Characterization of newly isolated oleaginous yeasts - Cryptococcus podzolicus, Trichosporon porosum and pichia segobiensis

The yeast strains Cryptococcus podzolicus, Trichosporon porosum and Pichia segobiensis were isolated from soil samples and identified as oleaginous yeast strains beneficial for the establishment of microbial production processes for sustainable lipid production suitable for several industrial applications. When cultured in bioreactors with glucose as the sole carbon source C. podzolicus yielded 31.8% lipid per dry biomass at 20°C, while T. porosum yielded 34.1% at 25°C and P. segobiensis 24.6% at 25°C. These amounts correspond to lipid concentrations of 17.97 g/L, 17.02 g/L and 12.7 g/L and volumetric productivities of 0.09 g/Lh, 0.1 g/Lh and 0.07 g/Lh, respectively. During the culture of C. podzolicus 30 g/l gluconic acid was detected as by-product in the culture broth and 12 g/L gluconic acid in T. porosum culture. The production of gluconic acid was eliminated for both strains when glucose was substituted by xylose as the carbon source. Using xylose lipid yields were 11.1 g/L and 13.9 g/L, corresponding to 26.8% and 33.4% lipid per dry biomass and a volumetric productivity of 0.07 g/Lh and 0.09 g/Lh, for C. podzolicus and T. porosum respectively. The fatty acid profile analysis showed that oleic acid was the main component (39.6 to 59.4%) in all three strains and could be applicable for biodiesel production. Palmitic acid (18.4 to 21.1%) and linolenic acid (7.5 to 18.7%) are valuable for cosmetic applications. P. segobiensis had a considerable amount of palmitoleic acid (16% content) and may be suitable for medical applications

Synthesis of buried silicon oxide layers by water plasma immersion implantation

Buried silicon oxide layers were produced by water plasma immersion oxygen ion implantation and investigated by transmission electron microscopy, optical emission spectrometry, elastic recoil-detection analysis and Rutherford backscattering. Especially H2O+-ions, but also HO+-, O2+- and O+-ions, were implanted into silicon by pulse biasing the silicon wafer to a voltage between −40 and −50 kV. The pulse duration was 15 μs, the repetition rate was 200 Hz and the pulse number was varied between 0.92 × 105 and 29.5 × 105 pulses. The temperature during implantation was between 420°C and 800°C. The subsequent annealing process at 1250°C for 5 h leads to buried silicon oxide layers with smooth interfaces. The shape of the oxygen concentration profiles is caused by superposition of the low-energy O+-ion and the high-energy H2O+- and HO+-ion profiles. The thickness of the damaged regions and the hydrogen contents decrease with increasing temperature. The application of water plasma has the advantage that the ion range is about twice the given ion energy because ionized oxygen atoms are implanted

A quantitative targeted proteomics approach to validate predicted microRNA targets in C. elegans

Efficient experimental strategies are needed to validate computationally predicted microRNA (miRNA) target genes. Here we present a large-scale targeted proteomics approach to validate predicted miRNA targets in Caenorhabditis elegans. Using selected reaction monitoring (SRM), we quantified 161 proteins of interest in extracts from wild-type and let-7 mutant worms. We demonstrate by independent experimental downstream analyses such as genetic interaction, as well as polysomal profiling and luciferase assays, that validation by targeted proteomics substantially enriched for biologically relevant let-7 interactors. For example, we found that the zinc finger protein ZTF-7 was a bona fide let-7 miRNA target. We also validated predicted miR-58 targets, demonstrating that this approach is adaptable to other miRNAs. We propose that targeted mass spectrometry can be applied generally to validate candidate lists generated by computational methods or in large-scale experiments, and that the described strategy should be readily adaptable to other organisms