New method for selection of hydrogen peroxide adapted bifidobacteria cells using continuous culture and immobilized cell technology

Abstract

BackgroundOxidative stress can severely compromise viability of bifidobacteria. Exposure of Bifidobacterium cells to oxygen causes accumulation of reactive oxygen species, mainly hydrogen peroxide, leading to cell death. In this study, we tested the suitability of continuous culture under increasing selective pressure combined with immobilized cell technology for the selection of hydrogen peroxide adapted Bifidobacterium cells. Cells of B. longum NCC2705 were immobilized in gellan-xanthan gum gel beads and used to continuously ferment MRS medium containing increasing concentration of H2O2 from 0 to 130 ppm.ResultsAt the beginning of the culture, high cell density of 1013 CFU per litre of reactor was tested. The continuous culture gradually adapted to increasing H2O2 concentrations. However, after increasing the H2O2 concentration to 130 ppm the OD of the culture decreased to 0. Full wash out was prevented by the immobilization of the cells in gel matrix. Hence after stopping the stress, it was possible to re-grow the cells that survived the highest lethal dose of H2O2 and to select two adapted colonies (HPR1 and HPR2) after plating of the culture effluent. In contrast to HPR1, HPR2 showed stable characteristics over at least 70 generations and exhibited also higher tolerance to O2 than non adapted wild type cells. Preliminary characterization of HPR2 was carried out by global genome expression profile analysis. Two genes coding for a protein with unknown function and possessing trans-membrane domains and an ABC-type transporter protein were overexpressed in HPR2 cells compared to wild type cells.ConclusionsOur study showed that continuous culture with cell immobilization is a valid approach for selecting cells adapted to hydrogen peroxide. Elucidation of H2O2 adaptation mechanisms in HPR2 could be helpful to develop oxygen resistant bifidobacteria.

Bifidobacterium asteroides PRL2011 Genome Analysis Reveals Clues for Colonization of the Insect Gut

“…Tolerance to H 2 O 2 exposure of PRL2011 strain was evaluated by cultivating cells in presence of hydrogen peroxide at a concentration of 0.002% or 0.004%, which were previously shown to be inhibitory for bifidobacteria [19] . Growth was monitored using a microplate reader (Biotek, Vermont, USA), which have been set as described above.…”

“…The toxic effects of oxygen on bifidobacterial growth and survival have been covered by several studies [18] , [19] . Bifidobacterial growth is reportedly inhibited by oxygen, and prolonged aeration of bifidobacterial cultures can lead to cell death and DNA degradation [20] .…”

Advanced Biotechnology of Specialized Fermented Milk Products

“…Continuous cultivation with cell immobilization is an effective approach to the selection of cells adapted to hydrogen peroxide. Elucidation of mechanisms of adaptation of probiotics to H 2 O 2 may be useful for the development of acid-resistant bifidobacteria [20,21].…”

RNA-Seq reveals transcriptomic interactions of Bacillus subtilis natto and Bifidobacterium animalis subsp. lactis in whole soybean solid-state co-fermentation

“…Bifidobacteria are obligate anaerobes. Oxidative stress can severely compromise viability of bifidobacteria (Mozzetti et al, 2010). Bacillus subtilis has also been used as probiotic (Cutting, 2011).…”