Bioconversion of wild Ipomoea pes-caprae and Suaeda fruticosa biomass: a novel application of thermostable xylanase from Neobacillus sedimentimangrovi.

Abstract

Biomass from halophytes is considered as a promising chemical feedstock. Its bioconversion to obtain reducing sugars and to concomitantly improve antioxidant potential has been described less frequently. This is the first report describing application of xylanase from Neobacillus sedimentimangrovi for the saccharification of Ipomoea pes-caprae (IPC) and Suaeda fruticosa (SF). In this study, the biomass IPC and SF was separately or co-pretreated by freeze-thaw and 1% H₂SO₄. Results showed that significant amount of reducing sugar was obtained by saccharification of acid and freeze-thaw pretreated IPC (44 mg g^- 1) and freeze-thaw pretreated SF (43 mg g^- 1). The residues after saccharification were also analyzed for their antioxidant potential where IPC residues exhibited 1.13 folds higher potential than that of SF. Antioxidant potential (83.9%) was obtained when purified xylanase was used for the saccharification of IPC. Moreover, absence of lignin-related peaks in the NMR and IR spectra of the treated substrates indicated efficient delignification. The characteristic peaks of the hemicellulosic fractions in saccharified samples were also disturbed, indicating changes in the crystallinity of the substrates. The SEM images and spectra of the saccharified substrates clearly indicated the degradation of hemicellulosic content by xylanse.