Bifidobacterium response to lactulose ingestion in the gut relies on a solute-binding protein-dependent ABC transporter

This study aims to understand the mechanistic basis underlying the response of Bifidobacterium to lactulose ingestion in guts of healthy Japanese subjects, with specific focus on a lactulose transporter. An in vitro assay using mutant strains of Bifidobacterium longum subsp. longum 105-A shows that a solute-binding protein with locus tag number BL105A_0502 (termed LT-SBP) is primarily involved in lactulose uptake. By quantifying faecal abundance of LT-SBP orthologues, which is defined by phylogenetic analysis, we find that subjects with 10(7) to 10(9) copies of the genes per gram of faeces before lactulose ingestion show a marked increase in Bifidobacterium after ingestion, suggesting the presence of thresholds between responders and non-responders to lactulose. These results help predict the prebiotics-responder and non-responder status and provide an insight into clinical interventions that test the efficacy of prebiotics. Yoshida et al. investigate the role of an ABC transporter (LT-SBP) in lactulose metabolism and its putative role in enriching the gut microbiota with bifidobacteria that encode this transporter. Their results might help in predicting prebiotics-responder and nonresponder status, helping the clinical interventions testing the efficacy of prebiotics.

Automated summary

This study investigated the response of Bifidobacterium to lactulose ingestion in healthy Japanese subjects, focusing on a lactulose transporter. The results showed a correlation between the abundance of specific genes and the increase in Bifidobacterium after lactulose ingestion, suggesting different thresholds for responders and non-responders to lactulose. These findings could help predict who will respond positively to prebiotics and guide clinical interventions testing the efficacy of prebiotics.