3.3 Classification of intestinal microbes at different dietary protein levels
The data presented in Figure 3 show that, at the phylum level, bacteria present in jejunum and cecum samples from Bamei pigs are mainly representatives of Firmicutes or Bacteroidetes. The relative abundance of members of phylum Firmicutes at the three protein levels in jejunum samples was 92.1%, while the average relative abundance in cecum samples was 73.88%. Relative abundance values for Bacteroidetes and Actinobacteria in jejunum samples from test group II were higher than those recovered from the other two groups. Similarly, relative abundances of Bacteroidetes in test group II cecum samples were also higher than those of the other two groups, although this difference is not significant. Selecting microbes at the phylum level for further differential analysis shows that members of four of the top ten were significantly present in jejunum samples. Representatives of phylum Firmicutes were present in significantly higher numbers in test group II compared to test group I (P = 0.02), while representatives of phylum Actinobacteria were present in significantly higher numbers in test group I compared to the control group (P = 0.011). Similarly, representatives of phylum Proteobacteria were present in significantly higher numbers in the control group than in test group II (P = 0.024), while representatives of phylum Euryarchaeota were present in significantly higher numbers in test group I than in either the control group or test group II (P = 0.001). Data for all other phyla reveal no significant differences while two from cecum sample did vary. Representatives of phylum Firmicutes were present in significantly higher numbers in test group II than in test group I (P = 0.034), while representatives of phylum Bacteroidetes were present in significantly higher numbers in test group I compared to test group II (P = 0.011). Data for other phyla show no significant differences. Comparing microbes at the phyla level in jejunum and cecum samples shows that representatives of phylum Firmicutes in former samples occurred at significantly higher levels than in the cecum (P = 0.032). Representatives of phylum Bacteroidetes in the cecum were also significantly more abundant than in the jejunum (P = 0.070), while data for other phyla show no clear differences (P> 0.05).
Bacteria in jejunum and cecum samples at the genus level given different dietary protein levels mainly include unidentified Clostridiales ,Terrisporobacter , and Turicibacter . Analysis of species differences shows that just the genus Pseudoscardovia in the jejunum varied significantly; samples from test group I contain this genus at significantly higher levels than the control group and test group II (P = 0.079). Data for other phyla did not vary significantly. Overall, three significant differences in pig cecum contents were seen; unidentified Clostridiales composition in test group II samples was significantly higher than test group I (P = 0.029) while genus Romboutsia contents in the control group was significantly higher than in test group I. Composition ofStreptococcus in the control group (P = 0.030) was also significantly higher than in test group I samples (P = 0.079). Comparing microbial differences at the genus level between jejunum and cecum samples, it is clear that representatives of unidentified_Clostridiales in the former occurred at significantly higher proportions than in the latter (P = 0.021). Differences between other phyla were not significant.