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.

No abstract

No abstract

Komagataeibacter sp. W1 produced high-quality BC, the properties and synthesis mechanisms of which were analyzed by SEM, XRD and FTIR, and genome sequencing, respectively.

No abstract

No abstract

Hydrophobic carboxymethyl starch (HCMS) was successfully synthesized, and major factors affecting esterification were systematically investigated. The physicochemical properties of HCMS were determined through FTIR spectroscopy, scanning electron microscopy (SEM), and viscosity analysis. The results indicated that the suitable parameters for the preparation of HCMS from carboxymethyl corn starch (CMS) were as follows: temperature, 35°C; reaction time, 60 min; benzoyl chloride (BC), 2.5 (in mole proportion to CMS); and sodium hydroxide (NaOH), 1.0 (in mole proportion to BC). Under these conditions, the degree of substitution (DSBz) was approximately 0.85 and the reaction efficiency (REBz) was approximately 43%. FTIR analysis revealed that benzoyl groups were grafted onto the CMS chain units. SEM images showed that HCMS granules exhibited slightly rough surfaces and their edges lost some definition; their sides were porous. The HCMS displayed good solubility and hydrophobicity. The selected HCMS (DSBz, 0.31) drilling fluids provided a remarkably effective reservoir protection in the cores, and its permeability recovery value reached 90%.

A novel zeolitic imidazolate framework (ZIF-8) nanoparticles@polyphosphazene (PZN) core-shell architecture was synthesized, and then, ZIF-8@PZN and ammonium polyphosphate (APP) were applied for increasing the flame retardancy and mechanical property of epoxy resin (EP) through a cooperative effect. Herein, ZIF-8 was used as the core; the shell of PZN was coated to ZIF-8 nanoparticles via a polycondensation method. The well-designed ZIF-8@PZN displayed superior fire retardancy and smoke suppression effect. The synthesized ZIF-8@PZN observably raised the flame retardancy of EP composites, which could be demonstrated by thermogravimetric analysis (TGA) and a cone calorimeter test (CCT). The chemical structure of ZIF-8@PZN was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Compared with pure epoxy, with the incorporation of 3 wt% ZIF-8@PZN and 18 wt% APP into the EP, along with 80.8%, 72.6%, and 64.7% decreased in the peak heat release rate (pHRR), the peak smoke production rate (pSPR), and the peak CO production rate (pCOPR), respectively. These suggested that ZIF-8@PZN and APP generated an intumescent char layer, and ZIF-8@PZN can strengthen the char layer, resulting in the enhancement in the flame resistance of EP. K E Y W O R D S epoxy resin, flame retardancy, mechanical properties, polyphosphazene, ZIF-8