Insights into Bacterial Cellulose Biosynthesis from Different Carbon Sources and the Associated Biochemical Transformation Pathways in Komagataeibacter sp. W1.

Cellulose is the most abundant and widely used biopolymer on earth and can be produced by both plants and micro-organisms. Among bacterial cellulose (BC)-producing bacteria, the strains in genus Komagataeibacter have attracted wide attention due to their particular ability in furthering BC production. Our previous study reported a new strain of genus Komagataeibacter from a vinegar factory. To evaluate its capacity for BC production from different carbon sources, the present study subjected the strain to media spiked with 2% acetate, ethanol, fructose, glucose, lactose, mannitol or sucrose. Then the BC productivity, BC characteristics and biochemical transformation pathways of various carbon sources were fully investigated. After 14 days of incubation, strain W1 produced 0.040⁻1.529 g L-1 BC, the highest yield being observed in fructose. Unlike BC yields, the morphology and microfibrils of BCs from different carbon sources were similar, with an average diameter of 35⁻50 nm. X-ray diffraction analysis showed that all membranes produced from various carbon sources had 1⁻3 typical diffraction peaks, and the highest crystallinity (i.e., 90%) was found for BC produced from mannitol. Similarly, several typical spectra bands obtained by Fourier transform infrared spectroscopy were similar for the BCs produced from different carbon sources, as was the Iα fraction. The genome annotation and Kyoto Encyclopedia of Genes and Genomes analysis revealed that the biochemical transformation pathways associated with the utilization of and BC production from fructose, glucose, glycerol, and mannitol were found in strain W1, but this was not the case for other carbon sources. Our data provides suggestions for further investigations of strain W1 to produce BC by using low molecular weight sugars and gives clues to understand how this strain produces BC based on metabolic pathway analysis.

Development of nanofibrous scaffolds for vascular tissue engineering.

Small-diameter vascular grafts can easily lead to thrombosis and intimal hyperplasia. So the rate of the long-term patency is not satisfactory. Scaffolds that can support the growth of cells and remain stable and passable in vivo are in great demand. Vascular scaffolds were fabricated by electrospinning RGD-recombinant spider silk protein (pNSR32), polycaprolactone (PCL) and chitosan (CS). In addition, the cytocompatibility, the stability and the patency of scaffolds in vivo were studied. The results demonstrated that Sprague-Dawley rat aortic endothelial cells (SDRAECs) could highly enhanced adhesion and proliferation, together with increasing stress of fiber formation, and intensive biological function (the expression of PECAM-1 and vWF, the secretion of NO), in the pNSR32/PCL/CS scaffolds, compared with in the pNSR32/PCL and PCL scaffolds. The cell cycle studies of SDRAECs also revealed that the scaffolds promoted the cells to enter the stage of divisional proliferation. Furthermore, pNSR32/PCL/CS scaffolds could support the growth of cells under physiologic conditions and are able to maintain the structural integrity and patency for at least 8 weeks in a SD rat abdominal aortic defect model.

Jeotgalibacillus soli sp. nov., isolated from non-saline forest soil, and emended description of the genus Jeotgalibacillus.

A Gram-stain-positive, endospore-forming, motile, catalase- and oxidase-positive, aerobic, rod-shaped bacterium, designated strain JSM 081008(T), was isolated from non-saline forest soil in China. Strain JSM 081008(T) was able to grow with 0-20% (w/v) NaCl, at pH 6.0-10.5 and at 10-45 degrees C; optimum growth was observed with 2-5% (w/v) NaCl, at pH 7.0-8.0 and at 30-35 degrees C. The peptidoglycan type was A1alpha linked directly through L-Lys. The major cellular fatty acids (>10% of the total) were anteiso-C15:0, iso-C15:0, anteiso-C17:0 and C16:0. The predominant respiratory quinone was menaquinone 7 and the genomic DNA G + C content of the strain was 42.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain JSM 081008(T) should be assigned to the genus Jeotgalibacillus and was related most closely to the type strains of Jeotgalibacillus alimentarius (sequence similarity 99.4%) and Jeotgalibacillus salarius (97.0%), followed by Jeotgalibacillus campisalis (95.4%) and Jeotgalibacillus marinus (95.2%). The combination of phylogenetic analysis, DNA-DNA relatedness values, phenotypic characteristics and chemotaxonomic data supports the view that strain JSM 081008(T) represents a novel species of the genus Jeotgalibacillus, for which the name Jeotgalibacillus soli sp. nov. is proposed. The type strain is JSM 081008(T) (=DSM 22174(T) = KCTC 13528(T)). An emended description of the genus Jeotgalibacillus is also presented.