Background Salivary mucin MUC5B seems to promote biodiversity in dental biofilms, and thereby oral health, for example, by inducing synergistic 'mucolytic' activities in a variety of microbial species that need to cooperate for the release of nutrients from the complex glycoprotein. Knowledge of how early colonizers interact with host salivary proteins is integral to better understand the maturation of putatively harmful oral biofilms and could provide key insights into biofilm physiology. Methods The early oral colonizer Streptococcus gordonii DL1 was grown planktonically and in biofilm flow cell systems with uncoated, MUC5B or low-density salivary protein (LDP) coated surfaces. Bacterial cell proteins were extracted and analyzed using a quantitative mass spectrometry-based workflow, and differentially expressed proteins were identified. Results and conclusions Overall, the proteomic profiles of S. gordonii DL1 were similar across conditions. Six novel biofilm cell proteins and three planktonic proteins absent in all biofilm cultures were identified. These differences may provide insights into mechanisms for adaptation to biofilm growth in this species. Salivary MUC5B also elicited specific responses in the biofilm cell proteome. These regulations may represent mechanisms by which this mucin could promote colonization of the commensal S. gordonii in oral biofilms.

BACKGROUND: To respond and adapt to environmental challenges, prokaryotes regulate cellular processes rapidly and reversibly through protein phosphorylation and dephosphorylation. This study investigates the intracellular proteome and Ser/Thr/Tyr phosphoproteome of the oral commensal Streptococcus gordonii. Intracellular proteins from planktonic cells of S. gordonii DL1 were extracted and subjected to 2D-gel electrophoresis. Proteins in general were visualized using Coomassie Brilliant Blue and T-Rex staining. Phosphorylated proteins were visualized with Pro-Q Diamond Phosphoprotein Gel Stain. Proteins were identified by LC-MS/MS and sequence analysis.

RESULTS: In total, sixty-one intracellular proteins were identified in S. gordonii DL1, many of which occurred at multiple isoelectric points. Nineteen of these proteins were present as one or more Ser/Thr/Tyr phosphorylated form. The identified phosphoproteins turned out to be involved in a variety of cellular processes.

CONCLUSION: Nineteen phosphoproteins involved in various cellular functions were identified in S. gordonii. This is the first time the global intracellular Ser/Thr/Tyr phosphorylation profile has been analysed in an oral streptococcus. Comparison with phosphoproteomes of other species from previous studies showed many similarities. Proteins that are consistently found in a phosphorylated state across several species and growth conditions may represent a core phosphoproteome profile shared by many bacteria.

Here we report an enzymic fuel cell in a vein replica that generates sustained electricity, enough to power an e-​ink display, in an authentic human blood stream. We also detail a simple and safe approach for fuel cell evaluation under homeostatic conditions. Our results demonstrate proof-​of-​principle operation of a biocompatible and safe biodevice that could be implanted in superficial human veins, which we anticipate to be a starting point for more sophisticated investigations of personal sources of electricity.

A review. Being inspired by a very recent review entitled: "Electrocatalysis and bioelectrocatalysis - Distinction without a difference" and following the general approach employed by Prof. Dr. Schuhmann, in the current work we point to the similarities and differences between oxygen electroredn. and bioelectroredn. processes. To addnl. distinguish our paper from the recent review we touch on different bioelements, such as redox proteins and living cells, but we still keep a special emphasis on oxidoreductases, biocatalysts par excellence. Moreover, we also exclusively focus on oxygen electroredn. based on direct electron transfer reactions. On the one hand, we corroborate the previously made conclusion regarding intrinsically high activity of the active sites of biol. catalysts, esp. redox enzymes, which results in mass transfer and heterogeneous electron transfer limited currents from oxygen reducing bioelectrodes. On the other hand, we disagree with the statements regarding the exceptionality of precious metal catalysts, and the notion of a huge trade-​off between high activity and stability of non-​precious metal catalysts and bioelements. We show that the activity and stability of noble metal based cathodes is very far from perfect, esp. when these electrodes operate in complex electrolytes, such as physiol. fluids, e.g. human blood.

A review. This work provides an overview of the recent advances in the field of tear-​based wearable electrochem. biodevices, including non-​invasive biosensors, biol. fuel cells and biosupercapacitors. Contact lenses are attractive platforms for fabricating non-​invasive self-​contained gadgets for different applications, starting from devices with casual or mundane purposes only, like personalized smart lenses with direct (invisible for others) displays, and ending with biomedical devices for continuous fitness status and​/or health care monitoring. Key requirements and challenges that confront researchers in this exciting area are discussed.

Here the authors detail an optimized transparent capacitive glucose oxidizing bioanode, capable of supplying current densities of 10 μA cm-​2 at applied potentials of 0.1 V-​0.2 V vs. SCE, when continuously performing in a simple phosphate buffer, pH 7.4 and artificial human tears, both with a glucose concn. of 0.05 mM only. When operating in pulse mode, the bioanode was able to deliver current densities ≤21 μA cm-​2 at the beginning of the pulse with 571 μC cm-​2 total charges stored. The biogenic part of the enzymic device was a recombinant glucose oxidase mutant from Penicillium amagasakiense with high catalytic efficiency towards glucose, up to 14.5x104 M-​1 s-​1. The nonbiogenic part of the anodic system was based on a poly(3,​4-​ethylenedioxythiophene)​-​graphene nanocomposite, as a highly capacitive component with a capacitance d. in the 1 mF cm-​2 range, multi-​walled carbon nanotubes, as an addnl. nanostructuring element, and a conductive org. complex, as an electron shuttle between the redox enzyme and the electrode surface. The bioanode could potentially serve as a prototype of a double-​function enzymic anode for hybrid elec. power biodevices, energizing smart contact lenses.

We herein report on an entirely new kind of electric power device. In the hybrid device, chemical energy is directly converted into electric energy, which is capacitively stored within a singular contrivance. The device is built based on dual-function electrodes, viz. discrete electrodes manifesting simultaneous electrocatalytic and charge-storage features.