Upgrading the Nutritional Value of PKC Using a Bacillus subtilis Derived Monocomponent β-Mannanase

Abstract

Palm kernel cake (PKC) is an abundant side stream that can only be added to non-ruminant feed in small concentrations due to its content of antinutritional factors, mainly galactomannan, which cannot be digested by non-ruminants. β-mannanases can be added to partially hydrolyze galactomannan to form mannose oligosaccharides, which are known to be prebiotic. We here investigate the action of a β-mannanase from B. subtilis on PKC by colorimetry, NMR and fluorescence microscopy. The amount of mannan oligosaccharides in solution was significantly increased by the β-mannanase and their degree of polymerization (DP) was significantly reduced. There was a dose-response behavior in that larger β-mannanase concentrations increased the amount of soluble mannose oligosaccharides while reducing their average DP. Using confocal immunofluorescence microscopy, solubilization of galactomannan in PKC was clearly visualized. Images show a clear disruption of the cellulose and galactomannan structures of the PKC cell walls. We thus show in this study that using commercial dosages of β-mannanase on PKC can lead to formation of prebiotic compounds. Thus, this study suggests that utilization of PKC in poultry feed formulation might be increased by addition of a β-mannanase and would improve the return on investment.

Nutrient Composition and Cell-Wall Structure of Palm Kernel Cake Supplemented with Enzymes

“…PKC has a nonporous surface, whereas its fermented counterpart exhibits a looser shape and better microbial penetration and aeration (Saw et al, 2012). Osorio et al (2022) reported that using confocal immunofluorescence, showed a disruption in the structure of cellulose and galactomannan in the cell wall of PKC treated with β-mananase enzyme. This suggests that the use of β-mananase in PKC could convert mannan into mannan oligosaccharides, leading to the formation of prebiotic compounds.…”

Improving Mannanase Production inBacillus subtilisfor Fibre Hydrolysis during Solid-State Fermentation of Palm Kernel Meal

“…Microscopy images of PKC cell wall showed an overlapping signal from mannan and cellulose (Gomez-Osorio et al, 2022). The close association between mannan and other polysaccharides may hinder the accessibility of mannan for further hydrolysis.…”

Emericella nidulans (4DP5), Cladosporium herbarum (7DF12) and Bacillus subtilis improve the nutritional value of palm kernel cake (PKC) through solid-state fermentation (SSF)

“…are strong producers of β-mannanase (Abe et al, 1994;Chin, 2006;Pangsri et al, 2015;Gomez-Osorio et al, 2022). Several studies also reported that B. subtilis has high βmannanase activities and is capable of hydrolysing hemicellulose (Cheng et al, 2016) including those in PKC (Gomez-Osorio et al, 2022). Interestingly, Treatment 1 consisting of only three Bacilli spp.…”