Disassembly and reassembly of polyhydroxyalkanoates: recycling through abiotic depolymerization and biotic repolymerization

Jaewook Myung; Nathaniel I Strong; Wakuna M Galega; Eric R Sundstrom; James C A Flanagan; Sung-Geun Woo; Robert M Waymouth; Craig S Criddle

doi:10.1016/j.biortech.2014.07.105

Disassembly and reassembly of polyhydroxyalkanoates: recycling through abiotic depolymerization and biotic repolymerization

Bioresour Technol. 2014 Oct:170:167-174. doi: 10.1016/j.biortech.2014.07.105. Epub 2014 Aug 4.

Authors

Jaewook Myung¹, Nathaniel I Strong¹, Wakuna M Galega¹, Eric R Sundstrom¹, James C A Flanagan², Sung-Geun Woo¹, Robert M Waymouth², Craig S Criddle³

Affiliations

¹ Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305-4020, USA.
² Department of Chemistry, Stanford University, Stanford, CA 94305-4401, USA.
³ Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305-4020, USA; Woods Institute for the Environment at Stanford, USA; William and Cloy Codiga Resource Recovery Center at Stanford, USA. Electronic address: ccriddle@stanford.edu.

PMID: 25129232
DOI: 10.1016/j.biortech.2014.07.105

Abstract

An abiotic-biotic strategy for recycling of polyhydroxyalkanoates (PHAs) is evaluated. Base-catalyzed PHA depolymerization yields hydroxyacids, such as 3-hydroxybutyrate (3HB), and alkenoates, such as crotonate; catalytic thermal depolymerization yields alkenoates. Cyclic pulse addition of 3HB to triplicate bioreactors selected for an enrichment of Comamonas, Brachymonas and Acinetobacter. After each pulse, poly(3-hydroxybutyrate) (P3HB) transiently appeared: accumulation of P3HB correlated with hydrolysis of polyphosphate; consumption of P3HB correlated with polyphosphate synthesis. Cells removed from the cyclic regime and incubated with 3HB under nitrogen-limited conditions produced P3HB (molecular weight>1,000,000Da) at 50% of the cell dry weight (<8h). P3HB also resulted from incubation with acetate, crotonate, or a mixture of hydrolytic depolymerization products. Poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) resulted from incubation with valerate or 2-pentenoate. A recycling strategy where abiotic depolymerization of waste PHAs yields feedstock for customized PHA re-synthesis appears feasible, without the need for energy-intensive feedstock purification.

Keywords: PHB; PHBV; Polyhydroxyalkanoate; Polyphosphate; Recycling.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

3-Hydroxybutyric Acid / biosynthesis
3-Hydroxybutyric Acid / chemistry
Bioreactors*
Biotechnology / methods
Crotonates / chemistry
Gas Chromatography-Mass Spectrometry
Hot Temperature
Models, Biological*
Molecular Structure
Polyhydroxyalkanoates / biosynthesis
Polyhydroxyalkanoates / chemical synthesis
Polyhydroxyalkanoates / chemistry*
Polymerization*
Polyphosphates / chemistry
Recycling / methods*

Substances

Crotonates
Polyhydroxyalkanoates
Polyphosphates
3-Hydroxybutyric Acid