Changes of supramolecular cellulose structure and accessibility induced by the processive endoglucanase Cel9B from Paenibacillus barcinonensis

The gene yvpA from Bacillus subtilis was cloned and expressed in Escherichia coli. It encoded a pectate lyase of 221 amino acids that was denominated PelC. The heterologously expressed enzyme was purified by His-tag affinity chromatography and characterized. PelC depolymerized polygalacturonate and pectins of methyl esterification degree from 22 % to 89 %, exhibiting maximum activity on 22 % esterified citrus pectin. It showed an absolute Ca2+ requirement and the optimum temperature and pH were 65 °C and pH 10, respectively. The deduced amino acid sequence of PelC showed 53 % identity to pectate lyase PelA from Paenibacillus barcinonensis, which was also characterized. Similarly to PelC, purified PelA showed activity on polygalacturonate and pectins with a high degree of methyl esterification. The two enzymes cleaved pectic polymers to a mixture of oligogalacturonates, indicating an endo mode of action. Analysis of activity on trigalacturonate showed that PelC cleaved it to galacturonic acid and unsaturated digalacturonate, whereas PelA did not show activity on this substrate. PelC and PelA showed high homology to a few recently identified pectate lyases of family 3 and form with them a cluster of small-sized pectate lyases from non-pathogenic micro-organisms.

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Influence of Cellulose Structure on Its Digestibility in the Rat

Journal of Nutrition ◽

10.1093/jn/119.6.872 ◽

1989 ◽

Vol 119 (6) ◽

pp. 872-878 ◽

Cited By ~ 21

Author(s):

Juinn-Chin Hsu ◽

Michael H. Penner

Keyword(s):

Cellulose Structure

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Cellulose structure modification and hydrolysis, Raymond A. Young and Roger M. Rowell, Eds., Wiley-Interscience, New York, 1986, 379 pp.

Journal of Polymer Science Part C Polymer Letters ◽

10.1002/pol.1987.140250313 ◽

1987 ◽

Vol 25 (3) ◽

pp. 139-140

Author(s):

R. H. Marchessault

Keyword(s):

New York ◽

Structure Modification ◽

Cellulose Structure

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ALKALINE HYDROLYSIS OF MUNITIONS-GRADE NITROCELLULOSE

Water Science & Technology ◽

10.2166/wst.1994.0065 ◽

1994 ◽

Vol 30 (3) ◽

pp. 63-72 ◽

Cited By ~ 12

Author(s):

James E. Alleman ◽

Byung J. Kim ◽

David M. Quivey ◽

Lucina O. Equihua

Keyword(s):

Alkaline Hydrolysis ◽

Environmental Problem ◽

Research Effort ◽

Chemical Degradation ◽

Cellulose Structure ◽

Manufacturing Operations ◽

Explosive Materials ◽

High Level ◽

Hydrolysis Of ◽

Lower Contact

Cellulose nitrate compounds constitute an important industrial feedstock, with applications ranging from fingernail polish to photographic films to explosives. Indeed, the latter use has strategic implications associated with the production of military munitions. However, the particularly high level of cellulose nitration required for these explosive materials creates a significant environmental problem with respect to the necessary degradation of waste ‘fines’ inevitably discharged from their manufacturing operations. Rather ironically, these waste solids have proven to be remarkably stable, leading to a traditional reliance upon a primitive treatment approach (i.e., open-field incineration) which is neither safe nor environmentally acceptable. This paper, therefore, describes an alternative chemical degradation procedure based on alkaline hydrolysis. Primarily using sodium hydroxide at low percent dosage levels, this research effort has successfully achieved significant levels of denitration and apparent breakdown of the backbone cellulose structure. Furthermore, as compared with prior research on thi s topic, these results were achieved at markedly lower contact times and temperatures. However, two uncertainties still remain regarding this process, involving both the fate of a significant fraction of the original nitrogen and the apparently lingering recalcitrant nature of the post-degradation organics. In both cases, ongoing investigations have been instituted to resolve these issues.

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Regulation of Major Cellulosomal Endoglucanases of Clostridium thermocellum Differs from That of a Prominent Cellulosomal Xylanase

Journal of Bacteriology ◽

10.1128/jb.187.7.2261-2266.2005 ◽

2005 ◽

Vol 187 (7) ◽

pp. 2261-2266 ◽

Cited By ~ 37

Author(s):

Tali W. Dror ◽

Adi Rolider ◽

Edward A. Bayer ◽

Raphael Lamed ◽

Yuval Shoham

Keyword(s):

Growth Rate ◽

Clostridium Thermocellum ◽

Transcript Level ◽

Clear Correlation ◽

Transcript Levels ◽

Batch Cultures ◽

Processive Endoglucanase ◽

The Family ◽

Genes Encoding ◽

Family 10 Xylanase

ABSTRACT The expression of scaffoldin-anchoring genes and one of the major processive endoglucanases (CelS) from the cellulosome of Clostridium thermocellum has been shown to be dependent on the growth rate. For the present work, we studied the gene regulation of selected cellulosomal endoglucanases and a major xylanase in order to examine the previously observed substrate-linked alterations in cellulosome composition. For this purpose, the transcript levels of genes encoding endoglucanases CelB, CelG, and CelD and the family 10 xylanase XynC were determined in batch cultures, grown on either cellobiose or cellulose, and in carbon-limited continuous cultures at different dilution rates. Under all conditions tested, the transcript levels of celB and celG were at least 10-fold higher than that of celD. Like the major processive endoglucanase CelS, the transcript levels of these endoglucanase genes were also dependent on the growth rate. Thus, at a rate of 0.04 h−1, the levels of celB, celG, and celD were threefold higher than those obtained in cultures grown at maximal rates (0.35 h−1) on cellobiose. In contrast, no clear correlation was observed between the transcript level of xynC and the growth rate—the levels remained relatively high, fluctuating between 30 and 50 transcripts per cell. The results suggest that the regulation of C. thermocellum endoglucanases is similar to that of the processive endoglucanase celS but differs from that of a major cellulosomal xylanase in that expression of the latter enzyme is independent of the growth rate.

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Uptake of p-Nitrophenol (PNP) from model aqueous solutions using raw and quaternised Afromomum melegueta peels

African Journal of Pure and Applied Sciences ◽

10.33886/ajpas.v1i1.165 ◽

2020 ◽

Vol 1 (1) ◽

pp. 1-8

Author(s):

J. Ndiritu ◽

I W. Mwangi ◽

J. I. Murungi ◽

R. N. Wanjau

Keyword(s):

Quaternary Ammonium ◽

Anthropogenic Activities ◽

Freundlich Isotherm ◽

Isotherm Models ◽

Ammonium Compound ◽

Cellulose Structure ◽

Experimental Parameters ◽

Ftir Technique ◽

Design Simplicity ◽

The Impact

Anthropogenic activities contribute large amounts of pollutants to the environment which threaten animal and human health. There is increased realization of the effect of these toxins on surface and ground water, consequently, their elimination is vital in rendering secure water for drinking as well as culpable release of effluents to our habitats. Phenolic compounds cause serious health effects to both humans and animals; a p-Nitrophenol concentration of 1 ppb changes the taste and odour of water as well as meat and fish quality. In humans, exposure to PNP causes eye and skin burns while its interaction with blood leads to confusion, cyanosis and unconsciousness. It is imperative therefore to find ways for removing PNP from water. Among the available techniques for removing PNP from water, adsorption is more convenient and offers more advantages because of its design, simplicity, and operating flexibility. The present study involved application of peels of raw Afromomum melegueta (RAM) and quaternised Afromomum melegueta (QAM) to remove PNP from water through adsorption. The raw adsorbents were modified with a quaternary ammonium salt to improve their uptake efficiency. The impact of experimental parameters; contact time, pH, sorbent dose, temperature and concentration were investigated. Attenuated FTIR technique was employed to characterize the adsorbent materials. It was established that the quaternary ammonium compound was anchored chemically within the cellulose structure of Afromomum melegueta peels. The behavior of adsorption of PNP was investigated using Langmuir and Freundlich isotherm models. The physical sorption load was 8.70 and 106.38 mg/g for RAM and QAM peels respectively from Langmuir adsorption equation. Uptake of PNP is high at the first 30 mins of contact and at sorbent dosage of 0.01 g and 0.03 g for RAM and QAM respectively. Quantity of PNP removed increases as the initial concentration rises however, adsorption decreases after a concentration exceeding 30 mg/L. The ideal pH and temperature for PNP removal is at pH 3 and 25 ˚C respectively. In conclusion, the findings suggest that Afromomum melegueta peels can be friendly to the environment, cheap biosorbents and efficient which can be applied for the uptake of PNP from drinking water

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Calorimetry, chemical composition and in vitro digestibility of sugarcane treated with calcium hydroxide

Crop and Pasture Science ◽

10.1071/cp17287 ◽

2018 ◽

Vol 69 (4) ◽

pp. 406

Author(s):

Alexandre M. Dias ◽

Luís C. V. Ítavo ◽

Júlio C. Damasceno ◽

Camila C. B. F. Ítavo ◽

Geraldo T. Santos ◽

...

Keyword(s):

Weight Loss ◽

Chemical Composition ◽

Calcium Hydroxide ◽

Nutritive Value ◽

Low Cost ◽

Alkaline Treatment ◽

In Vitro Digestibility ◽

Cellulose Structure ◽

High Dry Matter

Sugarcane is a source of roughage in animal feeding. It presents high production per unit of cultivated area, relatively easy cultivation and low cost of production per hectare, and better quality and a high dry matter (DM) yield in periods when forage is scarce. This study aimed to evaluate the effect of increasing levels of calcium hydroxide (Ca(OH)2) in sugarcane forage on chemical composition, in vitro digestibility values of DM, neutral detergent fibre (NDF) and acid detergent fibre (ADF), and kinetics of thermal decomposition processes of weight loss and heat flow. Sugarcane was collected close to the ground and 50-kg heaps of the fresh material were formed and mixed with four doses of Ca(OH)2 (0, 8, 16 and 24 g kg–1 sugarcane). Concentrations of NDF and ADF decreased linearly with increasing amount of Ca(OH)2, whereas concentration of hemicellulose increased linearly. In vitro digestibilities of DM, NDF and ADF were enhanced in a quadratic manner with increasing amounts of Ca(OH)2. The release of heat, measured by ΔH, increased linearly with increased Ca(OH)2 levels, likely due to enhanced digestibility of the fibre components. Weight loss decreased linearly between 272.2°C and 397.7°C with increased amounts of Ca(OH)2 added to sugarcane, likely due to changes in cellulose structure, which became denser and thermodynamically more stable than native cellulose following the alkaline treatment. Calcium hydroxide changed chemical composition and digestibility of the fibrous fraction of sugarcane, resulting in better nutritional value. The greatest release of heat and highest in vitro digestibility of fibre were observed when adding 15.2 g Ca(OH)2 kg–1 sugarcane; therefore, this dose is recommended to enhance the nutritive value of sugarcane as ruminant feed.

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