Modeling lipid accumulation in oleaginous fungi in chemostat cultures. II: Validation of the chemostat model using yeast culture data from literature

A model that predicts cell growth, lipid accumulation and substrate consumption of oleaginous fungi in chemostat cultures (Meeuwse et al. in Bioproc Biosyst Eng. doi:10.1007/s00449-011-0545-8, 2011) was validated using 12 published data sets for chemostat cultures of oleaginous yeasts and one published data set for a poly-hydroxyalkanoate accumulating bacterial species. The model could describe all data sets well with only minor modifications that do not affect the key assumptions, i.e. (1) oleaginous yeasts and fungi give the highest priority to C-source utilization for maintenance, second priority to growth and third priority to lipid accumulation, and (2) oleaginous yeasts and fungi have a growth rate independent maximum specific lipid production rate. The analysis of all data showed that the maximum specific lipid production rate is in most cases very close to the specific production rate of membrane and other functional lipids for cells growing at their maximum specific growth rate. The limiting factor suggested by Ykema et al. (in Biotechnol Bioeng 34:1268–1276, 1989), i.e. the maximum glucose uptake rate, did not give good predictions of the maximum lipid production rate

Self-organized monolayer films of stimulus-responsive micelles

Weakly charged micelles of poly(2-(dimethylamino)ethyl methacrylate) [10% quaternized]-block-poly(2-(diethylamino)ethyl methacrylate) (10qDMA-DEA) adsorb to form a highly ordered monolayer at the mica-solution interface at pH 8.9. Rinsing with solvent at pH 9 has little effect on the adsorbed layer. Reduction of the pH to 4 results in an irreversible swelling of the thin film, in contrast to a micelle-to-unimer transition seen for the diblock in bulk solution. The resilience of the adsorbed layer opens up potential nanotechnological applications