Fermentation method for producing xylitol and ethanol by using undetoxified cellulose raw materials

Abstract

In view of problems in the existing cellulose ethanol preparation technologies that inhibitors in a cellulose hydrolyzate inhibit fermentation, xylose cannot be completely converted, glucose inhibitsfermentation of the xylose, and a cellulase acting temperature and a microbe fermentation temperature are non-uniform, the invention provides a fermentation method for producing xylitol and ethanol byusing undetoxified cellulose raw materials. The fermentation method comprises the steps of inoculum culture, xylose fermentation, cellulase adding, synchronous diastatic fermentation and the like. According to the method, simultaneous utilization of the xylose and the inhibitors is achieved by adopting an acetic acid and xylose co-utilization based Kluyveromyces marxianus strain, and thus, the problem in inhibitor removal is avoided; by adopting high-temperature synchronous diastatic fermentation, the problem that the cellulase is unmatched with a fermentation temperature is avoided; and compared with the existing cellulose ethanol fermentation technologies, the production cost can be remarkably reduced.

Description

technical field [0001] The invention belongs to the field of bioengineering, and relates to a fermentation method for producing xylitol and ethanol by using non-detoxified cellulose raw materials, specifically, it is a method for producing xylitol and ethanol by using a two-step fermentation method using cellulose raw materials. Background technique [0002] In the past three decades, due to the rapid development of global industrialization and accelerated urbanization, the world's demand for energy has doubled [Popp J, Biofuels and Their Co-Products as Livestock Feed: Global Economic and Environmental Implications [J]. Molecules, 2016, 21(3):285.], the problem of depletion of non-renewable petroleum resources is becoming increasingly prominent. Secondly, the burning of fossil fuels produces a large amount of greenhouse gases, which aggravates environmental pollution and other problems. As of 2015, CO in the air 2 Concentrations are 40% higher than in the Middle Ages, most...

AI Technical Summary

Problems solved by technology

The development of cellulosic ethanol faces some unresolved problems, such as: ① Cellulosic raw materials cannot be directly used by microorganisms, and the raw materials need to be pretreated, but the inhibitors produced during the pretreatment process affect the subsequent fermentation

Although it can be improved by detoxification of hydrolyzate, it increases production cost and produces waste water to pollute the environment; ②Current ethanol production strains cannot utilize xylose and arabinose, which are hydrolysates of hemicellulose in cellulosic materials

Although genetic engineering is used to modify the strain to make it able to utilize xylose, the fermentation performance of the recombinant bacteria in the real hydrolyzate cannot meet the requirements of industrial production, and the sugar utilization rate and product yield are low; ③The current optimal fermentation process For synchronous saccharification and fermentation, but the fermentation temperature of the strain is quite different from the optimal temperature of cellulase, the amount of cellulase is large, and the cost is high [Ojeda K, Energy analysis and process integration of bioethanol production from acid preserved biomass: comparison of SHF, SSF and SSCF pathways[J].Chemical Engineering Journal,2011, 176-177(3):195-201.]

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