THE EFFECT OF CHROMIC OXIDE (CR2O3) ON AEROBIC BACTERIAL-POPULATIONS ASSOCIATED WITH THE INTESTINAL EPITHELIAL MUCOSA OF ARCTIC CHARR, SALVELINUS-ALPINUS (L)
E. Ringo, THE EFFECT OF CHROMIC OXIDE (CR2O3) ON AEROBIC BACTERIAL-POPULATIONS ASSOCIATED WITH THE INTESTINAL EPITHELIAL MUCOSA OF ARCTIC CHARR, SALVELINUS-ALPINUS (L), Canadian journal of microbiology, 39(12), 1993, pp. 1169-1173
Populations of aerobic heterotrophic bacteria present in the gastroint
estinal tract of healthy Arctic charr, Salvelinus alpinus (L.), were e
stimated using the dilution plate technique. The gastrointestinal bact
erial flora of fish fed an unsupplemented diet was dominated by Gram-n
egative bacteria of the genera Acinetobacter, Aeromonas, Agrobacterium
, Alcaligenes, Cytophaga, Flavobacterium, Pseudomonas, and Vibrio, and
Gram-positive bacteria of the genera Arthrobacter, Brevibacterium, Co
rynebacterium, Kurthia, Lactobacillus, Microbacterium, Micrococcus, St
aphylococcus, and Streptococcus. The composition of the indigenous aer
obic bacterial flora in the digestive tract, and especially the microo
rganisms isolated from the midgut and hindgut regions, was affected by
inclusion of 1% chromic oxide (Cr2O3) in the diet. Many of the Gram-n
egative bacterial genera and some of the Gram-positive bacterial gener
a were not detectable in the Cr2O3-fed fish. The midgut and hindgut re
gions in the Cr2O3-fed fish were dominated by Gram-positive microorgan
isms of the genera Lactobacillus and Streptococcus. It is suggested th
at the increased accumulation of Cr2O3 in the alimentary tract, as die
tary compounds are removed, affects the attachment sites for the gastr
ointestinal microflora or affects the gut epithelium directly.