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The use of insect sex pheromones is an alternative technology for pest control in agriculture and forestry, which, in contrast to insecticides, does not have adverse effects on human health or environment and is efficient also against insecticide-resistant insect populations.1,2 Due to the high cost of chemically synthesized pheromones, mating disruption applications are currently primarily targeting higher value crops, such as fruits.3 Here we demonstrate a biotechnological method for the production of pheromones of economically important moth pests using engineered yeast cell factories. Biosynthetic pathways towards several pheromones or their precursors were reconstructed in the oleaginous yeast Yarrowia lipolytica, which was further metabolically engineered for improved pheromone biosynthesis by decreasing fatty alcohol degradation and downregulating storage lipid accumulation. The sex pheromone of the cotton bollworm Helicoverpa armigera was produced by oxidation of fermented fatty alcohols into corresponding aldehydes. The resulting pheromone was just as efficient and specific for trapping of H. armigera male moths in cotton fields in Greece as a synthetic pheromone mixture. We further demonstrated the production of the main pheromone component of the fall armyworm Spodoptera frugiperda. Our work describes a biotech platform for the production of commercially relevant titres of moth pheromones for pest control by yeast fermentation.Significance statementAgriculture largely relies on insecticides and genetically modified crops for pest control, however alternative solutions are required due to emerging resistance, toxicity and regulatory issues, and consumer preferences. Mating disruption with sex pheromones that act by preventing insect reproduction is considered the most promising and scalable alternative to insecticides. This method is highly efficient and safe for human health and environment. The likelihood of insect resistance development is very low and can be handled by adjusting the pheromone composition. The high cost of chemically synthesized pheromones is the major barrier for the wider adoption of pheromones. A novel method based on yeast fermentation enables the production of insect sex pheromones as a lower cost from renewable feedstocks.

This article presents a novel method for selective acquisition of Fourier transform infrared (FT-IR) spectra of microorganisms in-line during fermentation, using Saccharomyces cerevisiae as an example. The position of the cells relative to the sensitive region of the attenuated total reflection (ATR) FT-IR probe was controlled by combing a commercially available ATR in-line probe with contact-free, gentle particle manipulation by ultrasonic standing waves. A prototype probe was successfully constructed, assembled, and tested in-line during fed-batch fermentations of S. cerevisiae. Control over the position of the cells was achieved by tuning the ultrasound frequency: 2.41 MHz was used for acquisition of spectra of the cells (pushing frequency fp) and 1.87 MHz, for retracting the cells from the ATR element, therefore allowing spectra of the medium to be acquired. Accumulation of storage carbohydrates (trehalose and glycogen) inside the cells was induced by a lack of a nitrogen source in the feed medium. These changes in biochemical composition were visible in the spectra of the cells recorded in-line during the application of fp and could be verified by reference spectra of dried cell samples recorded off-line with a FT-IR microscope. Comparison of the cell spectra with spectra of trehalose, glycogen, glucose, and mannan, i.e., the major carbohydrates present in S. cerevisiae, and principal components analysis revealed that the changes observed in the cell spectra correlated well with the bands specific for trehalose and glycogen. This proves the applicability and capability of ultrasound-enhanced in-line ATR mid-IR spectroscopy as a real-time PAT method for the in situ monitoring of cellular biochemistry during fermentation.

The paper describes a new phenomenon discovered in the electrolytic analog of a semiconductor diode. As an example, the phenomenon is studied in the 0.1M KOH-0.1M HCl diode where the alkaline and the acidic reservoirs are connected by a hydrogel cylinder. First the traditional, so-called positive salt effect is discussed. In that case some salt is added to the alkaline reservoir of a reverse biased electrolyte diode and as a result, close to a critical concentration of the added salt the electric current increases sharply. The so-called negative salt effect appears as a suppression of the positive one. It is shown by numerical simulations, by approximate analytical formulae, and also by experiments that the high current caused by the salt contamination in the alkaline reservoir can be mostly suppressed by relatively small salt concentrations in the acidic reservoir. Thus a straightforward application of the negative salt effect would be the sensitive detection of nonhydrogen cations in an acidic medium (e.g., in ion chromatography).

Spherical micron sized terbutylazine imprinted polymers have been obtained by copolymerization of acrylates in solvent mixtures containing a highly viscous ('oil') component. The new method requires much less organic solvent than precipitation polymerization to produce spherical MIP particles. Different proportions of oil have been used to clarify its role on the morphology. The particles obtained with the optimal composition could be easily packed into short HPLC columns. Chromatographic retention of the template and other compounds has been determined on the novel ('OMIP') columns and was compared to MIP prepared by bulk polymerization. In 70% aqueous acetonitrile eluent the OMIP shows a higher imprinting factor (i. e. less non-selective binding) and lower retention than the bulk MIP. The chromatographic selectivity against template analogs is similar on OMIP and bulk MIP, while the selectivity against non-related substances is better on the OMIP. The effect of oil on the polymer structure appears to be due to its high viscosity.