A multienzyme NSP product solubilises and degrades NSP structures in canola and mediates protein solubilisation and degradation in vitro

Abstract

To conclusively assess the value enhancing effect of enzymes targeting antinutritional non–starch polysaccharides in a specific feed source, in depth understanding of the substrate is required, to use the right enzyme for the relevant polysaccharides. In the current study a commercial non-starch polysaccharide multienzyme product obtained by submerged fermentation of Aspergillus aculeatus was supplemented to canola non-starch polysaccharides. The enzyme effects studied included substrate viscosity reduction and solubilisation of non-starch polysaccharides and crude protein as well as peptide cleavage. Results were compared with the effects obtained by a monocomponent protease and a combination of protease and the multienzyme product. Viscosity reduction of solutions of xyloglucan and galactomannan solution clearly showed the presence of xyloglucanase and galactomannan activity in the product. On enzyme supplementation, there was an increase (P<0.05) in the solubilisation of rhamnose, fucose, arabinose, xylose, galactose and glucose non-starch polysaccharide residues. In a separate experiment using a different measuring system (HPLC) the product was also shown to solubilise galacturonic acid from canola meal. Highest concentrations of solubilised crude protein and peptides measured by combining the protease and the multienzyme product together.Antibodies (LM25, LM19 and LM 6) targeting different cell wall components were used in microscopy studies. Monoclonal antibody LM25, directed towards xyloglucan, bound abundantly to the intercellular spaces on the cytoplasmic side of the cell wall lining. On enzyme treatment with the multienzyme product the LM25 binding disappeared, indicating a reduction of xyloglucans as also was observed in a polysaccharide analysis of enzyme incubated canola meal.Monoclonal antibody LM19 recognizes de-esterified homogalacturonan epitopes in pectin also bound to the uronic acid residues in canola meal. The LM 19 signal was weak in samples treated only with buffer, but became stronger when the xyloglucan layer was removed by a purified experimental xyloglucanase.Monoclonal antibody LM6, directed towards arabinan, also became more visible in canola meal after the removal of the xyloglucan layer by the experimental xyloglucanase.Treatment with the commercial non starch polysaccharide multienzyme product resulted in degradation of arabinan and thereby also a disappearance of the LM6 signal. Both the pectin and the arabinan signal were visible mainly/only after removal of the xyloglucan layer in both the seed and the meal.