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汽爆秸秆半纤维素水解物提取及其丙酮丁醇发酵
张连华
Subtype硕士
Thesis Advisor陈洪章 ; 王岚
2013-05-01
Degree Grantor中国科学院研究生院
Degree Discipline生物化工
Keyword汽爆   水解液   abe发酵   抑制解除
Abstract本研究旨在建立一种不添加脱毒步骤,直接将汽爆半纤维素水解液用于丙酮丁醇发酵(Acetone-butanol-ethanol,简称为ABE发酵)的工艺。首先进行汽爆条件优化,得到尽量多的糖,尽量少的木质素降解物,然后研究水解液中酚酸抑制物对于ABE发酵的具体作用,同时研究了黄酮类物质对于提高ABE发酵抑制点的影响,在以上研究基础上,探究不脱毒直接进行发酵的抑制解除方法。主要研究内容和结果如下。 (1)半纤维素水解物中总糖得率与汽爆压力成正比,与加水量成正比,汽爆挤出后再热提总糖得率高于直接热提,1.5 MPa时差距最大为45.87%。木质素降解物多少与木质素降解程度还与其溶解度有关,汽爆条件越剧烈,水越多则溶出的木质素降解物越多,直接挤出要比晾干后再洗得到的木质素降解物少,综合考虑最佳工艺为1.3 MPa,固水比1:1,采用汽爆后直接挤出工艺。 (2) 低浓度酚酸(低于100 mg/L)对丁醇发酵与丙酮丁醇梭菌生长具有促进作用,当加入50 mg/L对羟基苯甲酸时,实验组丁醇产量比对照组高21.32%,加入100 mg/L香草酸实验组生物量为对照组的4.50倍,而酚酸浓度继续增大时(高于100 mg/L),呈现明显抑制作用,且浓度越高,抑制作用越强,当香草酸浓度为1000 mg/L时,丁醇产量抑制率达到96.67%,1000 mg/L时所有实验组生物量为0;据此结果提出了通过加大接种量增强菌体抑制点来解除抑制的方法。 (3)加入含有植物黄酮的银杏叶和大豆能提高C. acetobutyliucm ATCC824菌种的生长速率和丁醇产量,在接入未活化菌种的发酵中,他们的最高产量分别为12.63 g/L和11.27 g/L,分别比对照组高186.42%和155.6%。同时发现促进作用呈现出低剂量兴奋效应,黄酮添加量增加到一定量时会出现抑制效果,且不同种类黄酮该转折点不同,大豆更加敏感。将银杏叶提取物和大豆黄酮提取物按照10 mg/L加入到未活化的发酵液中,验证了黄酮的促进作用,并且发现10 mg/L大豆黄酮提取物可以使未活化的ABE发酵与活化正常发酵达到相同的效果,因此可以通过添加适量植物黄酮来使ABE发酵省去活化步骤,节约50%发酵时间。 (4)采用增加接种量和添加大豆营养物质的方法来进行稀释和提高抑制点,当接种量为30%并添加10 mg/L大豆营养物质时,发现可以成功实现汽爆半纤维素水解物不脱毒直接发酵的目的,丁醇产量达到11.82 g/L。
Other AbstractThe purpose of this study is to establish an acetone-butanol fermentation without toxic-free step. Firstly, an optimization of the steam explosion was made to get as much sugar as possible and as little lignin degradation products as possible, and then the role of the phenolic inhibitor played in the ABE fermentation was studied, the effects of flavonoids on improving the ABE fermentation suppression point were also investigated. (1) The yield of total sugar was proportional to the pressure of the steam explosion, and the amount of water. The total sugar yield obtained in extrusion was higher than that in direct washing,with the largest gap of 45.87% at 1.5 MPa. The amount of lignin degradation products was proportional to the degree of lignin degradation as well as its solubility, which meant the more severe conditions of steam explosion and more water, the more dissolution of lignin degradation products. A lignin degradation product obtained in direct extrusion way was less than that in dry-and-wash. The optimum conditions of method were 1.3 MPa, solid water ratio of 1:1 and extrusion way. (2) Low concentration of phenolic acids (lower than 100 mg/L) played a promotive role in butanol fermentation. Butanol yield was increased by 21.72% when 60 mg/L hydroxybenzoic acid was added into fermentation culture, whereas biomass reached 4.50 times that of the control group when 100 mg/L vanillic acid was added. However as the inhibitor concentrations increased (higher than 100 mg/L), the inhibition effect was remarkable. The inhibition rate of butanol production reached 96.67% when 1000 mg/L vanillic acid was added, and the biomass of all experimental groups decreased to 0. A direct butanol fermentation way without detoxification steps by increasing the inoculation rate to enhance bacterial inhibition point was established. (3) The cell growth of C. acetobutyliucm ATCC824 and butanol production in inactivated fermentation was drasticallly increased by adding gingko leaf and soybean containing flavonoids as activator, with the highest butanol production of 12.63 g/L and 11.27 g/L, 186.42% and 155.6% higher than those in the control. Especially when 10 mg/L soybean flavonoid extracts was added into inactivate ABE fermentation medium, it was found that fermentation performance was equivalent to that of the activated fermentation, with butanol production of 18.03 g/L, 228.2% higher than that in the control. It suggested that activation can be omitted in ABE fermentation by adding a certain amount of ginkgo leaf and soybean flavonoids, which decreased 50% fermentation time. The effects showed hormesis phenomenon. (4) Butanol production reached 11.82 g/L when the inoculation amount was 30% and 10 mg/L soy flavonoids was added, which meant hydrolytic solution from steam explosion starch was successfully fermented without detoxification process.
Pages63
Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/8274
Collection研究所(批量导入)
Recommended Citation
GB/T 7714
张连华. 汽爆秸秆半纤维素水解物提取及其丙酮丁醇发酵[D]. 中国科学院研究生院,2013.
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