Xylanosomes produced by Cellulosimicrobium cellulans F16 were diverse in size, but resembled in subunit composition.

The hemicellulolytic enzyme system produced by Cellulosimicrobium cellulans strain F16 was resolved by ultracentrifugation and size exclusion chromatography. The particle size and molecular weight were determined by both dynamic light scattering and negative stain electron microscopy. The results showed that xylanosomes produced by strain F16 were found to have an apparent sedimentation coefficient of 28 S, were diverse in size (18-70 nm), molecular weight (11-78 MDa) and morphology, but resembled in subunit composition (SDS-PAGE and proteomic results). It is proposed that particles of 22 nm may be the basic unit, while 43 nm and 60 nm particles observed may be dimer and trimer of the basic unit, or xylanosomes with smaller size might be degradation products of larger size xylanosomes. Moreover, such xylanosomes are also found to have strong binding affinity toward water-insoluble substrates such as Avicel, birchwood xylan, and corn cob.

Effects of Different Carbon Sources on Enzyme Production and Ultrastructure of Cellulosimicrobium cellulans.

The secretomes of the strain Cellulosimicrobium cellulans F16 grown on different carbon sources were analyzed by zymography, and the subcellular surface structures were extensively studied by electron microscope. The exo-cellulase and xylanase systems were sparse when cells were grown on soluble oligosaccharides, but were significantly increased when grown on complex and water-insoluble polysaccharides, such as Avicel, corn cob, and birchwood xylan. The cellulosome-like protuberant structures were clearly observed on the cell surfaces of strain F16 grown on cellulose, with diameters of 15-20 nm. Fibrous structures that connected the adjacent cells can be seen under microscope. Moreover, protuberances that adsorbed the cell to cellulose were also observed. As the adhesion of Cellulosimicrobium cellulans cells onto cellulose surfaces occurs via thick bacterial curdlan-type exopolysaccharides (EPS), such surface layer is potentially important in the digestion of insoluble substrates such as cellulose or hemicellulose, and the previously reported xylanosomes are part of such complex glycocalyx layer on the surface of the bacterial cell.

Gram-negative bacteria recognition and photodynamic elimination by Zn-DPA based sensitizers.

The abuse and overuse of antibiotics let drug-resistant bacteria emerges. Antibacterial photodynamic therapy (APDT) has shown outstanding merits to eliminate the drug-resistant bacteria via cytotoxic reactive oxygen species produced by irradiating photosensitizer. However, most of photosensitizers are not effective for Gram-negative bacteria elimination. Herein conjugates of NBS, a photosensitizer, linked with one (NBS-DPA-Zn) or two (NBS-2DPA-Zn) equivalents of zinc-dipicolylamine (Zn-DPA) have been designed to achieve the functional recognition of different bacteria. Due to the cationic character of NBS and metal transfer channel effect of Zn-DPA, NBS-DPA-Zn exhibited the first regent to distinguish P. aeruginosa from other Gram-negative bacteria. Whereas NBS-2DPA-Zn showed broad-spectrum antibacterial effect because the two arm of double Zn-DPA enhanced interactions with anionic membranes of bacteria, led the bacteria aggregation and thus provided the efficacy of APDT to bacteria and corresponding biofilm. In combination with a hydrogel of Pluronic, NBS-2DPA-Zn@gel shows promising clinical application in mixed bacterial diabetic mouse model infection. This might propose a new method that can realize functional identification and elimination of bacteria through intelligent regulation of Zn-DPA, and shows excellent potential for antibacterial application.

Functional Connectivity Abnormalities of Brain Regions With Structural Deficits in Primary Insomnia Patients.

OBJECTIVES: The present study examined the abnormal resting state functional connections (RSFCs) in structural deficit brain regions of primary insomnia (PI) patients. METHODS: Thirty-three PI patients and 38 well-matched healthy controls participated in our study. We used voxel-based morphometry and RSFC to study functional connectivity abnormalities of brain regions with structural deficits in PI patients. RESULTS: PI patients showed decreased gray matter (GM) volume in the left dorsolateral prefrontal cortex, left orbitofrontal cortex (OFC), bilateral middle frontal gyrus (MFC), right inferior frontal gyrus (IFG), and left inferior temporal gyrus. Gray matter volume in the right MFC negatively correlated with Self-Rating Scale of Sleep (SRSS) scores, and GM volume in the right IFG negatively correlated with SRSS and Insomnia Severity Index (ISI) scores. Therefore, the right MFC and right IFG were selected as regions of interest for RSFC analysis. PI patients had weakened RSFC between the right inferior parietal gyrus (IPC) and the right MFC compared to the healthy controls and between the left OFC and right IFG. The RSFC between the right MFC and right IPC negatively correlated with SRSS scores. The RSFC between the right IFG and left OFC negatively correlated with SRSS, ISI, SAS, and SDS scores. CONCLUSIONS: The present study found structural changes in the right MFC and right IFG accompanied by RSFC changes. This finding may provide novel insights into the neural mechanisms of PI via combining structural and functional modality information.