School of Pharmacy and Biomolecular Sciences, University of Brighton, Huxley Building, Lewes Road, Brighton, BN2 4GJ, UK.
Appl Biochem Biotechnol. 2020 Dec;192(4):1368-1375. doi: 10.1007/s12010-020-03406-7. Epub 2020 Aug 17.
Biofuels have the capacity to contribute to carbon dioxide emission reduction and to energy security as oil reserves diminish and/or become concentrated in politically unstable regions. However, challenges exist in obtaining the maximum yield from industrial fermentations. One challenge arises from the nature of alcohols. These compounds are chaotropic (i.e. causes disorder in the system) which causes stress in the microbes producing the biofuel. Brewer's yeast (Saccharomyces cerevisiae) typically cannot grow at ethanol concentration much above 17% (v/v). Mitigation of these properties has the potential to increase yield. Previously, we have explored the effects of chaotropes on model enzyme systems and attempted (largely unsuccessfully) to offset these effects by kosmotropes (compounds which increase the order of the system, i.e. the "opposite" of chaotropes). Here we present some theoretical results which suggest that high molecular mass polyethylene glycols may be the most effective kosmotropic additives in terms of both efficacy and cost. The assumptions and limitations of these calculations are also presented. A deeper understanding of the effects of chaotropes on biofuel-producing microbes is likely to inform improvements in bioethanol yields and enable more rational approaches to the "neutralisation" of chaotropicity.
生物燃料具有减少二氧化碳排放和保障能源安全的潜力，因为石油储量减少和/或集中在政治不稳定的地区。然而，从工业发酵中获得最大产量存在挑战。一个挑战源于醇的性质。这些化合物是离液剂（即引起系统混乱），这会给生产生物燃料的微生物带来压力。啤酒酵母（Saccharomyces cerevisiae）通常不能在乙醇浓度高于 17%（v/v）的情况下生长。减轻这些特性有可能提高产量。以前，我们已经研究了离液剂对模型酶系统的影响，并试图（但基本上没有成功）通过同晶盐（增加系统有序性的化合物，即离液剂的“相反”）来抵消这些影响。在这里，我们提出了一些理论结果，表明高分子量聚乙二醇可能是最有效的同晶盐添加剂，无论是在功效还是成本方面。还介绍了这些计算的假设和限制。更深入地了解离液剂对生产生物燃料的微生物的影响，可能有助于提高生物乙醇的产量，并能够更合理地处理离液剂的“中和”问题。
