Cleavage Of Cellulose Research Articles

Micromechanism Study on Deterioration Effect of Vegetable Oil and Mineral Oil on Insulating Paper by Molecular Dynamics

In the era of low carbon and environmental protection, sustainable development ideas win support among the people. Vegetable oils have excellent environmental performance compared with traditional mineral insulating oils. The aging characteristics of insulating paper in vegetable oil have been discussed in experiments, but the deterioration mechanism at the microscopic level is still lacking. In this paper, the microscopic deterioration mechanism of insulating paper in vegetable oil and mineral oil is investigated by molecular dynamics. In addition, the intermolecular properties of insulating paper under different insulating oils are compared. It is found that the cellulose cleavage in insulating paper is divided into three ways: glycosidic bond breaking, pyran ring opening and dehydroxylation. The number of hydrogen bonds, binding energy and electrostatic energy between insulating paper and vegetable oil are higher than those of mineral oil. It proves that there is a stronger interaction between insulating paper and vegetable oil. Finally, the change rules of characteristic products CO, H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O, H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and formic acid are counted. It is found that vegetable oil can delay the deterioration and prolong the life of insulating paper compared to mineral oil. The above study reveals the microscopic influence law of vegetable oil and mineral oil on the degradation of insulating paper. It provides theoretical support for the large-scale application of vegetable oil in oil-immersed transformers.

CELLULOSOLYTIC ACTIVITY OF SOILS OF THE ODESA CITY

Problem Statement and Purpose. Cellulose cleavage is of great importance in the carbon cycle, as it contains more than 50% of all organic carbon in the biosphere. This is a fairly stable organic compound that is destroyed only by very strong oxidants. Under natural conditions, the destruction of cellulose is carried out by various microorganisms that produce cellulase enzymes. The activation of cellulose decomposition is influenced by temperature, pH level, soil aeration, biological properties of vegetation, etc. Being very resistant to physicochemical factors, cellulose is easily decomposed by microorganisms with the release of carbon, which in the form of various compounds is involved in creating soil fertility. Cellulose is broken down by aerobic microorganisms (bacteria and fungi) and anaerobic mesophilic and thermophilic bacteria. The peculiarity of cellulose-destroying microorganisms is their high demand for nitrogen sources. Soil-destroying soil microorganisms are the most important suppliers of organic matter to various groups of microorganisms (including nitrogen-fixing) in the common food chain. Since the activity of cellulose-destroying microorganisms also depends on the presence of available phosphorus and other elements in the soil, the degree of decomposition of fiber can be considered to reflect the direction of microbiological processes in general. Cellulolytic activity indicates the intensity of biological processes in the soil. The more intensively the cellulose decomposes, the faster the biological cycle of elements takes place and the fuller the plants are provided with nutrients. Therefore, cellulose activity is used as one of the indicators of biological activity of the soil environment. Data &amp;Methods. The author, in the study of cellulosolytic activity of soils in the city of Odessa, used the method of applications (laying in the soil strips of filter paper or linen cloth fixed on the glass). Applications were laid vertically in the upper 15-cm layer of soil of 5 pieces on the site. A month later, they were dug up, carefully washed from the soil and decay products, dried and weighed again. Cellulolytic activity was determined by weight loss of exposed tissue. Results. As a result of research on the study of cellulolytic activity of soils in the city of Odessa, it was found that cellulolytic activity is an important indicator of the intensity of destructive processes in the soil. The intensity of cellulose decomposition in the soil is determined by the combined action of several factors: weather conditions, the nature of vegetation, the amount of organic matter entering the soil, soil type, its physical properties, chemical composition. In an urban environment, the intensity of cellulosolytic processes is also regulated by the nature and degree of anthropogenic impact on soil, atmosphere and vegetation. The intensity of cellulose destruction in the city soils is estimated to be very weak, weak and medium. The cellulolytic processes in the soils of the city of Odessa in 2021 were stimulated by abundant precipitation (r = 1,000). The decrease in CA in some parts of the city may be due to minimal anthropogenic impact on the soil cover.

Oxidative cleavage of cellulose in the horse gut

BackgroundLytic polysaccharide monooxygenases (LPMOs) belonging to the auxiliary activity 9 family (AA9) are widely found in aerobic fungi. These enzymes are O2-dependent copper oxidoreductases that catalyze the oxidative cleavage of cellulose. However, studies that have investigated AA9 LPMOs of aerobic fungi in the herbivore gut are scare. To date, whether oxidative cleavage of cellulose occurs in the herbivore gut is unknown.ResultsWe report for the first time experimental evidence that AA9 LPMOs from aerobic thermophilic fungi catalyze the oxidative cleavage of cellulose present in the horse gut to C1-oxidized cellulose and C1- and C4-oxidized cello-oligosaccharides. We isolated and identified three thermophilic fungi and measured their growth and AA9 LPMO expression at 37 °C in vitro. We also assessed the expression and the presence of AA9 LPMOs from thermophilic fungi in situ. Finally, we used two recombinant AA9 LPMOs and a native AA9 LPMO from thermophilic fungi to cleave cellulose to yield C1-oxidized products at 37 °C in vitro.ConclusionsThe oxidative cleavage of cellulose occurs in the horse gut. This finding will broaden the known the biological functions of the ubiquitous LPMOs and aid in determining biological significance of aerobic thermophilic fungi.

A thermostable bacterial lytic polysaccharide monooxygenase with high operational stability in a wide temperature range

BackgroundLytic polysaccharide monooxygenases (LPMOs) are oxidative, copper-dependent enzymes that function as powerful tools in the turnover of various biomasses, including lignocellulosic plant biomass. While LPMOs are considered to be of great importance for biorefineries, little is known about industrial relevant properties such as the ability to operate at high temperatures. Here, we describe a thermostable, cellulose-active LPMO from a high-temperature compost metagenome (called mgLPMO10).ResultsMgLPMO10 was found to have the highest apparent melting temperature (83 °C) reported for an LPMO to date, and is catalytically active up to temperatures of at least 80 °C. Generally, mgLPMO10 showed good activity and operational stability over a wide temperature range. The LPMO boosted cellulose saccharification by recombinantly produced GH48 and GH6 cellobiohydrolases derived from the same metagenome, albeit to a minor extent. Cellulose saccharification studies with a commercial cellulase cocktail (Celluclast®) showed that the performance of this thermostable bacterial LPMO is comparable with that of a frequently utilized fungal LPMO from Thermoascus aurantiacus (TaLPMO9A).ConclusionsThe high activity and operational stability of mgLPMO10 are of both fundamental and applied interest. The ability of mgLPMO10 to perform oxidative cleavage of cellulose at 80 °C and the clear synergy with Celluclast® make this enzyme an interesting candidate in the development of thermostable enzyme cocktails for use in lignocellulosic biorefineries.

Cleavage of cellulose by a CBM33 protein

Bacterial proteins categorized as family 33 carbohydrate-binding modules (CBM33) were recently shown to cleave crystalline chitin, using a mechanism that involves hydrolysis and oxidation. We show here that some members of the CBM33 family cleave crystalline cellulose as demonstrated by chromatographic and mass spectrometric analyses of soluble products released from Avicel or filter paper on incubation with CelS2, a CBM33-containing protein from Streptomyces coelicolor A3(2). These enzymes act synergistically with cellulases and may thus become important tools for efficient conversion of lignocellulosic biomass. Fungal proteins classified as glycoside hydrolase family 61 that are known to act synergistically with cellulases are likely to use a similar mechanism.

The behavior and derivatizations of carbohydrates in hydrogen fluoride

Low molecular weight β, 1 → 4-glucans (cellodextrins) are favorably prepared by cleavage of cellulose in liquid hydrogen fluoride at temperatures between −15 and −30°C. This is due to the suppression of the reversion reaction in that low temperature range. Under conditions favorable for reversion the presence of water leads to a competing hydrolysis and lower the average degree of polycondensation. For the preparation of defined O-glycosides from glucose and alcohols, hydrogen fluoride is not suitable as a reaction medium. Under reversion conditions, monohydroxy compounds are inferior in their reactivity to the competing carbohydrate molecules, and polyols like sorbitol furnish mixtures of isomeric glycosides. Gaseous hydrogen fluoride represents a highly suitable agent for the degradation of carbohydrate and lignin containing biomass, such as waste wood, for the purpose of providing fermentation raw material. As a model, lignocellulose was studied and the heat of reaction of the hydrogen fluoride sorption and desorption processes were examined. The practically important desorption value was found to be approximately 870 kJ/kg HF.