Comparative analysis of intestinal flora between rare wild red-crowned crane and white-naped crane

Abstract

Introduction: Animal intestines are extremely rich in microbial ecosystems. Numerous studies in different fields, such as epidemiology and histology, have revealed that gut microorganisms considerably mediate the survival and reproduction of animals. However, gut microbiology studies of homogeneously distributed wild cranes are still rare. This study aimed to understand the structural composition of the gut microbial community of wild cranes and elucidate the potential roles of the microorganisms.

Methods: We used high-throughput sequencing to analyze the gut microbial community structure of wild cranes in the Zhalong Nature Reserve.

Results: A total of 1,965,683 valid tags and 5248 OTUs were obtained from 32 fecal samples. Twenty-six bacteria phyla and 523 genera were annotated from the intestinal tract of the red-crowned crane. Twenty-five bacteria phyla and 625 genera were annotated from the intestine of the white-naped crane. Firmicutes, Proteobacteria, and Bacteroidetes are the dominant bacterial phyla in the intestinal tract of red-crowned cranes, while Catellicoccus, Lactobacillus, Neisseria, and Streptococcus were the dominant genera. The dominant bacterial phyla in the intestinal tract of white-naped cranes were Firmicutes, Proteobacteria, Bacteroidetes, Epsilonbacteraeota, Actinobacteria, and Fusobacteria. However, the dominant genera were Catellicoccus, Lactobacillus, Neisseria, Campylobacter, Streptococcus, Anaerobiospirillum, Romboutsia, Turicibacter, Haemophilus, and Lautropia. Firmicutes had significantly higher relative abundance in the intestine of the red-crowned than white-naped cranes (P < 0.05). However, the relative abundance of Actinobacteria and Bacteroidetes was significantly higher (P < 0.05) in the intestines of white-naped than red-crowned cranes. The diversity of the intestinal flora between the two crane species was significantly different (P < 0.05). Besides, the alpha diversity of the intestinal flora was higher for white-naped than red-crowned cranes. Eight of the 41 functional pathways differed in the gut of both crane species (P < 0.05).

Discussion: Both species live in the same area and have similar feeding and behavioral characteristics. Therefore, host differences are possibly the main factors influencing the structural and functional differences in the composition of the gut microbial community. This study provides important reference data for constructing a crane gut microbial assessment system. The findings have implications for studying deeper relationships between crane gut microbes and genetics, nutrition, immunity, and disease.

Keywords: Zhalong Nature Reserve; high-throughput sequencing technology; intestinal microorganisms; red-crowned crane; white-naped crane.

FIGURE 1

Map of geographical location of the Zhalong China and sampling point.

FIGURE 2

(A) Relative abundance bar plot of the relative abundance of the strains. Relative abundance (%) of the two cranes Top10 phyla. Red-crowned crane, A1–A14; white-naped crane, B1–B18. (B) Annotated branching diagram of differential strains. Red nodes indicate species with relatively high abundance in the red group, green nodes indicate species with relatively high abundance in the green group, yellow nodes indicate species with no significant difference in the comparison between the two groups, the node diameter size is proportional to the relative abundance size, each layer of nodes indicates the phylum/class/order/family/genus from the inside out. (A) Red-crowned crane, (B) white-naped crane.

FIGURE 3

Alpha diversity index of microbial communities in violin map. (A) Representative chao1 Index, (B) representative observed species, (C) representative Shannon Index, (D) representative Simpson index. *Correlation significant at 0.05 level. **Correlation significant at 0.01 level.

FIGURE 4

PCoA analysis graph of the colony. The same color in the graph is the same grouping. PC1 and PC2 are the first and second principal coordinates with the greatest explanation of the difference between samples.

FIGURE 5

Heat map of differential functional clustering. Horizontal is the sample number; vertical is the functional annotation information; the clustering tree on the left side of the figure is the functional clustering tree; the upper clustering branches represent samples from different subgroups. The red color indicates a higher relative abundance of species, the blue color indicates a lower relative abundance of species. A, Red-crowned crane; B, white-naped crane.