Utilization of beet molasses for sterol production by some moulds.

Different moulds were cultivated in beet molasses (BM)-containing medium. Penicillium crustosum Thom was superior to the other moulds in total sterols production (4% on dry weight basis), efficiency of convertibility of the BM sugars to sterols (2%), total lipids (19.4%) and unsaponified lipids (13.4%). The treatment of BM with H2SO4- followed by centrifugation allowed maximum fermentation yields. The highest unsaponified lipids (16.5%) and total sterols level (7.4%) were obtained with a medium composed of (g/1): NaNO3, 3; K2HPO4, 3; MgSO4.7H2O, 1.5; K2SO4, 0.11; ZnSO4.7H2O, 0.05; FeCl3.6H2O, 0.16; H2SO4-treated BM, 60. Maximal sterol yields (8.4%) and high growth rate were achieved at the accelerated growth phase (8 days old cultures), when the initial pH value of the medium was adjusted to 7.0.