Electron
microscopy of the intestinal microflora of fish
E. Ringų, R.E. Olsen, T.M. Mayhew, R. Myklebust
Aquaculture, 227(1-4): 395-415
Abstract:
The role, and even the existence, of stable
indigenous microbiota in fish was not accepted until the 1970s. In the last
decade, our understanding of adhesion and translocation of bacteria in the
fish gut has increased, and electron microscopy has contributed
significantly to this knowledge. This review summarises the information
available on gut-associated bacteria and on the translocation of bacteria in
fish gastrointestinal tract.
In several studies on various fresh- and saltwater
fish, bacteria in the intestinal lumen and epithelium-associated bacteria
have been demonstrated by using transmission electron microscopy and/or
scanning electron microscopy. Some of these studies have demonstrated
translocation of bacterial cells by endocytosis in the gastrointestinal
tract of larvae and adult fish as well as uptake of intact bacterial
antigens. Endocytosis of bacteria in the digestive tract is highly relevant
as the gastrointestinal tract is a potential port of entry for pathogens.
(Department of Arctic Veterinary Medicine, The
Norwegian School of Veterinary Science, NO-9292, Tromsų, Norway, e-mail: Einar.Ringo@veths.no)