An enzymatic approach to cell wall structure

Abstract

Ruminococcus albus was incubated with isolated alfalfa cell wall material for 72 h in batch culture. Cellulose in the cell walls was digested to a somewhat greater extent (88%) than were the fermentable sugars of the hemicellulose fraction (62- 76%). The digestibility of the total insoluble alfalfa cell wall, including lignin but not material solubilized during heat sterilization, was 66%. A cellulase, a-arabinosidase and xylanase were partially purified from the concentrated supernatant of R. albus cultures and a purified polygalacturonase was obtained from the fungus Verticillium. Of the enzymes tested, the most effective in digesting cell walls was the polygalacturonase. In addition, when mixed with a-arabinosidase, the amount digested exceeded the sum of the materials digested by the two enzymes separately.

Ruminococcus albus is vir 72 h met ge"isoleerde lusernselwandmateriaal ge"inkubeer in lotskultuur. Die sellulose in die selwande is tot 'n groter mate (88%) verteer as die fermenteerbare suikers van die hemisellulose gedeelte (62- 76%). Die verteerbaarheid van die totale onoplosbare lusern selwande, insluitende lignien, maar nie materiaal wat tydens hittesterilisasie opgelos is nie, was 66%. 'n Sellulase, aarabinosidase en xilanase is gedeeltelik gesuiwer vanuit die gekonsentreerde supernaat van die R. albus kulture en 'n gesuiwerde poligalakturonase is van die fungus Verticillium verkry. Van die ensieme wat getoets is, was die poligalakturonase die mees effektiewe verteerder van selwande. Verder het dit, wanneer gemeng met aarabinosidase, 'n groter hoeveelheid selwandmateriaal verteer as die hoeveelheid materiaal verteer deur die twee ensieme afsonderlik.

Keywords: Ruminococcus albus, alfalfa cell walls, cellulose, hemicellulose, enzymic digestion