Multi-omics analysis of the biofilm forming mechanism of Bifidobacterium longum

Abstract

Biofilm is considered to be a protective lifestyle formed by bacteria to adapt to the environment. To study the biofilm formation mechanism of Bifidobacterium longum, we used comparative genes to find their biofilm functional genes, then exogenously added signal molecules and inhibitors to verify related genes by using transcriptome and targeted metabolome. Finally, a time series transcriptome and metabolome were performed to completly analyze the biofilm formation pathways on wheat fiber. These results indicated B. longum mainly regulated biofilm formation through AI-2/QS, cAMP, and LuxC/LuxE TCS system by regulating Tad IV pilin and extracellular substances secretion. In the initial biofilm stage of B. longum, cAMP reduced cell motility through Tad IV pilin to promote biofilm state transition and enhanced cell repair through LuxC/LuxE TCS. With increasing cell numbers, AI-2/QS promoted biofilm growth by enhancing the transport of extracellular matrix by the Tat and Sec secretion systems. During the biofilm disperse stage, AI-2/QS enhanced the stress response to external stimuli. In addition, seventeen WGCNA modules were identified and two of them positively correlated with pH value, indicating biofilm formation associated with acid stress. These results can provide a theoretical basis for the formation mechanism of Bifidobacterium biofilm on food-grade particles.