Co-cultivation of a bacteriocin-producing mixed culture of Bifidobacterium thermophilum RBL67 and Pediococcus acidilactici UVA1 isolated from baby faeces.
OBJECTIVE
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.


RESULTS
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 degrees C. The balance of the two strains in mixed cultures was stable, yielding high cell count of 10(9) 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 microg ml(-1)). Furthermore, a real-time PCR assay was developed and allowed gene-expression analysis of the pediocin-gene pedA.


CONCLUSIONS
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.


CONCLUSIONS
This is the first study reporting of a stable mixed culture of two bacteriocin-producing strains of human origin.
Mathys
S
S
Laboratory of Food Biotechnology, Institute of Food Science and Nutrition, ETH Zurich, Switzerland.
Meile
L
L
Lacroix
C
C
D019342:Acetic Acid / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000898:Antibiosis; D001430:Bacteriocins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D001644:Bifidobacterium / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D019149:Bioreactors; D018920:Coculture Techniques; D004269:DNA, Bacterial / Q000235:genetics; D005243:Feces / Q000382:microbiology*; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007223:Infant; D019344:Lactic Acid / Q000378:metabolism; D008087:Listeria / Q000187:drug effects; D010376:Pediococcus / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods; D012336:RNA, Ribosomal, 16S / Q000235:genetics
D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D019344:Lactic Acid; D005947:Glucose; D019342:Acetic Acid