Biological pretreatment of rice straw with cellulase-free xylanolytic enzyme-producing Bacillus firmus K-1: Structural modification and biomass digestibility

Sirilak Baramee, Ake-kavitch Siriatcharanon, Prattana Ketbot, Thitiporn Teeravivattanakit, Rattiya Waeonukul, Patthra Pason, Chakrit Tachaapaikoon, Khanok Ratanakhanokchai and Paripok Phitsuwan

Renewable Energy, 2020, vol. 160, issue C, 555-563

Abstract: Biological pretreatment using microorganisms or enzymes offers an eco-friendly process for biomass processing. Herein, the efficiency of pretreatment of rice straw with the cellulase-free xylanolytic enzyme-producing Bacillus firmus K-1 and its enzymes was assessed. After pretreatment with strain K-1 (BRS), the xylan content in rice straw reduced significantly (21% removal), thus increasing exposure of the cellulose crystal structure (Crystallinity index (CrI) = 40.2%) and creating biomass porosity. Subsequent treatment of BRS with the in-house xylanase preparation (BRS-E) slightly increased xylan removal (30% removal). The reduction of xylan thus led to larger pore size and increased crystallinity (CrI = 42.8%). Compared to untreated rice straw (24% glucan conversion), hydrolysis of BRS and BRS-E with the commercial cellulase preparation Accellerase 1500 at 100 g/L substrate load showed comparable glucose yield, giving about 74% glucan conversion. The results indicate that the removal of xylan can enhance accessibility of cellulose to cellulases, although the lignin content was not reduced (24% for BRS and 25% for BRS-E). This work demonstrates a new insight into the improvement of pretreatment efficiency using a xylan-degrading microorganism, which is an alternative to conventional lignin removal by fungal pretreatment.

Keywords: Bacillus firmus K-1; Biological pretreatment; Rice straw; Xylanolytic bacterium; Cellulase-free xylanolytic enzyme (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S096014812030971X
Full text for ScienceDirect subscribers only

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:160:y:2020:i:c:p:555-563

DOI: 10.1016/j.renene.2020.06.061

Access Statistics for this article

Renewable Energy is currently edited by Soteris A. Kalogirou and Paul Christodoulides

More articles in Renewable Energy from Elsevier
Bibliographic data for series maintained by Catherine Liu ().