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Soybean meal alters autochthonous microbial populations, microvilli morphology and compromises intestinal enterocyte integrity of rainbow trout, Oncorhynchus mykiss (Walbaum)
Author(s) -
Merrifield D L,
Dimitroglou A,
Bradley G,
Baker R T M,
Davies S J
Publication year - 2009
Publication title -
journal of fish diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 85
eISSN - 1365-2761
pISSN - 0140-7775
DOI - 10.1111/j.1365-2761.2009.01052.x
Subject(s) - enterocyte , biology , rainbow trout , brush border , soybean meal , enteritis , microbiology and biotechnology , myxozoa , fish meal , ileum , zoology , small intestine , fish <actinopterygii> , biochemistry , fishery , ecology , raw material , vesicle , spore , membrane
Rainbow trout were fed either a diet containing fishmeal (FM) as the crude protein source or a diet containing 50% replacement with soybean meal (SBM) for 16 weeks. An enteritis‐like effect was observed in the SBM group; villi, enterocytes and microvilli were noticeably damaged compared with the FM group. The posterior intestine microvilli of SBM‐fed fish were significantly shorter and the anterior intestine microvilli significantly less dense than the FM‐fed fish. Electron microscopy confirmed the presence of autochthonous bacterial populations associated with microvilli of both fish groups. Reduced density of microvilli consequently led to increased exposure of enterocyte tight junctions, which combined with necrotic enterocytes is likely to diminish the protective barrier of the intestinal epithelium. No significant differences in total viable counts of culturable microbial populations were found between the groups in any of the intestinal regions. A total of 1500 isolates were tentatively placed into groups or genera, according to standard methods. Subsequent partial 16S rRNA sequencing revealed species that have not been identified from the rainbow trout intestine previously. Compared with the FM group levels of Psychrobacter spp. and yeast were considerably higher in the SBM group; a reduction of Aeromonas spp. was also observed.