Background: Bifidobacterium longum subsp. longum, as a probiotic, has been annotated to be added to food. Our previous study found that Dictyophora indusiata polysaccharide (DIP) promoted the proliferation of B. longum and produced acetic acid. The aim of this work was to elucidate the pathway by which B. longum F2 utilizes DIP to produce acetic acid.
Results: The results showed that strain F2 is a rod-shaped Gram-positive bacterium, and whole genome sequencing indicated that strain F2 could be identified as B. longum, which has a genome length of 2 477 907 bp encoding 2158 genes. In addition, B. longum F2 survived in harsh environments. Notably, two fractions of DIP were utilized by B. longum F2 to produce 1.17-fold and 1.10-fold acetic acid, which is associated with the powerful carbohydrate metabolism genes. KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway annotation and quantitative polymerase chain reaction showed that the galE gene was significantly upregulated by 1.90-fold and 2.59-fold in two fractions of DIP.
Conclusion: The galE gene is a key gene in the production of acetic acid by B. longum F2 using DIP, which synthesizes acetic acid through the Leloir pathway. This finding provides new insights into the mechanism of acid production by probiotics using carbohydrates, and establishes a theoretical basis for the high-value application of edible fungi polysaccharides. © 2025 Society of Chemical Industry.
Keywords: Bifidobacterium longum subsp. longum; Dictyophora indusiata polysaccharide; acetic acid; galE.
© 2025 Society of Chemical Industry.