Intestinal microbial diversity and enzyme activities of crested ibis

Abstract:

[Background] The crested ibis (Nipponia nippon) is a national protected animal in China and one of the most endangered birds in the world. In this study, we analyzed the microbial diversity and extracellular enzyme activity in the gut of crested ibis, aiming to provide ideas for restoring the population of crested ibis. [Objective] To reveal the intestinal microbial diversity and extracellular enzyme activities of crested ibis.[Methods] The intestinal microorganisms of crested ibis were isolated by the pure culture method. The bacteria were identified by Gram-staining, physiological and biochemical tests, and 16S rRNA gene sequencing. The strains producing amylase, protease, cellulose, and lipase were screened out by the hydrolysis circle method. [Results] A total of 296 strains of bacteria were isolated from the fresh excreta of artificially breeding Crested Ibis, belonging to 11 genera of 2 phyla. The 236 isolates of Proteobacteria accounted for 79.73% of the total isolates, including 137 (46.28%) isolates of Escherichia, 39 (13.18%) isolates of Hafnia, 28 (9.46%) isolates of Proteus sp., 23 (7.77%) isolates of Citrobacter sp., 6 (2.03%) isolates of Aeromonas, 1 (0.34%) isolate of Enterobacter, 1 (0.34%) isolate of Shigella, and 1 (0.34%) isolate of Klebsiella. The rest isolates (60, 20.27%) belonged to Firmicutes, including 33 (11.15%) isolates of Enterococcus, 14 (4.73%) isolates of Kurthia, 13 (4.39%) isolates of Bacillus. The dominant genus was Escherichia of Proteobacteria, with the isolates accounting for 46.28% of the total. The physiological and biochemical properties of each strain were consistent with the result of identification based on 16S rRNA gene sequence. The enzyme production experiments showed that 238, 25, 24, and 15 strains produced protease, lipase, amylase, and cellulase, accounting for 80.41%, 8.45%, 8.11%, and 5.07%, respectively. [Conclusion] The bacteria isolated from the intestine of crested ibis belonged to 11 genera of 2 phyla, among which Escherichia of Proteobacteria was dominant with the isolates accounting for 46.28% of the total, and 80.41% of the strains had the ability of producing protease.