Institute of Food Science and Biotechnology, Department of Bioprocess Engineering (150K), University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, Germany.
Sci Rep. 2021 Jul 20;11(1):14802. doi: 10.1038/s41598-021-94400-4.
A key challenge to advance the efficiency of bioprocesses is the uncoupling of biomass from product formation, as biomass represents a by-product that is in most cases difficult to recycle efficiently. Using the example of rhamnolipid biosurfactants, a temperature-sensitive heterologous production system under translation control of a fourU RNA thermometer from Salmonella was established to allow separating phases of preferred growth from product formation. Rhamnolipids as bulk chemicals represent a model system for future processes of industrial biotechnology and are therefore tied to the efficiency requirements in competition with the chemical industry. Experimental data confirms function of the RNA thermometer and suggests a major effect of temperature on specific rhamnolipid production rates with an increase of the average production rate by a factor of 11 between 25 and 38 °C, while the major part of this increase is attributable to the regulatory effect of the RNA thermometer rather than an unspecific overall increase in bacterial metabolism. The production capacity of the developed temperature sensitive-system was evaluated in a simple batch process driven by a temperature switch. Product formation was evaluated by efficiency parameters and yields, confirming increased product formation rates and product-per-biomass yields compared to a high titer heterologous rhamnolipid production process from literature.
提高生物工艺效率的一个关键挑战是将生物量与产物形成解偶联，因为生物量是一种副产物，在大多数情况下难以有效地回收。以鼠李糖脂生物表面活性剂为例，建立了一个受沙门氏菌的四 U RNA 温度计翻译控制的温度敏感异源生产系统，以允许将优先生长阶段与产物形成阶段分离。作为大宗化学品的鼠李糖脂是未来工业生物技术过程的模型系统，因此与化学工业的效率要求竞争相关。实验数据证实了 RNA 温度计的功能，并表明温度对特定鼠李糖脂生产速率有重大影响，在 25 和 38°C 之间，平均生产速率提高了 11 倍，而这一增长的主要部分归因于 RNA 温度计的调节作用，而不是细菌代谢的整体非特异性增加。在简单的批处理过程中，通过温度开关驱动，评估了开发的温度敏感系统的生产能力。通过效率参数和产率评估产物形成，与文献中高滴度异源鼠李糖脂生产过程相比，确认了更高的产物形成速率和产物/生物量产率。
