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.

太阳鸟以烟草树花蜜为食，其中含有有毒的尼古丁和花青素次生代谢产物。我们的目的是了解尼古丁和金刚烷胺对太阳鸟肠道菌群组成的影响。十六只圈养的太阳鸟被随机分配到两种饮食中：添加（治疗）或不添加（对照）尼古丁和金刚烷胺的人造花蜜。在治疗的0、2、4和7周收集粪便，并对样品进行细菌培养和16S rRNA基因的高通量扩增子测序。在七个星期的实验中，处理过的鸟类和对照鸟类的肠道微生物组多样性发生了不同的变化。尽管在前三次采样（0、2和4周）中对照组的多样性下降，但在治疗组中多样性却增加了。微生物群组成分析表明，与对照鸟相比，含尼古丁和鸟苷的饮食显着改变了鸟类肠道微生物群的组成。与对照组相比，经过处理的禽类排泄物中，尼古丁和鸟嘌呤降解细菌的丰度在第4周和第7周后显着升高。此外，可培养分离株的分析包括乳球菌显示，太阳鸟的肠道相关细菌能够降解尼古丁和金刚烷胺，这与其假设的排毒和营养共生作用相一致。