马尾藻发酵生产生物乙醇的两步法糖化预处理

Two-stage hydrolysis of Sargassum fulvellum for bioethanol fermentation

马尾藻是典型的大型褐藻,含有大量的碳水化合物,通过糖化处理后能够用于生物乙醇的发酵生产。研究了马尾藻的两步水解方法,优化了两步水解法中酸水解和酶水解的最适水解条件。试验发现在料液比为6%(w/v),H2SO4浓度1.5%(v/v),时间40 min,温度为120℃的水解条件下马尾藻的第1步酸水解效率可以达到(31.05±0.32)%(w/w)。进一步用海藻酸盐裂解酶进行第2步水解,最适水解条件:料液比5%(w/v)、酶用量0.0025%(w/v)、时间2 h,第2步酶水解后马尾藻的水解效率可以在第1步水解的基础上提高9.68%(w/w)。最终两步法的总水解效率可以达到38%～40%(w/w),达到理论产量的89%。用工业酿酒酵母R1-11对水解液进行发酵实验,在未优化发酵条件的情况下每千克马尾藻生产乙醇60.75 g,当水解液补充1%(w/v)(NH4)2SO4时乙醇的产量可以达到每千克马尾藻生产乙醇91.9 g。

As the typical brown alage,Sargassum fulvellum contains a large amount of the carbohydrate,it can be used to produce bioethanol after pretreatment.The overall goal of this work was to develop a saccharification method for the production of bioethanol using Sargassum fulvellum.A two-step hydrolysis method including acid hydrolysis（first stage） and enzyme hydrolysis（second stage） was carried out to optimize the condition for the saccharification of sargassum.Results displayed that the acid hydrolysis efficiency of first stage was 31.05%±0.32%（w/w dry biomass） of the reducing sugar under optimum conditions of feed content 6%（w/v）,1.5%（v/v） sulfuric acid,120℃ and 40min.After enzyme hydrolysis of second stage,the efficiency of the saccharification was increased by 9.68% under optimum conditions of feed content 5%（w/v）,alginate lyase concentration 0.0025%（w/v） and reaction time 2h.The reducing sugar yields from Sargassum fulvellum using a two-stage hydrolysis method was 38%~40%（w/w dry biomass）,which reached 89% of the theoretical yields.The hydrolyzate derived from Sargassum fulvellum by a two-stage hydrolysis was employed for conversion to ethanol by industrial Saccharomyces cerevisiae R1-11.The highest ethanol yield was 91.9 g/kg dry biomass.