Biosynthesis of Poly-(3-hydroxybutyrate) under the Control of an Anaerobically Induced Promoter by Recombinant Escherichia coli from Sucrose.

Fangting Wu,Xiaohui Yan,Wenyu Pei,Yuhan Jiang,Ying Zhou,Hong Wu

doi:10.3390/molecules27010294

Abstract

Poly-(3-hydroxybutyrate) (PHB) is a polyester with biodegradable and biocompatible characteristics and has many potential applications. To reduce the raw material costs and microbial energy consumption during PHB production, cheaper carbon sources such as sucrose were evaluated for the synthesis of PHB under anaerobic conditions. In this study, metabolic network analysis was conducted to construct an optimized pathway for PHB production using sucrose as the sole carbon source and to guide the gene knockout to reduce the generation of mixed acid byproducts. The plasmid pMCS-sacC was constructed to utilize sucrose as a sole carbon source, and the cascaded promoter P3nirB was used to enhance PHB synthesis under anaerobic conditions. The mixed acid fermentation pathway was knocked out in Escherichia coli S17-1 to reduce the synthesis of byproducts. As a result, PHB yield was improved to 80% in 6.21 g/L cell dry weight by the resulted recombinant Escherichia coli in a 5 L bed fermentation, using sucrose as the sole carbon source under anaerobic conditions. As a result, the production costs of PHB will be significantly reduced.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
Findings from this study offer a deeper understanding of PHB production in E. coli with anaerobic promoter expression systems
Reached 7.71 g/L in E. coli SAPL in MM medium sucrose in shake flasks (Table 3). These results indicated that E. coli SAPL was more suitable and efficient for PHB production from sucrose as the carbon source under anaerobic culture conditions

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Global warming concerns and environmental problems, such as microplastics and non-degradable plastics, are necessitating the transition from petrochemical-dependent industries into biorefineries and the production of polymers from renewable biomassbased resources such as microbes [1,2]. Researchers have emphasized the need to produce biodegradable bio-based plastics including polyhydroxyalkanoates (PHAs), polylatic acid (PLA), poly(butylene adipate-co-terephthalate) (PBAT), and so on, as a sustainable solution to the issues of plastic pollution and fuel depletion [3,4,5,6]. PHAs, as a family of biodegradable and biocompatible thermal polyesters, have attracted considerable attention to be developed as environmentally friendly bioplastics. The properties of PHAs are similar to those of conventional plastics [7].

Methods

Results

Conclusion