Optimization of Bacillus subtilis natto growth parameters in glycerol-based medium for vitamin K (Menaquinone-7) production in biofilm reactors

Bioprocess and Biosystems Engineering - Menaquinone-7 (MK-7) is the key form of vitamin K used as a dietary supplement and its production revolves around Bacillus subtilis natto. Current...     

Implementation of fed-batch strategies for vitamin K (menaquinone-7) production by Bacillus subtilis natto in biofilm reactors

Recent studies show the essential health benefits associated with vitamin K, especially menaquinone-7 (MK-7). These benefits include reducing risks of cardiovascular diseases, osteoporosis, and even cancer. However, MK-7 production on an industrial level is only possible through bacterial fermentation and also current static fermentation strategies are not potent enough with difficulties to scale up. Biofilm reactors, however, may be a practical alternative. Biofilm reactors provide a controlled environment for the microorganisms to form mature and robust biofilms that enable them to produce value-added products with enhanced efficiencies. In this study, fed-batch addition of glucose and glycerol were investigated to the base media in biofilm reactors, as carbon source addition seemed crucial in batch fermentations. Results indicated that fed-batch strategies can be significantly effective in glucose-based medium, increasing the end-product concentrations to 28.7 ± 0.3 mg/L of MK-7 which was 2.3 fold higher than the level produced in suspended-cell bioreactors and renders the biofilm reactors as a potential replacement for static fermentation strategies. Moreover, morphological changes of B. subtilis were tracked during the 12-day long fermentation runs and finally, SEM investigations confirmed significant biofilm and extracellular matrices formed on the plastic composite support (PCS) in the biofilm reactors. In conclusion, biofilm reactors especially with fed-batch fermentation regimes seem to be an effective tool for MK-7 production at industrial scales.

     

Brucellosis Causes Alteration in Trace Elements and Oxidative Stress Factors

Brucellosis is regarded as one of the most common diseases among humans and livestock. In the present study, we aimed to assess the effect of this disease on the level of various cations including copper (Cu), manganese (Mn), zinc (Zn), and magnesium (Mg) as well as oxidative stress status in the serum of people suffering from brucellosis. The present case-study was carried out on 40 patients with brucellosis (case) and 20 healthy people (control). Blood specimens were taken from all the people and the level of essential trace elements and oxidative stress status were measured. The serum level of copper in the case group (165.39 ± 43.19 μg/dl) was significantly higher compared with that in the control group (122.12 ± 28.88 μg/dl). Whereas the serum level of zinc was significantly lower in the case group compared with that in the control group (76.47 ± 28.88 vs. 92.85 ± 23.16 μg/dl). The manganese and magnesium serum levels did not differ significantly between the two groups. Furthermore, total antioxidant capacity level was significantly lower in the case group (122.12 ± 28.22 μmol/ml) than that in the control group (3.08 ± 0.12 μmol/ml) and the level of serum malondialdehyde was significantly higher in the case group (7.20 ± 0.23 mmol/ml) than that in the control group (4.0 ± 0.19 mmol/ml). Brucellosis can cause alteration in the serum level of essential trace elements. Moreover, the present study indicated that brucellosis produces oxidative stress in patients.     

Intraspecific killing among Leopards (Panthera pardus) in Iran (Mammalia: Felidae)

Intraspecific aggression is one of the most common causes of death in leopards. Here, we report four cases of intraspecific killing amongst Persian Leopards (Panthera pardus saxicolor) in Iran. A young male leopard was found on 7 June 2008 which, according to camera trap images, had been killed by an adult male over a Red Deer (Cervus elaphus) kill, with trauma to his neck in Dorfak No-Hunting Area. A young female that had been fitted with a satellite GPS collar on 6 December 2015 in Tandoureh National Park died on 29 January 2016 at a site where an Urial Sheep (Ovis orientalis) ram had been freshly killed. Necropsy results, footprints at the scene of death and camera trap footage all supported the deduction that the animal was killed by a larger female leopard at the kill site. On 13 January 2017, a young, partially eaten female leopard was found with double puncture on the side of her throat. Finally, a rehabilitated adult female fitted with a satellite GPS collar found on 19 December 2017 with a double puncture on her head with several trauma and haemorrhages on her back. These instances seem to be the first documented reports of intraspecific killing among free-ranging leopards in Asia.     

Synthesis,structure–activity relationship and molecular docking of 3-oxoaurones and 3-thioaurones as acetylcholinesterase and butyrylcholinesterase inhibitors

The present study describes efficient and facile syntheses of varyingly substituted 3-thioaurones from the corresponding 3-oxoaurones using Lawesson’s reagent and phosphorous pentasulfide. In comparison, the latter methodology was proved more convenient, giving higher yields and required short and simple methodology. The structures of synthetic compounds were unambiguously elucidated by IR, MS and NMR spectroscopy. All synthetic compounds were screened for their inhibitory potential against in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. Molecular docking studies were also performed in order to examine their binding interactions with AChE and BChE human proteins. Both studies revealed that some of these compounds were found to be good inhibitors against AChE and BChE.     

Insight into the interaction of antitubercular and anticancer compound clofazimine with human serum albumin: spectroscopy and molecular modelling

The binding of clofazimine to human serum albumin (HSA) was investigated by applying optical spectroscopy and molecular docking methods. Fluorescence quenching data revealed that clofazimine binds to protein with binding constant in the order of 10⁴ M^?1, and with the increase in temperature, Stern–Volmer quenching constants gradually decreased indicating quenching mode to be static. The UV–visible spectra showed increase in absorbance upon interaction of HSA with clofazimine which further reveals formation of the drug–albumin complex. Thermodynamic parameters obtained from fluorescence data indicate that the process is exothermic and spontaneous. Forster distance (R_o) obtained from fluorescence resonance energy transfer is found to be 2.05 nm. Clofazimine impelled rise in α-helical structure in HSA as observed from far-UV CD spectra while there are minor alterations in tertiary structure of the protein. Clofazimine interacts strongly with HSA inducing secondary structure in the protein and slight alterations in protein topology as suggested by dynamic light scattering results. Moreover, docking results indicate that clofazimine binds to hydrophobic pocket near to the drug site II in HSA.     

Electronic properties and stability phase diagrams for cubic BN surfaces

This contribution investigates structural and electronic properties as well as stability phase diagrams of surfaces of the cubic boron nitride (c-BN). Our calculated parameters for bulk c-BN agree reasonably well with both experimental and computed values available in the literature. Based on the energies of the three experimentally recognised phases of bulk boron, i.e. α-B₃₆, β-B₁₀₅ and γ-B₂₈, we estimate enthalpy of formation of c-BN to be ?2.8 eV. The c-BN(1?0?0) surface offers separate B and N terminations (denoted as c-BN(1?0?0)_B and c-BN(1?0?0)_N), whereas c-BN(1?1?1) and c-BN(1?1?0) are truncated with combinations of boron and nitrogen atoms (denoted as c-BN(1?1?1)_BN and c-BN(1?1?0)_BN). Optimised geometries of surfaces display interlayer displacements up to the three topmost layers. Downward displacement of surface boron atoms signifies a common geometric feature of all surfaces. Bulk c-BN and its most stable surface c-BN(1?0?0)_N possess no metallic character, with band gaps of 5.46 and 2.7 eV, respectively. We find that, only c-BN(1?0?0)_B configuration exhibits a metallic character. c-BN(1?1?0)_BN and c-BN(1?1?1)_BN surfaces display corresponding band gaps of 2.5 and 3.9 eV and, hence, afford no metallic property.     

Australian Hajj pilgrims’ knowledge about MERS-CoV and other respiratory infections

<正>Dear Editor,With the intense crowding in mass gatherings such as Hajj,there is a high risk of acquisition of airborne in-fections with the potential for its transmission in the pilgrims’country of origin(Memish Z A,et al.,2014).The risk of importing serious infections from Hajj has escalated since the emergence of the Middle East respiratory syndrome coronavirus(MERS-CoV)in Saudi Arabia and other neighbouring countries from September2012.Active surveillance of Hajj pilgrims in 2012 and 2013