Bioengineered Polyhydroxyalkanoates as Immobilized Enzyme Scaffolds for Industrial Applications.

Jin Xiang Wong,Shuxiong Chen,Kampachiro Ogura,Bernd H. A. Rehm

doi:10.3389/fbioe.2020.00156

Abstract

Enzymes function as biocatalysts and are extensively exploited in industrial applications. Immobilization of enzymes using support materials has been shown to improve enzyme properties, including stability and functionality in extreme conditions and recyclability in biocatalytic processing. This review focuses on the recent advances utilizing the design space of in vivo self-assembled polyhydroxyalkanoate (PHA) particles as biocatalyst immobilization scaffolds. Self-assembly of biologically active enzyme-coated PHA particles is a one-step in vivo production process, which avoids the costly and laborious in vitro chemical cross-linking of purified enzymes to separately produced support materials. The homogeneous orientation of enzymes densely coating PHA particles enhances the accessibility of catalytic sites, improving enzyme function. The PHA particle technology has been developed into a remarkable scaffolding platform for the design of cost-effective designer biocatalysts amenable toward robust industrial bioprocessing. In this review, the PHA particle technology will be compared to other biological supramolecular assembly-based technologies suitable for in vivo enzyme immobilization. Recent progress in the fabrication of biological particulate scaffolds using enzymes of industrial interest will be summarized. Additionally, we outline innovative approaches to overcome limitations of in vivo assembled PHA particles to enable fine-tuned immobilization of multiple enzymes to enhance performance in multi-step cascade reactions, such as those used in continuous flow bioprocessing.

Highlights

We have summarized the recent proof-of-concept demonstrations of the PHA particle technology for industrial applications reported by our group and others (Table 1)
We reviewed the advances in the development of several promising biological supramolecular assemblies suitable for in vivo enzyme immobilization
We compared the PHA particle technology with the other scaffolding platforms and discussed innovative strategies to address the challenges associated with developing enzyme-coated PHA particles for industrial applications

Summary

Introduction

PAPs can be translationally fused to target proteins, including industrially relevant enzymes, to enable the recombinant production of functionalized PHA particles in vivo (Figures 2C,D). Immobilized tyrosinase showed enhanced specific activity catalyzing L-tyrosine conversion to L-dopaquinone when compared to its soluble counterpart. Specific activity of soluble β-gal catalyzing the hydrolysis of o-nitro-phenyl-β-D-galactopyranoside cleaved from β-gal displaying PHA particles: 2.2 × 105 U/mg of enzyme.

Results

Conclusion