A metabolic engineering strategy for producing free fatty acids by the Yarrowia lipolytica yeast based on impairment of glycerol metabolism.

In recent years, bio-based production of free fatty acids from renewable resources has attracted attention for their potential as precursors for the production of biofuels and biochemicals. In this study, the oleaginous yeast Yarrowia lipolytica was engineered to produce free fatty acids by eliminating glycerol metabolism. Free fatty acid production was monitored under lipogenic conditions with glycerol as a limiting factor.

Metabolic evolution and (13) C flux analysis of a succinate dehydrogenase deficient strain of Yarrowia lipolytica.

Bio-based succinic acid production can redirect industrial chemistry processes from using limited hydrocarbons to renewable carbohydrates. A fermentation process that does not require pH-titrating agents will be advantageous to the industry. Previously, a Yarrowia lipolytica strain that was defective for succinate dehydrogenase was constructed and was found to accumulate up to 17.

Theoretical study of atomic structure and elastic properties of branched silicon nanowires.

The atomic structure and elastic properties of Y-shaped silicon nanowires of "fork"- and "bough"-types were theoretically studied, and effective Young moduli were calculated using Tersoff interatomic potential. The oscillation of fork Y-type branched nanowires with various branch lengths and diameters was studied. In the final stages of the bending, the formation of new bonds between different parts of the wires was observed.

The effect of sulfur re-addition on H(2) photoproduction by sulfur-deprived green algae.

Sulfur deprivation of algal cultures selectively and partially inactivates photosystem II (PSII)-catalyzed O(2) evolution, induces anaerobiosis and hydrogenase expression, and results in sustained H(2) photoproduction for several days. We show that re-addition of limiting amounts of sulfate (1-10 microM final concentration) to the cultures during the H(2)-production phase temporarily reactivates PSII photochemical and O(2)-evolution activity and re-establishes higher rates of electron transport through the photosynthetic electron transport chain. The reactivation of PSII occurs by de novo D1 protein synthesis, but does not result in the re-establishment of aerobic conditions in the reactor, detectable by dissolved-O(2) sensors.

Continuous hydrogen photoproduction by Chlamydomonas reinhardtii: using a novel two-stage, sulfate-limited chemostat system.

This study demonstrates, for the first time, that it is possible to couple sulfate-limited Chlamydomonas reinhardtii growth to continuous H2 photoproduction for more than 4000 h. A two-stage chemostat system physically separates photosynthetic growth from H2 production, and it incorporates two automated photobioreactors (PhBRs). In the first PhBR, the algal cultures are grown aerobically in chemostat mode under limited sulfate to obtain photosynthetically competent cells.