Characterisation of cellulose and hemicellulose digestion in land crabs with special reference to Gecarcoidea natalis

2011 ◽  
Vol 59 (6) ◽  
pp. 380 ◽  
Author(s):  
Benjamin J. Allardyce ◽  
Stuart M. Linton

This article reviews the current knowledge of cellulose and hemicellulose digestion by herbivorous land crabs using the gecarcinid Gecarcoidea natalis as a model species for this group. Cellulose digestion in the gecarcinids is hypothesised to require mechanical fragmentation and enzymatic hydrolysis. Mechanical fragmentation is achieved by the chelae, mandibles and gastric mill, which reduce the material to particles less than 53 µm. The gastric mill shows adaptations towards a plant diet; in particular, there are transverse ridges on the medial and lateral teeth and ventral cusps on the lateral teeth that complement and interlock to provide efficient cutting surfaces. Enzymatic hydrolysis of cellulose and hemicellulose is achieved through cellulase and hemicellulase enzymes. In the gecarcinids, 2–3 endo-β-1,4-glucanases, one β-glucohydrolase and a laminarinase have been identified. The endo-β-1,4-glucanases are multifunctional, with both endo-β-1,4-glucanase and lichenase activity. Complete cellulose hydrolysis is achieved through the synergistic action of the endo-β-1,4-glucanase and β-glucohydrolase. The evidence for the endogenous production of the cellulase and hemicellulase enzymes, their evolutionary origin and possible evolution in invertebrates as they colonised land is also discussed.

2018 ◽  
pp. 1-9
Author(s):  
Mirjana Antov ◽  
Aleksandar Fistes

Sugar beet shreds were pretreated by hydrothermal procedure to investigate the effect of beta-glucosidase supplementation at different substrate loading on the rate of cellulose hydrolysis. Cellulose in the hydrothermally pretreated substrate was more efficiently hydrolyzed by enzymes than in untreated material, resulting in more than two times higher release of reducing sugars. In the investigated range of solids load, supplementation of fungal cellulases cocktail by beta-glucosidase increased production of reducing sugars from substrates, while 0.25 U/g was sufficient to achieve the highest effect under applied conditions.


2012 ◽  
Vol 60 (5) ◽  
pp. 299 ◽  
Author(s):  
Benjamin J. Allardyce ◽  
Stuart M. Linton

This study investigated synergism between endo-β-1,4-glucanase and β-glucohydrolase enzymes from Gecarcoidea natalis. Together, these enzymes efficiently hydrolyse the cellulose-like polymer, carboxymethyl cellulose, to glucose. Endo-β-1,4-glucanase and β-glucohydrolase, isolated previously from G. natalis, were incubated in vitro using a ratio of the measured activities that matches that found in their digestive juice (5.4 : 1). Their combined activity, measured as the release of glucose from carboxymethyl cellulose, was greater than the sum of their separate activities. Hence they synergistically released glucose from carboxymethyl cellulose (degree of synergy: 1.27). This may be due to the complementary nature of the products of endo-β-1,4-glucanase activity and the preferred substrates of the β-glucohydrolase. β-glucohydrolase may also enhance cellulose hydrolysis by removing cellobiose, a potential competitive inhibitor of endo-β-1,4-glucanase. The synergistic interaction of these two enzymes further supports the previous suggestion that this species possesses a novel two-enzyme cellulase system that differs from the traditional three-enzyme fungal model.


2019 ◽  
Vol 15 (3) ◽  
pp. 296-303 ◽  
Author(s):  
Swapnil Gaikwad ◽  
Avinash P. Ingle ◽  
Silvio Silverio da Silva ◽  
Mahendra Rai

Background: Enzymatic hydrolysis of cellulose is an expensive approach due to the high cost of an enzyme involved in the process. The goal of the current study was to apply magnetic nanomaterials as a support for immobilization of enzyme, which helps in the repeated use of immobilized enzyme for hydrolysis to make the process cost-effective. In addition, it will also provide stability to enzyme and increase its catalytic activity. Objective: The main aim of the present study is to immobilize cellulase enzyme on Magnetic Nanoparticles (MNPs) in order to enable the enzyme to be re-used for clean sugar production from cellulose. Methods: MNPs were synthesized using chemical precipitation methods and characterized by different techniques. Further, cellulase enzyme was immobilized on MNPs and efficacy of free and immobilized cellulase for hydrolysis of cellulose was evaluated. Results: Enzymatic hydrolysis of cellulose by immobilized enzyme showed enhanced catalytic activity after 48 hours compared to free enzyme. In first cycle of hydrolysis, immobilized enzyme hydrolyzed the cellulose and produced 19.5 ± 0.15 gm/L of glucose after 48 hours. On the contrary, free enzyme produced only 13.7 ± 0.25 gm/L of glucose in 48 hours. Immobilized enzyme maintained its stability and produced 6.15 ± 0.15 and 3.03 ± 0.25 gm/L of glucose in second and third cycle, respectively after 48 hours. Conclusion: This study will be very useful for sugar production because of enzyme binding efficiency and admirable reusability of immobilized enzyme, which leads to the significant increase in production of sugar from cellulosic materials.


2013 ◽  
Vol 85 (17) ◽  
pp. 8121-8126 ◽  
Author(s):  
Britta Opitz ◽  
Andreas Prediger ◽  
Christian Lüder ◽  
Marrit Eckstein ◽  
Lutz Hilterhaus ◽  
...  

2015 ◽  
Vol 51 (52) ◽  
pp. 10502-10505 ◽  
Author(s):  
Aiping Chang ◽  
Qingshi Wu ◽  
Wenting Xu ◽  
Jianda Xie ◽  
Weitai Wu

The physical trapping of cellulose in microgels leads to a low-ordered cellulose, favoring enzymatic hydrolysis of cellulose to generate glucose.


1977 ◽  
Vol 23 (2) ◽  
pp. 139-147 ◽  
Author(s):  
D. Sternberg ◽  
P. Vuayakumar ◽  
E. T. Reese

The enzymatic conversion of cellulose is catalyzed by a multiple enzyme system. The Trichoderma enzyme system has been studied extensively and has insufficient β-glucosidase (EC 3.2.1.21) activity for the practical saccharification of cellulose. The black aspergilli (A. niger and A. phoenicis) were superior producers of β-glucosidase and a method for production of this enzyme in liquid culture is presented. When Trichoderma cellulase preparations are supplemented with β-glucosidase from Aspergillus during practical saccharifications, glucose is the predominant product and the rate of saccharification is significantly increased. The stimulatory effect of β-glucosidase appears to be due to the removal of inhibitory levels of cellobiose.


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