TEM and STEM-EDS evaluation of metal nanoparticle encapsulation in GroEL/GroES complexes according to the reaction mechanism of chaperonin

Microbial Mineralization with Lysinibacillus sphaericus for Selective Lithium Nanoparticle Extraction

Lithium is a critical mineral in a wide range of current technologies, and demand continues to grow with the transition to a green economy. Current lithium mining and extraction practices are often highly ecologically damaging, in part due to the large amount of water and energy they consume. Biomineralization is a natural process that transforms inorganic precursors to minerals. Microbial biomineralization has potential as an ecofriendly alternative to current lithium extraction techniques. This work demonstrates Lysinibacillus sphaericus biomineralization of lithium chloride to lithium hydroxide. Quantitative analysis of biomineralized lithium via the 2-(2-hydroxyphenyl)-benzoxazole fluorescence assay reveals significantly greater recovery with L. sphaericus than without. Furthermore, L. sphaericus biomineralization is specific to lithium over sodium. The nanoparticles produced were further characterized via Fourier transform infrared and transmission electron microscopy analysis as crystalline lithium hydroxide, which is an advanced functional material. Finally, ESI-LC/MS was used to identify several proteins involved in this microbial biomineralization process, including the S-layer protein. Through the isolation of L. sphaericus ghosts, this work shows that the S-layer protein alone plays a critical role in the biomineralization of crystalline lithium hydroxide nanoparticles. Through this study of microbial biomineralization of lithium with L. sphaericus, there is potential to develop innovative and environmentally friendly extraction techniques.

Chaperonins: Nanocarriers with Biotechnological Applications

Chaperonins are molecular chaperones found in all kingdoms of life, and as such they assist in the folding of other proteins. Structurally, chaperonins are cylinders composed of two back-to-back rings, each of which is an oligomer of ~60-kDa proteins. Chaperonins are found in two main conformations, one in which the cavity is open and ready to recognise and trap unfolded client proteins, and a "closed" form in which folding takes place. The conspicuous properties of this structure (a cylinder containing a cavity that allows confinement) and the potential to control its closure and aperture have inspired a number of nanotechnological applications that will be described in this review.