Shining a Light on Wastewater Treatment with Microalgae.

Microalgae can produce biofuels, nutriceuticals, pigments and many other products, but commercialization has been limited by the cost of growing, harvesting and processing algal biomass. Nutrients, chiefly nitrogen and phosphorus, are a key cost for growing microalgae, but these nutrients are present in abundance in municipal wastewater where they pose environmental problems if not removed. This is not a traditional review article; rather, it is a fact-based set of suggestions that will have to be investigated by scientists and engineers.

Enhancement of Microbial Biodesulfurization via Genetic Engineering and Adaptive Evolution.

In previous work from our laboratories a synthetic gene encoding a peptide ("Sulpeptide 1" or "S1") with a high proportion of methionine and cysteine residues had been designed to act as a sulfur sink and was inserted into the dsz (desulfurization) operon of Rhodococcus erythropolis IGTS8. In the work described here this construct (dszAS1BC) and the intact dsz operon (dszABC) cloned into vector pRESX under control of the (Rhodococcus) kstD promoter were transformed into the desulfurization-negative strain CW25 of Rhodococcus qingshengii. The resulting strains (CW25[pRESX-dszABC] and CW25[pRESX-dszAS1BC]) were subjected to adaptive selection by repeated passages at log phase (up to 100 times) in minimal medium with dibenzothiophene (DBT) as sole sulfur source.

Biodesulfurization: a model system for microbial physiology research.

Biological desulfurization (biodesulfurization) of dibenzothiophene (DBT) by the 4S pathway is a model system for an enviromentally benign way to lower the sulfur content of petroleum. Despite a large amount of effort the efficiency of the 4S pathway is still too low for a commercial oil biodesulfurization process, but the 4S pathway could potentially be used now for commercial processes to produce surfactants, antibiotics, polythioesters and other chemicals and for the detoxification of some chemical warfare agents. Proteins containing disulfide bonds are resistant to temperature, pH, and solvents, but the production of disulfide-rich proteins in microbial hosts is challenging.

Far-field optical nanothermometry using individual sub-50 nm upconverting nanoparticles.

We demonstrate far-field optical thermometry using individual NaYF4 nanoparticles doped with 2% Er(3+) and 20% Yb(3+). Isolated 20 × 20 × 40 nm(3) particles were identified using only far-field optical imaging, confirmed by subsequent scanning electron microscopy. The luminescence thermometry response for five such single particles was characterized for temperatures from 300 K to 400 K.