Unrevealing model compounds of soil conditioners impacts on the wheat straw autohydrolysis efficiency and enzymatic hydrolysis

Xinxing Wu; Wei Tang; Chen Huang; Caoxing Huang; Chenhuan Lai; Qiang Yong

doi:10.1186/s13068-020-01763-3

Unrevealing model compounds of soil conditioners impacts on the wheat straw autohydrolysis efficiency and enzymatic hydrolysis

Biotechnol Biofuels. 2020 Jul 13:13:122. doi: 10.1186/s13068-020-01763-3. eCollection 2020.

Authors

Xinxing Wu^{1

2}, Wei Tang^{1

2}, Chen Huang^{1

2}, Caoxing Huang^{1

2}, Chenhuan Lai^{1

2}, Qiang Yong^{1

2}

Affiliations

¹ Key Laboratory of Forestry Genetics & Biotechnology (Nanjing Forestry University), Ministry of Education, Nanjing, 210037 People's Republic of China.
² Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037 People's Republic of China.

Abstract

Background: Soil-derived exogenous ash (EA) poses a challenge toward lignocellulosic autohydrolysis due to its buffering capacity. Previous works focusing on this phenomenon have failed to also investigate the role that soluble salts, and organic matter plays in this system. Herein, sodium phosphate and sodium humate were employed as model buffering compounds representing soluble salts and organic matter and dosed into a de-ashed wheat straw (DWS) autohydrolysis process to show the potential impacts of WS attached soil conditioners on the WS autohydrolysis efficiency which would further affect the enzymatic digestibility of autohydrolyzed WS.

Results: Results showed that with the increasing loadings of sodium phosphate and sodium humate resulted in elevated pH values (from 4.0 to 5.1 and from 4.1 to 4.7, respectively). Meanwhile, the reductions of xylan removal yields from ~ 84.3-61.4% to 72.3-53.0% by loading (1-30 g/L) sodium phosphate and sodium humate during WS autohydrolysis lead to a significant decrease of cellulose accessibilities which finally lead to a reduction of the enzymatic digestibility of autohydrolyzed WS from ~ 75.4-77.2% to 47.3-57.7%.

Conclusion: The existence of different types soil conditioner model compounds results in various component fractions from autohydrolyzed WS in the process of autohydrolysis. A lack of sufficient xylan removal was found to drive the significant decrease in enzymatic accessibility. The results demonstrated the various effects of two typical tested soil conditioners on WS autohydrolysis and enzymatic hydrolysis.

Keywords: Autohydrolysis; Enzymatic accessibility; Enzymatic hydrolysis; Humate; Phosphate.