Mash must be enriched with secondary nutrients in addition to the sugar source for ethanol production. Secondary nutrients are necessary for cell maintenance and growth [82]. Yeast extract NH4C1, MgSO4, CaCl2 are a few of the ingredients which promote very rapid cell growth and ethanol production at laboratory scale [30, 31]. Ammonium ions provide nitrogen for protein and nucleic acid synthesis. Yeast extract contains all the necessary yeast growth factors viz., amino acid, purines, pyrimidines, vitamins, and minerals. Phosphorous, potassium (from yeast extract), magnesium, and calcium are incorporated into cell mass and are also cofactors activating several enzymes. The wide variation in media compositions used for different yeasts for alcohol production resulted in different yields.

Several organic and inorganic nitrogen sources in media for ethanol production by Z. mobilis were tested [176]. Urea and yeast extract were found to be better sources and calcium pantothenate was found to be an essential vitamin for ethanol production.