a b s t r a c tSubtulene A, a new cyclic lipopeptide, was isolated from the culture broth of Bacillus subtilis SSE4. This antibiotic compound contained the seven common, L-Ser-7 and the unique b-amino acid-8 present in the iturin family. 1D and 2D NMR, as well as MS analyses, identified the b-amino acid as 3-amino-13-methyltetradec-8-enoic acid, an Iso C15 long chain b-amino acid. B. subtilis SSE4 was also found to produce iturin A. B. subtilis SSE4 culture filtrate exhibited both antifungal and antibacterial activities.

No abstract

Deoxyribonucleic acid (DNA) nanotechnology, a frontier in biomedical engineering, is an emerging field that has enabled the engineering of molecular-scale DNA materials with applications in biomedicine such as bioimaging, biodetection, and drug delivery over the past decades. The programmability of DNA nanostructures allows the precise engineering of DNA nanocarriers with controllable shapes, sizes, surface chemistries, and functions to deliver therapeutic and functional payloads to target cells with higher efficiency and enhanced specificity. Programmability and control over design also allow the creation of dynamic devices, such as DNA nanorobots, that can react to external stimuli and execute programmed tasks. This review focuses on the current findings and progress in the field, mainly on the employment of DNA nanostructures such as DNA origami nanorobots, DNA nanotubes, DNA tetrahedra, DNA boxes, and DNA nanoflowers in the biomedical field for therapeutic purposes. We will also discuss the fate of DNA nanostructures in living cells, the major obstacles to overcome, that is, the stability of DNA nanostructures in biomedical applications, and the opportunities for DNA nanostructure-based drug delivery in the future.

Engineering and design of genetic circuit in living cell is critical in accessing the beneficial application of synthetic biology. Directed evolution can avoid the complicated rational design of such circuit by screening or selecting functional circuit from non-functional one. Here, we proposed a positive-negative selection system for selecting a transcription factor that activates gene expression in response to arsenic in solution. First, we developed a whole cell biosensor for sensing arsenite in liquid using a regulator (ArsR) and a reporter (GFP), and evaluated its performance. Second, we developed a positive selection system for active ArsR using compartmentalized partnered replication that uses thermostable DNA polymerase as the reporter of activity. Third, we developed a negative selection system using sucrose-induced suicide gene SacB as the reporter for exclusion of inactive ArsR variants.