Energy, Vol.135, 32-39, 2017
Stimulatory effect of in-situ detoxification on bioethanol production by rice straw
An effective ferulic acid degrading bacterium, Escherichia sp. HHQ-1, was added to alkali-pretreated rice straw degrading system to in-situ detoxify the ferulic acid inhibitors existed in the hydrolysates. It was shown that the production of reducing sugars in Escherichia sp. HHQ-1-Trichoderma reesei consortia degrading system could achieve 221.33 mg L-1 at 60 h, which was 7.84% higher than that in single degrading system. All the three main cellulases were more stable in consortia degrading system, and the 'activity of beta-glucosidase was 4.23 fold higher than that in single degrading system. Besides, it was supposed that cell membrane was more integrally protected in consortia degrading system. Scanning Electron Microscope (SEM), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectrometer (FTIR) were used to observe the morphological changes of rice straw biomass. It was indicated that in-situ detoxification could severely destroy basic tissue of rice straw, dramatically decrease crystallinity index of crystalline region and effectively degrade refractory-degraded lignin parts of lignocellulose. Compared to the single degrading system, the consortia degrading system could in-situ detoxify the main inhibitors which existed in pretreated rice straw hydrolysates, realize simultaneous pretreatment and detoxification, thus increasing the bioethanol yield and reducing the cost of bioethanol production. (C) 2017 Elsevier Ltd. All rights reserved.