may also be used in animal production, especially in the rearing of pigs. After the Caesarean birth, these animals are introduced to their natural microflora in a stepwise fashion. This avoids undesired infections and leads to faster growth.

References

^ Reyniers JA (1959). "Germfree Vertebrates: Present Status". Annals of the New York Academy of Sciences 78 (1): 3. doi:10.1111/j.1749-6632.1959.tb53091.x.
^ ^a ^b Foster, John W.; Slonczewski, Joan L. (2009). Microbiology, An Evolving Science. W. W. Norton. p. 871. ISBN 978-0-393-93447-2.

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English Journal

Intestinal bacterial hydrolysis is required for the appearance of compound K in rat plasma after oral administration of ginsenoside Rb1 from Panax ginseng.

Akao T, Kida H, Kanaoka M, Hattori M, Kobashi K.SourceFaculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Japan.
The Journal of pharmacy and pharmacology.J Pharm Pharmacol.1998 Oct;50(10):1155-60.
Ginsenoside Rb1 from Panax ginseng root is transformed into compound K via ginsenosides Rd and F2 by intestinal bacterial flora. Among 31 defined intestinal strains from man, only Eubacterium sp. A-44 transformed ginsenoside Rb1 into compound K via ginsenoside Rd. The ginsenoside Rb1-hydrolysing enz
PMID 9821663

Metabolism and pharmacokinetics of orally administered saikosaponin b1 in conventional, germ-free and Eubacterium sp. A-44-infected gnotobiote rats.

Kida H, Akao T, Meselhy MR, Hattori M.SourceDepartment of Cell-Resources Engineering, Research Institute for Wakan-Yaku (Traditional Sino-Japanese Medicines), Toyama, Japan.
Biological & pharmaceutical bulletin.Biol Pharm Bull.1998 Jun;21(6):588-93.
The metabolic fate of saikosaponin b1 (1) was investigated using conventional, germ-free and Eubacterium sp. A-44-infected gnotobiote rats. After the oral administration of 1 to germ-free rats at a dose of 50 mg/kg, no metabolite was detected in the plasma, the cecal contents or the cumulative feces
PMID 9657043

A purgative action of barbaloin is induced by Eubacterium sp. strain BAR, a human intestinal anaerobe, capable of transforming barbaloin to aloe-emodin anthrone.

Akao T, Che QM, Kobashi K, Hattori M, Namba T.SourceFaculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Japan.
Biological & pharmaceutical bulletin.Biol Pharm Bull.1996 Jan;19(1):136-8.
Orally administered barbaloin (100 mg/kg) did not induce any diarrhea in male Wistar rats, in spite of severe diarrhea with sennoside B (40 mg/kg). Also, in gnotobiote rats mono-associated with Peptostreptococcus intermedius, a human intestinal anaerobe capable of reducing sennidins to rhein anthron
PMID 8820926