DL-Glutamic acid

In the natural environment bacteria predominantly live adhered to a surface as part of a biofilm. While many of the components needed for biofilm assembly are known, the mechanism by which microbes sense and respond to contact with a surface is poorly understood. Bacillus subtilis is a Gram-positive model for biofilm formation. The DegS-DegU two-component system controls several multicellular behaviours in B. subtilis, including biofilm formation. Here we identify the B. subtilis flagellum as a mechanosensor that activates the DegS-DegU regulatory pathway. Inhibition of flagellar rotation by deletion or mutation of the flagellar stator gene, motB, results in an increase in both degU transcription and DegU∼P driven processes, namely exoprotease production and poly-γ-dl-glutamic acid biosynthesis. Similarly, inhibition of flagellar rotation by engaging the flagellar clutch or by tethering the flagella with antibodies also promotes an increase in degU transcription that is reflective of increased DegU∼P levels in the cell.

In this communication, we demonstrate that chiral self-assembled monolayers can be used for polymorphism control of chiral crystals. We studied the crystallization of DL-glutamic acid on chiral self-assembled monolayers and showed that crystallization of DL-glutamic acid on the chiral SAMs resulted in stabilization of the metastable conglomerate form.

Staphylococcus epidermidis is a highly significant nosocomial pathogen mediating infections primarily associated with indwelling biomaterials (e.g., catheters and prostheses). In contrast to Staphylococcus aureus, virulence properties associated with S. epidermidis are few and biofilm formation is the defining virulence factor associated with disease, as demonstrated by animal models of biomaterial-related infections. However, other virulence factors, such as phenol-soluble modulins and poly-gamma-DL-glutamic acid, have been recently recognized that thwart innate immune system mechanisms. Formation of S. epidermidis biofilm is typically considered a four-step process consisting of adherence, accumulation, maturation and dispersal. This article will discuss recent advances in the study of these four steps, including accumulation, which can be either polysaccharide or protein mediated. It is hypothesized that studies focused on understanding the biological function of each step in staphylococcal biofilm formation will yield new treatment modalities to treat these recalcitrant infections.

Local conformation and overall conformation of poly(γ-DL-glutamic acid) (PγDLGA) and poly(γ-L-glutamic acid) (PγLGA) in aqueous solution was studied as a function of degree of ionization ε by (1) H-NMR, circular dichroism, and potentiometric titration. It was clarified that their local conformation is represented by random coil over an entire ε range and their overall conformation is represented by expanded random-coil in a range of ε > ε(*) , where ε(*) is about 0.3, 0.35, 0.45, and 0.5 for added-salt concentration of 0.02M, 0.05M, 0.1M, and 0.2M, respectively. In a range of ε < ε(*) , however, ε dependence of their overall conformation is significantly differentiated from each other. PγDLGA tends to aggregate intramolecularly and/or intermolecularly with decreasing ε, but PγLGA still behaves as expanded random-coil. It is speculated that spatial arrangement of adjacent carboxyl groups along the backbone chain essentially affects the overall conformation of PγGA in acidic media.