Wine lactic acid bacteria (LAB, Wine Bacteria) and specifically O. oeni strains are known to have complex nutritional needs for carbon including fructose, glucose, malic acid, citric acid, vitamins, minerals and nitrogen. A deficiency can have a major impact on malolactic fermentation (MLF). A few hundred mg of hexoses per litre are enough to ensure growth of O. oeni, but due to their numerous amino acids auxotrophies (inability to synthesize a particular compound required for its growth) the presence of organic nitrogen is essential. It is important to understand the nitrogen requirements of wine bacteria to ensure a successful MLF, especially under difficult and limiting wine conditions.

NITROGEN – AMINO ACIDS AND PEPTIDES

Free amino acids, and those from the hydrolysis of peptides, are the main sources of the nitrogen used by wine bacteria. Wine bacteria don’t have the ability to synthesize amino acids like yeast, thus the amino acids must be provided by the must or wine or be obtained by the metabolism of wine LAB from organic sources like peptides. They can also be supplied by specific MLF activators formulations based on an organic nitrogen source. A comparison with wine yeast and the relevant quantitative criteria for Yeast Assimilable Nitrogen (YAN) to ensure a good development of the alcoholic fermentation is not possible for wine bacteria because their nitrogen needs are entirely different from those of wine yeasts.

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