APPLICATION OF MANNANASE FROM LOCALLY ISOLATED BACILLUS SPP. PKC3 TO PRODUCE OLIGOSACCHARIDES FROM PALM KERNEL CAKE

Abstract

Palm kernel cake (PKC) is the by-product of oil palm industry which contains a high amount of mannan. This component acts as anti-nutrient resulting the application of this by-product is limited to ruminants. However, mannan can be converted into oligosaccharides which also a potential source of prebiotic. In this study, icroorganisms were isolated from different kind of sources namely decayed oil palm trunk, decayed oil palm fronds, the soil underneath oil palm tree, PKC, and rotten fruits. The isolated microorganisms were screened for the ability to produce cell walldegrading enzymes such as mannanase, amylase, cellulase, pectinase, and xylanase. The selected microorganism was fermented in a shake flask and subsequently, the nitrogen and carbon content in the medium were studied to obtain the maximum yield of mannanase. Production of mannanase was upscaled to a 2 L bioreactor after selection. The enzyme obtained from the broth was partially purified using ammonium sulphate precipitation method and the best pH and temperature for the enzyme were determined. Oligosaccharides were produced by treating the PKC with partially purified mannanase and the prebiotic properties were tested against commercial probiotics to determine its effectiveness. The mannan-degrading enzyme was obtained from the fermentation of locust bean gum using isolate named Bacillus spp. PKC3 as an inoculum. The best nitrogen and carbon source for the production of mannan-degrading enzyme were 0.5 % (w/v) peptone from soymeal and 4.0 % (w/v) locust bean gum respectively. At this selected condition, highest mannanase activity was obtained which is at 0.14 U/mL. Highest specific activity of partially purified mannanase was obtained at 60 % ammonium sulphate concentration which gives the value of 0.48 U/mg protein and this enzyme attained its highest activity at pH 5 and 40 °C. Treating PKC with the enzyme altered the surface structure of PKC and also released a number of oligosaccharides into the filtrate. The oligosaccharides released include mannotetraose, mannopentaose, and other xylan- and cellulosederived oligosaccharides. Prebiotic effectiveness test proves that this treated PKC have the potential to be a source of prebiotic. Two out of three probiotics tested gives a positive result in prebiotic activity score.