Molecular response of bifidobacteria to a cholesterol rich environment

We investigated the capabilities of bifidobacteria to reduce the cholesterol level in the media, which clearly evidenced a high ratio of assimilation of this molecule by specific bifidobacterial strains including Bifidobacterium bifidum PRL2010. The transcriptomics of PRL2010 cells cultivated in the presence of cholesterol evidenced a significant higher expression of carriers as well as reductase encoding genes In order to investigate whether and how B. bifidum PRL2010 cells respond to cholesterol treatment, transcriptional profiling experiments were carried out. We first investigated the transcriptomes of PRL2010 cultures grown in only MRS representing the reference conditions. In addition, we investigated the transcriptomes of PRL2010 cells incubated with cholesterol in presence or absence of oxgall. Based on what previously described, the presence of oxgall in the culture medium mimics the intestinal environment. Two conditions were analysed, the former involving B. bifidum PRL2010 cells that were grown to an OD of 0.6, followed by the addition of cholesterol; the latter including 5% oxgall and 100µg/ml cholesterol and subsequent incubation for 180 minutes, after which RNA was harvested and labelled for microarray analysis. Every experiment was performed in duplicate.