【摘要】 用经过两步碱法(氢氧化钠-氢氧化钙)预处理的玉米秸秆为原料,以树干毕赤酵母为发酵菌株,分别研究在三角瓶体系和发酵罐体系中,未水洗和水洗物料在不同pH下对玉米秸秆半同步糖化共发酵的影响.结果表明:在三角瓶体系中,未水洗物料在pH 4.8下预酶解48 h之后维持pH不变,乙醇产率为0.193 g/g(以物料中纤维素和半纤维素含量计,下同),预酶解48 h之后将pH调至6.0时乙醇产率为0.234 g/g,改变pH对乙醇产率有较大提高,提高了21.24%;水洗物料在pH 4.8下预酶解48 h之后维持pH不变时乙醇产率为0.287 g/g,预酶解48 h之后将pH调至6.0时乙醇产率为0.292 g/g,改变pH对乙醇产率的提高不明显.同时进行了3 L发酵罐的放大实验,在与三角瓶同样的反应条件下,未水洗和水洗物料的乙醇产率分别为0.220和0.234 g/g.综合考虑水洗所带来的环境污染等问题后发现,未水洗物料同样可用于乙醇发酵.更多还原

【Abstract】 Corn stover pretreated with two-step alkaline method(sodium hydroxide combined with calcium hydroxide) was used as material. Pichia stipitis was used as fermentation strain. The influence of washed and unwashed material under different pH conditions on the semi-simultaneous saccharification and co-fermentation of corn stover were investigated. The experiment results showed: in erlenmeyer flask system, the ethanol yield of unwashed materials was 0.193 g/g after pre-enzymatic hydrolysis for 48 h under pH 4.8 and then maintained the pH(based on the cellulose and hemicellulose in the material. The same is true below). The ethanol yield of unwashed materials was 0.234 g/g after pre-enzymatic hydrolysis for 48 h under pH 4.8 and then changed the pH to 6.0. Changing the pH can increased the ethanol yield by 21.24%. The ethanol yield of washed materials after pre-enzymatic hydrolysis for 48 h under pH 4.8 and then maintained the pH was 0.287 g/g. The ethanol yield of washed materials after pre-enzymatic hydrolysis for 48 h under pH 4.8 and then changed the pH to 6.0 was 0.292 g/g. Changing the pH can not improve the ethanol yield obviously. Meanwhile, 3 L fermenter enlarger experiment was also carried out. Under the same reaction condition with erlenmeyer flask system, the ethanol yields of washed and unwashed materials were 0.220 and 0.234 g/g, respectively. Taking the environmental pollution caused by washing into consideration, unwashed material can also be used for ethanol production.更多还原