Addition of Soybean Protein Improves Saccharification and Ethanol Production from Hydrothermally Pretreated Sugarcane Bagasse
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The bioconversion yield of ethanol from lignocellulosic feedstocks is negatively affected by the unproductive adsorption of cellulolytic enzymes onto lignin. In this work, soybean protein was used as a lignin-blocking additive, with the aim of improving the production of ethanol from enzymatic hydrolysates of pretreated sugarcane bagasse. Investigation was made of the effects of the type of hydrothermal pretreatment process—steam explosion (SE) or liquid hot water (LHW), loadings of solids and enzymes, and bioreactor type. The addition of soybean protein led to a exceptional 76% increase of glucose released using the LHW pretreated bagasse, after 24 h of reaction, employing a high-solids loading (15%, w/v) and a low enzyme dosage (5 FPU/g dry biomass). A significant improvement was also achieved for industrial-like mixing conditions in a bench-scale stirred tank reactor, increasing the glucose released by 61 and 42% for the LHW and SE processes, respectively. Ethanol production was also positively affected by the presence of soybean protein, with increases of up to 86 and 65% for the LHW and SE hydrolysates, compared to the control experiment. Characterization of the sugarcane bagasse after the adsorption of soybean protein, using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), corroborated the higher affinity of the additive for the LHW bagasse. These findings suggest that soybean protein supplementation during enzymatic hydrolysis by commercially available enzymes is an effective strategy for achieving higher saccharification yields from hydrothermally pretreated biomass, hence improving ethanol production.
KeywordsEnzymatic hydrolysis Lignin Unproductive adsorption Lignocellulosic biomass Sugarcane bagasse Soybean protein
We are grateful to Dr. Eduardo Ximenes and Dr. Michael Ladisch from Purdue University (IN, USA) for their very insightful suggestions for this work.
Embrapa, CNPq (Process 401182/2014-2), CAPES, and FAPESP (Processes 2014/19000-3 and 2016/10636-8) (all from Brazil) provided financial support.
- 20.Yang B, Wyman CE (2006) Lignin blockers and uses thereof. US PatentGoogle Scholar
- 25.Jin WX, Chen L, Hu M, Sun D, Li A, Li Y, Hu Z, Zhou SG, Tu YY, Xia T, Wang YT, Xie GS, Li YB, Bai BW, Peng LC (2016) Tween-80 is effective for enhancing steam-exploded biomass enzymatic saccharification and ethanol production by specifically lessening cellulase absorption with lignin in common reed. Appl Energy 175:82–90CrossRefGoogle Scholar
- 26.Brondi MG, Vasconcellos VM, Giordano RC, Farinas CS (2018) Alternative low-cost additives to improve the saccharification of lignocellulosic biomass. Appl Biochem Biotechnol. https://doi.org/10.1007/s12010-018-2834-z
- 30.Gouveia ER, do Nascimento RT, Souto-Maior AM, Moraes Rocha GJ (2009) Validation of methodology for the chemical characterization of sugar cane bagasse. Quim Nova 32:1500–1503Google Scholar
- 33.Ghose TK (1987) Measurement of cellulase activities. Pure Appl Chem 59:257–268Google Scholar
- 48.Carvalheiro F, Duarte LC, Girio FM (2008) Hemicellulose biorefineries: a review on biomass pretreatments. J Sci Ind Res 67:849–864Google Scholar
- 60.Novaes Reis Corrales RC, Teixeira Mendes FM, Perrone CC, Sant'Anna C, de Souza W, Abud Y, da Silva Bon EP, Ferreira-Leitao V (2012) Structural evaluation of sugar cane bagasse steam pretreated in the presence of CO2 and SO2. Biotechnol Biofuels 5:36. https://doi.org/10.1186/1754-6834-5-36
- 62.Crepin L, Truong NM, Bloem A, Sanchez I, Dequin S, Camarasa C (2017) Management of multiple nitrogen sources during wine fermentation by Saccharomyces cerevisiae. Appl Environ Microbiol 83(5):e02617-16Google Scholar