Sunbirds feed on tobacco tree nectar which contains toxic nicotine and anabasine secondary metabolites. Our aim was to understand the effect of nicotine and anabasine on the gut microbiota composition of sunbirds. Sixteen captive sunbirds were randomly assigned to two diets: artificial nectar either with (treatment) or without (control) added nicotine and anabasine. Excreta were collected at 0, 2, 4 and 7 weeks of treatment and samples were processed for bacterial culture and high-throughput amplicon sequencing of the 16S rRNA gene. The gut microbiome diversity of the treated and control birds changed differently along the seven-week experiment. While the diversity decreased in the control group along the first three samplings (0, 2 and 4 weeks), it increased in the treatment group. The microbiota composition analyses demonstrated that a diet with nicotine and anabasine, significantly changed the birds’ gut microbiota composition compared to the control birds. The abundance of nicotine- and anabasine- degrading bacteria in the excreta of the treated birds, was significantly higher after four and seven weeks compared to the control group. Furthermore, analysis of culturable isolates, including Lactococcus, showed that sunbirds’ gut-associated bacteria were capable of degrading nicotine and anabasine, consistent with their hypothesised role as detoxifying and nutritional symbionts.
Bibliographical noteFunding Information:
The authors would like to thank Dr. Sivan Laviad-Shitrit and Rotem Sela for their valuable help and suggestions. Our special thanks also go to Vered Maiman for taking care of and feeding the sunbirds. This work was supported by a grant from the Israel Science Foundation (ISF grant no. 296/16). The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the paper.
© 2020, The Author(s).
ASJC Scopus subject areas
- Applied Microbiology and Biotechnology