sThe single yeast extract concentration curve corresponds to both types since they have the same dry weight.
Yeast extracts considerably increase biomass (two times and three times, respectively, with powdered yeast extract and liquid yeast extract). Liquid yeast extract is more efficient than the powder at the same dry weight. Supplementation of the medium with liquid yeast extract and powdered yeast extract increased the lactic acid production from about 9 to 19 g l21 and 13.5 g l21, respectively (data not shown).