Co-cultivation of a bacteriocin-producing mixed culture of Bifidobacterium thermophilum RBL67 and Pediococcus acidilactici UVA1 isolated from baby faeces
2009
Mathys, S. | Meile, L. | Lacroix, C.
We investigated the kinetics of growth, metabolism and antimicrobial activity of Bifidobacterium thermophilum RBL67 and Pediococcus acidilactici UVA1 previously isolated as a consortium from human baby faeces and producing antimicrobial proteinaceous compounds. Cell growth, antimicrobial activity, glucose consumption, organic acid production and pediocin-gene expression were monitored during pure and mixed strain batch cultures with controlled pH (6·0) at 37°C. The balance of the two strains in mixed cultures was stable, yielding high cell count of 10⁹ CFU ml⁻¹ after a very short incubation time of 4 h for UVA1 and 7 h for RBL67, and RBL67 was not affected by the high production of pediocin by UVA1 during co-culture (up to 12·8 μg ml⁻¹). Furthermore, a real-time PCR assay was developed and allowed gene-expression analysis of the pediocin-gene pedA. The co-culture of RBL67 and UVA1 showed high stability, cell yields and bacteriocin production during batch cultures and has potential for use as a probiotic mixture with antibacterial properties. In addition, a gene-expression real-time PCR assay was successfully developed, used for the relative quantification of the pediocin transcript pedA and demonstrated to be a valuable complementary tool to activity assay. This is the first study reporting of a stable mixed culture of two bacteriocin-producing strains of human origin.
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