Lignins and lignin-derived compounds are known to have antibacterial properties. The wound healing agents in the form of dressings produce faster skin repair and decrease pain in patients. In order to create an efficient antimicrobial agent in the form of dressing in the treatment of chronic wounds, a composite hydrogel of bacterial cellulose (BC) and dehydrogenative polymer of coniferyl alcohol (DHP), BC-DHP, was designed. Novel composite showed inhibitory or bactericidal effects against selected pathogenic bacteria, including clinically isolated ones. The highest release rate of DHP was in the first hour, while after 24 h there was still slow release of small amounts of DHP from BC-DHP during 72 h monitoring. High-performance liquid chromatography coupled with mass-spectrometry showed that BC-DHP releases DHP oligomers, which are proposed to be antimicrobially active DHP fractions. Scanning electron microscopy and atomic force microscopy micrographs proved a dose-dependent interaction of DHP with BC, which resulted in a decrease of the pore number and size in the cellulose membrane. The Fourier-transform infrared absorption spectra of the BC-DHP showed that DHP was partly bound to the BC matrix. The swelling and crystallinity degree were dose-dependent. All obtained results confirmed BC-DHP composite as a promising hydrogel for wounds healing.

A kombucha multimicrobial culture (KMC) was exposed to simulated Mars-like conditions in low Earth orbit (LEO). The study was part of the BIOlogy and Mars EXperiment (BIOMEX), which was accommodated in the European Space Agency's EXPOSE-R2 facility, outside the International Space Station. The aim of the study was to investigate the capability of a KMC microecosystem to survive simulated Mars-like conditions in LEO. During the 18-month exposure period, desiccated KMC samples, represented by living cellulose-based films, were subjected to simulated anoxic Mars-like conditions and ultraviolet (UV) radiation, as prevalent at the surface of present-day Mars. Postexposure analysis demonstrated that growth of both the bacterial and yeast members of the KMC community was observed after 60 days of incubation; whereas growth was detected after 2 days in the initial KMC. The KMC that was exposed to extraterrestrial UV radiation showed degradation of DNA, alteration in the composition and structure of the cellular membranes, and an inhibition of cellulose synthesis. In the ''space dark control'' (exposed to LEO conditions without the UV radiation), the diversity of the microorganisms that survived in the biofilm was reduced compared with the ground-based controls. This was accompanied by structural dissimilarities in the extracellular membrane vesicles. After a series of subculturing, the revived communities restored partially their structure and associated activities.

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This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.New experimental and theoretical results on the silicon diinterstitial (I 2 ) and its interactions with oxygen and carbon impurity atoms in Si crystals are reported. Electronic structure calculations indicate that I 2 has an acceptor and a donor level in the gap, which are close to the conduction and the valence band edges, respectively. Experimental results, which support the theoretically predicted high mobility of I 2 , are discussed. It is argued that mobile I 2 can be trapped by oxygen and carbon impurities. The I 2 O center has a donor level at E v þ0.09 eV. Two absorption bands at 936 and 929 cm À1 are assigned to the local vibrational modes of the I 2 O defect in the neutral and positively charged states, respectively. The binding energy of I 2 O relative to the separated I 2 and O i species is 0.22 eV. The disappearance of the I 2 O complex upon thermal annealing occurs in the temperature range 50-100 8C and is accompanied by the introduction of another defect, which gives rise to two hole emission signals from energy levels at E v þ0.54 and E v þ0.45 eV. It is argued that these levels are related to a complex consisting of interstitial carbon and interstitial silicon atoms (C i I). The stable configurations of the C i I pair have been found.