Effects of SBL-1 on Jejunal Microbiota in Total Body 60 Cobalt Gamma-Irradiated Mice - A Metagenomic Study with Implications towards Radioprotective Drug Development

In earlier study, single dose of a standardized leaf extract of Hippophae rhamnoides (code SBL-1), @ 30 mg/kg body weight (b.w.) 30 min before whole body 60 Co-gamma-irradiation (10 Gy), rendered >90% survivors in comparison to zero survivor in non-SBL-1 treated 60 Co-gamma-irradiated (10 Gy) mice population. Present study investigated the modifying effects of SBL-1 on jejunal microbiota. 9 weeks old Swiss albino Strain‘A’ male mice were segregated as Untreated Control; 60 Co-gamma-irradiated (10 Gy); Drug alone (30 mg/kg b.w. SBL-1) and Drug + Radiation (30 mg/kg b.w. SBL-1, 30 min before 10 Gy). 16S rRNA gene amplicons, prepared using universal primers were sequenced on ABI3130, Genetic Analyzer. After removing vector contamination and chimeras, the sequences [GenBank Acc.No. KF681283 to KF681351] were taxonomically classified by using Sequence Match program, Ribosomal Database Project and by nucleotide-BLAST [E-value: 10, database: 16S rRNA gene sequences, Bacteria and Archea]. Phylogenetic Tree was prepared by MEGA, using maximum likelihood algorithm after sequence alignment by MUSCLE. Branch stability was assessed by bootstrap analysis. Rooted tree had Thermus aquaticus as out-group. Untreated Control and Drug alone groups had 100% Lactobacillus; Drug + Radiation had 89% Lactobacillus and 11% Clostridium; 60 Co-gamma-irradiated group had 55% Cohaesibacter (Alphaproteobacteria); 27% Mycoplasma (Tenericutes) and only 18% Lactobacillus. The radioprotective SBL1 countered the radiation caused microbiota dysbiosis.