3.4 | Depletion of the intestinal microbiota improves the intestine regeneration rate of Apostichopus japonicus
The differences in bacterial 16S rRNA abundances in samples from different groups were determined by qPCR assays targeting the bacterial 16S rRNA gene. The abundances of bacterial 16S rRNA genes were 2.47×107 and 2.44×107 copies per sea cucumber in CV animals in the 10 d and 14 d stages, respectively. The bacterial 16S rRNA gene abundances were 8.23×106 and 8.18×106 copies per sea cucumber in GF animals in the 2 stages, respectively (Figure 5). The number of bacterial 16S rRNA copies per sea cucumber decreased significantly in GF samples during intestine regeneration and was reduced by 66% compared to that in CV samples. Notably, the intestinal growth of GF sea cucumbers was faster than that of CV animals during intestine regeneration. The average intestine lengths of CV animals in the 10 d and 14 d stages were 4.48 and 4.88 cm, and the average intestine weights were 0.041 and 0.079 g, respectively. The average intestine lengths of GF animals in the 2 stages were 6.8 and 6.86 cm, and the average intestine weights were 0.064 and 0.114 g, respectively (Figure 6). The intestinal bacterial 16S rRNA gene abundance correlated with significant influences on the intestine weight and intestine length of A. japonicus during intestine regeneration (P < 0.05).