Levan is a fructose homopolysaccharide which gained attention recently for its unusual combination of properties distinguishing it from other natural biodegradable polysaccharides like chitosan, cellulose or starch. Among the strongest bioadhesives, film-forming levan is garnering interest for its role in some simple solutions to difficult problems. One of these is illustrated by the elegant research using laser-based techniques to construct levan films for healing wounds and burned tissue. Another is the development of bioresorbable electronic implants. Levan has been found in habitats as diverse as salterns and thermal waters to tropical plants and sugar factories. This review of the low viscosity, levan adhesive describes the mechanisms by which it forms bonds and the reasons behind some of its practical and industrial applications. Here we present descriptions from the literature for feasible approaches ready to transition from the laboratory to those searching for answers in fields as varied as medicine, packaging and furniture assembly.

BAckground:Recently, exploring novel dietary nondigestible carbohydrates, which are able to influence the gut flora, has drawn much attention. The objective of this study was to find out the effective dose of levan, as a prebiotic, in rats in order to further apply in food industry.Methods:Levan at various doses (2-10%) was orally administered to male Wistar Albino rats once a day for 90 days. At the end of experiment, fecal and blood samples were collected to measure gut bacteria population and to carry out serum biochemical assay. The rats were sacrificed, and the colon tissues were stained with hematoxylin and eosin and analyzed by histopathology.Results:Of note, levan effectively controlled body weight gain in the rats. Serum biochemical analysis revealed that 5% levan significantly diminished the serum level of total cholesterol, LDL, and glucose as well. More notably, 5% levan intake significantly increased the abundance of bifidobacteria population, highlighting its bifidogenic effect. Furthermore, our histopathological result revealed that daily intake of levan was associated with a higher degree of thickness of the mucosa layer compared to the rats in control group. Moreover, these findings manifested no colon inflammation in the rats fed with levan.Conclusion:The findings of this study provide the fundamental data to use levan at a definite dose for further development in functional foods.

Levan is a fructose homopolysaccharide which gained attention recently for its unusual combination of properties distinguishing it from other natural biodegradable polysaccharides like chitosan, cellulose or starch. Among the strongest bioadhesives, film-forming levan is garnering interest for its role in some simple solutions to difficult problems. One of these is illustrated by the elegant research using laser-based techniques to construct levan films for healing wounds and burned tissue. Another is the development of bioresorbable electronic implants. Levan has been found in habitats as diverse as salterns and thermal waters to tropical plants and sugar factories. This review of the low viscosity, levan adhesive describes the mechanisms by which it forms bonds and the reasons behind some of its practical and industrial applications. Here we present descriptions from the literature for feasible approaches ready to transition from the laboratory to those searching for answers in fields as varied as medicine, packaging and furniture assembly.

Levan is a high molecular weight fructose-based biotechnologically available polysaccharide with a range of interesting properties qualifying this molecule for applications in biomedicine. In this study, new levan derivatives containing methacrylate groups attached either via ester or urethane linkages to the fructan backbone could be synthesized and structurally characterized by conventional analytical techniques. The photochemical crosslinking of these substances applying different photoinitiator systems and reaction conditions resulted in hydrogels of diverse properties which were investigated with regard to mechanical behaviour, hydrolytic degradability, and cytocompatibility. It was found that crosslinkable levan derivatives represent a new class of promising biopolymer-based macromers broadening the spectrum of available biomaterials to facilitate the adaption to the requirements of specific applications.

Levan is a fascinating β-(2,6)-linked fructose polymer with an unusual combination of properties characterized in this review. In nature, levan is synthesized from sucrose by a wide range of microorganisms and a few plant species. Bacterial levans often have molecular weights over 500,000 Da, are commonly branched, and form compact nanospheres offering a broad spectrum of applications. The most relevant genetic, biochemical and structural aspects of the biosynthetic enzyme levansucrase are detailed. Optimization of parameters for levan production by intact bacteria and by the isolated enzyme is surveyed. The diversity of current and potential applications of levan is illustrated by a discussion of uses ranging from personal care and aquaculture to the medical and food industries.

Levan is an unusual polysaccharide that does not swell in water and that has an uncommonly low intrinsic viscosity. Animal studies have shown levan can lower blood cholesterol and a derivative of levan will increase calcium absorption. As a strong adhesive and a water soluble film former, levan has the potential to make a temporary coating or bandage.

Many adhesives are not particularly environmentally friendly. Montana Biotech has been working on an affordable, water-based adhesive produced from a renewable resource. The high molecular weight polysaccharide is non-cytotoxic, biodegradable and has a melting point of 225 °C. This “green” adhesive has good tensile strength approximately 6.2 mPa on bare aluminum and is especially useful on epoxy glass and manufactured woods. Cured adhesive maintained full strength in an environmental chamber during a week-long 85% humidity, temperature-cycling program.

/3-Glucuronidase from Patella vulgata, Helix aspersa, Helix pomatia, and bovine liver were evaluated for usefulness inroutinehydrolysis ofdrug-glucuronic acidconjugates from equine urine samples. Factors affecting the reaction rate (enzyme concentration, ligand concentration, temperature, and pH) were optimized. A 3-h incubation at 65 #{176}C with 5000 U of /3-glucuronidase from P. vulgata per milliliter of urine resulted In complete hydrolysis of all morphineglucuronide intheurinesamples.Notonlywas the enzyme preparation from P. vulgata the most costeffective/3-glucuronidaseource studied,but also its thermal stability is suchthat it can be usedat a temperature high enough to substantially shorten the incubation interval. Preliminary work on other drugs that form glucuronide conjugates indicates that this same procedure is similarly superior for use in their hydrolysis.

The wood adhesive market is very large and problems due to volatile organic compounds and toxic chemicals in many adhesives and their production are significant. In addition, most of the adhesives are derived from depleting petrochemical resources. An environmentally friendly wood adhesive based on renewable resources and produced by microbial fermentation has been explored. Using the shear block test method, a microbially produced polysaccharide has been tested and the effects of wood type, humidity, set time, partial acetylation, and surface wetting agents were determined. Shear strength of the microbial polysaccharide adhesive was compared to that of a commercial wood adhesive and other polysaccharides. Shear strengths of up to 20MPa (3000psi) for bonding maple have been obtained at 53% relative humidity and 22°C.

A water-based adhesive from non-petrochemical feedstock was produced by an efficient microbial fermentation process. The adhesive was susceptible to water but very resistant to solvents such as jet fuel. After curing, the adhesive could be re-moistened and used again to bond surfaces together. Shear strength on anodized aluminum averaged 819 psi and tensile strength ranged from 500 to 1500 psi depending on the substrate and production method. The parent adhesive was modified to several water resistant forms which maintained good adhesive strength.

Extracts of the biomasses and fermentation broths of 217 extremophilic microorganisms isolated from a number of locales were screened for antifungal activity using whole-cell and mechanism-based in vitro assays. Importantly, eleven broth extracts had activity against several Candida species and Aspergillus fumigatus in whole-cell in vitro assays. One broth specificallyinhibited(1,3) beta -glucan synthase activity and four specifically inhibited ketol-isomerase activity, suggesting a mode of action of the antifungal compound(s) present in these extracts. The extract from one thermophile, a novel species of Pseudomonas, was fractionated, an active compound purified and its structure determined. The compound was identified as pyochelin, a previously identified iron-binding compound with heretofore undescribed antifungal activity. To our knowledge, this is the first report demonstrating that extremophiles synthesize compounds that have antifungal activity.

Physical evidence of life (physical biomarkers) from the deposits of carbonate hot springs were documented at the scale of microorganisms--submillimeter to submicrometer. The four moderate-temperature (57 to 72 degrees C), neutral pH springs reported on in this study, support diverse communities of bacteria adapted to specific physical and chemical conditions. Some of the microbes coexist with travertine deposits in endolithic communities. In other cases, the microbes are rapidly coated and destroyed by precipitates but leave distinctive mineral fabrics. Some microbes adapted to carbonate hot springs produce an extracellular polymeric substance which forms a three-dimensional matrix with living cells and cell remains, known as a biofilm. Silicon and iron oxides often coat the biofilm, leading to long-term preservation. Submicrometer mineralized spheres composed of calcium fluoride or silica are common in carbonate hot spring deposits. Sphere formation is biologically mediated, but the spheres themselves are apparently not fossils or microbes. Additionally, some microbes selectively weather mineral surfaces in distinctive patterns. Hot spring deposits have been cited as prime locations for exobiological exploration of Mars. The presence of preserved microscopic physical biomarkers at all four sites supports a strategy of searching for evidence of life in hot spring deposits on Mars.

Martian rock and soil, collected by robotic spacecraft, will be returned to terrestrial laboratories early in the next century. Current plans call for the samples to be immediately placed into biological containment and tested for signs of present or past life and biological hazards. It is recommended that Controlled distribution of unsterilized materials from Mars should occur only if rigorous analyses determine that the materials do not constitute a biological hazard. If any portion of the sample is removed from containment prior to completion of these analyses it should first be sterilized. While sterilization of Mars samples may not be required, an acceptable method must be available before the samples are returned to Earth. The sterilization method should be capable of destroying a wide range of organisms with minimal effects on the geologic samples. A variety of biological sterilization techniques and materials are currently in use, including dry heat, high pressure steam, gases, plasmas and ionizing radiation. Gamma radiation is routinely used to inactivate viruses and destroy bacteria in medical research. Many commercial sterilizers use Co-60 , which emits gamma photons of 1.17 and 1.33 MeV. Absorbed doses of approximately 1 Mrad (10(exp 8) ergs/g) destroy most bacteria. This study investigates the effects of lethal doses of Co-60 gamma radiation on materials similar to those anticipated to be returned from Mars. The goals are to determine the gamma dose required to kill microorganisms in rock and soil samples and to determine the effects of gamma sterilization on the samples' isotopic, chemical and physical properties. Additional information is contained in the original extended abstract.

Rock and soil samples from the planet Mars are due to be returned to Earth within a decade. Martian samples initially will be tested for evidence of life and biological hazard under strict biological containment. Wider distribution of samples for organic and inorganic analysis may occur only if neither evidence of life nor hazard is detected, or if the samples are first sterilized. We subjected a range of Mars analog rocks and minerals to high doses of gamma radiation in order to determine the effects of gamma sterilization on the samples' isotopic, chemical, and physical properties. Gamma photons from 60 Co (1.17 and 1.33 MeV) in doses as high as 3×10 7 rads did not induce radioactivity in the samples and produced no measurable changes in their isotopic and chemical compositions. This level of irradiation also produced no measurable changes in the crystallographic structure of any sample, the surface areas of soil analogs, or the fluid inclusion homogenization temperature of quartz. The only detectable effects of irradiation were dose‐dependent changes in the visible and near‐infrared spectral region (e.g., discoloration and darkening of quartz and halite and an increase in albedo of carbonates) and increases in the thermoluminescence of quartz and plagioclase. If samples returned from Mars require biological sterilization, gamma irradiation provides a feasible option.