Towards biofilm reactors for flow biocatalysis: investigating the productivity of biofilms for commodity chemical production in a microfluidic scale-d

面向流动生物催化的生物膜反应器：管理人员：Nicolas Szita教授，伦敦大学学院Gary Lye教授，伦敦大学学院生物化学工程合作学者John Ward教授，Marco Marques博士，Duygu Dikicioglu博士，伦敦大学学院外部合作学者Nigel Scrutton教授，在过去的二十年里，连续流合成领域有了显著的发展。虽然连续流的应用最初更多地集中在化学合成上，但最近使用全细胞和酶进行生物催化合成已成为流行。使用连续流进行生物催化合成被称为“流动生物催化”。连续流动允许生物催化过程在多相催化状态下进行。更重要的是，流动生物催化反应器提供了更好的质量和传热，自动化（减少过程变化），在线净化和加压操作。流动系统可以与过程分析技术（PAT）集成。因此，流动生物催化能够为药物、增值化学品和材料的合成建立新的工艺窗口。在这个博士项目中，我们将评估和进一步探索生物膜在流动生物催化（全细胞生物催化）和商品化学品生产的流动生物催化反应器中的应用。因此，要测试的第一个假设是微流体培养装置是否可以用于在装置中形成和维持生物膜。评估生物膜和细菌培养物在（或限制在）培养室区域内的保留程度将是特别有趣的（考虑到设备的连续灌注模式）。第二个假设是，可以找到生物膜中的细胞优于非生物膜生长细胞的条件。与此相关的，作为一个子假设，基于生物膜的系统优于基于酶的系统。比较的指标包括每个细胞质量（酶蛋白质量）的柠檬酸盐生产率，底物上的柠檬酸盐产量，以及可能的时空产量（反应器配置），不同稀释率，即不同水平的流体动力剪切应力。研究方法研究条件将包括单个生物膜生长细菌与共同培养，碳源浓度（可能不同类型），细胞生长基质，流体动力剪切应力（在高剪切环境中，生物膜可能更平坦或形成长链），以及物理化学条件，如流体动力剪切应力和溶解氧水平。通过分析每个细胞的生产力，我们将确定生物膜的最佳条件。从这项研究中获得的知识有望为流动生物催化反应器提供设计标准，例如结构/支架支持，以在不同规模下保持最佳代谢物生产条件。感兴趣的可能是生物膜固定化结构，如表面固定化生物膜，支架生物膜的单体，以及可能促进生物膜特定空间排列的多孔/水凝胶状微珠。符合EPSRC的战略和研究领域该项目符合未来制造技术

Title: Towards biofilm reactors for flow biocatalysis: investigating the productivity of biofilms for commodity chemical production in a microfluidic scale-down modelSupervisors and affiliationsProfessor Nicolas Szita, University College London Professor Gary Lye, University College LondonCollaborating academics at UCL Dept Biochemical Engineering Professor John Ward, Dr Marco Marques, Dr Duygu Dikicioglu,Collaborating academics outside UCLProf Nigel Scrutton, University of ManchesterContextThe field of continuous flow synthesis has grown significantly over the last two decades. Whilst the application of continuous flow focussed more on chemical synthesis initially, recently the use of whole cells and enzymes for biocatalytic synthesis has become popular. The use continuous flow for biocatalytic synthesis is termed 'Flow Biocatalysis'. Continuous flow allows the biocatalytic process to be performed in a heterogeneous catalysis regime. More importantly, flow biocatalysis reactors offer improved mass and heat transfer, automation (reducing process variations), in-line purification and pressurised operation. And the flow systems can be integrated with process analytical technology (PAT). Flow Biocatalysis therefore enables the establishment of new process windows for the synthesis of pharmaceuticals, value-added chemicals, and materials.Aims and ObjectivesIn this PhD project, we will evaluate and further explore the use of biofilms specifically for their application in flow biocatalysis (whole-cell biocatalysis) and flow biocatalysis reactors for commodity chemicals production.The first hypothesis to test is thus whether a microfluidic culture device can be employed for forming and maintaining biofilms in the device. Evaluating how well the biofilm and the bacterial culture can be retained in (or limited to) the culture chamber area will be of particular interest (given the continuous, perfusion mode of the device).The second hypothesis is that conditions can be found where the cells in a biofilm outperform non-biofilm growing cells. Related to that, as a sub-hypothesis, that biofilm-based systems outperform enzyme-based systems. Metrics for comparison include productivity of citramalate per cell mass (enzyme protein mass), yield of citramalate on substrate, and space time yield where possible (reactor configuration), for different dilution rates, i.e. different levels of hydrodynamic shear stresses.Research MethodologyConditions to investigate will include single biofilm growing bacteria vs co-culture, concentration of carbon source (potentially different types), cell growth substrate, hydrodynamic shear stress (in high shear environments, biofilms may be flatter or form long strands), and physico-chemical conditions, such as hydrodynamic shear stress and dissolved oxygen levels. By analysing the productivity per cell, we will determine optimal conditions for the biofilms.The knowledge gained from this research is expected to provide design criteria for flow biocatalysis reactors, such as the structural/scaffold support to maintain optimal metabolite producing conditions at different scales. Of interest could be biofilm-immobilisation structures, such as surface-immobilised biofilms, monoliths to scaffold biofilms, and porous/hydrogel-like beads which may foster particular spatial arrangements for the biofilm.Alignment to EPSRC's strategies and research areasThe project aligns with Future Manufacturing Technologies