흰 코뿔소 배설물로부터 분리한 Bacillus pumilus H10-1의 Xylanase 활성

Abstract

Xylanase have been used to convert the polymetric xylan into fermentable sugars from the production of ethanol and xylitol from plant biomass. The aim of this study was to isolate and identify xylanolytic bacterium from herbivore feces and was to used the xylanase for enzymatic hydrolysis of biomass. Xylanolytic strains were isolated from 59 different feces of herbivores from Seoul Grand Park located in Gwacheon Gyeonggi-do. The xylanolytic strains were selected by congo red staining and DNS method. Total 67 strains isolated from the herbivores feces were tested for xylanase activity. Among the strains, H10-1, which has the highest xylanase activity, was isolated from feces of Ceratotherium simum. The H10-1 strain was identified as Bacillus pumilus based on its morphological/biochemical characteristics and partial 16S rDNA gene sequences. Culture conditions of B. pumilus H10-1 such as initial medium pH, incubation temperature and incubation time were optimized for maximum xylanase production. And also xylanase produced by B. pumilus H10-1 was applied for the saccharification of Miscanthus sacchariflorus cv. 'Geodae 1', which was pretreated with 1.5M NaOH. The optimized culture conditions of B. pumilus H10-1 were pH 9, <TEX>$30^{\circ}C$</TEX> incubation temperature, and 7 day incubation time, respectively. This xylanase activity under the optimized conditions was <TEX>$20.4{\pm}3.3IU$</TEX>. The crude xylanase produced by B. pumilus H10-1 was used for the saccharification of xylan derived from pretreated 'Geodae 1'. The saccharification conditions were <TEX>$50^{\circ}C$</TEX>, 200 rpm, and 5 days. Saccharification efficiency of pretreated 'Geodae 1' by B. pumilus H10-1 was 8.2%.