Free nucleotides as important growth factors for L. bulgaricus

Nucleotides are the building blocks to make DNA and RNA, and are therefor needed for cell growth. For many lactic acid bacteria and Bifidobacteria nucleotides are important growth factors, and needed for fast growth as required for industrial production. One strain that clearly benefits from the addition of free nucleotides to its growth medium is the widely used starter culture L. bulgaricus.

This study shows the effects that nucleotide presence in culture media can have on not only L. bulgaricus growth, but also its activity. The pattern of use of nucleotides and associated compounds in different media is shown via offline measurements. In addition, the study explores the influence of different peptide sources to complement the action of nucleotides.

Main observations

  • Yeast-derived nucleotides as supplied by X-SEED® Nucleo Max has a clear positive impact on L. bulgaricus growth and activity.
  • In combination with X-SEED® Nucleo Max, lower amounts of yeast peptone showed the same level of performance compared to the use of casein, proving it to be a more cost-effective alternative.
  • High CFU counts do not always translate into high cell capacity for milk acidification. Therefore, the activity of the culture should be checked in addition to cell counts.

Growth of L. bulgaricus in complex media with (diamonds, triangles) or without (squares) free nucleotides. On the right, measurements show the change in purine and pyrimidine after 0hr (white bars) and 6 hr (black bars) of fermentation in one of the media containing free nucleotides.

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