Effects of Phaffia rhodozyma on microbial community dynamics and tobacco quality during tobacco fermentation

Introduction: Carotenoids are important precursors of various aroma components in tobacco and play an important role in the sensory quality of tobacco. Phaffia rhodozyma is a species of Xanthophyllomyces capable of synthesizing a highly valuable carotenoid-astaxanthin, but has not yet been used in improving tobacco quality. Methods: The dynamic changes of microbial community and metabolites during tobacco fermentation were analyzed in combination with microbiome and metabolome, and the quality of tobacco after fermentation was evaluated by sensory scores. Results: P. rhodozyma could grow and produce carotenoids in tobacco extract, with a maximum biomass of 6.50 g/L and a maximum carotenoid production of 36.13 mg/L at 100 g/L tobacco extract. Meanwhile, the correlation analysis combined with microbiome and metabolomics showed that P. rhodozyma was significantly positively correlated with 11 metabolites such as 6-hydroxyluteolin and quercetin. Furthermore, the contents of alcohols, ketones and esters, which were important aromatic components in fermented tobacco, reached 77.57 mu g/g, 58.28 mu g/g and 73.51 mu g/g, increasing 37.39%, 265.39% and 266.27% compared to the control group, respectively. Therefore, the aroma and flavor, and taste scores of fermented tobacco increased by 0.5 and 1.0 points respectively. Discussion: This study confirmed that P. rhodozyma fermentation could effectively improve the sensory evaluation of tobacco, and provided a novel microbial fermentation method to improve tobacco quality.