Collaborative Research: Harnessing synergism between biosurfactants and enzymes to enable efficient valorization of cellulose: towards a sustainable materials bioeconomy

纤维素是一种丰富的、可再生的、环境可持续的资源，可用于生产纳米纤维素和增值燃料和化学品。因此，纤维素是建立循环生物经济的理想原料。然而，为了实现这一潜力，需要可扩展和可持续的方法来有效地将纤维素转化为纳米纤维素。目前的化学和机械纳米纤维素生产工艺效率很高，但不可持续，因为它们需要大量的能源和水投入，使用有毒和腐蚀性溶剂，并产生大量的温室气体排放和大量的废物流。酶促过程可以实现可持续的纳米纤维素生产，但产量低。石油衍生的表面活性剂经常被添加到纤维素的酶促生物转化中，但选择一种理想的表面活性剂并不简单，并且在该过程中包含不可再生资源。腐生真菌通过分泌一种充满酶的混合物来分解纤维素生物质，这种混合物包括纤维素酶和天然存在的被称为疏水酶的生物表面活性剂。疏水性化合物与促进酶促纤维素分解有关，因此为石化表面活性剂提供了一种潜在的绿色替代品。然而，疏水蛋白在提高纤维素酶活性方面的作用尚不清楚。该项目的目标是开发一种可扩展的、环境可持续的纳米纤维素生产工艺，利用疏水蛋白的表面活性来改善纤维素的分解和改性。这项研究将产生新的工具来改善酶促纤维素转化，从而实现基于纤维素的循环生物经济。该项目的动机是需要可扩展和可持续的过程，将纤维素生物质转化为纳米纤维素和增值燃料和化学品。研究的重点是通过加入疏水蛋白生物表面活性剂来提高纤维素酶水解的速度和程度，这似乎可以协同提高纤维素酶的性能。该项目旨在阐明生物表面活性剂增强酶-纤维素界面相互作用的机制，从而控制纤维素水解和功能化纳米纤维素生产的动力学。该项目有三个具体目标。目的1将研究疏水蛋白如何与纤维素相互作用，影响表面和材料性质，并确定疏水蛋白如何促进酶与纤维素的相互作用和周转。目的2将建立对疏水蛋白的进化多样性如何导致纤维素和酶吸附差异的理解。这些知识将用于设计具有改进界面相互作用的新型疏水蛋白，从而增加纳米纤维素的产量。目标3将评估酶、疏水性蛋白和纤维素的整合，以设计理想的综合生物处理条件，考虑体外和以里氏木霉为宿主的细胞系统。最终，这项工作将导致在纤维素解构过程中生物系统如何修改界面的新知识，这是开发高效纳米纤维素生产的酶促方法的关键。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Cellulose is an abundant, renewable, and environmentally-sustainable resource that can be used to produce nanocellulose and value-added fuels and chemicals. As such, cellulose is an ideal feedstock for building a circular bioeconomy. To realize this potential, however, scalable and sustainable methods are needed to efficiently convert cellulose into nanocellulose. Current chemical and mechanical nanocellulose production processes are efficient but unsustainable, as they require high energy and water inputs, use toxic and corrosive solvents, and generate large amounts of greenhouse gas emissions and high-volume waste streams. Enzymatic processes enable sustainable nanocellulose production but suffer from low yields. Petroleum-derived surfactants are often added to enhance enzymatic bioconversion of cellulose, but selecting an ideal surfactant is not straightforward and incorporates non-renewable resources into the process. Saprophytic fungi decompose cellulosic biomass by secreting an enzyme-laden mixture that includes cellulases as well as naturally-occurring biosurfactants called hydrophobins. Hydrophobins have been implicated in enhancing enzymatic cellulose decomposition and, thus, offer a potential green alternative to petrochemical surfactants. However, the role hydrophobins play in enhancing cellulase activity on cellulose remains unclear. The goal of this project is to develop a scalable, environmentally-sustainable process for nanocellulose production by leveraging the surface activity of hydrophobins to improve cellulose deconstruction and modification. This research will result in new tools to improve enzymatic cellulose conversion, thereby enabling the cellulose-based circular bioeconomy.This project is motivated by the need for scalable and sustainable processes to convert cellulosic biomass into nanocellulose and value-added fuels and chemicals. The investigation focuses on improving the rate and extent of enzymatic hydrolysis of cellulose by incorporating hydrophobin biosurfactants, which appear to synergistically enhance cellulase performance. The project aims to elucidate the mechanisms of biosurfactant-enhanced enzyme-cellulose interfacial interactions such that the kinetics of cellulose hydrolysis and functionalized nanocellulose production can be controlled. The project has three specific aims. Aim 1 will examine how hydrophobins interact with cellulose to affect surface and material properties and determine how hydrophobins facilitate enzymatic interactions and turnover with cellulose. Aim 2 will build an understanding of how the evolutionary diversity of hydrophobins leads to differences in cellulose and enzyme adsorption. This knowledge will be used to engineer novel hydrophobins with improved interfacial interactions that increase nanocellulose production. Aim 3 will evaluate the integration of enzymes, hydrophobins, and cellulose to engineer ideal conditions for consolidated bioprocessing, considering both in vitro and cell-based systems using Trichoderma reesei as a host. Ultimately, this work will lead to new knowledge of how biological systems modify interfaces during cellulose deconstruction, which is key to developing enzymatic approaches for efficient nanocellulose production.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.