Mechanical Genomic Studies Reveal the Role of d-Alanine Metabolism in Pseudomonas aeruginosa Cell Stiffness.

The stiffness of bacteria prevents cells from bursting due to the large osmotic pressure across the cell wall. Many successful antibiotic chemotherapies target elements that alter mechanical properties of bacteria, and yet a global view of the biochemistry underlying the regulation of bacterial cell stiffness is still emerging. This connection is particularly interesting in opportunistic human pathogens such as that have a large (80%) proportion of genes of unknown function and low susceptibility to different families of antibiotics, including beta-lactams, aminoglycosides, and quinolones.

Imaging mycobacterial growth and division with a fluorogenic probe.

Control and manipulation of bacterial populations requires an understanding of the factors that govern growth, division, and antibiotic action. Fluorescent and chemically reactive small molecule probes of cell envelope components can visualize these processes and advance our knowledge of cell envelope biosynthesis (e.g.

The FtsLB subcomplex of the bacterial divisome is a tetramer with an uninterrupted FtsL helix linking the transmembrane and periplasmic regions.

In , FtsLB plays a central role in the initiation of cell division, possibly transducing a signal that will eventually lead to the activation of peptidoglycan remodeling at the forming septum. The molecular mechanisms by which FtsLB operates in the divisome, however, are not understood. Here, we present a structural analysis of the FtsLB complex, performed with biophysical, computational, and methods, that establishes the organization of the transmembrane region and proximal coiled coil of the complex.

Decoding the Chemical Language of Motile Bacteria by Using High-Throughput Microfluidic Assays.

Motile bacteria navigate chemical environments by using chemoreceptors. The output of these protein sensors is linked to motility machinery and enables bacteria to follow chemical gradients. Understanding the chemical specificity of different families of chemoreceptors is essential for predicting and controlling bacterial behavior in ecological niches, including symbiotic and pathogenic interactions with plants and mammals.

Microfluidics for High School Chemistry Students.

We present a laboratory experiment that introduces high school chemistry students to microfluidics while teaching fundamental properties of acid-base chemistry. The procedure enables students to create microfluidic systems using nonspecialized equipment that is available in high school classrooms and reagents that are safe, inexpensive, and commercially available. The experiment is designed to ignite creativity and confidence about experimental design in a high school chemistry class.

Localization of anionic phospholipids in Escherichia coli cells.

Cardiolipin (CL) is an anionic phospholipid with a characteristically large curvature and is of growing interest for two primary reasons: (i) it binds to and regulates many peripheral membrane proteins in bacteria and mitochondria, and (ii) it is distributed asymmetrically in rod-shaped cells and is concentrated at the poles and division septum. Despite the growing number of studies of CL, its function in bacteria remains unknown. 10-N-Nonyl acridine orange (NAO) is widely used to image CL in bacteria and mitochondria, as its interaction with CL is reported to produce a characteristic red-shifted fluorescence emission.

Bacterial cellulose as a substrate for microbial cell culture.

Bacterial cellulose (BC) has a range of structural and physicochemical properties that make it a particularly useful material for the culture of bacteria. We studied the growth of 14 genera of bacteria on BC substrates produced by Acetobacter xylinum and compared the results to growth on the commercially available biopolymers agar, gellan, and xanthan. We demonstrate that BC produces rates of bacterial cell growth that typically exceed those on the commercial biopolymers and yields cultures with higher titers of cells at stationary phase.

Rapid identification of ESKAPE bacterial strains using an autonomous microfluidic device.

This article describes Bacteria ID Chips ('BacChips'): an inexpensive, portable, and autonomous microfluidic platform for identifying pathogenic strains of bacteria. BacChips consist of a set of microchambers and channels molded in the elastomeric polymer, poly(dimethylsiloxane) (PDMS). Each microchamber is preloaded with mono-, di-, or trisaccharides and dried.

Two-channel microelectrochemical bipolar electrode sensor array.

We report a two-channel microelectrochemical sensor that communicates between separate sensing and reporting microchannels via one or more bipolar electrodes (BPEs). Depending on the contents of each microchannel and the voltage applied across the BPE, faradaic reactions may be activated simultaneously in both channels. As presently configured, one end of the BPE is designated as the sensing pole and the other as the reporting pole.

Design and operation of microelectrochemical gates and integrated circuits.

Here we report a simple design philosophy, based on the principles of bipolar electrochemistry, for the operation of microelectrochemical integrated circuits. The inputs for these systems are simple voltage sources, but because they do not require much power they could be activated by chemical or biological reactions. Device output is an optical signal arising from electrogenerated chemiluminescence.

Bipolar electrodes: a useful tool for concentration, separation, and detection of analytes in microelectrochemical systems.

Over the past decade, bipolar electrochemistry has emerged from relative obscurity to provide a promising new means for integrating electrochemistry into lab-on-a-chip systems. This article describes the fundamental operating principles of bipolar electrodes, as well as several interesting applications.

Two-dimensional bipolar electrochemistry.

This paper introduces the concept of two-dimensional bipolar electrochemistry and discusses its principle of operation. The interesting new result is that electrochemical reactions can be localized at particular locations on the perimeter of a two-dimensional bipolar electrode (2D-BPE), configured at the intersection of two orthogonal microfluidic channels, by controlling the electric field within the contacting electrolyte solution. Experimentally determined maps of the electric field in the vicinity of the 2D-BPEs are in semiquantitative agreement with finite element simulations.

Snapshot voltammetry using a triangular bipolar microelectrode.

In this paper, we report a new electroanalytical technique we call snapshot voltammetry. This method combines the properties of bipolar electrodes with electrogenerated chemiluminescence (ECL) to provide a means for recording optical voltammograms in a single micrograph. In essence, the information in a snapshot voltammogram is contained in the spatial domain rather than in the time domain, which is the case for conventional voltammetry.

A large-scale, wireless electrochemical bipolar electrode microarray.

We report a microelectrochemical array composed of 1000 individual bipolar electrodes that are controlled with just two driving electrodes and a simple power supply. The system is configured so that faradaic processes occurring at the cathode end of each electrode are correlated to light emission via electrogenerated chemiluminescence (ECL) at the anode end. This makes it possible to read out the state of each electrode simultaneously.

Effect of particle size on the kinetics of the electrocatalytic oxygen reduction reaction catalyzed by Pt dendrimer-encapsulated nanoparticles.

Platinum dendrimer-encapsulated nanoparticles (DENs) containing an average of 55, 100, 147, 200, and 240 atoms were prepared within sixth-generation, hydroxyl-terminated, poly(amidoamine) dendrimers. These DENs were immobilized on glassy carbon electrodes, and the effect of particle size on the kinetics of the oxygen reduction reaction (ORR) was quantitatively evaluated using rotating disk voltammetry. The total areas of the Pt DENs were determined by electrochemical CO stripping and hydrogen desorption, and the results were found to be in reasonable agreement with calculated values.