Bio-based Energy and Materials|Erik Ng: Engineering the transformation of novel alcohol-producing Clostridium perfringens into high value-added bio-based chemicals

Background & Challenge

Due to the non-renewable nature of fossil resources and the environmental pollution caused in the mining, using the biomass resources to convert biomass fuels and chemicals is in line with the current national energy policy of "carbon neutrality". Biobutanol is considered to be one of the best alternatives to fossil fuels due to its high energy value and low corrosiveness. However, the traditional fermentation process of solvent-producing Clostridium difficile faces problems such as excessive by-products and low conversion efficiency of high value-added products. This seriously hinders its process of large-scale industrialization.

In response to such problems, a research team from Tidetron took advantage of the natural metabolic pathway of wild-type strain, Clostridium sp. WK. They established an efficient and economical system by reducing byproducts and improving conversion efficiency with the aim of promoting the industrialization of bio-based compounds. Based on this, the team built a metabolic engineering modification platform based on strain WK to enhance the conversion efficiency of high value-added products by eliminating its by-products and making the carbon metabolic stream flow more to the mixed alcohols.

First, the α-acetolactate decarboxylase (alsD) gene was introduced through engineering modification to achieve 2,3-butaneiol synthesis while maintaining intracellular redox homeostasis and reducing acetone. The engineered WK::alsD could produce 740 mg/L of 2,3-butaneiol at the end of fermentation when 30 g/L glucose was used as the substrate. Its acetone production was reduced by 20.5% compared with that of wild strain.

Second, the team also achieved further conversion of the by-product acetone to IPA by introducing a secondary alcoholdehydrogenase (adh) gene. Among an experiment in batches of fermentation with 60 g/L glucose as substrate, the WK::adh could produce 4.38 g/L of isopropanol in 72 hours. Compared with the wild strain, the acetone outcome was significantly reduced by 95.1%. But this did not affect the produce of butanol, which greatly enhanced the conversion efficiency of the high value-added product.

These results not only provide enlightenment in microbial metabolic engineering but also provide theoretical basis and data support for the conversion of different cheap substrates into a variety of high value-added bio-based chemicals, so as to enhance the value of end products.

Yirui Wu, PhD in Microbiology from the City University of Hong Kong, postdoctoral fellow at the National University of Singapore, professor at Shantou University, and visiting professor at the University of Technology Sydney, has joined Tidetron as a full-time. Dr. Wu has published more than 30 papers in top international journals such as Bioresource Technology and Science of the Total Environment as the first or corresponding author. He presided over dozens of projects under institutions including National Natural Science Foundation of China, Guangdong Natural Science Foundation, Guangdong "Yangfan Plan" and others.

He will attend Bio-based 2022 (Ningbo, China) to share "Engineering the Process of Transforming New Alcohol-Producing Clostridium Perfringens to Achieve High Value-Added Bio-based Chemicals", jointly exploring the development of chemicals by synthetic biology technology.

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