Species composition analysis at different classification levels in fecal samples
The chloroplast rbcL gene was used to sequence the plant-based composition of mandarin ducks. At the order level, there were only three orders in group A had relative abundance of more than 1% in the top 15 orders, which mainly composed Poales (75.75%), Fagales (15.56%) and Fabales (3.69%). However, In group B, there were 9 orders had the relative abundance of more than 1% in the top 15 orders, which composed of Poales (64.68%), Caryophyllales (7.71%), Saxifragales (7.39%), Lamiales (3.75%), Fagales (3.18%), Rosales (2.58%), Asparagules (2.37%), Cucurbitales (2.35%) and Brassicales (1.73%) (Fig. 2a)(Table S1). The taxonomic composition for each group was then successfully outlined at the phylum, class, order, family, and genus level (Table S1). The mitochondria COI gene was used to sequence the animal-based composition of mandarin ducks. At the order level, there were 8 orders in group A that had relative abundance of more than 1% in the top 15 orders, which mainly composed of Coleoptera (42.0%), Anura(20.0%), Ploima(11.0%), Cypriniformes(9.0%), Sarcoptiformes(5.0%), Decapoda(1.0%), Rotaria(1.0%) and Diptera(1.0%). However, The group B had 4 more orders than group A, which composed Decapoda(19.0%), Diplostraca(19.0%), Anura(18.0%), Coleoptera(7.0%), Rotaria(4.0%)、Diptera (3.0%), Lepidoptera(3.0%), Mesostigmata(2.0%), Primates(2.0%), Philodinida(2.0%), Scleractinia(2.0%) and Zoantharia (2.0%) (Fig. 2b). The taxonomic composition for each group was then successfully outlined at the phylum, class, order, family, and genus level (Table S2).
Sequencing v3-v4 region of 16S rRNA, at the level of phylum, there were only 3 phylums in group A, that had relative abundance of more than 1% in the top 15 phylums, which mainly composed Firmicutes (58.04%), Proteobacteria (40.58%) and Actinobacteria (0.55%). However, In group B, there were 6 phylums had the relative abundance of more than 1% in the top 15 orders, which composed of Firmicutes (59.00%), Proteobacteria (23.15%) and Actinobacteria (10.55%), Cyanobacteria (2.54%), Chloroflexi (0.63%) and Verrucomicrobia (0.53%) (Fig. 2c). At the order level, there were 5 orders that were Bacillus (38.76%), Enterobacteriales (28.42%), Clostridiales (15.23%), Pseudomonasdales (10.64%) and Lactobacillus (2.93%), which had relative abundance of more than 1% in the top 15 orders. It had 4 orders less than the group B, which composed Bacillus (51.05%), Actinomyceteles (9.15%), Pseudomonadales (8.04%), Clostridiales (7.02%), Sphingomonadales (5.38%), Rhizobiales (3.05%), Streptophyta (1.88%), Enterobacteriales (1.77%) and Burkholderiales (1.43%) (Fig. 2d).
At the top 15 genera level of relative abundance of intestinal microbiota of mandarin ducks (Fig. 3), group A was mainly composed 10 genera that were Pseudomonadaceae Pseudomonas(10.4%), Cronobacter(9.2%), Bacillaceae Bacillus(9.1%), Exiguobacterium(3.4%), Planococcaceae Bacillus(2.8%), Clostridiaceae Clostridium (2.8%), Solibacillus (1.9%), Sporosarcina (1.2%), Ruminococcus (1.1%) and Lactococcus (1.1%). In group B, Exiguobacterium (24.6%), Sporosarcina (7.4%), Arthrobacter (6.1%), Pseudomonadaceae Pseudomonas (5.9%), Sphingomonas(5.0%), Bacillaceae Bacillus(4.0%), Paenisporosarcina(2.8%), Planococcaceae Bacillus(2.4%), Acinetobacter(1.6%), Clostridiaceae Clostridium (1.4%) and Solibacillus (1.1%) were the main components.
Prediction of intestinal microbiota function in Mandarin Ducks
Using PICRUSt as a function prediction tool, the functions of bacteria in the whole intestine of mandarin ducks were predicted, including cellular processes, environmental information processing and genetic information processing. In this paper, we have studied the mechanism of metabolism, metabolism, biosynthesis, degradation, utilization and assembly, generation of precursor metabolite and energy, and so on. Among them, the relative abundance of classification function of biosynthesis and metabolism was the highest.
In the Biosynthesis functional groups, the secondary level classification function of intestinal bacteria in two groups of mandarin ducks mainly includes: Cofactor, Prosthetic Group, Electron Carrier, and Vitamin Biosynthesis (A: 36871.36, B: 36989.26), Amino Acid Biosynthesis (A: 34333.08, B: 33687.49), Nucleoside and Nucleotide Biosynthesis (A: 30747.56, B: 32945.66), Fatty Acid and Lipid Biosynthesis (A: 19776.19, B: 18799.73), Carbohydrate Biosynthesis (A: 8708.59, B: 9207.04), in which the abundance of Cofactor, Prosthetic Group, Electron Carrier, and Vitamin Biosynthesis, Nucleoside and Nucleotide Biosynthesis, Carbohydrate Biosynthesis in group B was higher than that in group A (Fig. 5a). In the Metabolism function groups, the secondary level classification function of intestinal bacteria in two groups of mandarin ducks mainly includes: Carbohydrate Metabolism (A: 4739.79, B: 5082.460, Amino Acid Metabolism (A: 4373.49, B: 4989.34), Metabolism of Cofactors and Vitamins (A: 4152.87, B: 4502.65), Lipid Metabolism (A: 2353.63, B: 2925.93), Metabolism of Terpenoids and Polyketides (A: 2405.62, B: 2741.96), Xenobiotics Biodegradation and Metabolism (A: 1855.68, B: 2462.6), and the abundances of the above six secondary level metabolic functions in group B were significantly higher than those in group A (Fig. 5b). Indicating that the intestinal flora function of mandarin duck in group B was mainly involved in the host intestinal metabolic activities.