title: Ultrastructural study on the morphological changes in indigenous bacteria of mucous layer and chyme throughout the rat intestine.
abstract: Indigenous bacteria in the alimentary tract are exposed to various bactericidal peptides and digestive enzymes, but the viability status and morphological changes of indigenous bacteria are unclear. Therefore, the present study aimed to ultrastructurally clarify the degeneration and viability status of indigenous bacteria in the rat intestine. The majority of indigenous bacteria in the ileal mucous layer possessed intact cytoplasm, but the cytoplasm of a few bacteria contained vacuoles. The vacuoles were more frequently found in bacteria of ileal chyme than in those of ileal mucous layer and were found in a large majority of bacteria in both the mucous layer and chyme throughout the large intestine. In the dividing bacteria of the mucous layer and chyme throughout the intestine, the ratio of area occupied by vacuoles was almost always less than 10%. Lysis or detachment of the cell wall in the indigenous bacteria was more frequently found in the large intestine than in the ileum, whereas bacterial remnants, such as cell walls, were distributed almost evenly throughout the intestine. In an experimental control of long-time-cultured Staphylococcus epidermidis on agar, similar vacuoles were also found, but cell-wall degeneration was never observed. From these findings, indigenous bacteria in the mucous layer were ultrastructurally confirmed to be the source of indigenous bacteria in the chyme. Furthermore, the results suggested that indigenous bacteria were more severely degenerated toward the large intestine and were probably degraded in the intestine.
authors.affiliation: Laboratory of Histophysiology, Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo 657-8501, Japan.
authors.forename: Youhei
authors.initials: Y
authors.lastname: Mantani
authors.forename: Eri
authors.initials: E
authors.lastname: Ito
authors.forename: Miho
authors.initials: M
authors.lastname: Nishida
authors.forename: Hideto
authors.initials: H
authors.lastname: Yuasa
authors.forename: Natsumi
authors.initials: N
authors.lastname: Masuda
authors.forename: Wang-Mei
authors.initials: WM
authors.lastname: Qi
authors.forename: Junichi
authors.initials: J
authors.lastname: Kawano
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Yokoyama
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Hoshi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitagawa
mesh_terms: D000818:Animals; D002432:Cecum / Q000382:microbiology / Q000648:ultrastructure; D003106:Colon / Q000382:microbiology / Q000648:ultrastructure; D000069196:Gastrointestinal Microbiome; D007082:Ileum / Q000382:microbiology / Q000648:ultrastructure; D007413:Intestinal Mucosa / Q000382:microbiology* / Q000648:ultrastructure; D007422:Intestines / Q000382:microbiology* / Q000648:ultrastructure; D008297:Male; D046529:Microscopy, Electron, Transmission; D051381:Rats / Q000033:anatomy & histology / Q000382:microbiology*; D017208:Rats, Wistar