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固态发酵基质水分特征及供水方式的研究
Alternative TitleOccurrence Characteristics of Matrix Water and Humidity Control Strategies in Solid-state Fermentati
贺芹
Subtype博士
Thesis Advisor陈洪章
2013-05-01
Degree Grantor中国科学院研究生院
Degree Discipline生物化工
Keyword固态发酵   供水方式   水分特征
Abstract论文通过宏观研究固态发酵过程中水分对发酵过程参数和发酵产物的影响证明水分研究的重要性并确立评价供水效果的参数。从基质水分的物理学性质出发,考察了基质的水分特征,提出了固态发酵供水方式的指导原则,同时建立了影响微生物发酵特性的水分常数测定方法。在前两者基础上,确定并考察了基于保水剂和负压控水方式的基质毛管水供水方式以及基于载体吸附发酵的基质游离水供水方式。 本论文的主要研究内容及结果如下: 1) 通过考察不同固态发酵方式下(强制通风的气相双动态发酵和静置发酵)起始水含量与发酵过程中水含量的变化对不同微生物固态发酵温度、水活度、菌体生长速率及生物量、孢子数等初级代谢产物和酶活等次级代谢产物的影响,证实了水分与水分保持在固态发酵中的重要性。建立了以不同堆料深度下水分、温差等参数表征发酵过程中的传质、传热差异,以酶活、生物量等参数来表征发酵过程中的微生物发酵活性的供水方式评价标准。该方法直观、简便,为供水性能的考察提供参考依据。 2) 从物理学角度建立了基质水分特征参数、水分的动力学和热力学特征参数研究方法,为固态发酵中传质、传热方程的建立和参数值的选择提供参考。通过固态发酵基质水分蒸发过程的分析,提出了基于水非饱和基质湿分分层特征的特异性水分供水模式,即:采用发酵基质上方补重力水,而基质下方供毛管水的方式实现固态发酵体系的供水。 3) 利用计算法估算液膜厚度,结果表明:水活度越低,相同液膜厚度所对应的毛管半径越小,水活度值大于0.90,基质的毛管作用最强。利用低场核磁共振成像分析的方法与手段建立基质水分常数的快速检测方法。将该方法应用于固态发酵过程的研究,发现固态发酵过程中水分流失以毛管水为主;成像分析表明相比于静置发酵,气相双动态发酵过程中水分分布更为均一,湿度梯度较小。 4) 研究了新型保水材料-保水剂用于固态发酵供水的可行性,保水剂具有优越的保水供水性能,对产物产量的提高有一定的促进作用。确定了产纤维素酶、哈茨木霉和产漆酶发酵过程中保水剂供水的关键因素。研究结果发现不同的微生物和产物发酵所需的保水要求不同,关键影响因素也不同。 5) 采用负水头供水控水方式,解决了发酵过程水分的量难以在线控制的难题,发酵结束后发酵基质水分含量基本保持,并且湿度梯度较小。纤维素酶和漆酶发酵过程中的温度控制较好,发酵产物产量有一定的增加。而哈茨木霉实验出现的负面效果可能与产孢过程需要低含水量环境相关。添加1‰含量保水剂与负水势供水控水方式相耦合的发酵方式更适合三种模式菌株的发酵和产物的形成。 6) 与其他多孔载体相比,碱处理-汽爆秸秆作为吸附载体能够提高丙酮丁醇发酵得率。研究了最佳的载体吸附固态发酵条件,最优的丁醇发酵条件为:载体汽爆条件,1.1 MPa维压4 min;体系中固液比1:10;底物浓度为100 g/L葡萄糖;并且底物中六碳糖含量越高,发酵效果越好。对该发酵方式的促发酵机理进行考察,载体能够很好地吸附丙酮丁醇等产物尤其是丙酮,一定程度上消除了产物抑制作用。载体对菌体的吸附提高了载体上和发酵液中的生物量,有利于丁醇发酵性能的提高。进一步的研究发现发酵体系中添加适量纤维素酶使溶剂产量增加了71%,同时获得高纤维细胞含量(纤维细胞面积含量由53%提高到90%)的纤维材料。基于此提出了新型的生物质炼制技术体系,这一研究结果对丁醇的工业化生产和提高丙酮丁醇工业的经济竞争力具有重要意义。
Other AbstractIn this study, the macroscopic study on the effects of water on the process parameters and fermentation products showed the importance of water and the evaluation index for water supply was established. The occurrence characteristics of water in substrate were investigated from the aspects of the physical features of matrix water, and the guiding principles for water supply were summarized, also the measure methods for physiologic characteristics of matrix water were established and studied. On the basis of the former studies, some water control strategies such as water supply by super absorbent polymers (SAP), negative hydraulic pressure controlled auto irrigator (NHPCAI) and initial water addition were established and evaluated. The main research contents and results were obtained as follows: 1) Through the studies on the effects of initial water content and water content variation in fermentation process on temperature, water activity, cell growth rate, primary metabolites such as biomass amount, number of spores, etc., and secondary metabolites e.g. enzymes activities production from different microorganisms in different types of solid-state fermentation (SSF) (the gas dual-dynamic SSF and static SSF), it confirmed the importance of moisture and moisture retention in SSF. Additionally, the differences in mass and heat transfer were evaluated by moisture and temperature variances caused by stacking depth. The evaluation criteria for the moisture controlling in fermentation process was characterized by microbial activity such as enzyme activity, biomass and other parameters. The method was brief and simple; it provided reference data for the investigation of water supply methods. 2) The measure methods for parameters of matrix water characteristics, kinetics and thermodynamics were established from the view of physics; they supplied reference data for the heat and mass transfer equations in SSF.
Pages167
Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/8292
Collection研究所(批量导入)
Recommended Citation
GB/T 7714
贺芹. 固态发酵基质水分特征及供水方式的研究[D]. 中国科学院研究生院,2013.
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