High Enzymatic Recovery and Purification of Xylooligosaccharides from Empty Fruit Bunch via Nanofiltration

Hans Wijaya,Bambang Prasetya,Kengo Sasaki,Chiaki Ogino,Nanik Rahmani,Akihiko Kondo,Yopi Yopi,Euis Hermiati,Prihardi Kahar

doi:10.3390/pr8050619

Abstract

Xylooligosaccharides (XOS) are attracting an ever-increasing amount of interest for use as food prebiotics. In this study, we used efficient membrane separation technology to convert lignocellulosic materials into a renewable source of XOS. This study revealed a dual function of nanofiltration membranes by first achieving a high yield of xylobiose (a main component of XOS) from alkali-pretreated empty fruit bunch (EFB) hydrolysate, and then by achieving a high degree of separation for xylose as a monosaccharide product. Alkali pretreatment could increase the xylan content retention of raw EFB from 23.4% to 26.9%, which eventually contributed to higher yields of both xylobiose and xylose. Nanofiltration increased the total amount of XYN10Ks_480 endoxylanase produced from recombinant Streptomyces lividans 1326 without altering its specific activity. Concentrated XYN10Ks_480 endoxylanase was applied to the recovery of both xylobiose and xylose from alkali-pretreated EFB hydrolysate. Xylobiose and xylose yields reached 41.1% and 17.3%, respectively, and when unconcentrated XYN10Ks_480 endoxylanase was applied, those yields reached 35.1% and 8.3%, respectively. The last step in nanofiltration was to separate xylobiose over xylose, and 41.3 g.L−1 xylobiose (90.1% purity over xylose) was achieved. This nanofiltration method should shorten the processes used to obtain XOS as a high-value end product from lignocellulosic biomass.

Highlights

The use of xylooligosaccharides (XOS) as ingredients in functional foods has increased rapidly because prebiotic oligosaccharides (OS) have various beneficial health effects, such as enhancing mineral absorption and suppressing the activity of harmful or putrefactive bacteria [1,2,3,4,5]
The first purpose of this study was to increase the yield of XOS from alkali-pretreated empty fruit bunch (EFB) obtained by enzymatic hydrolysis using XYN10Ks_480 endoxylanase produced by S. lividans 1326, expressing an endo-xylanase gene from the Kitasatospora sp. strain ID06-480
The high-performance liquid chromatographic (HPLC) was equipped with a refractive index (RI) detector and a column set of dual series TSKgel G2500PWXL

Summary

Introduction

The use of xylooligosaccharides (XOS) as ingredients in functional foods has increased rapidly because prebiotic oligosaccharides (OS) have various beneficial health effects, such as enhancing mineral absorption and suppressing the activity of harmful or putrefactive bacteria [1,2,3,4,5]. XOS are sugar oligomers comprised of xylose units through β-(1-4)-xylosidic linkages that are produced from lignocellulosic materials [1,4]. XOS are produced using chemical, enzymatic, or autohydrolysis methods. In order to increase the production of XOS, the hydrolysates produced by these processes must be refined, and by-products such as monosaccharides and monosaccharide compounds must be separated to increase the purity of XOS [6,7,8]. Enzymatic hydrolysis by xylanase produces monosaccharides in addition to XOS, which lowers the concentration of XOS [9]. The microbial production of recombinant endo-1,4-β-xylanase (XYN10Ks_480 endoxylanase) was realized using Streptomyces lividans 1326 expressing an endoxylanase gene from the Kitasatospora sp

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Conclusion