Integrated multi-omics analysis to reveal roles of fungal and bacterial microbiota in regulating the taste compounds of sun-dried processing coffee in Baoshan of Yunnan province, China

• The sun-dried processing coffee was classified as specialty coffee (82.13 cupping score). • Agaricus, Micromonospora and Gilliamella promoted sucrose and phenylalanine catabolism of coffee beans. • Sucrose catabolites contributed to sensory properties of overall, balance and fragrance/aroma. • Phenylalanine catabolites contributed to sensory properties of overall, balance, fragrance/aroma and acidity. In this research, the roles of fungal and bacterial microbiota in the taste formation of traditional sun-dried processing coffee in Baoshan of Yunnan province, China were explored. Changes regarding sensory properties, qualities, flavor compounds and microbiota of coffee were analyzed. Results showed the cupping test score of coffee was 82.13. Contents of phenolics and flavonoids increased significantly (2.12 mg GAE/g FW and 100.15 mg Rutin/g FW, respectively) by the end of sun-dried processing. Analysis of microbiota gene sequencing showed relative abundances of Agaricus, Micromonospora and Gilliamella remarkably increased to 0.054 %, 0.015 % and 0.015 %, respectively. Besides, by the end of sun-dried processing, the relative abundances of sucrose and phenylalanine were reduced by 7.15 % and 21.53 %, respectively. Caffeic acid and ferulic acid increased by 25.77 % and 51.37 %, respectively, compared with fresh coffee beans. Further KEGG pathway enrichment analysis showed significantly changed metabolites were annotated in pathways of starch and sucrose metabolism, carbon metabolism and phenylpropanoid biosynthesis implying that metabolic transformations of sucrose and phenylalanine were promoted, which regulated accumulations of downstream catabolites (gluconic acid, citric acid, L-aspartic acid, caffeic acid, ferulic acid, chlorogenic acid and benzoic acid). Correlation analysis revealed that those catabolites contributed to the sensory properties of overall, balance, fragrance/aroma and acidity. Overall, the indigenous taste formation of sun-dried processing coffee was due to accumulations of Agaricus, Micromonospora and Gilliamella which regulated metabolic transformations of sucrose and phenylalanine to promote taste compound formations.