Isolation and probiotic characteristics of lactic acid bacteria from intestinal tract of giant panda in captivity

Abstract:

[Background] The giant pandas are rare, difficult to be bred, and susceptible to digestive system diseases during the growth process. [Objective] To reveal the community structure features and the roles of lactic acid bacteria (LAB) in the intestinal tract of the giant panda and screen out the LAB strains with probiotic characteristics for the prevention of digestive system diseases and the research on intestinal flora in the giant panda. [Methods] Three culture media were employed to isolate the LAB from the intestines of giant pandas in captivity. The isolates were preliminarily identified by Gram staining microscopy and hydrogen peroxide test. The representative strains were selected for 16S rRNA gene sequencing and Principal component analysis (PCA) based on the genetic diversity of BOXA1R-PCR spectrum, and the safety and probiotics of LAB were further analyzed. [Results] A total of 58 LAB strains were isolated, from which 20 representative strains were selected for 16S rRNA gene sequencing according to BOXA1R-PCR results. The 20 strains belonged to Streptococcus, Leuconostoc, Weissella, and Enterococcus, respectively. The principal component analysis showed that the community structure of LAB varied in the giant pandas at different ages. All the 20 strains showed negative results in hemolysis, and 17, 11, and 14 strains were susceptible to 11 antibiotics, tolerant to acidic conditions of pH 2.0, and tolerant to 0.3% bile salts, respectively. Strains SW-51, SW-48, MQ-41, SW-58, and MX-23 demonstrated strong inhibitory activities to 3 pathogenic bacterial species. Over 50% of the strains showed high auto-aggregation and co-aggregation capacities. Three strains showed consistent acid production and growth rate, among which Leuconostoc lactis MX-23 showed the best performance in growth and acid production. [Conclusion] The intestines of giant pandas harbor abundant LAB with valuable probiotic characteristics and application prospects, and the structure and composition of the LAB were influenced by age.