Activiteit

Lactobacillus casei group bacteria improve cheese ripening and may interact with host intestinal cells as probiotics, where surface proteins play a key role. Three complementary methods [trypsin shaving (TS), LiCl-sucrose (LS) extraction, and extracellular culture fluid precipitation] were used to analyze cell surface proteins of Lactobacillus paracasei GCRL163 by label-free quantitative proteomics after culture to the mid-exponential phase in bioreactors at pH 6.5 and temperatures of 30-45 °C. A total of 416 proteins, including 300 with transmembrane, cell wall anchoring, and secretory motifs and 116 cytoplasmic proteins, were quantified as surface proteins. Although LS caused significantly greater cell lysis as growth temperature increased, higher numbers of extracytoplasmic proteins were exclusively obtained by LS treatment. Together with the increased positive surface charge of cells cultured at supra-optimal temperatures, proteins including cell wall hydrolases Msp1/p75 and Msp2/p40, α-fucosidase AlfB, SecA, and a PspC-domain putative adhesin were upregulated in surface or secreted protein fractions, suggesting that cell adhesion may be altered. Prolonged heat stress (PHS) increased binding of L. paracasei GCRL163 to human colorectal adenocarcinoma HT-29 cells, relative to acid-stressed cells. This study demonstrates that PHS influences cell adhesion and relative abundance of proteins located on the surface, which may impact probiotic functionality, and the detected novel surface proteins likely linked to the cell cycle and envelope stress.The metallobiochemistry underlying the formation of the inorganic N-N-bond-containing molecules nitrous oxide (N2O), dinitrogen (N2), and hydrazine (N2H4) is essential to the lifestyles of diverse organisms. Similar reactions hold promise as means to use N-based fuels as alternative carbon-free energy sources. This review discusses research efforts to understand the mechanisms underlying biological N-N bond formation in primary metabolism and how the associated reactions are tied to energy transduction and organismal survival. These efforts comprise studies of both natural and engineered metalloenzymes as well as synthetic model complexes.Redox-active organic molecules such as anthraquinone-2,6-disulfonate (AQDS) and natural organic matter (NOM) can act as electron shuttles thus facilitating electron transfer from Fe(III)-reducing bacteria (FeRB) to terminal electron acceptors such as Fe(III) minerals. In this research, we examined the length scale over which this electron shuttling can occur. We present results from agar-solidified experimental incubations, containing either AQDS or NOM, where FeRB were physically separated from ferrihydrite or goethite by 2 cm. Iron speciation and concentration measurements coupled to a diffusion-reaction model highlighted clearly Fe(III) reduction in the presence of electron shuttles, independent of the type of FeRB. Based on our fitted model, the rate of ferrihydrite reduction increased from 0.07 to 0.19 μmol d-1 with a 10-fold increase in the AQDS concentration, highlighting a dependence of the reduction rate on the electron-shuttle concentration. To capture the kinetics of Fe(II) production, the effective AQDS diffusion coefficient had to be increased by a factor of 9.4. Thus, we postulate that the 2 cm electron transfer was enabled by a combination of AQDS molecular diffusion and an electron hopping contribution from reduced to oxidized AQDS molecules. Our results demonstrate that AQDS and NOM can drive microbial Fe(III) reduction across 2 cm distances and shed light on the electron transfer process in natural anoxic environments.Silicon fascinates with incredibly high theoretical energy density as an anode material and considered as a primary candidate to replace well-established graphite. However, further commercialization is hindered by abnormal volume changes of Si in every single cycle. Silicon embedded in a buffer matrix using melt-spinning process is a promising approach; however, its metastable nature significantly reduces the microstructure homogeneity, the quality of the composition, and, therefore, the electrochemical performances. Herein we developed a new approach to design high-performance Si-alloy with improved microstructure uniformity and electrochemical properties. Namely, annealing at a certain temperature of melt-spun amorphous alloy ribbon allowed us to evenly distribute Si nanocrystallites in the microstructure with control of average grain size. As a result, Si-alloy electrode delivers initial discharge capacity of 900 mAh g-1 and exhibits high Coulombic efficiency >99% from the 2nd cycle with capacity retention of ~98% after 100 cycles. buy PCO371 This study provides powerful insights and evidence for the successful application of the proposed approach for commercial purposes.Despite the fact that lithium-sulfur batteries are regarded as promising next-generation rechargeable battery systems owning to high theoretical specific capacity (1675 mA h g-1) and energy density (2600 W h kg-1), several issues such as poor electrical conductivity, sluggish redox kinetics, and severe “shuttle effect” in electrodes still hinder their practical application. MXenes, novel two-dimensional materials with high conductivity, regulable interlayer spacing, and abundant functional groups, are widely applied in energy storage and conversion fields. In this work, a Ti3C2/carbon hybrid with expanded interlayer spacing is synthesized by one-step heat treatment in molten potassium hydroxide. The subsequent experiments indicate that the as-prepared Ti3C2/carbon hybrid can effectively regulate polysulfide redox conversion and has strong chemisorption interaction to polysulfides. Consequently, the Ti3C2/carbon-based sulfur cathode boosts the performance in working lithium-sulfur batteries, in terms of an ultrahigh initial discharge capacity (1668 mA h g-1 at 0.1 C), an excellent rate performance (520 mA h g-1 at 5 C), and an outstanding capacity retention of 530 mA h g-1 after 500 cycles at 1 C with a low capacity fade rate of 0.05% per cycle and stable Coulombic efficiency (nearly 99%). The above results indicate that this composite with high catalytic activity is a potential host material for further high-performance lithium-sulfur batteries.