Abstract
Feeding habit determines the digestive tract structure and
intestinal microflora. However, the
relationship among feeding habit, digestive physiology intestinal, and
microbial diversity of omnivorous, herbivorous, filter-feeder and
carnivorous fish reared in the same pond has not been compared. This
study compared the digestive enzyme activities, intestinal morphology
and intestinal microflora of omnivorous (Carassius auratus ),
herbivorous (Ctenopharyngodon idellus ), carnivorous
(Siniperca chuatsi ) and filter-feeder (Shizothorax
grahami ) and predicted the potential functions of specific microflora
on different nutrients. Twelve intestine samples were collected from
each of the four fishes from Dianchi Lake. The composition and diversity
of microbial communities were determined by using high throughput
sequencing of 16S rDNA. The results showed that the filter-feeder fish
had significantly higher protease but lower amylase activities in the
intestine than herbivorous. The carnivorous fish intestine had more
microvilli branches and complex structures than other fish species in
the order carnivorous > herbivorous >
filter-feeder > omnivorous. The diversity of intestinal
microflora was higher in omnivorous and followed the order omnivorous
> herbivorous > filter-feeder >
carnivorous. Acinetobacter species and Bacteroides species
were the most dominant flora in carnivorous and herbivorous fish,
respectively. Acinetobacter johnsonii , Acinetobacter
lwoffii and Pseudomonas stutzeri might help the host to digest
protein, while Bacteroidetes species may help the host to digest
cellulose. Taken together, feeding habit
determines the digestive enzyme
activities, intestinal tissue morphology and differential colonization
of fish intestinal flora. The knowledge obtained is useful in designing
appropriate approaches for feed formulation and feeding practices in for
fish.
KEYWORDS feeding habit; intestinal microbiota; digestive
enzymes; 16S rDNA