Effect of Chitosan on Intestinal Bacteria of Allogynogenetic Crucian Carp, Carassius auratus gibelio, as Depicted by polymerase chain reaction-denaturing Gradient Gel Electrophoresis

Abstract

A 16S rDNA-based polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method was applied to detect intestinal bacterial communities of juvenile allogynogenetic crucian carp, Carassius auratus gibelio, fed with chitosan-containing diet. This is the first time to use the molecular method to analyze the bacterial communities in the allogynogenetic crucian carp intestine. The DGGE profile with universal bacterial primers revealed simple communities in all treatment groups. Sequencing and phylogenetic analysis of excised DGGE bands showed that the dominant bacteria belonged to class gamma-Proteobacteria and Fusobacteria. The relative abundance and diversity of detected bacteria suggested that 0.5 and 0.75% of chitosan in diet were optimum for juvenile allogynogenetic crucian carp. As in these concentrations, some detected pathogen bacteria either disappeared or decreased. However, the DGGE profile with Aeromonas-specific primers showed a similar composition among all treatment groups, which suggested that Aeromonas was one of relative stable bacteria components in the intestine of juvenile allogynogenetic crucian carp.