Structure Of Cell Wall Polymers Research Articles

Cell wall hydrolases act in concert during aerenchyma development in sugarcane roots.

Cell wall disassembly occurs naturally in plants by the action of several glycosyl-hydrolases during different developmental processes such as lysigenous and constitutive aerenchyma formation in sugarcane roots. Wall degradation has been reported in aerenchyma development in different species, but little is known about the action of glycosyl-hydrolases in this process. In this work, gene expression, protein levels and enzymatic activity of cell wall hydrolases were assessed. Since aerenchyma formation is constitutive in sugarcane roots, they were assessed in segments corresponding to the first 5 cm from the root tip where aerenchyma develops. Our results indicate that the wall degradation starts with a partial attack on pectins (by acetyl esterases, endopolygalacturonases, β-galactosidases and α-arabinofuranosidases) followed by the action of β-glucan-/callose-hydrolysing enzymes. At the same time, there are modifications in arabinoxylan (by α-arabinofuranosidases), xyloglucan (by XTH), xyloglucan-cellulose interactions (by expansins) and partial hydrolysis of cellulose. Saccharification revealed that access to the cell wall varies among segments, consistent with an increase in recalcitrance and composite formation during aerenchyma development. Our findings corroborate the hypothesis that hydrolases are synchronically synthesized, leading to cell wall modifications that are modulated by the fine structure of cell wall polymers during aerenchyma formation in the cortex of sugarcane roots.

Changes in the structure of cell wall polymers in thermomechanical treatment of highly lignified plant feedstock

The effect of mechanical treatment at various temperatures on structural changes in polymers contained in highly lignified plant feedstock was studied by the example of reed stems. The optimal conditions (about 10°C) of mechanical activation of plant feedstock were determined, under which its structure is disordered enough for subsequent enzymatic hydrolysis, but the lignin decomposition is prevented, and so is the formation of a layer of substances inhibiting enzymes on the surface of particles.

Mechanically activated enzymatic hydrolysis of yeast biomass

Experimental data obtained in studying processes that occur during the mechanoenzymatic hydrolysis of cell wall polymers of Saccharomyces cerevisiae yeast are presented. Special emphasis is placed on studying the reactivity of polymers contained in the supramolecular structure of cell walls, and on scaling the technology using pilot and industrial equipment. It is shown that mechanical treatment of yeast biomass allows us to alter the supramolecular structure of cell wall polymers and increase their reactivity in the enzymatic hydrolysis. Mechanical treatment disintegrates yeast cells and changes the supramolecular structure of polymers in their cell walls; the structural layers of a cell wall become disordered and diffused. A phenomenological model of mechanically activated enzymatic hydrolysis is proposed; the model is based on an autolocalization mechanism of the process. The domestic commercially available enzyme preparation CelloLux 2000 (OOO PA Sibbiopharm, Berdsk, Novosibirsk oblast) is used in this work. It is shown that changes in the supramolecular structure of yeast cell wall polymers occur during mechanically activated enzymatic hydrolysis. The yields of mannanoligosaccharides (1.1%) and mannanoproteins (2.7%) in the main extract are determined. Using pilot and industrial equipment at OOO PA Sibbiopharm, the technology is scaled and the production of a new mannanoligosaccharide product for animal husbandry is established. The pilot batch of the final product is effective against salmonellosis and is shown to increase the weight gain of experimental animals.

Mechanically Activated Enzymatic Hydrolysis of Yeast Biomass

Experimental studies were focused on the processes that occur during mechanoenzymatic hydrolysis of cell wall polymers of yeast Saccharomyces cerevisiae. Particular attention was paid to the reactivities of polymers involved in the supramolecular structures of the cell walls, as well as to the technology scaling-up using pilot and industrial facilities. The Russian commercially available enzymatic agent CelloLux 2000 (from Sibbiofarm LLC, Berdsk) was used for the studies. It was shown that mechanical treatment of the yeast biomass allows the supramolecular structure of cell wall polymers to be changed and their reactivity to enzymatic hydrolysis to be improved. The yields of mannanoligosaccharide (1,1 %) and mannanoproteins (2,7 %) to the alkali extract were determined. A phenomenological model based on autolocalized process mechanism was suggested for the mechanically activated enzymatic hydrolysis. Pilot and industrial facilities of Sibbiofarm LLC was used for the technology scaling-up and for preparation of the new mannanoligosaccharide product for animal industry. A pilot batch of the product was tested, its efficiency in fighting salmonellosis and gaining in weight of animals demonstrated.

Factors contributing to helical shape determination and maintenance in Bacillus subtilis macrofibres

Bacillus subtilis, normally a rod-shaped organism, can grow in the form of a helix with pitch ranging over a spectrum from tight right-handed to tight left-handed depending upon the growth environment and genetic composition of the strain. Five factors have been identified which contribute either to the helical shape deformation or its maintenance: 1) a biomechanical component involving blocked rotation during growth; 2) cell wall polymer conformation; 3) a protein(s) concerned with the left-hand form produced at high temperature; 4) electrostatic aspects of the cell wall; and 5) water, as it affects the mechanical properties of cell walls and the structure of cell wall polymers. The findings are compatible with a model in which the cell wall polymers are inserted in helical orientation along the cylindrical portion of the cell during growth.