Effect of Temperature and Photoperiod on Development, Survival, and Growth Rate of Mealworms, Tenebrio molitor.

Insects are a potential substitute for conventional meat and can be part of a sustainable human diet due to their valuable nutrients and relatively low environmental production impact. One species that is already produced for human consumption and livestock feed is the mealworm, i.e., larvae of Tenebrio molitor. Knowledge of the effects of temperature, and particularly photoperiod, on mealworm development is scarce, but crucial for the improvement of rearing. Therefore, the effects of three temperatures (20 °C, 25 °C, and 30 °C), in combination with three photoperiods (long-day-16 h:8 h light:dark; short-day-8 h:16 h light:dark, and constant darkness) on mealworm survival, developmental time, and growth rate were tested. We describe a significant effect of temperature on survival rate, developmental time, and growth rate. Furthermore, significant effects of photoperiod on developmental time and growth rate were found. At 25 and 30 °C and constant darkness, the highest survival and growth rate, along with the shortest developmental time, were observed. Our data can be used to improve the mass rearing of mealworms for an efficient production of food and feed.

Correlation between the solid state of lipid coating and release profile of API from hot melt coated microcapsules.

Solvent-free hot melt coating (HMC) provides a safer and more economic process compared to the conventional solvent coating techniques. However, drug release instability and the lack of fundamental understanding on it are limiting factors for application of HMC for industrial productions. In this work, we investigated glyceryl dibehenate, glyceryl monostearate and behenoyl polyoxyl-8 glyceride as HMC materials. The microstructure and solid state alteration of lipids were studied via polarized light microscopy, DSC and powder x-ray diffraction. Microcapsules of N-acetylcysteine particles were provided with these excipients and stored under long term and accelerated conditions for 3 months. The feasibility of selected lipids as HMC excipients was confirmed. The drug release from freshly coated microcapsules was dictated by microstructure, solid state and HLB of lipid coating. Alterations in the release profiles after storage under accelerated conditions were correlated with time-dependent structural alterations of selected lipids. The faster drug release from glyceryl dibehenate and behenoyl polyoxyl-8 glyceride microcapsules was correlated with a low-melting small fraction composed by mixed phases in glyceryl dibehenate and the amorphous region of polyoxyl part in behenoyl polyoxyl-8 glyceride, respectively. The slower drug release from glyceryl dibehenate after storage was explained by the transition of lipid crystals to the ß-form with dense crystalline structure. The gained information can be used to design effective tempering strategies for providing stable pharmaceutical products.

Effect of Technically Relevant X-Ray Doses on the Structure and Function of Alcohol Dehydrogenase and Hen Egg-White Lysozyme.

PURPOSE: The effect of different irradiation doses on the structure and activity of lyophilized powders of Hen Egg-White Lysozyme (HEWL) and alcohol dehydrogenase (ADH) was investigated using these substances as models for robust and sensitive proteins, respectively. Three doses were selected to cover the ranges of radio-sterilization (25kGy), treatment of blood products (25Gy) and annual background radiation dose (approximately 2mGy). The results offer an initial screening of different irradiation doses and support the development of X-ray imaging methods as non-destructive process analytical technology (PAT) tools for detecting the visible particulate matters in such products. METHODS: HEWL and ADH were exposed to X-rays in the solid state. The effect of irradiation was determined directly after irradiation and after storage. Structural changes and degradation were investigated using SAXS, SDS-PAGE and HPLC-MS. Protein functionality was assessed via activity assays. RESULTS: Lower irradiation doses of 25Gy and 2mGy had no significant impact on the structure and enzyme activity. The dose of 25kGy caused a significant decrease in the enzyme activity and structural changes immediately after irradiation of ADH and after storage of irradiated HEWL at -20°C. CONCLUSION: The results emphasize the importance of careful selection of radiation doses for development of X-ray imaging methods as PAT tools inspection of solid biopharmaceutical products.

Conjugative type IV secretion in Gram-positive pathogens: TraG, a lytic transglycosylase and endopeptidase, interacts with translocation channel protein TraM.

Conjugative transfer plays a major role in the transmission of antibiotic resistance in bacteria. pIP501 is a Gram-positive conjugative model plasmid with the broadest transfer host-range known so far and is frequently found in Enterococcus faecalis and Enterococcus faecium clinical isolates. The pIP501 type IV secretion system is encoded by 15 transfer genes. In this work, we focus on the VirB1-like protein TraG, a modular peptidoglycan metabolizing enzyme, and the VirB8-homolog TraM, a potential member of the translocation channel. By providing full-length traG in trans, but not with a truncated variant, we achieved full recovery of wild type transfer efficiency in the traG-knockout mutant E. faecalis pIP501ΔtraG. With peptidoglycan digestion experiments and tandem mass spectrometry we could assign lytic transglycosylase and endopeptidase activity to TraG, with the CHAP domain alone displaying endopeptidase activity. We identified a novel interaction between TraG and TraM in a bacterial-2-hybrid assay. In addition we found that both proteins localize in focal spots at the E. faecalis cell membrane using immunostaining and fluorescence microscopy. Extracellular protease digestion to evaluate protein cell surface exposure revealed that correct membrane localization of TraM requires the transmembrane helix of TraG. Thus, we suggest an essential role for TraG in the assembly of the pIP501 type IV secretion system.